A bizarre 41-foot-wide (12.5-meter) circular structure made entirely of wooly mammoth bones was recently unearthed in Russia. Scientists believe that the structure is 25,000 years old. Whether it served as a dwelling, a ritualistic hotspot, or some other purpose is yet unclear.
As the name plainly suggests, hunter-gatherer societies obtained food by hunting, fishing, scavenging, and gathering wild plants and other edibles. It’s believed that before the advent of agriculture, our ancestors lived a nomadic lifestyle, moving in groups of a few dozens of people, consisting of several family units.
But this doesn’t mean that they mindlessly wandered the world. When food was plentiful in an area, it was common for hunter-gathers to stay put in the same place, employing techniques to store food and defending their territory against rival groups.
As out of the ordinary as it may sound, circular structures made from mammoth bones were quite common during the ice age in Eastern Europe.
Recently, Russian paleontologists have discovered the largest one yet: a huge structure made of hundreds of wooly mammoth bones, belonging to as many as 60 different mammoths.
The structure was found at an archaeological site, known as Kostenki 11, which is located by the Don River, close to the Russian city of Voronezh.
Radiocarbon dating suggests that the site is around 25,000 years old, making it one of the oldest mammoth bone structures in history.
Such structures are quite common around Russian and Eastern Europe. In fact, scientists have been discovering mammoth bone structures — albeit of much smaller dimensions — at Kostenski 11 since the 1950s. They’re all circular and flanked by a series of large pits, which may have been used to store food or dump waste.
About 70 such structures are known to exist in Ukraine and the west Russian Plain.
This most recent structure — and the largest found thus far — was first discovered in 2013. For three years the researchers had been excavating the site, employing flotation — a technique that involves water and sieves in order to separate ancient remains and artifacts from the soil.
A total of 51 lower jaws and 64 individual mammoth skulls were used to construct the walls, according to the investigation carried out by the team of researchers led by Dr. Alexander Pryor from the University of Exeter, UK.
In addition to the mammoth bones, the researchers were able to find evidence of charcoal and burnt bones, stone tool fragments, and soft plant tissue that hint at the diet consumed during those times.
Why would Pleistocene hunter-gatherers bother to erect such massive and, quite frankly, creepy structures?
“Kostenki 11 represents a rare example of Palaeolithic hunter-gatherers living on in this harsh environment. What might have brought ancient hunter gatherers to this site? One possibility is that the mammoths and humans could have come to the area on masse because it had a natural spring that would have provided unfrozen liquid water throughout the winter – rare in this period of extreme cold,” Pryor said in a statement.
The structure might have served as a dwelling for a small tribe or as a food stockpiling warehouse. The charcoal, for instance, suggests that fires were started inside the circular structure, providing solace against the harsh ice age nights. Climate modeling indicates that around the time the structure was erected, the last ice may have been at its worst, with temperatures around -20 degrees Celsius or lower.
Many of the bones were likely scavenged and transported to the site. Other bones likely came from hunting parties, with chunks of meat and tissue still attached to bones. Whatever their origin, a great deal of labor and planning was involved in order to transport such heavy loads.
The bones themselves don’t show signs of butchery. However, in the case of game of this size, the hunters probably removed the bulk of the meat, leaving small chunks to rot on the bone. Pryor says that humans butchering elephants in modern times using metal knives also didn’t leave any marks on the bones.
“These finds shed new light on the purpose of these mysterious sites. Archaeology is showing us more about how our ancestors survived in this desperately cold and hostile environment at the climax of the last ice age. Most other places at similar latitudes in Europe had been abandoned by this time, but these groups had managed to adapt to find food, shelter and water,” Pryor said.
However, Pryor writes that the amount of evidence that might point to intense activity at Kostenki 11 is rather low for what one might expect to find from a long-term base camp. He also has difficulty imagining how humans with limited technology could have been able to build the roof for such a large area, casting doubt on the site’s main use as a dwelling.
The structure perhaps also possessed a ritualistic significance. The Russian researchers speculate that it may have served as a shrine or monument honoring woolly mammoths. There is no evidence to back this assertion, which remains speculation at this point.
Whatever may be the case, this impressive archeological treasure trove shows that ice age humans were a lot more crafty than one might expect — after all, they had to in order to survive their extreme environment.
The findings appeared today in the journal Antiquity.
The last woolly mammoths lived on Wrangel Island in the Arctic Ocean, a new study reports.
An international team of researchers with members from the Universities of Helsinki, the University of Tübingen, and the Russian Academy of Sciences reports that the wooly mammoths likely went extinct due to a combination of habitat isolation and extreme weather events — as well as the spread of ancient humans.
Within a very short timeframe some 4,000 years old, the last population of these animals — which lived on Wrangel Island — went extinct, they add.
Last of the mammoths
“It’s easy to imagine that the population, perhaps already weakened by genetic deterioration and drinking water quality issues could have succumbed after something like an extreme weather event,” says professor Hervé Bocherens from the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tübingen, a co-author of the study.
Mammoths enjoyed great success during the last ice age, from around 100,000 to 15,000 years ago. The species ranged from Spain to Alaska and fared quite comfortably during that time. Around 15,000 years ago, however, temperatures started picking up, and the mammoths’ natural range started to shrink. The Wrangel Island population, the team notes, was cut off by rising sea levels from their mainland counterparts and would live in isolation for the next 7,000 years.
The team examined carbon, nitrogen, sulfur, and strontium isotopes from a large set of mammoth bones and teeth dug up from Northern Siberia, Alaska, the Yukon, and Wrangel Island. These specimens ranged in age from 40,000 to 4,000 years ago. The researchers aimed to document possible changes in the mammoths’ diets over this time (which would be ‘recorded’ in their bones as different isotope ratios) as proxies for the environmental disturbances the species was exposed to.
The results showed that the carbon and nitrogen isotope ratios in the collagen of Wrangel Island mammoths did not shift as the climate warmed up some 10,000 years ago. The values remained unchanged until the mammoths disappeared, seemingly from the midst of stable, favorable living conditions.
Such results show a stark contrast with those obtained from wooly mammoth bones in the Ukrainian-Russian plains, who died out 15,000 years ago. It’s also different from the mammoths of St. Paul Island in Alaska, who disappeared 5,600 years ago. In both cases, the last representatives of these populations (that we’ve found) show markedly-different isotope compositions, suggesting changes in their environment shortly before they became locally extinct.
