Tag Archives: extinction

Researchers are one step closer to saving the northern white rhino from complete extinction

Researchers in Europe have fertilized a rhino egg in vivo and then successfully transferred it back to the female. Their plan is to now perform the same procedure for the northern white rhino, to save the species from extinction.

Rhino.

Rhinos are under extreme pressure from habitat loss and poachers.
Image via Pixabay.

The procedure was performed by an international team of European researchers at the Chorzow zoo in Poland and involved a southern white rhino female. The work came as part of the BioRescue Project, an international team of scientists and conservationists trying to use IVF to save the almost-extinct northern white rhino.

Last of their kind

“This is the first positive proof that the entire procedure we’ve developed in theory can be successful,” said Thomas Hildebrandt (link in German) of the Leibniz Institute for Zoo and Wildlife Research in Berlin, who participated in the project.

There are only two northern white rhinos left in the world — and they’re both females. The last male (whose name was Sudan) died in March 2018 shortly after starting a Tinder account. However, researchers had preserved frozen samples from several males beforehand, as a kind of insurance policy that the species won’t be completely wiped out. Due to a lack of northern white rhinos, they’re testing the IVF transfer on southern white rhinos, a closely related sub-species whose numbers have stabilized in the wild. They now report that the transfer was successful.

As such, the BioRescue team was applied for permission from the Kenyan government to harvest eggs from the last two surviving northern rhino females — a mother and daughter called Najin and Fatu — and are currently awaiting a reply. Kenya’s ambassador in Germany, Joseph Magutt, said his country supports the effort but didn’t say how long it would take for the process to move forward.

The IVF technique is required in this case because the two females are unable to bear offspring themselves; once their embryos are fertilized in the lab, they will be implanted in a southern white rhino surrogate mother.

However, not all is rosy. Hildebrandt says that ultrasound tests show the embryo transferred at Chorzow zoo has grown, but that it’s smaller than expected. As of yet, it’s also unsure whether the embryo will implant in the female’s uterine lining, resulting in a pregnancy. In the meantime, the BioRescue team is working on ways to turn preserved skin cells (from deceased rhinos) into eggs or sperm.

Should it be successful, the technique would offer a safety net for other species on the brink of collapse — and there are many. A recent United Nations report warned that a million species are at risk of extinction in the coming decades, largely because of human activity.

Tree.

The birth of forests helped drive two massive, ancient extinctions

The first forests on Earth may have caused massive extinctions of shallow marine life, a new study finds.

Tree.

Image via Pixabay.

An international team of researchers led by members from The University of Alabama finds that the oldest forests in today’s southeastern North America popped up millions of years earlier than previously believed. At the time, North America was part of a minor supercontinent, which suggests that forests spread across all big land masses today at that time.

They also found evidence that this event happened around the same time as a massive extinction event of shallow marine life about 370 million years ago.

Wooden weapons

“This story is, I think, ironic because today trees are the symbol of eco-friendly green life,” said Dr. Takehito Ikejiri, a paleontologist with UA’s Alabama Museum of Natural History and one of the study’s co-authors.

“But, when they first appeared in Earth’s history, they seemed to be harmful and caused big trouble for other life.”

The work offer insight into the global extinctions 370 to 360 million years ago. It also lends some weight to the theory that these events were caused by a lack of oxygen in the ancient waters, as early forests dumped massive quantities of nutrient-rich soils into the oceans, leading to eutrophication.

We call this period in Earth’s history 393 to 382 million years ago the Devonian era. At the time, Earth’s surface was dominated by supercontinents. Present-day North America was meshed with Greenland and much of Europe into a minor supercontinent known as Euramerica. Here, to the best of our knowledge, the first trees (defined as plants with wood tissues) appeared near today’s New York 393 to 382 million years ago and spread across the continent.

Not long after this (in geological time), almost all of the day’s shallow-water species (such as trilobites, corals, and plankton) experienced two massive die-offs. The reason why was unknown, but our running theories included global cooling, extensive volcanism, asteroid impacts, and marine anoxia — the rapid drop of oxygen levels in the seas.

The team believed that this anoxia could be caused by the newly-spawned forests eroding soils with their deep roots, which would then wash into the sea and create an overabundance of nutrients.

They tested their theory by analyzing an outcrop of black shale from the period from northeastern Alabama. This outcrop lay on the southernmost margin of the Appalachian Basin. Geochemical and microscopic data show that forests first appeared in the region 370 million years ago, then spreading to the southern Euramerica landmass. Man Lu, a UA doctoral student in geological sciences and lead author on the paper, analyzed the samples from these shales and reports finding tiny wood fragments in this Devonian formation where no macro-fossils were reported previously.

Further geochemical data also suggest that these forests became an important carbon source to these black shales during the Late Devonian, providing a rough timeline of how fast these forests evolved during the era.

“Our data show the global forestation occurred in a relatively short time,” Ikejiri said. “Trees spread rapidly in very large areas across the Euramerica continent and likely caused a series of drastic environmental changes.”

It’s not a smoking gun, but the evidence does seem to point to a link between the extinctions and these early forests. Dr. YueHan Lu, UA associate professor of geological sciences and corresponding author of the paper, believes the timing of this rapid forestation is interesting considering it occurs near the time of the marine life extinctions.

The paper “Geochemical Evidence of First Forestation in the Southernmost Euramerica from Upper Devonian (Famennian) Black Shales” has been published in the journal Scientific Reports.

Paper leopard.

The UN says humanity is causing an ‘unprecedented’ decline in biodiversity — and it’s picking up

A new report from the United Nations says that humanity is putting a never-before-seen strain on the planet — over 1 million species of plants and animals are facing extinction.

Paper leopard.

Image via Pixabay.

Species loss is accelerating to a rate tens or hundreds of times faster than in the past, the report said. More than half a million species on land “have insufficient habitat for long-term survival” and are likely to go extinct, many within decades, unless their habitats are restored. The oceans are not faring any better. However, the report also says that it’s not too late to fix the issue.

Remade in our image

“We have reconfigured dramatically life on the planet,” said UN co-chairman Eduardo Brondizio of Indiana University at a press conference detailing the report.

Conservation scientists from around the world convened in Paris to issue the 1,000-page strong report. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) included more than 450 researchers who drew data from 15,000 scientific and government reports. The report’s summary had to be approved by representatives of all 109 nations.

The damage isn’t evenly distributed across the Earth. Some of the harder-hit nations, such as small island countries, wanted the report to be broader and use more conclusive language. Other countries however, such as the United States, were cautious in the wording they used but agreed that “we’re in trouble,” said Rebecca Shaw, chief scientist for the World Wildlife Fund, who observed the final negotiations.

“This is the strongest call we’ve seen for reversing the trends on the loss of nature,” Shaw said.

The findings don’t just show a planet where plants and animals need our intervention to survive (our own actions). It also shows a world in which humanity has a harder and harder time living in, according to Robert Watson, a former top NASA and British scientist who headed the report. The loss of biodiversity threatens to impact food and water security, the ecological mechanisms upon which our societies are built, and our health, he told Associated Press. It will also have a massive effect on our economies and can potentially give rise to security issues as countries and later, individual communities and groups, fight for ever-scarcer resources. The poor in less developed countries bear the greatest burden, Watson adds.

Here are the five main ways humanity is driving down biodiversity today:

  • Clearing forests, grasslands and other areas for farms, cities, and other developments. About three-quarters of Earth’s land, two-thirds of its oceans and 85% of crucial wetlands have been severely altered or lost, the report said. This basically destroys the natural habitats that species rely on, driving them to extinction.
  • Overfishing: A third of the Earth’s fish stocks are experiencing overfishing, according to the report.
  • Continued emissions of greenhouse gases which drive climate change. Almost half of the world’s land mammals — not including bats — and nearly a quarter of the birds have already had their habitats hit hard by global warming.
  • Land and water pollution. Between 300 to 400 million tons of heavy metals, solvents, and toxic sludge are dumped into the world’s waters each year.
  • The introduction of invasive species that outcompete native plants and animals. The number of invasive alien species per country has risen 70% since 1970, with one species of bacteria threatening nearly 400 amphibian species.

“The key to remember is, it’s not a terminal diagnosis,” said report co-author Andrew Purvis of the Natural History Museum in London.

The report says that fighting climate change and species conservation are equally important and that work on the two problems should go hand in hand. Both problems exacerbate each other because a warmer world means fewer species, and a less biodiverse world means fewer trees and plants to remove heat-trapping carbon dioxide from the air.

The International Union for the Conservation of Nature, or IUCN, reported in March that 27,159 species are threatened, endangered, or extinct in the wild out of nearly 100,000 species biologists examined in depth. That includes 1,223 mammal species, 1,492 bird species, and 2,341 fish species. Nearly half the threatened species are plants. The present report estimates that up to 1 million species are trouble by extrapolating the IUCN’s 25% threatened rate to the rest of the world’s species.

