Tag Archives: hominid

Running man.

One broken gene made us very good runners

A genetic fluke two to three million years ago turned humans into the best endurance runners around.

Running man.

Image via Pixabay.

A new paper published by researchers from the University of California San Diego School of Medicine reports that our ancestors’ functional loss of one gene called CMAH dramatically shifted our species’ evolutionary path. The loss altered significant metabolic processes, with impacts on fertility rates and risk of developing cancer.

The same change may have also made humans one of the best long-distance runners on Earth, the team adds.

These genes were made for runnin’

Our ancestors were presumably quite busy two to three million years ago transitioning from living in trees to live on the savannah. They were able to walk upright by this time, but they weren’t particularly good at it.

However, soon after this, some of our ancestors’ physiology starts undergoing some striking changes. Most relevant are shifts we see in their skeletons, resulting in long legs, big feet, and large gluteal muscles (butts) — all very good for walking around. These shifts were also accompanied by the evolution of sweat glands with much the same layout and capacity as ours which, according to the team, is quite expansive and much better at dissipating heat than that of other large mammals.

In other words, humanity received powerful legs and one of the most solid cooling systems in one fell swoop.

Our ancestors proceeded to use their new toys to hunt and eat anything they could bring down. They did so by adopting a hunting pattern unique among primates (and very rare among animals in general) known as persistence hunting: they would go out in the heat of the day, when other carnivores were resting, relying on their legs and sweat glands to chase prey until — exhausted and overheated — it couldn’t physically run away anymore.

We didn’t know much about the biological changes that underpinned this radical change, however. The first clues were uncovered around 20 years ago — when Ajit Varki, a physician-scientist at the University of California, San Diego (UCSD), and colleagues unearthed one of the first genetic differences between humans and chimps: a gene called CMP-Neu5Ac Hydroxylase (CMAH). Other species of primates also have this gene.

We, however, have a broken version of CMAH. Varki’s team calculated that this genetic change happened 2 million to 3 million years ago, based on the genetic differences among primates and other animals.

More recent research has shown that mice models with a muscular dystrophy-like syndrome exhibit more acute symptoms when this gene is inactivated. This hinted to Varki that the faulty gene might be what led to the changes our ancestors experienced in the savannahs.

“Since the mice were also more prone to muscle dystrophy, I had a hunch that there was a connection to the increased long distance running and endurance of Homo,” said Varki.

UCSD graduate student Jonathan Okerblom, the study’s first author, put the theory to the test. He built mouse running wheels, borrowed a mouse treadmill, and pitted mice with a normal and broken version of CMAH to the task.

“We evaluated the exercise capacity (of mice lacking the CMAH gene), and noted an increased performance during treadmill testing and after 15 days of voluntary wheel running,” Okerblom explained.

The two then consulted Ellen Breen, Ph.D., a research scientist in the division of physiology, part of the Department of Medicine in the UC San Diego School of Medicine. She examined the mice’s leg muscles before and after running different distances, some after 2 weeks and some after 1 month.

After training, mice with the human-like version of CMAH ran 12% faster and 20% longer than the other mice, the team reports. Breen adds that the mice displayed greater resistance to fatigue, increased mitochondrial respiration and hind-limb muscle, with more capillaries to increase blood and oxygen supply. Taken together, Varki says the data suggest CMAH loss contributed to improved skeletal muscle capacity for oxygen utilization.

“And if the findings translate to humans, they may have provided early hominids with a selective advantage in their move from trees to becoming permanent hunter-gatherers on the open range.”

The most likely cause of this change was evolutionary pressures associated with an ancient pathogen, the team explains.

The version of the gene we carry determines the loss of a sialic acid called N-glycolylneuraminic acid (Neu5Gc), and accumulation of its precursor, called N-acetylneuraminic acid or Neu5Ac, which differs by only a single oxygen atom. Sialic acids serve as vital contact points for cell-to-cell interaction and cellular interactions with the surrounding environment. This change likely led to enhanced innate immunity in early hominids, according to past research.

Sialic acids may also be a biomarker for cancer risk, and the team has also reported that certain sialic acids are associated with increased risk of type 2 diabetes; may contribute to elevated cancer risk associated with red meat consumption, and trigger inflammation.