Earlier research had shown that mammoths on Wrangel Island suffered certain mutations that affected their fat metabolism. In the present study, the team reports finding a different ratio of carbon isotopes in their bones compared to Siberian mammoths, likely due to a difference in the fat and carbohydrates in the diets of the two groups.
The bones of Wrangel Island mammoths also showed higher levels of sulfur and strontium, likely due to increased weathering of bedrock in the area close to the mammoths’ extinction. These elements likely found their way into rivers and streams, affecting the quality of the animals’ drinking water.
All in all, the mammoths of the island disappeared suddenly, but perhaps, not dramatically. The team says short-term events like extreme weather is what likely did them in in the end. A simple icing event can cover the ground in a thick enough layer of ice to prevent the animals from finding food — which is enough to cause a dramatic drop in numbers. Another possible reason is the spread of humans in the area, with the earliest evidence of their presence on the island preceding the last mammoth fossils by just a few hundred years. The chance of finding evidence that humans hunted Wrangel Island mammoths is very small, the team explains, yet a human contribution to the extinction cannot be ruled out.
The study shows just how fragile a small population of large mammals is to environmental shifts and human activity. The team says their findings can help preserve species by aiming conservation efforts at the populations that are not isolated from one another.
The paper “Thriving or surviving? The isotopic record of the Wrangel Island woolly mammoth population” has been published in the journal Quaternary Science Reviews.
What causes ice sheets and glaciers to expand? Despite movies may show it as a simple and fast phenomenon, ice ages are driven by a complex and interconnected set of factors. Here’s a guide of key questions and answers to try to get a better understanding of this extremely important geological process.
What’s an ice age?
Let’s start with the basics.
Over long periods of time, the temperature of the Earth fluctuates between a cold phase (an ice age) and a warmer, interglacial phase.
An ice age is a time where a significant amount of the Earth’s water is locked up on land in continental glaciers. During the last ice age, which finished about 12,000 years ago, enormous ice masses covered huge swathes of land now inhabited by millions of people. Canada and the northern USA were completely covered in ice, as was the whole of northern Europe and northern Asia. In Europe, Britain was connected to the rest of the continent through an area called Doggerland, and on average, the Earth’s average temperature was about 12 degrees Fahrenheit (6 degrees Celsius) colder than it is today.
At the moment the Earth is in an interglacial period — a short warmer period between glacial periods. The Earth has been alternating between long ice ages and shorter interglacial periods for around 2.6 million years. For the last million years or so these have been happening roughly every 100,000 years – around 90,000 years of ice age followed by a roughly 10,000-year interglacial warm period.
Within the ice ages more temperate and more severe periods occur. The colder periods are called glacial periods, the warmer periods interglacials — this is the period in which we are living now.
It should also be said that different disciplines sometimes use some different terminology. In glaciology, ice age implies the presence of extensive ice sheets in both northern and southern hemispheres. In most cases, the term “ice age” refers to the geological period called the Pleistocene, which lasted from about 2,588,000 to 11,700 years ago. The Pleistocene spanned the world’s most recent period of repeated glaciations — these glaciations are sometimes also called ice ages, though the term is improper.
Why does an ice age happen?
There are many aspects related to ice age onset, but if we want to truly understand this phenomenon, we have to look outside of the Earth itself and onto its orbit.
The main cause of ice ages is connected to something called the Milankovitch cycle. The Milankovitch cycle refers to the collective effects of changes in the Earth’s movements on its climate over thousands of years. Very small changes in the Earth’s orbit shift the angle at which the Sun’s rays hit the Earth. While this may seem like a small thing, it actually has a huge impact.
Even small tilt changes of the Earth can change the planet’s temperature by several degrees. When the tilt is low, ice sheets grow and snow continues to accumulate. When the tilt is high, the ice sheets melt away. Since then the tilt has reached a maximum of 24.2 degrees (10,000 years ago), current the Earth’s tilt measures approximately 23.5 degrees — and as a result, large ice sheets are restricted to the polar areas.
It’s not just the tilt — other factors about the Earth’s orbit can play a role. The three main orbital parameters are:
eccentricity (how circular the Earth’s orbit around the Sun); this varies with periods between 400,000 and 100,000 years.
obliquity (how tilted the Earth is with respect to its orbit); this varies with a period of around 40,000 years.
precession (changes between the distance of the Sun and the Earth in over the same season); this varies with a period of around 23,000 years and is particularly important around the Equator.
Having 3 major factors with different time periods leads to some hard-to-predict interactions, but the ice ages we know about can generally be traced back to these factors. The 100,000-year cycle seems to be the most significant one, and also coincides with interactions between 40,000 and 20,000-year cycles — it’s basically when all the factors “team up” to play their part. However, this is still an area of active research.
More to this story
Still, things aren’t really all that simple. It actually takes thousands of years for an ice age to begin, and things are not always neat and clear.
Ice ages are triggered when summer temperatures in the northern hemisphere fail to rise above freezing for years. This triggers a snowball effect: winter snowfall doesn’t melt, builds up, compresses, and over time starts to compact, or glaciate, into ice sheets. This further accentuates the cooling, as snow and ice have a higher albedo, meaning they reflect more of the solar energy and cool down even more.
Over thousands of years, these ice sheets start to build up. They seem to start out in the northern areas like Canada or Russia and then spread out across the northern hemisphere. The onset is, again, related to the Milankovitch cycles — but these changes in the Earth’s tilt and orbit combine are complemented by other geological factors to favor the emergence of ice ages.
When all these factors align so the northern hemisphere gets less solar radiation in summer, you have all the ingredients needed for an ice age.
Glacials are characterized by cooler and drier climates over most of the earth and large land and sea ice masses extending outward from the poles. Mountain glaciers in otherwise unglaciated areas extend to lower elevations due to a lower snow line
Could there be more factors involved?
We have the rough picture pretty well drawn out, but there are still some details missing. For instance, the position of continents, which is affected by plate tectonics, can also influence ice ages, as they control the circulation of the oceans and the atmosphere which in turn, affects how ocean currents carry heat to high latitudes.
The atmospheric composition (which can also shift somewhat in geologic time) is another important parameter.