Giant sloth.

Timeline for giant sloth extinction rewritten by new analysis

The giant sloth may have lived in the slow lane, but it went extinct much faster than previously estimated, a new study reports.

Giant Sloth Bones.

Lithic tool associated with giant ground sloth bones.
Image credits Gustavo Politis, Pablo Messineo.

Researchers at the National University of Central Buenos Aires, Olavarría, Stafford Research, and La Brea Tar Pits and Museum, report that the giant sloth went extinct before the Holocene, the current geological period.

Dirty collagen

Prior research had found that the giant sloth disappeared during the Pleistocene, the geological epoch spanning from about 2.5 million to 11 thousand years ago — the last period of repeated glaciations to grip the Earth (right before the Holocene). However, there was also some evidence pointing to the survival of this species in certain pocket areas (of today’s Pampas, Argentina) up to the Holocene.

The present study comes to invalidate that hypothesis: the giant sloths went completely extinct before the onset of the Holocene, it explains. This new paper used a more stringent testing technique to date the remains of giant sloths found at the Campo Laborde dig site in Argentina. The team recovered collagen from the remains — they note that a single bone had recoverable collagen — that they dated using the radiocarbon technique and used to establish the new timeline for the sloths’ extinction.

The study also provides a glimpse into what went wrong with earlier dating attempts: the collagen used in the current study had been heavily contaminated with compounds leaching from the soil around it. Earlier dating efforts had not taken this contamination into account, they explain, which fouled the results. The team used chemical purification techniques to clean up the collagen before running their analysis, and then extracted specific amino acids that could only have come from the sloth itself, the team explains.

Giant sloth.

Giant sloth.
Image credits Eden, Janine and Jim / Flickr

Their analysis shows that the giant sloth went extinct around 10,570 years ago. This would push the timeline of their disappearance out of the Holocene (previous research found that the animals went extinct around 9,730 years ago, which is during the Holocene).

It’s a distinction that might sound pedantic, but it’s actually quite significant. Humans are currently considered the driving force behind the extinction of many ancient megafauna species, including the giant sloth. The new findings don’t exonerate our ancestors, but they do suggest that they were only part of the problem; their hunting of the giant sloths certainly helped, but it likely happened during a time when the species was buckling, likely under environmental strain from changing climate patterns.

The findings also raise the possibility that other species of huge mammals, especially those in South America (but possibly other places around the globe as well) didn’t make it to the Holocene either. If the collagen in the remains those studies were based on is found to be contaminated, the findings could be off the mark by thousands of years.

The paper “A Late Pleistocene giant ground sloth kill and butchering site in the Pampas” has been published in the journal Science Advances.

Giraffes quietly dropped down to ‘Endangered list’

The International Union for the Conservation of Nature (IUCN) recently updated its Red List of Threatened Species. Two giraffe subspecies are now listed as critically endangered, and one as endangered.

Image credits: Rex Boggs / Flickr.

Giraffes are some of the most bizarre creatures on Earth — and they’re also some of the most popular ones. Over the past few years, giraffes have been undergoing a ‘silent extinction’ — although populations in some areas are growing slightly, others are declining at an alarming rate. Until 2016, all giraffe populations were classified as ‘least concern’, but later that year, the global Red List of threatened species classified them as ‘vulnerable’, which means that the population has declined by more than 30% over the past three generations. Since then, things have only gotten worse.

There are 9 subspecies of giraffes. Out of them, one is stable and two are improving slightly. The other five are declining at an alarming rate. The culprits are quite familiar: the rapid growth of human populations and intensive agriculture has led to massive habitat destruction and fragmentation. However, civil war has also taken a massive toll.

“In these war torn areas, in northern Kenya, Somalia, and Ethiopia in the border area with South Sudan, essentially the giraffes are war fodder, a large animal, extremely curious that can feed a lot of people,” Dr. Julian Fennessy, who co-chairs the IUCN giraffe specialist group, told the BBC.

Unfortunately, there is little conservationists can do to limit the effects of this war, although conservation campaigns can still be successful. However, there is a general lack of awareness, Fennessy adds.

“Whilst giraffe are commonly seen on safari, in the media, and in zoos, people – including conservationists – are unaware that these majestic animals are undergoing a silent extinction. While giraffe populations in southern Africa are doing just fine, the world’s tallest animal is under severe pressure in some of its core ranges across East, Central and West Africa. It may come as a shock that three of the currently recognised nine subspecies are now considered ‘Critically Endangered’ or ‘Endangered’, but we have been sounding the alarm for a few years now,” Fennessy added in a separate press release.

To make matters even more complicated, while the IUCN considers giraffes to be one species with nine subspecies, recent genetic analyses have found that there are four distinct species of giraffe — with potentially “immense” consequences for conservation.

The Northern giraffe Giraffa camelopardalis (which includes the ‘Critically Endangered’ Kordofan and Nubian giraffe, and the ‘Vulnerable’ West African giraffe) and Reticulated giraffe Giraffa reticulata can be considered some of the most threatened large mammals in the wild, with less than 5,200 and 15,785 individuals remaining in the wild, respectively.

 “Working collaboratively with governments and other partners, we feel that our proactive measures are saving giraffe in some areas before it is too late,” said Arthur Muneza, the East-Africa Coordinator of the Giraffe Conservation Foundation.

Shark numbers plummet by 92% in Australian waters

Often portrayed as a dangerous predator, the shark is suffering an unprecedented crisis.

Image credits: Terry Goss.

Sharks have been around for 425 million years — some 200 million years before dinosaurs emerged, and just before trees developed as a plant group. But their long tenure as apex predators might be coming to an end, at the hand of a regular culprit: humans.

It is estimated that 100 million sharks are killed by people every year, due to commercial and recreational fishing, and the demand for shark meat continues to rise, which puts even more pressure on their populations. A new study used information from a shark control program set in Australia in 1960. They found that the overall size of sharks has decreased — but more worryingly, the number of sharks has also dropped dramatically, in some cases by over 90%.

“What we found is that large apex sharks such as hammerheads, tigers and white sharks, have declined by 74 to 92 per cent,” said Dr. George Roff from the University of Queensland, who led the study. “And the chance of zero catch – catching no sharks at any given beach per year – has increased by as much as sevenfold.”

[panel style=”panel-default” title=”Finning” footer=””]Sharks are often killed for shark fin soup, which is considered a delicacy in some parts of the world. Fishermen capture live sharks, remove their fins with a hot metal blade, and then dump them back in the water. These immobilised sharks soon succumb to suffocation or predators.[/panel]

Hammerhead sharks, like the one depicted here, are endangered. Image credits: suneko.

Scientists also acknowledge the irony that their data was provided by a shark control program, which is preventing the recovery of vulnerable species.

Shark culls have also been carried out in Australia, the most recent one starting in 2014. The policy was ultimately cancelled in 2017 after public uproar, but the Australian government plans to re-introduce drum lines to kill sharks, using “smart” drum lines (a drum line is an unmanned aquatic trap used to lure and capture large sharks with baited hooks). Worldwide, around 80 unprovoked attacks are reported per year. Keeping in mind that we, in turn, kill 100 million of them, this is a disproportionately low figure.

While sharks are generally depicted as dangerous to humans, they serve a very important role in oceanic ecosystems. As top predators, they help to keep the ecosystem “clean”. As their numbers continue to decline, the oceans will suffer unpredictable and devastating consequences.

“Overexploitation of large apex marine predators is widespread in the world’s oceans, yet the timing and extent of declines are poorly understood,” researchers conclude. “Ongoing declines and lack of recovery of vulnerable and protected shark species are a cause for concern.”

Like all oceanic creatures, sharks are also threatened by rising water temperatures, pollution, and habitat destruction (especially around coastlines).

Journal Reference: Roff et al, “Decline of coastal apex shark populations over the past half century”, Communications Biology.

A supernova explosion may have triggered radiation exposure in Megalodon and countless other ancient marine megafauna. Credit: NASA Goddard Photo/Wikimedia Commons.

Exploding stars may have wiped off large ocean life 2.5 million years ago

A supernova explosion may have triggered radiation exposure in Megalodon and countless other ancient marine megafauna. Credit: NASA Goddard Photo/Wikimedia Commons.

A supernova explosion may have triggered radiation exposure in Megalodon and countless other ancient marine megafauna. Credit: NASA Goddard Photo/Wikimedia Commons.

About 2.6 million years ago, nearly a third of the world’s large marine species mysteriously disappeared from the world’s oceans. Among them were huge apex predators, such as Carcharocles megalodon, which ruled the seas for over 20 million years. Climate change played an important role in the demise of Megalodon and other creatures like it, but it alone doesn’t seem to explain the magnitude of the Pliocene marine megafauna extinction. Now, a new study suggests that the extinction event may have a cosmic origin — a supernova, or possibly a string of supernovae, may have bombarded the oceans with radiation that decimated the largest marine creatures.