“They are a double-edged sword,” said Varki. “The consequence of a single lost gene and a small molecular change that appears to have profoundly altered human biology and abilities going back to our origins.”

The paper “Human-like Cmah inactivation in mice increases running endurance and decreases muscle fatigability: implications for human evolution” has been published in the journal Proceedings of the Royal Society B.

P. robustus skull.

One of our extinct ancient relatives developed a chewing pattern unique among primates

Not all human ancestors chewed the same way, new research reveals.

P. robustus skull.

Paranthropus robustus fossil from South Africa SK 46 (discovered 1936, estimated age 1.9-1.5 million years) and the virtually reconstructed first upper molar used in the analyses.
Image credits Kornelius Kupczik / Max Planck Institute for Evolutionary Anthropology.

While we’re the only one that made it up to the present, we’re by no means the only species of hominins — the evolutionary group that includes modern humans and now-extinct bipedal relatives — that popped up throughout history. At least one of our human ancestors, new research shows, developed a unique way to chew.

Ancient chow

Being able to properly chew your food is a matter of life and death. It helps break food down into tiny pieces so they can be swallowed and digested. But every species has its own way of going about it — based on their diet and individual morphology.

You can learn a lot about an animal by looking at what it eats and the way it chews on it, and that stands true for humans as well as wildlife. Palaeoanthropologists go to great lengths to reconstruct the diets of ancient hominid species, as diet underpins our evolutionary history. A high-quality diet, for example, coupled with meat-eating, provided the nutrients that modern humans needed to develop our big brains. Some of our hominin relatives, by contrast, likely went extinct because of their diets (for example, the Neanderthals).

Two extinct hominin lineages — Australopithecus africanus and Paranthropus robustus — have constantly sparked debate in regards to their diet since their discovery. An international team of researchers, led by members from the Max Planck Institute for Evolutionary Anthropology, studied the splay and orientation of their fossil tooth roots in an attempt to settle the debate once and for all. Their findings surprisingly reveal that P. robustus employed a unique way of chewing food — one that hasn’t been seen in any other hominin species to date.

The team used high-resolution computed tomography and shape analysis to determine how teeth roots were oriented within the jaw of ancient hominin lineages. Based on this information, they then gauged the direction of the load during mastication — i.e. the direction force was applied while they chewed.

By comparing the virtual reconstructions of 30 hominin first molars from lineages in South and East Africa, the team found that Australopithecus africanus had much more widely-splayed roots than either Paranthropus robustus or the East African hominin Paranthropus boisei. This yielded a surprising revelation about P. robustus.

“This is indicative of increased laterally-directed chewing loads in Australopithecus africanus, while the two Paranthropus species experienced rather vertical loads,” says Kornelius Kupczik of the Max Planck Institute for Evolutionary Anthropology, first author of the paper.

Unlike all other hominins involved in the study, P. robustus showed a ‘twist’ in the roots of their teeth — suggesting a slight rotational and back-and-forth movement while chewing, the team explains. Other characteristics of their skulls support this observation, they add: the structure of the enamel also points towards a complex, multi-directional motion. Microwear patterns in the enamel (which the team reports are “unique among primates”) also point to a different motion of the jaw while masticating compared to how we do it, for example.

While diet also has a major part to play in shaping our and P. robustus‘ skulls, as well as in the patters of wear observable on their teeth, the team says dietary differences alone cannot account for all that they’re seeing.

“Perhaps palaeoanthropologists have not always been asking the right questions of the fossil record: rather than focusing on what our extinct cousins ate, we should equally pay attention to how they masticated their foods,” concludes co-author Gabriele Macho of the University of Oxford.

The research could have implications beyond paleoanthropology, the team explains. By studying the particularities of P. robustus‘ morphology, its mastication patterns, and its effect on the lineage’s teeth, “we can eventually apply such findings to the modern human dentition to better understand pathologies such as malocclusions,” explains co-author Viviana Toro-Ibacache.

The paper “On the relationship between maxillary molar root shape and jaw kinematics in Australopithecus africanus and Paranthropus robustus” has been published in the journal Royal Society Open Science.

Early human ancestors may not have passed down knowledge but simply crafted tools on instinct

Starting from a fist-size rock shaped into a tool in the early stone age, a new paper challenges the view that cultural transmission goes back for more than 2 million years.