Scientists at the Potsdam Institute for Climate Impact Research (PIK) in Germany have shown that the onsets of past ice ages were triggered mainly by decreases in carbon dioxide and that the dramatic increase of carbon dioxide in the atmosphere, because of human-caused emissions, has likely suppressed the onset of the next ice age for up to 100,000 years.
“Like no other force on the planet, ice ages have shaped the global environment and thereby determined the development of human civilization,” Hans Joachim Schellnhuber, former director of PIK, said. “For instance, we owe our fertile soil to the last ice age that also carved out today’s landscapes, leaving glaciers and rivers behind, forming fjords, moraines, and lakes. However, today it is humankind with its emissions from burning fossil fuels that determines the future development of the planet.”
Nevertheless, while some aspects may be more difficult to assess, the overall processes are pretty well understood.
What impacts have ice ages had on the planet?
Today, less than 10% of our continents are covered by ice, but that figure has been as high as 30% in the past.
Ice ages caused enormous changes to the Earth’s surface. Glaciers are not static — they reshaped the landscape by picking up rocks and soil and eroding hills during their unstoppable push, their sheer weight razoring the Earth’s crust. As temperatures dropped in areas adjacent to these ice cliffs, cold-weather plant life was driven to southern latitudes. These processes tend to create spectacular scenery which can be seen in many parts of Canada, Scandinavia, and the Alps.
Meanwhile, the dramatic drop in sea levels enabled rivers to carve out deeper valleys and produce enormous inland lakes, with previously submerged land bridges appearing between continents. Upon retreating during warmer periods, the glaciers left behind scattered ridges of sediment and filled basins with melted water to create new lakes.
During the last ice age, which ran from about 110,000 years ago to 10,000 years ago, the lower sea levels allowed humans to move out across the entire world. While there was still some water between Asia and Australia it took just a few short canoe trips to bring the first humans to Australasia.
The world’s ecosystems also try to adapt to these climatic changes. Some creatures survive and adapt, others don’t. The extreme glaciation periods put extreme pressure on species, who devise adaptations for the colder or warmer periods.
Scientists have a variety of methods they use. Evidence for the more recent ice ages comes from changing sea levels in the past, which can be seen by looking at coral reefs or modern landscapes, as well as samples conserved in glacial ice over millions of years.
Ice core records provide invaluable information on changes in temperature and greenhouse gases over the last 800,000 years. If we want to go back even further into the past, evidence for ice ages in the last tens of millions of years is predominantly seen in ocean sediments.
And for the
deep time ice ages that occurred tens to hundreds of millions of years ago,
scientists use the geological record where the story of sea level and climate
can be unraveled by analyzing rocks of various ages.
How many ice ages have happened so far?
At least five major ice ages took place in Earth’s history. These include the Huronian, Cryogenian, Andean-Saharan, Karoo, and the Quaternary ice ages.
The Huronian Ice Age is dated to the early Protezerozoic Eon, roughly 2.4 to 2.1 billion years ago. The Cryogenian Ice Age lasted from roughly 850 to 630 million years ago and was perhaps the most severe in Earth’s history. The Andean-Saharan Ice Age occurred during the Late Ordovician and the Silurian period (roughly 460 to 420 million years ago).
The Karoo Ice Age is attributed to the evolution of land plants during the onset of the Devonian period (ca. 360 to 260 million years ago). The current ice age, known as the Pliocene-Quaternary glaciation, started about 2.58 million years ago during the late Pliocene when the spread of ice sheets in the Northern Hemisphere began. Since then, the world has experienced several glacial and interglacial periods.
Approximately a dozen major glaciations have occurred over the past one million years, the largest of which peaked 650,000 years ago and lasted for 50,000 years.
The Earth is currently in an interglacial period, and the last glacial period ended about 10,000 years ago. What remains of the continental ice sheets that once stretched across the globe are now restricted to Greenland and Antarctic, as well as smaller glaciers
What would happen if a new ice age occurs?
While we may have delayed the onset of the next ice age, for now, a new one would have significant consequences for human civilization. Besides the fact it would be an awful lot colder, huge regions where hundreds of millions of people live would become completely uninhabitable. They’d be covered in thick ice sheets and subject to an inhospitable climate.
There would be a lot less agricultural land available, so it would be very difficult to support the human population. The physical shape of the continents would look completely different across the whole planet. Plus, a huge drop in sea level of up to 120 meters would close down marine channels – the Mediterranean Sea, Torres Strait, Bass Strait, and Bering Strait – and create new areas of land that could be used for habitation or agriculture.
Nevertheless, this is not really a matter of concern. As mentioned, the onset of ice ages is a geological process — it takes a really long time and is very gradual.
Which leads us to our final point.
Don’t blame man-made climate change on natural processes!
The world’s climate is currently heating up. This is not a natural process — there is ample and conclusive evidence that this process is caused by man-made greenhouse gas emissions.
However, although there is a scientific consensus on this issue, disinformation campaigns have been successful in spreading climate change denialism and doubts. “Climate change is natural” is one of the favorite quips of climate change deniers — but this is not the case here.
Climate does change naturally, and ice ages and glaciation periods are excellent examples of that. We are also currently in a warming phase. However, it is a simply incorrect to use this as an argument to suggest that the current climate heating is natural — it’s not.
Australia’s extinct short-faced kangaroos were more like marsupial giant pandas, new research reports.
The animals were massively thickset, with the largest species weighing more than 220 kg and had large heads shaped like a koala’s. Their jaws were also adapted to local vegetation, which was predominantly woody and relatively poor-quality in Ice Age Australia.
“The skull of the extinct kangaroo studied here differs from those of today’s kangaroos in many of the ways a giant panda’s skull differs from other bears,” says Dr. Rex Mitchell, a researcher with Australia’s University of New England (UNE) and the University of Arkansas and the sole author of the paper.
“It makes sense that the strange skull of this kangaroo was, functionally speaking, less like a modern-day kangaroo’s and more like a giant panda’s.”
The study finds that the skull of one species of these extinct kangaroos was tailored for crushing of food, which would make it useful for animals trying to make ends meet in low-productivity landscapes (as it allows them to eat basically any plant matter). Adaptations for this role include “enormous cheekbones and wide foreheads”, Dr. Mitchell explains, as well as an overall increase in the skull’s size.