Death from above

In a new study led by Adrian Melott, professor emeritus of physics and astronomy at the University of Kansas, researchers describe evidence of nearby supernovae, whose explosion coincided with the onset of the Pliocene megafauna die-off.

When a star is ready to drop the curtain, it goes out with a bang — a titanic explosion known as a supernova. Although it might sound dramatic, these highly energetic events are quintessential to seeding new stars and solar systems, as they expel and distribute matter throughout the universe. Thus, understanding supernovae is key to demystifying the grander astronomic picture — how the cosmos evolves and how we all came to be.

Supernovae can also be destructive if something happens to cross their path. Melott and colleagues claim that a series of such explosions occurred between 8.7 million and 1.7 million years ago, at about 325 light-years from Earth. That’s far away enough not to cause catastrophic damage but close enough to bombard Earth with cosmic radiation. And this radiation may have been powerful enough to triggered mutations that led to cancer among Earth’s megafauna. The larger an animal was during such conditions, the more radiation it would absorb, thereby making them more vulnerable to the supernova-sourced radiation. The researchers estimate that the cancer rate would have gone up by about 50% for something the size of a human, but it would have been much worse for something as big as an elephant or whale.

“I’ve been doing research like this for about 15 years, and always in the past it’s been based on what we know generally about the universe — that these supernovae should have affected Earth at some time or another,” said Melott, in a statement. “This time, it’s different. We have evidence of nearby events at a specific time. We know about how far away they were, so we can actually compute how that would have affected the Earth and compare it to what we know about what happened at that time — it’s much more specific.”

Scientists know that such supernovae have occurred and pointed towards Earth due to iron-60 isotopes that have been engraved on the seafloor. These isotopes have a half-life of about 2.6 million years, so if they formed with the Earth, they would have been long gone. But instead, such isotopes can still be found in sediments drilled from the bottom of the seas and oceans. This can only mean evidence of radiation bombardment from one or multiple supernova events.

Specifically, muons may have been the culprit for the Pliocene marine extinction. The muon is an elementary subatomic particle similar to the electron but 207 times heavier. Muons are all around us, the products of cosmic radiation interacting with the atmosphere. However, the supernova radiation may have triggered extra muon exposure — much more than life can normally tolerate.

“The best description of a muon would be a very heavy electron — but a muon is a couple hundred times more massive than an electron,” Melott said. “They’re very penetrating. Even normally, there are lots of them passing through us. Nearly all of them pass through harmlessly, yet about one-fifth of our radiation dose comes by muons. But when this wave of cosmic rays hits, multiply those muons by a few hundred. Only a small faction of them will interact in any way, but when the number is so large and their energy so high, you get increased mutations and cancer — these would be the main biological effects. We estimated the cancer rate would go up about 50 percent for something the size of a human — and the bigger you are, the worse it is. For an elephant or a whale, the radiation dose goes way up.”

But if that were the case, why didn’t land animals go extinct at a similar rate? Radiation from the sun and the cosmos typically can’t penetrate more than a couple of feet of water, thereby shielding marine life. However, the shielding doesn’t work for muons. Suddenly, creatures that had adapted to a low-radiation environment for millions of years become exposed to a lot of it. Land animals, on the other hand, were adapted to radiation exposure and weren’t as affected as marine life.

And as if supernova radiation wasn’t scary enough. Around the same time, 2.6 million years ago, the planet’s magnetic poles reversed, which opened the floodgates for muon bombardment. The final nail in the coffin was climate change — around the same time a new Ice Age started, greatly diminishing coastal food supplies.

All of these factors form a complex, but a plausible picture that may explain the extinction of Earth’s marine giants.

“There really hasn’t been any good explanation for the marine megafaunal extinction,” Melott said. “This could be one. It’s this paradigm change — we know something happened and when it happened, so for the first time we can really dig in and look for things in a definite way. We now can get really definite about what the effects of radiation would be in a way that wasn’t possible before.”

You can read the entire study here.

Researchers want to clone 40,000-year-old extinct horse — a step towards woolly mammoth resurrection

foal horse

Credit: Michil Yakovlev/SVFU.

The perfectly preserved remains of a baby horse belonging to a now-extinct species made headlines when they were unveiled to the world last week. Now, researchers in Russian and South Korea say that the 40,000-year-old foal, discovered in the Siberian permafrost, could be cloned back to life. If they are successful, the achievement would mark an important milestone towards the ultimate goal of resurrecting the wooly mammoth.

The 40,000-year-old horse was found buried beneath 30 meters of permafrost, which preserved it so well that its tail, mane, and hooves were still attached.

According to Semyon Grigoriev, the head of the Mammoth Museum in Yakutsk, the foal was only 20 days old when it perished. But thanks to the astonishing conservation power of the permafrost from the “Mouth of Hell” — the tadpole-shaped, one-km-long crater where the horse was found, initially created by the Soviets when they cleared the forest in the area  — researchers were able to recover muscle tissues from the animal.

These undamaged samples could prove extremely valuable to biotech research — among them, a project that aims to resurrect the now-extinct Equus lenesis, also known as the Lena horse.

Hwang Woo Suk flew in from Seoul, South Korea to personally supervise the DNA extraction process from the foal. If they find viable, undamaged cells, these could be used to clone this unique animal.

 “We are trying to make a primary culture using this baby horse,” said Suk, a former professor at Seoul National University. “If we get live cells from this ancient baby horse, it is a wonderful promise to people in terms of cloning.”

Suk is a pioneer of stem cell research, who has fallen out of grace in the scientific community after he was found guilty of falsifying some of his findings. He admitted to using eggs from paid donors in a study that claimed to recover stem cells from a cloned human embryo. Bringing an extinct species back from the dead may be a way for the scientist to redeem himself.

Credit: Michil Yakovlev/SVFU.

Previously, the South Korean researchers obtained living cells from a dead pet dog frozen by its owners. That was quite an important achievement because water crystalizes and destroys the cells.

Just like they would clone any other animal, the scientists plan to transplant genetic information from a specialized cell into an unfertilized egg cell whose genetic information has been destroyed or physically removed. The mare of a horse species similar to the extinct Lena will be used as a surrogate.

Once they are confident enough in their abilities, scientists plan to do the same for a wooly mammoth with an elephant as the surrogate.

Most of the world’s wooly mammoths were killed around 10,500 years ago, the prime causes are still up for debate. Human hunting, climate change or both have been identified by scientists as prime suspects. But on a small island off the coast of Alaska, an isolated population of wooly mammoths lingered on for thousands of years. They too died around 5,600 years, and with them, their entire species went extinct.

In 2014, a team of international researchers uncovered a 43,000-year-old female from the Siberian tundra which still had well-preserved muscles, kidneys, and even blood.

However, the differences between a mammoth and an elephant are much more significant than those between a modern-day horse and the extinct Lena.

Credit: Wikimedia Commons.

Credit: Wikimedia Commons.

As such, cloning the Lena horse would be an immense breakthrough for scientists looking to bring back species back from the dead. There’s a lot of ground to cover though and, right now, people are probing in the dark. For instance, no one has been able to recover a living cell from ancient tissue before — which is the current plan. That would be unique in itself.

Previously, scientists led by George Church, professor of genetics at Harvard University, merged elephant and mammoth DNA — another important step for cloning the extinct beasts. While DNA can survive for a long time under the ‘freezer’, it’s far from being perfect — it’s impractical for cloning purposes since many bits and pieces have been damaged by the environment, which is why the researchers had to piece together the mammoth DNA with bits from the elephant.

Besides wooly mammoths and the Lena horse, scientists would like to resurrect dozens of other extinct species such as the saber-tooth cat, the Dodo, or the Quagga.

Credit: Wikimedia Commons.

Extremely cold climate may have sealed Neanderthals’ extinction

Credit: Wikimedia Commons.

Credit: Wikimedia Commons.

Neanderthals were our most closely-related hominin species. They dominated Eurasia for thousands of years before suddenly disappearing around 40,000 years ago — around the time anatomically modern humans began to expand far and wide on the continent.

This prompted scholars to assert that the pressure our species exerted on our close Homo cousins eventually brought about their demise. While that may be true, a new study shows that human competition wasn’t the only important challenge Neanderthals faced. The researchers found that around the time Neanderthals started disappearing, the climate in Europe became unforgivingly cold and dry.