Idea.

Image credits Tero Vesalainen.

Common wisdom holds that humanity owes its success to our ability to share information. Living in today’s world, where we have almost instant access to immense volumes of information through conversation, texts, advertising, the internet, it’s easy to see why.

It’s a process anthropologists call cultural transmission, and there was a time where people simply didn’t pass information along. We don’t exactly know when the switch took place, but it’s generally believed to have happened more than 2 million years ago. Now, a team led by Claudio Tennie, Research Group Leader in the Department for Early Prehistory and Quaternary Ecology of the University of Tübingen comes to challenge that view.

Rock’a’chopper

The paper first debates the Oldowan chopper hypothesis. The term “Oldowan” is used to denote your entry-level stone-age technology. It’s represented by fist-sized rocks that are smooth on one side and had just enough material removed to make a rough edge on the other. Back in the 1960s, Louis Leaky, a prominent paleoanthropologist, attributed such an artifact to the first member of the human genus, Homo habilis, the ‘handy human’. While Leaky and his colleagues didn’t explicitly say Homo habilis learned how to produce the tools through cultural transmission of information, Premo says his usage of the word “culture” alone is enough to imply that such mechanisms were at work.

Oldowan chopper.

An Oldowan chopper.
Image credits José-Manuel Benito Álvarez.

“All of their contemporaries figured that any stone tool must be an example of culture because they thought that humans are the only animals that make and use tools and humans rely on cultural transmission to do so,” said Luke Premo, associate professor of anthropology at Washington State University, and paper co-author.

“It made sense to them at the time that this ability might in fact distinguish our genus from all others.”

Premo and his fellow co-authors say there currently isn’t enough evidence to support a cultural transmission of the techniques used to make such tools. The team writes that it’s more likely these tools are “latent solutions” which rely on an animal’s inherent skill rather than cultural transmission — i.e. that they’re simple enough to be thought-up on the spot when needed, rather than having to be told how to manufacture them. Just like crows or chimpanzees can spontaneously learn to use tools, so too could Homo habilis have learned to make simple tools, like the Oldowan chopper, on their own.

“Our main question is: How do we know from these kinds of stone tools that this was a baton that somebody passed on?” said Premo. “Or was it just like the chimp case, where individuals could figure out how to do this on their own during the course of their lifetimes?”

The team further warns against equating complexity to a cultural flow of ideas, pointing out that while the tool looks “like it would require a lot of brain power,” animals can create very complicated structures such as beehives, beaver lodges, or spider webs, without sharing any information.

They also point out that the type of tool (rough-cut stone edges) remained virtually unchanged for over 1 million years. A culturally transmitted technique generally suffers at least slight changes over time, as individuals add on what they’ve been taught, or as information is lost. This static nature, Premo says, points to individuals with the same mental and motor skills coming up with the same solution again and again instead of the constant addition of innovations owed to information sharing today.

If it didn’t start over 2 million years ago, however, when did it start? The team points out that the production of other early hominin technologies, such as the Mousterian stone tools in use by the Neanderthals and other hominids between 160,000 to 40,000 years ago, involved many steps — as such it’s more likely that people passed it down rather than constantly re-discover the processes involved.

Overall, the authors don’t debate the fact that cultural transmission allowed us to thrive in virtually all environments around the planet.

“It does explain our success as a species,” Premo said. “But the reason we are successful might be much more recent than what many anthropologists have traditionally thought.”

If it really is such a recent feature, it could explain why we’re still having trouble coping with too much information.

“[Cultural transmission of information]can be hijacked,” Permo adds. “If you’ve got this system in which you receive information that can affect your behaviors… all it takes is somebody broadcasting information to you that makes you act in a way they prefer. And if you’re getting hundreds of messages every day, it can be difficult to discern what is important for you from what is important for somebody else.”

The paper “Early Stone Tools and Cultural Transmission: Resetting the Null Hypothesis” has been published in the journal Current Anthropology.

Ancient molar (left) and canine (right) belonging to a yet unidentified ancient ape found in Germany. Credit: Naturhistorisches Museum Mainz.