He also explains that what we’re seeing isn’t a fluke of biology, but a deliberate change. It would take a lot of energy and nutrients to grow and maintain that bone, so “it follows that it wouldn’t have evolved unless [the kangaroos] really needed it to bite hard into at least some more resistant foods that were important in their diets.”
For the study, Dr. Mitchell created three-dimensional models from scans of a well-represented species of short-faced kangaroo, Simosthenurus occidentalis. This species is estimated to have lived up to 42,000 years ago and grow up to 120 kg in adulthood. Using the models, Mitchell examined the biomechanical performance of the skull’s bites and compared them to koalas, which have a similar skull shape.
Based on the skulls’ structure, Dr. Mitchell estimates that the short-faced kangaroo was much more vulnerable to injury than today’s koalas when biting with their back teeth. However, he also says that this risk would be greatly reduced if a muscle located on the inner surface of the kangaroo’s cheekbones was enlarged. That feature — the enlarged muscle — is seen on the giant panda, who feeds on thick and resilient bamboo.
The short-faced kangaroo model could also withstand twisting of the skull much more effectively than that of a koala during hard biting on one side of the mouth. This supports the view that the toughest vegetation it could eat — such as the woody twigs and branches of trees and shrubs — may have been fed directly to its premolars and molars to be crushed or otherwise broken apart (similar to how giant pandas chew bamboo).
“The skull of the extinct kangaroo studied here differs from those of today’s kangaroos in many of the ways a giant panda’s skull differs from other bears,” says Dr. Mitchell. “It makes sense that the strange skull of this kangaroo was, functionally speaking, less like a modern-day kangaroo’s and more like a giant panda’s.”
The paper “The anatomy of a crushing bite: the specialised cranial mechanics of a giant extinct kangaroo” has been published in the journal PLOS ONE.
About 15,000 years ago, changes in ocean circulation caused the North Pacific Ocean to discharge copious amounts of CO2 into the atmosphere, thereby warming the planet and sealing the end of the last Ice Age. The findings could prove highly important for managing and mitigating current climate change trends.
Credit: University of St Andrews.
Researchers studied the chemical composition of the fossilized shells of a type of plankton called foraminifera — some of the most abundant shelled organisms in many marine environments. This allowed British scientists at the University of St Andrews to reconstruct the exchange of CO2 between the North Pacific Ocean and the atmosphere. The analysis showed that around the end of the last Ice Age, the North Pacific released large amounts of CO2 during a time when the Atlantic ocean’s currents were rapidly changing.
The shift in ocean circulation not only explains the considerable release of CO2 by the North Pacific, which eventually helped end the Ice Age by warming the entire planet, but also the drop in oxygen levels in the Pacific Ocean seen at the time and first observed nearly two decades ago.
The findings have huge implications for climate research today. Just last week, scientists at the University College London reported that the Atlantic’s circulation is at its weakest point in 1,600 years, a trend that could disrupt weather patterns all the way from the United States to the African Sahel. The 15% slowdown, compared to peak circulation, is equivalent to three million cubic meters of water per second — water movement that is connected to fish stocks, industry and weather systems.
The link between ocean currents and very rapid changes in the climate, identified by the new study, gives us an example of just how intricately connected different parts of the climate system can be. In other words, “changes in circulation in one region can drive changes in CO2 and oxygen all the way over on the other side of the planet,” said Dr. Will Gray, lead author of the new study and a researcher at the School of Earth and Environmental Sciences, University of St Andrews.
“The North Pacific Ocean is very big and just below the surface the waters are brimming with CO2; because of this, we really need to understand how this region can change in the future, and looking into the past is a good way to do that,” Gray added.
Co-author Dr. James Rae, also from the University of St Andrews, added: “Although the CO2 rise caused by this process was dramatic in geological terms, it happened very slowly compared to modern man-made CO2 rise. Humans have driven CO2 rise in the atmosphere as large as the CO2 rise that helped end the last Ice Age, but the man-made CO2 rise has happened 100 times faster. This will have a huge effect on the climate system, and one that we are only just beginning to see.”
Scientific reference: William R. Gray et al. Deglacial upwelling, productivity and CO2 outgassing in the North Pacific Ocean, Nature Geoscience (2018). DOI: 10.1038/s41561-018-0108-6.
A new paper showcases the massive effect CO2 levels in the atmosphere have on Earth’s climate, describing its link to the great cooling period in the Carboniferous and Permian ages.
Image credits Kevin Gill / Flickr.
We call it a ‘greenhouse’ gas for a reason. Today, it’s most widely known for the part it plays in climate change — but 300 million years ago, CO2 was involved in one of the most severe cooling events in Earth’s history. Using a large ensemble of computer simulations, Georg Feulner from the Potsdam Institute for Climate Impact Research was able to model how coal formation in the late Paleozoic came inches away of locking Earth into a ‘snowball state’.
A leaky greenhouse
In the very distant geological past, Earth was a much warmer place. Overall, it had a more uniform, tropical, humid climate than exists today, and plant life was going rampant. Vegetation resembled what you’d expect to see in a jungle setting today, but even more bountiful. Trees especially (they were still recent-ish technology at the time) were turbocharged by warm temperatures and swampy environments, growing to huge sizes. They lacked tree-rings, suggesting they could sustain growth throughout the year. All off this eventually led to Pangea (the only continent at the time) becoming plastered with immense quantities of biomatter. Some 300 million years ago,
One unexpected side-effect of all this coal being formed, however, was that CO2 in the atmosphere was increasingly sequestered underground. Because of this, the Earth began to rapidly cool down. By the end of the Carboniferous, a full-fledged Ice Age had developed, one which came very close to lock our planet in a permanently frozen state.
“This illustrates the enormous dimension of the coal issue,” Feulner says. “The amount of CO2 stored in Earth’s coal reserves was once big enough to push our climate out of balance. When released by burning the coal, the CO2 is again destabilizing the Earth system.”
His research shows that some of the changes in temperature at the time can be attributed to other planetary factors, such as the axis tilt and the planet’s orbit. However, it also shows that CO2 concentrations in the atmosphere played the prime role in shaping the climate during the Carboniferous. Estimates drawn from samples of ancient soils and leaves show that CO2 levels fluctuated widely during this period, at one point dipping to about 100 parts per million (ppm) in the atmosphere — which is extremely low. Feulner’s models show that when atmospheric CO2 levels dip under 40 ppm, global glaciation is virtually guaranteed.