Vasile Ersek, a palaeoclimatologist and geochemist at Northumbria University, along with colleagues sampled stalagmites in two Romanian caves to see what the climate looked like in ancient times. We have instrumental records of climate only for the past 100 years or so, and if we want to look deeper into the past, we need to look at other climate records such as ice cores, tree rings, or stalagmites. The latter are particularly useful because stalagmites grow in thin layers each year, and each layer captures what the temperature and humidity looked like at the time of deposition. Therefore, these stalagmite layers can be likened to a natural archive of climate change over many thousands of years.

The stalagmite records suggest that, between 44,000 and 40,000 years ago, the climate in Europe went through successive phases of extreme cold and excessive dryness. During this time, the climate would cycle through periods of very low temperatures for centuries or even millennia at a time, then warming up again very abruptly.

When the researchers compared the paleoclimate records with archaeological records of Neanderthal activity, they found that the cold periods overlapped with the absence of Neanderthal tools. This suggests that climate change played a major role in the decline of the now-extinct species.

“For many years we have wondered what could have caused their demise. Were they pushed ‘over the edge’ by the arrival of modern humans, or were other factors involved? Our study suggests that climate change may have had an important role in the Neanderthal extinction.”

Credit: Pixabay.

Credit: Pixabay.

The reason why Neanderthals may have been wiped out by this period of extreme cold — while humans made through — is that we could adapt to the new conditions. Neanderthals were skilled hunters, toolmakers, and knew how to control fire, just like humans did. However, they also had a less flexible diet, largely consisting of the meat from the animals they hunted. Humans, on the other hand, had incorporated fish and plants into their diet alongside meat. This wider menu may have offered modern humans the edge they needed to survive through harsh times.

“Before now, we did not have climate records from the region where Neanderthals lived which had the necessary age accuracy and resolution to establish a link between when Neanderthals died out and the timing of these extreme cold periods,” he said, “But our findings indicate that the Neanderthal populations successively decreased during the repeated cold stadials.

“When temperatures warmed again, their smaller populations could not expand as their habitat was also being occupied by modern humans and this facilitated a staggered expansion of modern humans into Europe.”

After a number of depopulation-repopulation cycles, the fragile Neanderthals tribes may have become too weak to resist competition with humans — or the next cold cycle. But while the species is now long gone, there’s a bit of Neanderthal left in each of us — about 2% of your DNA is Neanderthal, the remnant of ancient interbreeding between the two species.

The findings appeared in the journal PNAS.

'Must conserve energy.' Credit: Pixabay.

‘Survival of the laziest’: species that consume less energy better suited to dodging extinction

'Must conserve energy.' Credit: Pixabay.

‘Must conserve energy.’ Credit: Pixabay.

Researchers analyzed the metabolic rates of hundreds of mollusk species from the Atlantic Ocean — some extinct, others still alive — and found a link between low metabolic rate and better survivability. In other words, more sluggish creatures have an edge over fast calorie-burning animals as far as risk of extinction goes. Bruce Lieberman, a professor of ecology and evolutionary biology at the University of Kansas and co-author of the new study, calls this the ‘survival of the laziest’, playfully teasing the famous Darwinian phrase. 

Is it better to be a turtle or a hare?

In any ecosystem, success is relative. Many species become extinct because they hyper-specialized — too adapted to a specific environment or ecological niche. When the environment changes, their highly specific adaptations become a liability rather than a benefit. That’s a big part of the extinction of the dinosaurs. Many birds in New Zealand were highly adapted to an environment with no large predators, which meant that they evolved to become flightless. In came large predators (i.e. humans), and many rapidly became extinct.

Many species go through a boom, then a bust — but the truth is some species can fend off extinction for longer than others. There are a lot of factors at play, and one of them is their metabolic rate, the amount of energy an organism needs in order to live its daily life.

Researchers at Kansas University investigated whether they could predict the probability of extinction of a species based on energy uptake. They analyzed the metabolic rates of 299 species of mollusks that lived over a period of roughly 5 million years from the mid-Pliocene to the present. The findings suggest that lazier, sluggish creatures have a slight edge over animals with a higher metabolic rate.

“Those that have gone extinct tend to have higher metabolic rates than those that are still living. Those that have lower energy maintenance requirements seem more likely to survive than those organisms with higher metabolic rates,” said Luke Strotz, postdoctoral researcher at KU’s Biodiversity Institute and Natural History Museum.

“Maybe in the long term the best evolutionary strategy for animals is to be lassitudinous and sluggish—the lower the metabolic rate, the more likely the species you belong to will survive,” Lieberman said. “Instead of ‘survival of the fittest,’ maybe a better metaphor for the history of life is ‘survival of the laziest’ or at least ‘survival of the sluggish.'”

Anadara aequalitas was included in a new large-data study of fossil and extant bivalves and gastropods in the Atlantic Ocean that suggests laziness might be a fruitful strategy for survival of individuals, species and even communities of species. Credit: Neogene Atlas of Ancient Life / University of Kansas. Caption: Press release.

As climate change rapidly alters ecosystems around the world, the new findings will serve to refine our predictions of extinction probability. The results suggest that metabolic rate — while not a be-all, end-all factor — is an important component of extinction likelihood.

The link between high metabolic rate and extinction probability was most pronounced for species that live in a small habitat, the authors reported in the Proceedings of the Royal Society B.

“We find the broadly distributed species don’t show the same relationship between extinction and metabolic rate as species with a narrow distribution,” Strotz said. “Range size is an important component of extinction likelihood, and narrowly distributed species seem far more likely to go extinct. If you’re narrowly distributed and have a high metabolic rate, your probability of extinction is very high at that point.”

One of the most interesting findings was that the cumulative metabolic rate for communities of species remained stable. Even as populations and individual species appeared or disappeared in an ecosystem, the overall metabolic rate of the community remained unchanged over time, seemingly in an energetic stasis.

“In terms of energy uptake, new species develop—or the abundance of those still around increases—to take up the slack, as other species go extinct. This was a surprise, as you’d expect the community level metabolic rate to change as time goes by. Instead, the mean energy uptake remains the same over millions of years for these bivalves and gastropods, despite numerous extinctions,” Strotz said.

The authors used mollusks for their study because there’s ample data about living and extinct species, including metabolic and extinction rates. A follow-up study will determine whether the same link or metabolic influence exists for other classes of animals.

“We see these results as generalizable to other groups, at least within the marine realm,” Strotz said. “Some of the next steps are to expand it out to other clades, to see if the result is consistent with some things we know about other groups. There is a question as to whether this is just a mollusk phenomenon? There’s some justification, given the size of this data set, and the long amount of time it covers, that it’s generalizable. But you need to look—can it apply to vertebrates? Can it apply on land?”

Bacteria lip print.

Bacteria species, too, can become extinct — and they do so quite often

Evolution is ruthless even with its tiniest creations.

Bacteria lip print.

Image credits Bnummer / Wikimedia.

New research led by researchers from the University of British Columbia (UBC) reports that bacteria also die off — and they do so at substantial rates. The findings go against the grain of the widely-held notion that bacterial species, owing to their very large populations, rarely go extinct.

To kill a M. ocking bacteria

Bacteria are, by far, one of the most prolific and successful bits of life that evolution spawned on our planet. They’re incredibly hardy, very good at drawing energy from their environments, and they reproduce with a vengeance. These tiny critters are so resilient and numerous, in fact, that most scientists took it as a given that bacteria species very rarely go extinct. However, new research suggests that this isn’t the case.

The team sequenced DNA information from 448,112 different bacterial species and drew on 60 previous environmental studies to create the most comprehensive bacteria evolutionary tree, which includes the majority of bacterial species over the past billion years. To get an idea of bacteria’s evolutionary history, they drew on the traces that speciation (differentiation of new species through evolution) leaves in the genetic makeup of these bacterial lineages.

The team estimates that there are around 1.4 to 1.9 different bacterial phyla (lineages) gracing our planet today. They were also able to estimate how that number varied over time: they report that anywhere between 45,000 to 95,000 phyla became extinct over the last million years.

“Bacteria rarely fossilize, so we know very little about how the microbial landscape has evolved over time,” says Stilianos Louca, lead researcher of the study. “Sequencing and math helped us fill in the bacterial family tree, map how they’ve diversified over time, and uncover their extinctions.”

It’s an impressive number. But, despite these relatively high extinction rates (which the team notes were quite steady over time), bacteria have kept diversifying exponentially throughout history. As a group, they also managed to weather planet-wide mass extinction events — those abrupt events that periodically cull plant and animal species — with very few losses. All in all, while the current number of bacterial lineages today is definitely impressive, “it’s only a tiny snapshot of the diversity that evolution has generated over Earth’s history,” Louca adds.

“This study wouldn’t have been possible 10 years ago,” says Michael Doebeli, senior author of the paper and a UBC mathematician and zoologist. “Today’s availability of massive sequencing data and powerful computational resources allowed us to perform the complex mathematical analysis.”