Mysterious 9.7-million-year-old fossilized teeth likely belong to unknown ancient European primate

Ancient molar (left) and canine (right) belonging to a yet unidentified ancient ape found in Germany. Credit: Naturhistorisches Museum Mainz.

Ancient molar (left) and canine (right) belonging to a yet unidentified ancient ape found in Germany. Credit: Naturhistorisches Museum Mainz.

In a former riverbed of the Rhine, near the town of Eppelsheim, a region famous for a treasure trove of fossils, German scientists found two fossilized teeth with contradictory features. The molar and left canine belonging to the same individual are nearly ten million years old and bear a resemblance to hominin species such as Australopithecus afarensis. The conundrum lies in the fact that A. afarensis is no more than 3 million years old and no human ancestor was found in Europe earlier than 100,000 years ago. This puts the entire debate under a whole new light.

The real planet of the apes

The findings were made in 2016 but the team led by Herbert Lutz, a paleontologist at the Mainz Natural History Museum in Germany, delayed publishing due to the controversial nature of the two fossilized teeth. What’s certain, says Lutz, is that the teeth dated to 9.7 million years ago belong to a primate and signify “the northernmost occurrences of Miocene primates in Europe.”

“Both teeth, the crowns of an upper left canine and an upper right first molar, are exceptionally well preserved and obviously come from the same body of unknown sex. Their sedimentological environment and the accompanying faunal elements point to an age shortly before the Mid-Vallesian crisis at ca. 9.7 Ma. While the molar shares characters with various other taxa, the canine reveals intriguingly potential hominin affinities: its lingual outline is clearly diamond-shaped; its ratio of lingual height / mesiodistal length is within the range of Australopithecus afarensis, Ardipithecus ramidus, Ardipithecus kadabba, and females of Pan troglodytes,” the authors reported in a paper, which appeared in pre-print. 

In the aftermath of the discovery, some have haphazardly painted this whole event into something far more spectacular than it really is, which in reality, is just ambiguous at this point. For instance, during a press conference announcing the discovery, the mayor of Mainz said he doesn’t want to “over-dramatize it” but “we shall have to start rewriting the history of mankind after today.” One can only wonder what the fine mayor’s view of overly dramatic looks like in this case.

The dig site in Eppelsheim. Credit: Bastian Lischewsky

The dig site in Eppelsheim. Credit: Bastian Lischewsky

Scientists are, of course, far more reserved. Despite the resemblances to hominin groups, it’s far likelier, as Lutz and colleagues themselves reported, that the molar and canine belong to a broader group called hominoids. In other words, “apes”.

As far back as 12 million years ago, Europe was a sort of an ape paradise. There’s no doubt that apes originated in Africa, or that our more recent evolution happened there, but up to eight million years ago they also flourished in Europe around the Mediterranean when climate change forced these populations to gradually disappear.

One of these apes was Oreopithecus, first unearthed in the 19th century in Italy. Though it does not belong to our branch of the ape evolutionary tree, Oreopithecus, one of the last surviving species from this ‘golden age’ of European apes, oddly looked a lot like an early member of our lineage. Perhaps, Eurasian primate bearing these teeth and its distant African relatives encountered similar environmental pressure, independently leading to very similar tooth configurations. There are many examples of convergent evolution, after all.

Maybe it’s not even an ape

The isolated discovery of two teeth, which are far less interesting than most other body parts such as a femur or skull, can’t “rewrite history”. However, it’s fascinating that ancient apes could have lived this far north in Europe, but speculating any further is just thoughtless sensationalism. What’s more, the fossils might not even belong to an ape.

Speaking to National Geographic,  Bence Viola, who is a paleoanthropologist at the University of Toronto and an authority on the teeth of extinct human relatives, says the fossils likely belong to some pliopithecoid species — an extinct superfamily of catarrhine primates that inhabited Asia and Europe during the Miocene. Pliopithecoids are very far away, evolutionary speaking, from humans, having diverged from the common ancestors of Old World monkeys and apes long before the two branches split.

“I think this is much ado about nothing,” Viola said. “The second tooth (the molar), which they say clearly comes from the same individual, is absolutely not a hominin, [and] I would say also not a hominoid.”

In other words, the teeth might belong to some primate species which is less related to modern humans than a baboon. However, the German scientists are still working on their paper, so the last word may yet to come.