The flipside of Feulner’s findings is that burning coal today releases the CO2 captured over 300 million years ago. Today, we’re past the 400 ppm mark, which is above the 350 ppm deemed safe by the ICCP, but still under 450 ppm — a point where our chances of stabilizing the climate before planetary-scale irreversible damage is done are basically 50-50.
That’s because CO2 traps incoming heat in the Earth’s atmosphere, warming up the planet. Higher concentrations mean a higher percentage of incoming energy is trapped.
“It is quite an irony that forming the coal that today is a major factor for dangerous global warming once almost lead to global glaciation,” Feulner adds. “We should definitely keep CO2 levels in the atmosphere below 450 parts per million to keep our climate stable, and ideally much lower than that. Raising the amount of greenhouse gases beyond that limit means pushing ourselves out of the safe operating space of Earth.”
“Earth’s past teaches us that periods of rapid warming were often associated with mass extinction events. This shows that a stable climate is something to appreciate and protect.”
The paper “Formation of most of our coal brought Earth close to global glaciation” has been published in the journal PNAS.
For those days when arthritis, here’s something to keep in mind: at one point in human history, it may have been the thing that kept early Europeans alive.
Image via Pixabay.
Roughly one-half of all Europeans living today carry a variant of the GDF5 gene which nearly doubles the chance of arthritis popping up in our golden years. People from other areas of the world have it too, but in much lower percentages of the population — so what gives?
Well, achy joints may have kept the early settlers of Europe survive frostbite and prevent fractures in the new, colder climate, researchers from the US report.
Little cavemen, short and stout
The same GDF5 variant which increases the likelihood of arthritis also seems to shave roughly 1 cm in the height of people who harbor it. So why on Earth would a gene that makes you shorter and ultimately less mobile not only persist but actually proliferate in a population?
Well, it’s all about context. While those traits above are arguably disadvantages when trying to secure a mate or going about your Stone Age day, they can also help a population recently moved out of Africa better adapt to the freezing northern territories of Europe. Being short and stocky makes it easier to retain heat in cold weather, and as the old saying informs us, the shorter you are the more lightly you fall — so you’re at less of a risk of fracturing bones in the process, a life-threatening experience back in those days.
As for the evolutionary costs, arthritis may actually carry less than you’d initially assume. As the condition usually develops past reproductive ages, it didn’t actually impair people’s ability to have babies. In other words, it brought more to the table than it took — so the gene got passed down.
“This gene variant is present in billions of people, and it’s likely responsible for millions of cases of arthritis around the globe” says Dr David Kingsley, Professor of developmental biology at Stanford University and paper co-author.
“Many people think of osteoarthritis as a kind of wear-and-tear disease, but there’s clearly a genetic component at work here as well. It’s possible that climbing around in cold environments was enough of a risk factor to select for a protective variant even if it brought along an increased likelihood of an age-related disease like arthritis, which typically doesn’t develop until late in life.”
The link between arthritis and GDF5 was first established back in the 1990s, and since then research has also linked its expression to a genetic mechanism called GROW1, which signals the gene to turn off bone growth.
The team analyzed the genomes of people from across the world who submitted their genetic material to the 1,000 Genomes project. They noticed that the genetic variant and the mechanism for switching off bone growth was far more common in populations from Europe or those of European descent. In much warmer places, such as Africa for example, the gene variant was extremely rare in the overall population.
The gene variant also seems to have been pretty common in Neanderthals and Denisovans, who inhabited Europe and Asia for about 600,000 years before modern humans came around and drove them extinct — in fact, it’s likely that Europeans today inherited the gene from these initial populations.
Of course, while it could have saved our ancestors during the Ice Age, arthritis may be overstaying its welcome today.
“The variant that decreases height is lowering the activity of GDF5 in the growth plates of the bone,” said Dr Terence Capellini, associate professor of human evolutionary biology at Harvard University and first author of the paper.
“Interestingly, the region that harbors this variant is closely linked to other mutations that affect GDF5 activity in the joints, increasing the risk of osteoarthritis in the knee and hip.”
The paper “Ancient selection for derived alleles at a GDF5 enhancer influencing human growth and osteoarthritis risk” has been published in the journal Nature Genetics.
Ancient shifts in climate may have powered the baleen whale’s growth to such “ginormous” sizes, a new paper reports.
“Ginormous” seems rather fitting.
With some individuals growing to be the length of an average basketball court and weighing upwards of 200,000 kilograms (441,000 pounds), the blue whale is big fry indeed — in fact, they’re believed to be one of the largest animals that have ever lived on Earth. Which naturally begs the question of what led them, and their kin, to grow to such proportions.
[Turns out that a long time ago, a larger-than-whales dinosaur roamed the Earth. Why not read about it?]
Up to now, biologists have had (and debated over) two main theories in regards to why. The first one is that whales simply grew because they could, as water provides a lot of buoyancy for their bodies. So although they’d weigh a lot on dry land, way too much to be able to even move, they’re pretty nippy underwater and can still catch prey quite easily. The other theory is that the whales grew out of necessity, as their monumental size made them virtually immune to the attacks of giant sharks or other mega-predators.
Another point of interest is when they got so large. One paper published in 2010 under the lead of Graham Slater, an evolutionary biologist currently at the University of Chicago in Illinois, estimates that cetaceans (the whale’s extended family) split into size groups around 30 million years ago. It’s a lineage that still holds today, the paper argues — so the baleen whales trace their ancestry to the giant group, predatory whales (such as the beaked whale) hail from the middle-sized group, and dolphins from the runts of the litter, becoming the smallest of cetaceans.
A new paper however could address both questions in one single swoop. Penned by Slater alongside Nicholas Pyenson, a whale expert at the Smithsonian Institution’s National Museum of Natural History in Washington D.C., and Jeremy Goldbogen at Stanford University in Palo Alto, California, the paper proposes that the whales’ size is a product of environmental stresses associated with global cooling in the Neogene some 4,5 million years ago.
The paper started taking shape a few years ago when Pyenson and Slater started working with the museum’s cetacean fossil collection to see if the diverging lineages theory holds water. Previously, Pyenson studied living whale populations to determine that a whale’s total size correlated well with the width of its cheekbones. So the duo gathered this numbers for 63 extinct whale species and 13 contemporary ones and plotted these values over the family’s timeline.