Next, Louca says he and his team plan to determine how the physiological properties of bacteria evolved over time. A particular point of interest for them is determining whether their ecological diversity has increased in tow with their taxonomic diversity — i.e. if they spread to new types of environments and roles in those environments as the total number of species increased. If so, this would suggest that even organisms as ancient and simple as bacteria can still find new roles in nature.

The paper “Bacterial diversification through geological time” has been published in the journal Nature ecology and evolution.

Hainan gibbon female with infant. Credit: Jessica Bryant ZSL.

One of the world’s rarest mammals is disappearing from folklore

The Hainan gibbon — what is perhaps the rarest mammal in the world — is not only disappearing from China’s forests but also from folklore.

Hainan gibbon female with infant. Credit: Jessica Bryant ZSL.

Hainan gibbon female with infant. Credit: Jessica Bryant ZSL.

Most of the world’s primate species are threatened with extinction, but for some this threat is far more immediate than for others. The Hainan gibbon is the world’s rarest ape, rarest primate, and quite possibly the rarest mammal species. It’s found only on one tropical island at the southern tip of China. Once numbering around 2,000 individuals in the 1950s, the Hainan gibbon underwent a severe decline due to habitat loss and hunting, with only an estimated 26 individuals remaining. Today, these apes are restricted to just two square kilometers of remnant rainforest in Bawangling National Nature Reserve on Hainan Island in the South China Sea.

Gibbons are small apes that live in the forests and can swing from tree to tree with remarkable dexterity and speed. Chinese culture has always cherished them, lending them an important place in Chinese folklore, particularly in the southern province of Hainan Island.

Unfortunately, not only is the Hainan gibbon (Nomascus hainanus) on the brink of extinction, its cultural existence is also eroding away, according to researchers working with the international conservation charity ZSL (Zoological Society of London).

The researchers, led by Dr. Samuel Turveys from ZSL’s Institute of Zoology, conducted ethnographic interviews with locals across the Hainan gibbon’s historical range. The survey was meant to measure the locals’ “traditional ecological knowledge” — a sort of cultural wisdom about wildlife passed from generation to generation.

“In an era of satellite imaging and GPS-tracking, using ethnographic surveys for conservation science might seem esoteric. However, there is an urgent need to understand the relationship between threatened species and local communities, and traditional folklore can often provide invaluable insights to inform future conservation strategies,” Turveys said in a statement.

Researchers interviewed locals about their cultural knowledge of Hainan gibbons. Credit: Helen Nash / ZLS.

Researchers interviewed locals about their cultural knowledge of Hainan gibbons. Credit: Helen Nash / ZLS.

People who live in regions of Hainan where the gibbons used to live until very recently were still aware of the apes’ cultural significance. However, elsewhere, these animals are becoming increasingly forgotten. Disturbingly, any local communities who are now unaware of Hainan gibbon folklore still retain knowledge of how to hunt gibbons, even in areas where they had disappeared decades ago.

“Folklore and stories give us a connection to our natural world, no matter where we live. And many animals regularly feature in the news or on nature documentaries or in books. As the range of the Hainan gibbon has shrunk, the number of people encountering this enigmatic animal has decreased, so the frequency with which people recall them in stories also decreases,” Dr. Susan M Cheyne, Vice-Chair of IUCN’s Primate Specialist Group Section on Small Apes, told ZME Science.

“Myths, legends, and fables about animals are often the first encounter many people have with an animal, even if they may never see it in the wild. Keeping these stories alive ensures we maintain a link between people and animals, this is especially important for the Critically Endangered Hainan gibbon,” she added.

Whether we like or not, culture plays a major role in conservation efforts. For instance, people are far more inclined to take action by donating or supporting conservation efforts when a species they’re very culturally familiar with is threatened, even if they’ve never seen that animal in person in their lives. Think of lions, giraffes, and elephants. Bearing all of this in mind, conservation efforts shouldn’t ignore the cultural significance of a species — it might make all the difference.

“Ethnographic research is becoming increasingly recognized as important for primate conservation. If you know about something, you are more likely to have empathy and to therefore care about the fate of the animal. Loss of wildlife and habitat often goes hand in hand with the erosion of local cultures and traditions. Some options would be to curate a museum of stories about the Hainan gibbon, compile all the tales into a book and ensure that culture plays a role in conservation education and outreach,” Cheyne said.

“Our human culture is often linked to wildlife, no matter where we live, so we should all celebrate the stories we have. We often will have read fables and stories about animals as children, we need to keep these alive,” she concluded.

The findings appeared in the journal Open Science. 

Bali eruption.

Ancient volcanism shows our emissions can trigger a mass marine extinction

Ancient volcanism offers a glimpse into the future effects of climate change.

Bali eruption.

Volcanic eruption in Bali, Indonesia.
Image credits Alit Suarnegara.

Right now, global climate patterns are swinging wildly (in geological terms), powered by all the greenhouse gases we’re pumping in the atmosphere. We have some broad idea of what these changes will entail, but we don’t know the details — and not knowing what to expect in such circumstances is quite scary. One thing we do know for sure right now is that the high concentrations of carbon dioxide in the atmosphere are draining oceans of oxygen. It’s happening faster than anything similar we’ve ever seen and has researchers worried and scrambling to find solutions.

For that, however, we’ll need to know what to expect. One team of researchers from Florida State University (FSU) dredged the geological record for similar events to use as a guideline. The magnitude and sheer destructiveness of what they found suggests that we were right to worry.

Volca-no

The team used ancient volcanism as a proxy for today’s anthropic emissions. Millions of years ago, during the Toarcian Oceanic Anoxic Event (T-OAE, during the Early Jurassic), powerful eruptions belched large quantities of carbon dioxide into the atmosphere. Oxygen levels in ocean waters soon plummeted. Most marine life followed suit, leading to a devastating mass extinction.

“We want to understand how volcanism, which can be related to modern anthropogenic carbon dioxide release, manifests itself in ocean chemistry and extinction events,” said study co-author Jeremy Owens.

“Could this be a precursor to what we’re seeing today with oxygen loss in our oceans? Will we experience something as catastrophic as this mass extinction event?”

The team set out to reconstruct ocean oxygen levels during the Early Jurassic in order to better understand the mass extinction event during the T-OAE. Their research reinforces previous findings regarding the (bad) effects of increased ocean temperature and acidification on marine life. However, it also revealed the importance of a third factor, oxygen level change, in leading to such an event.

Toarcian paleogeo.

Image credits Scotese CR (2001), Atlas of Earth History via R. Them et al., 2018, PNAS.

For the study, the team retrieved samples of ancient rock formations from North America and Europe. Thallium isotope analysis performed at the FSU-based National High Magnetic Field Laboratory revealed that oxygen levels in the oceans started to drop several hundred thousands of years before the interval we ascribe to the T-OAE. This initial drop was caused by massive bouts of volcanic activity, they explain, adding that it’s not that different a process from modern anthropic emissions of CO2.

“Over the past 50 years, we’ve seen that a significant amount of oxygen has been lost from our modern oceans,” says Theodore Them, a postdoctoral researcher at FSU who led the study. “While the timescales are different, past volcanism and carbon dioxide increases could very well be an analog for present events.”

“As a community, we’ve suggested that sediments deposited during the T-OAE were indicative of widespread oxygen loss in the oceans, but we’ve never had the data until now.”

High atmospheric levels of carbon dioxide increase average temperatures on the planet. This sets into motion multiple chains of events (chemical, biological, as well as hydrological) that compound to remove oxygen from ocean water. Ultimately, this process resulted in severe oceanic deoxygenation and mass extinction of marine life, which we see in the geological record as the T-OAE.

Extinction event

Sequence of events culminating in the Early Jurassic T-OAE. The massive die-off worked to sequester large amounts of carbon (δ13C line) from the atmosphere, allowing conditions to eventually stabilize. Top bars represent biodiversity.
Image credits R. Them et al., 2018, PNAS.

The findings help flesh out our understanding of how Earth’s systems function. But they also point to a worrying precedent. We’re already seeing signs of ocean acidification, increased average temperatures, and of falling levels of oxygen in ocean water. It’s safe to assume that the interplay between these events will have the same results as in the Early Jurassic. Should we continue pumping greenhouse gases such as CO2 in the atmosphere, we might just usher in an ocean mass extinction upon ourselves — one that will likely take society as we know it down, too.

“It’s extremely important to study these past events,” Them said. “It seems that no matter what event we observe in Earth’s history, when we see carbon dioxide concentrations increasing rapidly, the result tends to be very similar: a major or mass extinction event. This is another situation where we can unequivocally link widespread oceanic deoxygenation to a mass extinction.”