“Hopefully, in one or two years, we’ll know a lot more about what we’ve got on our hands,” Lutz told ResearchGate. “It’s definitely a fantastic, exciting story.”

Olive baboon

Earliest baboon found in a cave littered with hominid fossils

Olive baboon

A beautifully preserved skull fragment belonging to the earliest baboon species was found in a South African cave. The site in Malapa has constantly offered archaeologists and anthropologists plenty of work, since it was populated by various hominid species across millions of years. In fact, it is here that scientists discovered a distinct hominid species,  Australopithecus sedibafor the first time. Apart from the ancient baboon, no other non-hominid animal was found in the cave.

Judging from the skull, Papio angusticeps – the new baboon ancestor discovered at the  Unesco World Heritage site – is strikingly similar to modern baboon. Were it not for some very slight physiological differences, the two could have easily passed as identical.

Not much is known about baboon ancestry. Genome sequencing research suggests baboons first appeared once they split from a common ancestor some two million years ago. The P. sediba fossils are dated around the same time, lending credence to this hypothesis. Christopher C. Gilbert, an anthropologist at Hunter College in New York and an author of the study, says the findings will prove useful in dating other ancient baboon fossils found elsewhere. Ultimately, the complete baboon lineage might one day be identified.

A skull fragment belonging to the earliest baboon (left) compared to other baboons which came later. Image: Wits University

A skull fragment belonging to the earliest baboon (left) compared to other baboons which came later. Image: Wits University

While most hominid fossils were found in caves where our early ancestors chose to live, the Malapa cave 25 miles northwest of Johannesburg is actually a death trap. There was no escape for any creature unfortunate enough to fall in it, researchers say.  According to Josh Fischman, writing for National Geographic, “two million years ago, a cave-studded aquifer lay beneath an undulating plain of shallow, wooded valleys and rolling hills. Some of the caves were open to the surface through steep entryways or vertical shafts stretching up to 160 feet. In wet periods, when the water table was high, animals could easily drink from seepage ponds near the surface. During drier times they would venture into the darkness of a hole, following the sound or scent of water—and risking a plunge down a hidden shaft.”

It’s not surprising then to learn that this is the first monkey found in the Malapa cave – they simply stayed in trees more.

It was in the Malapa cave that paleontologists at the University of the Witwatersrand in Johannesburg announced they had found a new hominid species, Australopithecus sediba. The discovery is a milestone in science, since the hominid looks like the intermediate step between  the primitive australopiths and our genus, Homo. Somewhere around this cave in South Africa, the seed for nature’s most intense creation was planted.

Oldowan chopping flint dated from the Lower Paleolithic 900,000 years ago. Credit: World Museum of Man

The oldest stone cutting tools may have sparked the evolution of language

A far from definite, yet highly interesting explanation for the origin of language was recently proposed – not by linguists or geneticists, but by a psychologists who took an archaeological route. Thomas Morgan, a psychologist at the University of California, Berkeley presents us with a chicken or the egg dilemma: was tool use proliferated by language or was language evolutionary triggered by the need to proliferate tool use? The findings appeared in Nature. 

The tools of language

Oldowan chopping flint dated from the Lower Paleolithic 900,000 years ago. Credit: World Museum of Man

Oldowan chopping flint dated from the Lower Paleolithic 900,000 years ago. Credit: World Museum of Man

The debate over the origin of speech is long from over. Estimates range from as early 50,000 years ago to some 2 million years ago when the human genus as we know it first emerged. Unfortunately, words don’t leave fossil records and as such there’s room for much speculation. To unravel the mystery, researchers often focus their attention on proxies for language emergence like early art of sophisticated tool making. The latter caught Morgan’s attention, yet unlike his predecessors he approached the question in a novel manner.

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Him and colleagues recruited 184 students from the University of St. Andrews in the United Kingdom and organized them into five groups. One person from each group was taught how to make Oldowan tools, which include fairly simple stone flakes that were manufactured by early humans beginning about 2.5 million years ago. This makes the Oldowan  the oldest-known stone tool industry, and as such an important milestone in human evolutionary history: the earliest evidence of cultural behavior. Homo habilis, an ancestor of Homo sapiens, was the first hominid to manufacture Oldowan tools. To make an Oldowan cutting tool, you need to hit a stone “core” with a stone “hammer” in such a way that a flake sharp enough to butcher an animal is struck off.