The trend showed that there weren’t any big whales early on, contradicting Slater’s earlier theory. There wasn’t any gradual increase in size over time, either — instead, what the team saw was that whales became moderately large and stayed so up until about 4.5 million years ago. After this, baleen whales suddenly grew “from relatively big to ginormous,” Slater says.
In case you’re not familiar with the ginormity scale, whales 4.5 million years ago clocked in at around 10 meters (about 32.5 feet) long — whereas today’s blue whales grow to around 30 meters (98.5 feet). So evolutionary speaking, the whales’ size is a pretty recent development.
Long road, big fins
The next step was to look at the going-ons of the time to see what caused this very dramatic, 300% increase in size. The team found that the growth coincided with the beginning of the first ice ages. They explain that the colder climate lead to an increase in glacier cover which would melt during the warmer months of spring and summer, sending cold sediment (and nutrient) rich runoff into coastal waters which supported plankton and zooplankton (who like cold waters) blooms — which the whales were more than happy to dine on.
The problem was that until then, this krill was evenly distributed in the oceans and relatively plentiful, so the whales could go anywhere they pleased and dinner would be waiting for them. But climate change killed off most of the ocean biosphere at the time (ironic isn’t it) and severely weakened existing ecosystems, drastically lowering primary and secondary productivity (the rate at which plants turn sunlight into organic compounds, and the rate at which animals turn plant matter into their own biomass respectively).
Combined, this changed the pattern of food availability from “decent food pretty much anywhere” to “truckloads of food in far-apart areas at certain times during the year,” and the whales had to adapt. Goldbogen, who studies whale eating and diving behavior, helped explain the link between food availability and size. The more concentrated food becomes, larger whales with really big mouths gain a huge boost to feeding efficiency, he says. Moreover, larger whales could travel between feeding areas faster and with less effort than smaller ones.
Overall, these two factors put huge selective pressures on growing larger frames, so the bigger species thrived while smaller whales went extinct.
The paper, while not being the first to show how food and feeding habits shaped whale evolution, does offer a simple and pretty elegant explanation for the whales’ size. It also goes to show that evolution is powered by an interplay of factors, from climate to the way other species adapt to present conditions. And finally, it shows that a species’ adaptation to one particular constraint — in the whales’ case, food availability — can inadvertently address some of its other needs — such as safety from predators — or provide an unexpected boon to ecosystems.
The full paper “Independent evolution of baleen whale gigantism linked to Plio-Pleistocene ocean dynamics” has been published in the journal Proceedings of the Royal Society B.
Once any ice age is over, the increased surface temperature causes the ice caps to melt which lessens the pressure on the mantle and causing increased volcanic activity. A paper published by a team from the University of Cambridge found that erosion also plays a major role and can be just as important as melting ice caps. Since erosion is largely ignored by climate models, it may be that scientists underestimated CO2 levels following ice ages.
If we’re to look over the past million years only, we’ll notice that the planet has shifted numerous times between ice ages or glacial periods, and interglacial periods — the one we’re in now. Each of this period roughly lasts 100,000 years and is characterized by two major sub-periods: that of advancing and retreating ice. While it takes about 80,000 years for an ice age to kick in, deglaciation only lasts 20,000 years.
There are several factors that cause warming or, oppositely, cooling. Many of them are related to Earth’s orbital parameters, but this obviously can’t explain why warming happens so much faster than cooling. It has something to do with Earth’s system, and rising CO2 levels from volcanic eruptions definitely have a word to say. Lack of pressure from melting ice caps means volcanoes are freer to erupt. However, moving from an ice age to an interglacial period causes erosion to increase, as the numerical simulations performed by the researchers show.
A 3D model simulation of a glaciation on the Villarrica Volcano in Chile. Credit: Pietro Sternai.
As glaciers melt, the ground beneath is eroded by as much as ten centimetres per year, further decreasing the pressure on the volcano and increasing the likelihood of an eruption. The researchers claim erosion is just as important in driving volcanic activity as melting ice, they report inGeophysical Research Letters.The findings provide “an additional step towards a more general understanding of the links between a changing climate, glacial processes and the melting of the solid Earth,” the researchers conclude.
“It’s been established that melting ice caps and volcanic activity are linked – but what we’ve found is that erosion also plays a key role in the cycle,” said Dr Pietro Sternai of Cambridge’s Department of Earth Sciences, the paper’s lead author, who is also a member of Caltech’s Division of Geological and Planetary Science. “Previous attempts to model the huge increase in atmospheric CO2at the end of the last ice age failed to account for the role of erosion, meaning that CO2 levels may have been seriously underestimated.”
They like freezing conditions, but the Emperor penguins struggled during the last Ice Age, a new study concluded. In fact, if they hadn’t been able to change their breeding habits and even their genetic make-up, they might have not survived.
Emperor penguins. Image via Wiki Commons.
The Emperor penguin is the tallest and heaviest penguin on Earth, and it’s endemic to Antarctica. Reaching 1,22 meters (4 feet), it’s truly worthy of its royal name. But it’s a tough life being a penguin, and it was even harder during the last Ice Age. Back then, 30,000 years ago, ice covered much more sea than it does today, which mean that penguins could only breed in a few special locations.
“The distances from the open ocean, where the penguins feed, to the stable sea ice, where they breed, was probably too far. The three populations that did manage to survive may have done so by breeding near to polynyas – areas of ocean that are kept free of sea ice by wind and currents,” said Gemma Clucas from University of Southampton, one of the researchers.
By examining the genetic diversity of both ancient and modern Emperor penguins, scientists from the universities of Tasmania, Southampton and Oxford in Britain, and the Australian Antarctic Division were able to get a pretty good picture of how their numbers varied in time. At one moment, it’s estimated that there were only three populations living in the Antarctic.
“We hadn’t really thought about the fact that it would be too cold for them in the past,” said Jane Younger, a PhD student at the University of Tasmania who was also involved in the study. “They live through life in minus 30 degrees Celsius (-22 Fahrenheit) now so they are pretty cold adapted.”
They would have likely gone extinct if the ice age hadn’t waned away. As the temperatures slowly started to rise 12,000 years ago, penguin chicks had a better chance of surviving the winter, and more potential breeding sites opened up. Paradoxally, it’s the extremely low temperatures which they are so well adapted to that might have killed them.