Not all is lost, however. All out tech and know-how put us in this position, that’s true, but it also offers the way out. There are steps we can take to stop or at least slow down the rate of oxygen loss in our oceans, the team notes. For example, maintaining environments that absorb and store carbon dioxide (such as wetlands or estuaries) could help reduce the effect of our emissions. The single biggest change we can make, however, is to de-couple our industries and economies from fossil fuels — efforts are already underway, but it never hurts to double down.

Personal efforts also help. Many of the things you can do to reduce your impact on the planet are also quite healthy and beneficial choices on an individual level: drive less, to reduce the level of emissions you put in the air and get some exercise, too. Eat more veggies, cut out as much meat and dairy as you’re comfortable too, or just be more selective about what type of animal protein you eat — good for your health, your wallet, and the planet! Finally, waste not — it helps to reduce emissions from industry, reduces trash, and will give you a mood boost.

The paper “Thallium isotopes reveal protracted anoxia during the Toarcian (Early Jurassic) associated with volcanism, carbon burial, and mass extinction” has been published in the journal Proceedings of the National Academy of Sciences.

Humans are responsible for the sudden disappearance of world’s largest mammals

Humans likely had an important role to play in the extinction of the wooly mammoth. Credit: Wikimedia Commons.

Humans likely had an important role to play in the extinction of the wooly mammoth. Credit: Wikimedia Commons.

During the late Pleistocene, about 125,000 years ago, some of the world’s largest and most impressive mammals suddenly started disappearing. This was a time when huge beasts collectively known as megafauna roamed the planet; animals like a hornless rhino that was ten times bigger than today’s living variety or a short-faced bear that would have towered over the mighties grizzlies. But even such terrifying megafauna was no match for a seemingly inconsequential-looking species: Homo Sapiens. 

Paleontologists studied the entire mammal fossil record from 65 million years ago — after the dinosaurs became extinct following a giant asteroid impact — up to present day. They found that for the most part, being large was not correlated to a heightened risk of going extinct — not until a new apex predator arrived on the scene: Homo Erectus. This 1.8-million-year-old human ancestor disrupted ecosystems with its novel tool use and group hunting style.

Before Homo Erectus, hominids were mostly vegetarians. Afterward, their diet became increasingly dependent on meat, which offered far more bang for the buck, calories-wise. But even so, it made economic sense to go after the biggest, loudest animals out there. A hare might feed a small family for a day but a woolly mammoth, well, that’s enough food for the whole tribe.

When humans arrived, large mammals were really done far. According to lead author Felisa Smith, a paleontologist at the University of New Mexico, and colleagues, the mammals that disappear tend to be 100 to 1000 times bigger than those that survive, a pattern that occurred on every continent except Antarctica throughout the last 125,000 years.

Two centuries from now, the world’s largest mammal could be a cow

It’s not like it was too difficult for very well organized human hunters to drive such species extinct. The larger the mammal, the harder it is for it to reproduce (i.e. longer breeding cycles), and it was not like humans had to hunt down every last one specimen of a species — it’s enough to stress a population just enough to keep the fertility rate below the replacement rate. Eventually, the population collapses along with an entire species.

“It wasn’t until human impacts started becoming a factor that large body sizes made mammals more vulnerable to extinction,” said the University of Nebraska-Lincoln’s Kate Lyons, who authored the study with Smith and colleagues from Stanford University and the University of California, San Diego.

“The anthropological record indicates that Homo sapiens are identified as a species around 200,000 years ago, so this occurred not very long after the birth of us as a species. It just seems to be something that we do.

By around 15,000 years ago, the average mass of North America’s mammals had fallen from 216 pounds to just 17 pounds, roughly the size of a Yorkshire terrier. When the researchers made some extreme assumptions, such as presuming that all currently listed mammals as endangered or threatened will become extinct, they found that biggest mammal on the planet 200 years from now will be the domestic cow.

“If this trend continues, and all the currently threatened (mammals) are lost, then energy flow and taxonomic composition will be entirely restructured,” said Smith, professor of biology at New Mexico. “In fact, mammalian body size around the globe will revert to what the world looked like 40 million years ago.”

Scientists had long known about the sudden disappearance of large mammals from the fossil records, but it was never clear whether humans, climate change, or a combination of the two were responsible. However, large and small mammals seemed equally vulnerable to temperatures shifts through the studied time span, the authors note, with suggests climate change had little to do with the observed size-specific culling.

“If climate were causing this, we would expect to see these extinction events either sometimes (diverging from) human migration across the globe or always lining up with clear climate events in the record,” said Lyons, assistant professor of biology at Nebraska. “And they don’t do either of those things.”

It’s not just large mammals that are pressured to extinction by humans. The same size-selective pressures are affecting the world’s largest fish, reptiles, amphibians, and birds.

Losing the world’s largest mammals — the products of millions and millions of years of evolution — will pose profound implications for the world’s ecosystems. Large mammals such as elephants tend to be herbivores and have huge ranges over which they devour copious amounts of vegetations. As such, these mammals act like ecological engineers, clearing the land and making way for open terrain such as savannahs. They also dispense nutrients over large distances around an ecosystem. So if big mammals are gone, the smaller ones might follow.

“The kinds of ecosystem services that are provided by large mammals are very different than what you get from small mammals,” Lyons said. “Ecosystems are going to be very, very different in the future. The last time mammal communities looked like that and had a mean body size that small was after the extinction of the dinosaurs.

“What we’re doing is potentially erasing 40 to 45 million years of mammal body-size evolution in a very short period of time.”

Scientific reference: Felisa A. Smith, Rosemary E. Elliott Smith, S. Kathleen Lyons, Jonathan L. Payne. Body size downgrading of mammals over the late QuaternaryScience, 2018; DOI: 10.1126/science.aao5987.

A life-scene from 232 million years ago, during the Carnian Pluvial Episode after which dinosaurs took over. A large rauisuchian lurks in the background, while two species of dinosaurs stand in the foreground. Based on data from the Ischigualasto Formation in Argentina. Credit: Davide Bonadonna.

Mass extinction event 232 million years ago paved the way for the dinosaurs

A life-scene from 232 million years ago, during the Carnian Pluvial Episode after which dinosaurs took over. A large rauisuchian lurks in the background, while two species of dinosaurs stand in the foreground. Based on data from the Ischigualasto Formation in Argentina. Credit: Davide Bonadonna.

A life-scene from 232 million years ago, during the Carnian Pluvial Episode after which dinosaurs took over. A large rauisuchian lurks in the background, while two dinosaurs species stand in the foreground. Based on data from the Ischigualasto Formation in Argentina. Credit: Davide Bonadonna.

Much has been said about the famous asteroid impact that wiped out the dinosaurs 65 million years ago and ushered in the age of mammals, eventually clearing the path for our species to achieve total domination. However, in turn, the dinosaurs were also privileged by a different mass extinction event, which is far less studied than the asteroid impact. This was the conclusion of a new study which found that dinosaurs became far more prevalent across the world after a mass extinction called the Carnian Pluvial Episode.

Starting and ending with a bang

The Carnian Pluvial Episode occurred roughly 232 million years ago. During this time, a series of cataclysms, triggered by volcanic eruptions in western Canada, shifted the climate from wet to dry and from dry to wet again. The hostile periods of global warming and acid rain had taken their toll on countless species that eventually went extinct.

Researchers at the MUSE-Museum of Science Trento, Italy, the Universities of Ferrara and Padova, and the University of Bristol investigated ancient rock deposits in Northern Italy’s Dolomites mountain range which still had dinosaur tracks trapped inside them. This allowed them to build a timeline for dinosaur expansion; the more and diverse the tracks, the more successful the dinosaur must have become. For instance, in the early Triassic, some 245 million years ago, dinosaurs were very rare and stayed that way for at least 13 million years. After the Carnian extinction, however, dinosaur footprints became ubiquitous.

“We were excited to see that the footprints and skeletons told the same story,” Massimo Bernardi, a researcher at the University of Bristol, said in a news release. “We had been studying the footprints in the Dolomites for some time, and it’s amazing how clear cut the change from ‘no dinosaurs’ to ‘all dinosaurs’ was.”

When the researchers calculated the peak of this expansion, they found that it coincided with the end of the Carnian Pluvial Episode. What’s more, the Dolomite samples also contained evidence of climate change. Namely, the researchers detected four pulses of warming and climate disruptions within a million year span, which must have led to repeated extinctions.

“The discovery of the existence of a link between the first diversification of dinosaurs and a global mass extinction is important,” said Mike Benton, co-author of the new study and a professor at the University of Bristol.

“The extinction didn’t just clear the way for the age of the dinosaurs, but also for the origins of many modern groups, including lizards, crocodiles, turtles, and mammals — key land animals today.”

Scientific reference: Massimo Bernardi, Piero Gianolla, Fabio Massimo Petti, Paolo Mietto, Michael J. Benton. Dinosaur diversification linked with the Carnian Pluvial Episode. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-03996-1.