All groups were directed to build their own Oldowan tools, but each was taught how to do make them with different approaches.

  • Group #1: volunteers were shown finished flakes, then given core and hammer. They left to themselves with no further instructions;
  • Group #2: students learned how to make the tools just by watching the leading volunteer while he manufactured the flake, but with no other interactions;
  • Group #3: subjects worked together and actively showed each other how to build the flakes, but without gesturing;
  • Group #4: students were allowed to gesture and point, but no talking was allowed;
  • Group #5: leaders were allowed to talk and instruct apprentices as long and as much as they needed;
groups-langauge-tools-oldowan

(a) A diagram of the stone knapping process. The hammerstone strikes the core with the goal of producing the flake. The platform edge and angle are important to the success of knapping. (b-f) the five learning conditions. (g) The structureof the experiment. For each condition, six chanins were carried out (Four short and two long); one of two trained experimenters started each chain (equally with each condition). Credit: Morgan et all // Nature

The experiment tried to follow a natural path of skill transmission as possible, as each apprentice, once he acquired the necessary skills, became a teacher. In total, five different chains of transmission were demonstrated, which resulted in 5,000 completed Oldowan flakes. As expected, the students were left to themselves with no instructions performed the worse. Those who watched others how they built they tools performed mildly better. In fact, only those groups who were allowed to gesture or talk performed significantly better than the previous reverse engineering baselines. Performance was gauged based on several indicators of stone tool making like: the total number of  flakes produced that were long enough and sharp enough to be viable and the proportion of hits that resulted in a viable flake. Gestural teaching doubled and verbal teaching quadrupled the likelihood that a single strike would result in a viable flake, the team found.

“If someone is trying to learn a skill that has lots of subtlety to it, it helps to engage with a teacher and have them correct you,” Morgan said. “You learn so much faster when someone is telling you what to do.”

As for what the results mean for the Oldowan hominins: “They were probably not talking,” Morgan said. “These tools are the only tools they made for 700,000 years. So if people had language, they would have learned faster and developed newer technologies more rapidly.”

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Yet, for tool making to spread across vast communities of hominids you necessarily need a teaching system in place. Gestures work pretty well, but we can assume there was also some kind of protolanguage. As tools became more and more important, so did the need for conveying knowledge on how these are built. The ability to rapidly share the skill to make Oldowan tools would have brought fitness benefits” to early humans, Morgan says. Natural selection would soon come at play and improve on primitive language abilities. Eventually, a semantically rich language emerged. This hypothesis seems to be validated by the next generation of tools –  the advent of Acheulean hand-axes and cleavers some 1.7 million years ago.

“To sustain Acheulean technology, there must have been some kind of teaching, and maybe even a kind of language, going on, even just a simple proto-language using sounds or gestures for ‘yes’ or ‘no,’ or ‘here’ or ‘there,'” Morgan said.

“At some point they reached a threshold level of communication that allowed Acheulean hand axes to start being taught and spread around successfully and that almost certainly involved some sort of teaching and proto-type language,” Morgan said.

Some scientists, have criticized the study however. Ceri Shipton, an archaeologist at the University of Cambridge in the United Kingdom, believes Morgan’s paper “overreaches in its interpretations” because the subjects had grown up with language, but have not grown up with stone tools. Dietrich Stout, an archaeologist at Emory University in Atlanta argues that the participants were given far too less time to learn the Oldowan craft: 5 minutes to learn the toolmaking techniques, and then no more than 25 minutes to produce Oldowan flakes. Had they been given more time, Stout believes the differences in the five methods of transmission would have become largely indistinguishable.

Nevertheless, it’s an exciting paper. The debate ensues and this is far from being the last thing we’ll learn about the origin of language.