“We were actually really surprised by this. What we had thought was that the ice age, because there was so much more sea ice, which they need (to breed), and because they are so cold-adapted, that this would probably be a good thing for them,” Younger said.
In their study, one notable area is the Ross sea – a population survived at Ross sea because an area of ocean was always kept free of sea ice by wind and currents, allowing the penguins to feed and breed.
“The Ross Sea is probably really important,” said Younger of the area on the Pacific Ocean side of Antarctica, which is considered the world’s most intact marine ecosystem. They have survived there for at least the last 30,000 years and even when the environment has been really unsuitable in a lot of other places, the Ross Sea has been kind of a safe haven for them. The Ross Sea seems to come up time and time again as a really important part of the Antarctic ecosystem.”
Journal Reference: Jane L. Younger, Gemma V. Clucas, Gerald Kooyman, Barbara Wienecke, Alex D. Rogers4, Philip N. Trathan, Tom Hart and Karen J. Miller. Too much of a good thing: sea ice extent may have forced emperor penguins into refugia during the last glacial maximum. DOI: 10.1111/gcb.12882
The high temperatures of the meteorite impact 12,900 years ago produced mm-sized spherules of melted glass with the mullite and corundum crystal structure shown here Photographed by: Mukul Sharma
A recent study has revived an older controversy, after Dartmouth Professor Mukul Sharma and his team reported what they claim is the first conclusive evidence that links an extraterrestrial impact in Canada with the beginning of the Younger Dryas, a period of abrupt climate change that caused major cooling through the Earth. During this time, a number of species became extinct and the human hunger-gatherer population transitioned to an agricultural based lifestyle.
In the 1.5-billion-year-old Quebecia terrane in northeastern Canada, near the Gulf of Saint Lawrence and modern day Quebec, researchers believe a comet or meteor impact took place, after at they analyzed the chemical composition of spherules discovered at the location (droplets of solidified molten rock expelled by the impact of a comet or meteor). The chemical composition matched those of spherules deposited in Pennsylvania and New Jersey at the start of the Younger Dryas period.
The Younger Dryas or the Big Freeze as its also been called began some 12,900 years ago and enveloped the world in a short lasting (in geological terms – some 1,000 years) glacial period. During this time, a number of species became extinct, including saber-toothed cats, giant sloths, and mastodons. The same event marked the end of the Clovis hunter-gatherer culture in favor of the adoption of farming and animal husbandry, as supported by evidence dated from the time collected from the Near East – coincidentally or not the region was also home to the earliest city settlements we know of (Ur, Uruk).
“The Younger Dryas cooling impacted human history in a profound manner,” says Dartmouth Professor Mukul Sharma, a co-author of the study. “Environmental stresses may also have caused Natufians in the Near East to settle down for the first time and pursue agriculture.”
The newly discovered spherules do not originate from the 4km-wide Corossal crater – a known impact crater in Quebec. This fact leads the researchers to conclude that a series of comet or meteor impacts caused the beginning of the Younger Dryas 12,900 years ago. The meteor/compact impact theory sparking the Younger Dryas isn’t new and has for a long time been contested. The current accept theory is that an ice dam rupture released huge amounts of freshwater into the Atlantic. This in turn was thought to have shut down ocean currents moving warm tropical water, resulting in colder conditions.
“It may well have taken multiple concurrent impacts to bring about the extensive environmental changes of the Younger Dryas,” says Sharma. “However, to date no impact craters have been found and our research will help track one of them down.”
Worth noting is that ZME Science reported earlier of a newly discovered meteor impact site in Mexico dating from 13,000 years ago, where an eclectic geological mix of materials, including nanodiamonds, impact spherules, and more, which, according to the researchers, are the result of a cosmic body impacting Earth. Apart from the Mexican site, the researchers also identified sediment layers of the same age, dating back 13,000 years ago, in Canada, the United States, Russia, Syria and various sites in Europe.
One of the pottery fragments recovered from a layer dating approximately 20,000 years old in the Xianrendong cave in south China’s Jiangxi province. This makes it the oldest known pottery in the world. (C) Science/AAAS)/AP
In a fantastic discovery, a team of Chinese and US archaeologists have come across fragments belonging to a 20,000 year-old bowl in modern day China, confirmed as the earliest evidence of pottery. The findings push back the invention of pottery by 10,000 years and suggest that human were more socially advanced than previously thought.
The pottery fragments were discovered in Xianrendong Cave, Jiangxi Province, and it is believed the bowl was a cauldron to cook food, or quite possibly to brew alcohol. Previously, scientists used to believe the invention of pottery correlates to the period about 10,000 years ago when humans moved from being hunter-gathers to farmers.
This latest discovery pushes the invention of pottery back to the last ice age, which might provide new explanations for the creation of pottery, said Gideon Shelach, chair of the Louis Frieberg Center for East Asian Studies at The Hebrew University in Israel.
“Hunter-gatherers were under pressure to get enough food,” he told BBC News.
“If the invention is a good one, it spreads pretty fast. And it seems that in that part of southern China, pottery spread among hunter-gatherers in a large area,” said lead researcher, Prof Ofer Bar-Yosef of Harvard University.
In an accompanying Science article, Shelach wrote that such research efforts “are fundamental for a better understanding of socio-economic change (25,000 to 19,000 years ago) and the development that led to the emergency of sedentary agricultural societies.”
Earliest pottery used to brew alcohol?
Shelach also speculates that the invention of pottery may have been sparked by the need for a recipient for brewing alcohol – a social-driver.
“People were gathering together in larger groups and you needed social activities to mitigate against increased tensions,” he told BBC News.
“Maybe those potteries were used to brew alcohol.
Pottery emerged in Europe thousands of years later
“It used to be thought that the beginning of pottery was associated with agriculture and sedentary lifestyle,” he added.
“Yet here we find it 8,000 years or more before this transition. This is a very puzzling situation.”
In the darkest caves of southwest China, one can experience fragments of the long set Ice Age and travel back in time 30,000 years. No, there isn’t any time machine or stargate of some sort (scientists say time travel is impossible, I beg to differ), instead what you’ll find in one of the darkest corners of the Earth is an ecosystem so perfectly preserved, that its vegetation is practically unchanged since the last ice age.
A simple nettle. This one has plenty of light, though.