Mammoth.

Humanity killed off mega-herbivores — but climate change might warrant bringing them back

The spread of prehistoric humans across the world had a twofold effect that drove mega-herbivores extinct, new research reports. Our ancestors thinned the herds through hunting but also took over part of their ecosystem functions, undermining the species’ viability. However, this ecological shift was imperfect and left deficits in many areas — suggesting that the reintroduction of large animals in certain parts of the world could have a positive effect on local environments.

Mammoth.

Image credits Jens Hummelmose.

There are very few animal species today that grow to be one ton or more — like elephants, hippos, and the rhinoceros. Also known as mega-herbivores, this class of animal species came very close to complete extinction around 12,000 years ago — even those that are alive to this day boast limited populations.

A new paper published by Hervé Bocherens, from the Senckenberg Research Center for Human Evolution and Palaeoenvironment, analyzed this process and found that humans are to blame for the extinction of these terrestrial giants.

“Under geological aspects, the small number of so few large animal species presents an anomaly,” explains Dr. Bocherens. “The most prominent example of prehistoric giants is, of course, the dinosaurs.”

Dinosaurs moved off the stage after a particularly bad encounter with a meteorite, but a lot of other mega-herbivore species evolved in more recent geological history, such as giant sloths, wooly rhinos, and mammoths. Dr. Bocherens specifically looked at what pushed these species to extinction around 12,000 years ago and what consequences that had for the environment.

He reports that — much like modern-day elephants, for example — these behemoth species acted as ‘ecosystem engineers’. They kept tree cover in check through grazing, which in turn allowed lower plants more room and light to thrive. The reduced tree cover also meant more open landscape and clear watering holes, both of vital importance for other animals. Bocherens further explains that mega-herbivores also helped spread plant species over large distances by carrying them in their digestive tracts.

Big herbivores, big changes

Between 45,000 and 12,000 years ago, a part of these tasks was inadvertently taken over by modern humans. The gradual spread of mankind across Eurasia, the Americas, and Australia roughly coincides with the gradual extinction of giant herbivores across these continents. With the Neolithic revolution, the functions these ecosystem engineers performed were partially replaced by the practices of agriculture, animal husbandry, and those related to humanity’s more sessile lifestyle.

There were certain areas, however, that didn’t fully undergo this change. One example is the Subarctic: it lost its giant herbivores (such as mammoths), but because its harsh climate made it both uncomfortable to settle, as well as ill-suited for agriculture, humans never truly moved in. Bocherens reports that the gap these giant species left in the ecosystem impacted the entirety of the flora. They had kept trees in check, giving other plants room and nutrients to grow, which in turn had a positive effect on overall biodiversity. Since humans pushed these species to extinction but didn’t move in to take their ecological niche, there wasn’t anyone around to maintain the ecosystem services these species performed — as such, the once-steppes turned into thick, boreal, coniferous forests

In time, this reduced the planet’s albedo effect. The dark green color of these forests reflected much less of incoming sunlight than the steppes’ winter white or the yellow colors of its dry grasses during the rest of the year. Overall, this led to a slight warming of the climate. The soils in these areas also changed, Bocherens notes, as they used to be much drier and emitted less methane (they had less biomass mixed in) during the days of the mammoths. The extra greenhouse gases went on to contribute to climatic shifts.

“The presence of giant herbivores thus not only contributed to a higher species diversity, it also had an effect on the global climate,” he concludes in his paper.

“In some areas of the world, it may even make sense to reintroduce such mega-herbivores in order to increase biodiversity, thereby avoiding global warming.”

Bocherens thinks the extinction of mega-herbivores could teach us a lot about the changes we’re causing in ecosystems today. Understanding both the differences and similarities between the two processes could help us better predict changes in natural systems.

The paper “The Rise of the Anthroposphere since 50,000 Years: An Ecological Replacement of Megaherbivores by Humans in Terrestrial Ecosystems?” has been published in the journal Frontiers in Ecology and Evolution.

North Atlantic Right Whale.

Right whales face extinction if humans don’t intervene fast, NOAA researchers warn

Federal government officials aren’t mincing words on this one: North Atlantic right whales (Eubalaena glacialis) are in the fast lane to extinction unless we intervene.

North Atlantic Right Whale model.

Image credits Ryan Somma / Flickr.

North Atlantic right whales are some of the rarest marine mammals in the world. These gentle giants can grow up to 15m (50 ft) in length and weigh up to roughly 72 tons (158,000 lbs). They’re black colored, sometimes with white patches on their bellies, and have a stocky build, no dorsal fin, and a large head spanning about one-quarter of their body length.

They’re also well underway to becoming the rarest animal anywhere, and then going extinct. The right whales have had a very rough 2017, according to NOAA scientists, who report that the 450-or-so-strong species has lost 17 members this year.

Prospects are so bleak for the whales’ survival that the researchers urge U.S. and Canadian officials to intervene. Without action, and action taken soon, this dwindling species is likely never to recover, said John Bullard, the Northeast Regional Administrator for NOAA Fisheries.

Wrong decade for the right whales

NOAA Endangered Species Act consultant Mark Murray-Brown says that right whales have been in decline since 2010, constantly losing numbers. Females, he adds, seem to be taking the brunt of it, shrinking as a percentage in the overall population. They tend to be larger than males, although it’s not known if this contributes to their predicament.

Compounding the whales’ hardships is the fact that this year of high mortality is also a very poor one for whale-romance. There are fewer than 100 breeding female North Atlantic right whales left according to NOAA’s estimates, under a quarter of the total population — which doesn’t bode well for repopulation efforts. Factor in that gestation in the right whales lasts one whole year, with an average of about three to six years between individual pregnancies, and prospects are looking even bleaker.

“You do have to use the extinction word, because that’s where the trend lines say they are,” says Bullard. “That’s something we can’t let happen.”

“The current status of the right whales is a critical situation, and using our available resources to recover right whales is of high importance and high urgency,” Murray-Brown added.

North Atlantic Right Whale.

Image credits Lauren Packard / Flickr.

NOAA officials discussed the whales’ plight during a meeting of the regulatory New England Fishery Management Council, held last Tuesday. They warned that both the U.S. and Canada have to work together and safeguard the whales. Impacts with vessels and entanglement in fishing nets are the two most pressing concerns for the scientists, as these cause the majority of whale deaths. These are especially pressing issues as right whale nursery areas are in shallow, coastal waters.

All of this year’s deaths, the researchers added, were off the coast of New England and Canada. The whales come here over spring and summer to feed, before returning to the temperate waters off Georgia and northern Florida to give birth. Calving occurs from December through March.

Why are the whales dying?

The World Wildlife Fund (WWF) estimates that there are even fewer right whales, between 300 and 350, still alive and kicking. They blame a long history of human exploitation for leaving them “one of the most endangered of all large whales” even to this day, despite protection from whaling since the 1930s.

But if they’re not being hunted, why aren’t they recovering?

Previous research has shown that the whales tend to move around more than expected. This would put them at risk of colliding with fishing boats, if and when they move outside of protected areas in search of food. There are two areas designated as critical habitats for the species, one in the Northeast U.S., and one in the Southeast U.S.

Even if they manage to avoid a direct hit, fishermen spell more bad news for the whales. Fecal samples recovered from whales bound up in nets over longer periods revealed high concentrations of stress hormones in their system. These would have a dramatic impact on the mammals’ ability and willingness to reproduce for a long time after the traumatic event.

NOAA published a five-year assessment of the right whales in October, arguing that officials should keep the species listed as endangered. The document also includes recommendations on how best to protect the whales. Suggestions include the development of a plan to monitor population trends and habitat use over the long term, as well as more research into the impact of commercial fishing on right whales.

Mammals were free to occupy day-time niches after dinosaurs disappeared. Credit: Carl Buel.

After the dinosaurs went extinct, mammals crawled out of the dark to take over

New evidence backs up a 75-year-old evolutionary theory that said early mammals had to creep in the darkness to escape dinosaur predators which lurked at day.

Mammals were free to occupy day-time niches after dinosaurs disappeared. Credit: Carl Buel.

Mammals were freed to occupy day-time niches after the dinosaurs disappeared. Credit: Carl Buel.

Behavioral data on 2,415 mammal species, representing 91 percent of all mammal families, was plugged into a computer model that constructed multiple family trees (phylogenies). About 60 percent were nocturnal, like the vampire bat or the four-toed hedgehog, and 26 percent were diurnal, like squirrels or humans. The rest, like the star-nosed mole or muskrat, are characterized as cathemeral, meaning they exhibit irregular activity at day or night, and a few crepuscular (active only at twilight) and ultradian (active in cycles of only a couple of hours at a time) mammals were included in the analysis as well.