Levallois Core from the Douro Basin, Portugal. José-Manuel Benito Alvarez

Stone tools evolved independent of ancient African cultures

Neanderthals were one of the early hominids who used  Levallois technique to make stone tools. Image: Prisma/UIG/Getty

Neanderthals were one of the early hominids who used Levallois technique to make stone tools. Image: Prisma/UIG/Getty

A breakthrough finding in Armenia where thousands of ancient cutting tools were found beautifully preserved casts doubt on a currently prevailing hypothesis that these were solely invented in Africa. The tools discovered are between 325,000 and 335,000 years old. The age suggests the ancient paleolithic cultures of the time that inhabited the region independently developed the sophisticated technique to produce them.

Independent thought and inventions across the ancient hominid world

Levallois Core from the Douro Basin, Portugal.  José-Manuel Benito Alvarez

Levallois Core from the Douro Basin, Portugal. José-Manuel Benito Alvarez

Early Stone Age populations made their tools by chipping away a stone until it turned into a desired shape – a cutting tool, arrow or spear tip etc. In the so-called Levallois technology, named after the Levallois-Perret suburb of Paris where it was first described, the toolmaker first chisels a suitably shaped core from a stone and then slices off flakes from it.  Raw blocks of stone are prepared by striking pieces off the edges until it is shaped something like a turtle shell: flat on the bottom and humped on the top. That shape permits the knapper to control the results of using applied force: by striking the top edges of the prepared core, the knapper can pop off a series of similarly sized flattish, sharp stone flakes which can then be used as tools. The technique was reckoned a leap forward in stone technology and behavioral modernity: the production method is in stages, and requires forethought and planning.

“The discovery of thousands of stone artefacts preserved at this unique site provides a major new insight into how Stone Age tools developed during a period of profound human behavioral and biological change,” said Dr. Simon Blockley from the Department of Geography at Royal Holloway.

“The people who lived there 325,000 years ago were much more innovative than previously thought, using a combination of two different technologies to make tools that were extremely important for the mobile hunter-gatherers of the time.

Lavallois technology was discovered throughout Europe and Eurasia, but because such tools in African had been dated as being much older than those found in other regions, many researchers were led to believe the technique first developed there and was then introduced in other parts of the world following a great migration.

levalloise_tool

Levallois and biface tools. Credit: Royal Holloway, University of London

The Nor Geghi site in present day Armenia, discovered in 2008, shakes this theory which was already doubtful. For instance, it doesn’t explain  why some Levallois tools found in Eurasia are smaller, or otherwise different, from African ones and relies on a unvoked an unproven migration of unknown hominids out of Africa.

“Our findings challenge the theory held by many archaeologists that Levallois technology was invented in Africa and spread to Eurasia as the human population expanded. Due to our ability to accurately date the site in Armenia, we now have the first clear evidence that this significant development in human innovation occurred independently within different populations,”  Blockley said.

Researchers led by Daniel Adler at the University of Connecticut in Storrs discovered thousands of cutting tools of various shapes and size trapped inside a flood plain sediment with volcanic ash, and preserved by two lava flows dated to 200,000 and 400,000 years ago. Using chemical methods, the researchers found the tools came from local source, although some used material from as far as 120km away.

“We wouldn’t have found this mixture if the Levallois technology had simply replaced the old method,” says Adler. “The communities probably worked out for themselves how to make bifacial tools and then it was a short step to the Levallois method.” He argues that the Stone Age people used both approaches flexibly.

Findings were reported in the journal Science.

Tibetans acquired a unique gene by interbreeding with a now-extinct human species. Photo: easytourchina.com

Unique gene passed by extinct human species makes Tibetans superhuman

Tibetans acquired a unique gene by interbreeding with a now-extinct human species. Photo: easytourchina.com

Tibetans acquired a unique gene by interbreeding with a now-extinct human species. Photo: easytourchina.com

Advancements in genetic sequencing has allowed genomic research to flourish. DNA sequencing is now much faster, cheaper and accurate than ever before, and we’re only now beginning to reap the rewards. It’s the first step to a complete understanding of our bodies. The Human Genome Project, once finally completed, mapped and identified all the genes of the human genome. This helps us get an idea of where are, but to understand how we got here, we also need to peek into ancient DNA. For instance, a recent study found that Tibetans share at least one gene with the ancient Denisovans, an ancient human species that interbred with the Tibetan homo sapiens ancestors. Ironically, the Denisovans’ extinctions was pushed by the homo sapiens presence.