Part of a joint scientific effort between researchers from southwest China and UK, scientists have identified seven species of nettle that grow in isolated, dark corners of the karst landscapes of Guangxi and Yunnan provinces. The nettles are only found in the darkest corners of the provinces’ caves and gorges, places where barely any sunlight ever shines. In fact, some survive in conditions in which just 0.02 per cent of sunlight penetrates the cave, a characteristic similar only to deep ocean vegetation.
Actually, one of the discovered species, Elatostema retrorstrigulosum, is limited to only 10 adult plants, which makes it “critically endangered” under the criteria of the International Union for Conservation of Nature.
“They grow at the backs of the main caverns in near-dark conditions. There must be something quite special about their photosynthesis. They probably activate the photosynthetic process very quickly, which enables them to take advantage of very short bursts of light, and they might go for slightly different wavelengths. [They could be] relics of a vegetation from a previous cooler climate that resembled that of the caves, ” says Natural History Museum researcher Alex Monro.
The last part is the most interesting of course. You see, all around these caves one can find typical tropical vegetation, where as the vegetation found in these caves is totally opposite from any specs one might expect to find.
It’s conceivable that the nettles evolved completely independently of the surrounding area, meaning they arose independently in the cave. The only problem with this hypothesis is that the cave is only 1 million years old, too short of a period on the evolutionary scale, so this assumptions kinda falls off the table. The only other possible explination is that they’re actually “relicts of a vegetation from a previous cooler climate that resembled that of the caves”, as Monro suggests. There you have it, 30.000 years and nothing’s changed. Mammoths, anyone?
Global warming is one of the main concerns on everybody’s lips, causing more and more damage to the environment every year, sometimes in ways that seem hard to believe; everyday there seems to be a new report about something that went, is going, or will be going terribly wrong. However, in the early 1800s, the situation was in diametric contradiction with everybody being worried about a global cooling that seemed to come out of nowhere.
It all peaked in 1816, when in most places of the world there was actually no summer at all ! That year’s chill was blamed by climatologists on the eruption of the Indonesian volcano called Tambora, but why the few years before 1816 were also way colder than usually remained a mystery. However, newly uncovered evidence from the ice of Antarctica and Greenland suggests that another volcanic eruption was probably responsible for it.
Jihong Cole-Dai, a chemistry professor at South Dakota State University led the expeditions that cleared this intriguing question that seemed to be without an answer. He found evidence of another eruption some 6 years before the 1815 one (which was responsible for the 1816 cooling). Here’s why major volcano eruptions have such a big influence: they practically dump immense quantities of sulfur dioxide and ash that act pretty much like an umbrella, shading the Earth and reflecting sunlight for several years.
However, it’s obvious that a single volcanic eruption couldn’t be responsible for ‘freezing’ a whole decade. Cole-Dai and his team found evidence of one more eruption that helped trigger the mini ice age. However, they weren’t able to pinpoint the volcano, saying that they only know it has to be somewhere close to the equator and really big. I don’t know for sure but I’m guessing that a more detailed analysis will give some more clues regarding this volcano and researchers will be able to find it, despite the fact that it seems to be a ‘needle in the haystack’ kind of search.
An amateur Dutch archaeologist named Jan Meulmeester made a startling find which pleases scientists: an amazing collection of 28 flint hand-axes, dated by archaeologists to be around 100,000 years-old. He found them in an area about 13km off Great Yarmouth.
Jan Meulmeester diggs regularly for mammoth bones and fossils in marine sand and gravel delivered the materials, but nobody expected him to find something of this significance. These are the finest hand axes ever to be found from the Ice Age and from the English waters. Phil Harding of Wessex Archaeology and Channel 4’s Time Team programme has studied the Ice Age for a big part of his life. His claim on the issue:
“These finds are massively important. In the Ice Age the cold conditions meant that water was locked up in the ice caps. The sea level was lower then, so in some places what is now the seabed was dry land. The hand-axes would have been used by hunters in butchering the carcasses of animals like mammoths.”
He added: “Although we don’t yet know their precise date, we can say that these hand-axes are the single most important find of Ice Age material from below the North Sea.”
The fact that mammoth teeth and bones were discovered along with the axes seems to support his ideas. The findings were made public by Wessex Archaeology. Also, Ian Oxley, Head of Maritime Archaeology at English Heritage points out the importance of these findings:
“These are exciting finds which help us gain a greater understanding of The North Sea at a time when it was land. We know people were living out there before Britain became an island, but sites actually proving this are rare.”
There have been many climatic shifts throughout the geologic period of our time. The abrupt climate change events that occurred thousands of years ago are very important to us because they took place closer to this day and so there is a greater chance of repeatability. We must understand that in order to prevent it from happening again or be ready should it happen again.
So paleoclimatologists analyze glaciers and the icy plains trying to find clues about what happened and the factors that made it happen. But Georgia Tech Assistant Professor Kim Cobb and graduate student Jud Partin did something more creative than that: they went underground.
They claim that inside the caves of the tropical Pacific island of Borneo are some of the keys to understanding how the Earth’s climate suddenly changed – several times – over the last 25,000 years. They do that by studying the pilar-like rock formations that stem from the ground in caves. Those are called stalagmites. They are formed due to the dripping of mineralized solutions and the deposition of calcium carbonate so it makes sense that they hold clues.
“These stalagmites are, in essence, tropical ice cores forming over thousands of years,” said Partin. “Each layer of the rock contains important chemical traces that help us determine what was going on in the climate thousands of years ago, much like the ice cores drilled from Greenland or Antarctica.”. The tropical Pacific plays a very important role in the climate variations around the globe. Just look at Pacific’s El Nino and the numerous weather patterns it influences. But it is harder to say what role it played those years ago.
Partin and Cobb cut open each stalagmite and took 1,300 measurements of their chemical content to determine the relative moisture of the climate at various periods in history starting from the oldest layers at the bottom to the present at the top.
“Currently our knowledge of how these dramatic climate changes occurred comes from just a few sites,” said Cobb. “As more studies are done from caves around the world, hopefully we’ll be able to piece together a more complete picture of these changes. Understanding how the dominoes fell is very important to our understanding of our current warming trend.”. “In addition, the Borneo records indicate that the tropical Pacific began to get wetter before the North Atlantic recovered from the Heinrich 1 event 14,000 years ago. Perhaps the tropical Pacific is again driving that trend,” said Partin.
Their results are published in the 2007 issue of the journal Nature and they show great promise.