The so-called “nocturnal bottleneck” hypothesis was first coined in 1942 by paleontologist Gorden Lynn Wall, who reckoned mammals had to be nocturnal to survive in a dinosaur-dominated world. Ever since the theory was first proposed, scientists have been looking for proof.

There are quite a few clues that point towards a darker mammalian past. Most mammals, humans not included, lack a fovea — a small, central pit composed of closely packed cone cells in the eye, located at the center of the retina — which biologists say can perceive for the sharpest images. The shape of mammalian eyes also seems to favor low-light conditions.

Now, with such an extensive behavioral dataset in their palm, the authors say mammals were likely nocturnal throughout the Mesozoic, an era which lasted between 252 million to 66 million ago. Quite the long night.

Remarkably, the first mammals that were active during both day and night appeared only 200,000 years after the extinction event that wiped out the dinosaurs, as reported in the journal Nature Ecology & Evolution. The researchers at Tel Aviv University in Israel and University College London say these mammalian day-time pioneers were most likely the ancestors of today’s even-toed ungulates (cattle, llamas etc.) but also those of cetaceans like dolphins. In evolutionary time, that’s really fast, signaling that the numerous empty niches favored rapid adaptation of diurnal activity.

The first truly diurnal mammals seem to have appeared 52.4 million years ago, or 13 million years since the last dinosaur was alive. These were the ancestors of simian primates — such as gorillas, gibbons, and tamarins. The analysis bodes well with what our current understanding of the biology of various animal families. The visual acuity and color perception of simians, for instance, is comparable to those of diurnal reptiles and birds, which never left the daytime niche.

“We were very surprised to find such close correlation between the disappearance of dinosaurs and the beginning of daytime activity in mammals, but we found the same result unanimously using several alternative analyses,” explained lead author Roi Maor, Phd. student at Tel Aviv University and UCL.

The research is quite brilliant in the sense that it found a workaround for the scarcity of the fossil record and for the challenge of inferring behavioral traits from fossils. Working with data on the behavior and ancestry of living animals can tell us surprisingly many things about their ancestors’ past. At the same time, no one can say for sure that dinosaurs going extinct is what eventually let mammals out of the dark. For instance, maybe there were actually day-time mammals living alongside dinosaurs. There’s pretty strong evidence, however, that at least most mammals alive until 66 million years ago likely lurked under the cover of darkness.

To come up with more accurate results, the authors plan on populating the mammalian family tree with more species.
Artist impression of Chicxulub. Credit: NASA.

Asteroid impact that wiped out dinosaurs was far worse than previously thought

If it weren’t for a city-sized asteroid that that slammed into Chicxulub, a gaping crater near the same-named city on Mexico’s Yucatan Peninsula, dinosaurs would have still dominated this planet. But then again, humans might have never evolved, so kudos to us. According to a new study which recalculated the angle of the asteroid impact, you certainly wouldn’t have wanted to be there when it happened. The 66-million-year-old impact unleashed an unforgiving global cooling event that was far worse than previously thought, scientists say.

Artist impression of Chicxulub. Credit: NASA.

Artist impression of Chicxulub. Credit: NASA.

This tragic event has remained etched permanently in the planet’s geological history, through a band called the K-T Boundary, which separates the Cretaceous and Tertiary periods in geologic history. That and the gaping scar of the 180-kilometer-wide crater rim called Chicxulub. All dinosaurs went extinct, along with 60 to 80 percent of all life on Earth.

Oddly enough, the crater was discovered only twenty years ago. Previously, scientists called to attention a thin layer of iridium that could be found in rocks all over the world and dated around the time of the dinosaurs’ demise. This material is extraterrestrial, typically found in asteroids, but also in some volcanic ejections. In 1991, Alan Hildebrand, a geologist at the University of Calgary in Canada, found shocked quartz and a layer of iridium-enriched dust in samples collected in the 1950s by Mexican geologists looking for oil at the Chicxulub, and this ultimately led to finding the crater.

In the 25 years since the asteroid’s impact point was identified, scientists have learned a lot about how this event altered the planet.

Now, British researchers at Imperial College London have come up with refined calculations that paint a more accurate picture of how it all went down one ominous day 66 million years ago.

“Many climate models can’t currently capture all of the consequences of the Chicxulub impact due to uncertainty in how much gas was initially released,” said Joanna Morgan, a geophysicist at Imperial College London in the United Kingdom, in a press release. “We wanted to revisit this significant event and refine our collision model to better capture its immediate effects on the atmosphere.”

Among the key findings was that a large amount of sulfur and a smaller amount of carbon dioxide were found to be ejected by the asteroid impact compared to other studies. For this reason, the team claims that the climatic consequences may have been more dramatic than we thought.

Based on a computer model that simulated the pressure of the impact’s shock waves, the British researchers estimate the asteroid collision released about 325 gigatons of sulfur and 425 gigatons of carbon dioxide into the atmosphere, more than 10 times global human emissions of carbon dioxide in 2014. The asteroid crashed into the Earth with the explosive force of 40,000 US nuclear warheads, all triggered in a matter of seconds.

In the aftermath of the cataclysmic chain of events, a cloud of dust and sulfur engulfed the whole planet, reflecting sunlight and dramatically cooling Earth’s surface temperature. According to the paper published in Geophysical Research LettersEarth’s average surface air temperature dropped by as much as a staggering 26 degrees Celsius (47 degrees Fahrenheit). The sub-freezing temperatures persisted for over three years — enough to destroy plant life and everything else up the food web. Marine life likely had it even worse than terrestrial animals. It would have taken “hundreds of years after the Chicxulub impact” before ocean temperatures rebounded.

Neanderthals were doomed to fail, new study suggests

Neanderthals lived at the same time as early humans. They were strong, smart, and in many ways better than their counterparts. Yet humans endured, while Neanderthals went extinct (though in a way, we still carry them around through our DNA). So what killed them?

Migration of species, via Wikipedia.

The extinction of the Neanderthals is a long debate which won’t end anytime soon. This new study doesn’t try to explain if the main culprit was climate change, epidemics, or the inability to compete with humans. Instead, it argues that Neanderthals were doomed to fall either way.

Oren Kolodny of Stanford University approached his colleague Marcus Feldman. Together, they carried out a computer simulation that represented small bands of Neanderthals and modern humans in Europe and Asia. They then sent these populations randomly into extinction, regardless of whether they were Neanderthals or humans. Neither of the populations was considered to have an advantage over the other. However, there was one small, but extremely important difference.

While Neanderthal populations were generally stable, human populations had a small trickle of reinforcements coming in from Africa. This small number of extra bands of humans coming in was enough to tip the balance in the favor of humans.

The computer model is consistent with the anthropological evidence. Neanderthals first emerged in Europe around 400,000 years ago. Sometime between about 51,000 and 39,000 years ago, humans and Neanderthals shared the same landscape. They may have fought and competed for the same resources, they may have gotten along well, and they certainly interbred. When it was all said and done, humans survived, while Neanderthals didn’t. It’s a simple ecological principle: two different species can’t survive occupying the exact same niche at the exact same time. So it’s safe to assume that the former had some kind of selective evolutionary advantage over the latter. But what was it?

Not that different, right? Comparison of Neanderthal and Modern human skulls from the Cleveland Museum of Natural History.

It’s hard to assume what that advantage was, especially as the environmental conditions at the time weren’t precisely known. So Kolodny and Feldman tried to establish a simple model, without any hard-to-prove claims. They ran their simulation more than a million times, changing different assumptions and variables, but almost every time, Neanderthals slowly faded away — all due to the extra migration coming in from Africa.

If survival was a game of chance, “it was rigged by the fact that there’s recurring migration,” Kolodny said. “The game was doomed to end with the Neanderthals losing.”

“We have also demonstrated that even if bidirectional migration between Europe and Africa had occurred, [modern humans] would have been extremely likely to eventually replace Neanderthals, given the estimated differences in population size between the species, in favor of [modern humans].”

This seems to indicate that humans weren’t necessarily better than Neanderthals at any given task — they simply survived by migrating more. This is consistent with previous studies based on physical evidence. These studies found that humans and Neanderthals were much more similar than previously believed.

‘It confirms the so-called “null hypothesis” — based solely on we know about humans and Neanderthals, and considering that the two populations are similar, we can say that Neanderthals were very likely to fail even in the absence of decisive enviromental changes.

However, it’s important to note that this study is suggestive, not conclusive, Kolodny cautioned. However, it does suggest that even without climate change or another environmental change, mankind still would have won the species war.

“Even if there were no selection and no climate change, the end result would have been the same. It’s a subtle distinction but it’s important,” Kolodny concludes.

Journal Reference: Oren Kolodny et al. A parsimonious neutral model suggests Neanderthal replacement was determined by migration and random species drift, Nature Communications (2017). DOI: 10.1038/s41467-017-01043-z .