A unique gene that makes the Tibetans genuine supermen (atop the Himalayas of course)

The gene in question is called EPAS1 and helps the Tibetans adapt to extreme altitudes of 15,000 feet or more. In a way, Tibetans are superhuman mountain people, since they are able to survive in conditions that could normally kill a non-Tibetan.

“We have very clear evidence that this version of the gene came from Denisovans,” said principal author Rasmus Nielsen, a Berkeley professor of integrative biology, in a press release.

The Denisovans are a group of ancient humans that have only recently come to our knowledge. In March 2010, scientists announced the discovery of a finger bone fragment of a juvenile female who lived about 41,000 years ago, found in the remote Denisova Cave in the Altai Mountains in Siberia – a cave which was also inhabited by humans and Neanderthals. Nobody knows what Denisovans looked like because there are so few fossils. But geneticists have managed to sequence their entire genome to a high degree of accuracy.

An artist's interpretation of how a Denisovan might have looked like. Artwork:  Joe McNally / NGS

An artist’s interpretation of how a Denisovan might have looked like. Artwork: Joe McNally / NGS

The present study is of great significance, because it not only proves without reason of a doubt that homo sapiens interbred with the Denisovan hominids, but is also the first study of its kind that shows a gene from another species of human was used to help modern humans adapt to their environment.

A breakthrough discovery

Particularly, the gene only activates a high-altitudes or atmospheres with low-oxygen content. It’s during this time that a normal homo sapiens gets in trouble, because the low-oxygen atmosphere triggers a rush of hemoglobin, which is the red-colored protein responsible for transporting oxygen in blood. But it’s too much of a good thing causing blood thickening, which can result in heart attacks and death. When the EPAS1 gene activates, however, only a slight increase of hemoglobin is triggered – just enough to compensate for the oxygen reduction.

“We found part of the EPAS1 gene in Tibetans is almost identical to the gene in Denisovans and very different from all other humans,” Nielsen said. “We can do a statistical analysis to show that this must have come from Denisovans. There is no other way of explaining the data.”

The gene can also be found in certain members of the Han Chinese population, which had the gene passed down by the Tibetans. Interestingly enough, natives to the island of Melanesia – an indigenous group which shares up to 5% of its DNA with Denisovans – don’t have this gene. Clearly, because they interbred, the Melanesians also had the gene at one time, but because they never had to use it, the gene came off.

So, how much of us is homo sapiens? The short answer is we don’t know yet. Not too long ago, the community thought modern homo sapiens never interbred with other hominids. Later it was shown that homo sapiens indeed interbred with both Neanderthals and Denisovans, with which we share DNA, and possibly other groups of yet unknown hominids as well. A more refined understanding of the human genome and future remarkable findings will definitely shed further light onto this.

“There might be many other species from which we also got DNA, but we don’t know because we don’t have the genomes,” Nielsen said. “The only reason we can say that this bit of DNA is Denisovan is because of this lucky accident of sequencing DNA from a little bone found in a cave in Siberia. We found the Denisovan species at the DNA level, but how many other species are out there that we haven’t sequenced?”

The results appeared in the journal Nature.

early-biped-ancestor

Early hominids started walking on two legs because of shifting geology

early-biped-ancestor

Walking a four legs definitely has its perks. You can run faster, you have more stability because of the lower center of gravity, there’s lower wind resistance and so on. How did our early hominid ancestors ever come to discard their quadruped locomotion for an upright stance, though? Many theories have been formulated in this direction, and researchers at University of York have recently made their own contribution – they believe shifting geology in East and South Africa may have offered our ancestors just the right reasons to turn biped.

A prevailing hypothesis regarding bipedal evolution says that some 2.5 million years ago climate change forced  our australopithecine ancestors to descend from trees and venture into the open savanna, where walking on two legs was thought to be better than on four. However, there is some evidence that bipedal primates evolved before the biggest temperature swings kicked in and that some australopithecines ancestors lived in forests, adapted to both tree-climbing and upright walking, plugging holes into the climate change theory.

Researchers at University of York suggest that bipedalism may have developed as a response to the terrain, rather than a response to climatically-driven vegetation changes. Around the time when the first bipedal strides were made by our ancestors, volcanoes and shifting tectonic plates were shaping   East and South Africa into a rugged landscape. The resulting rocky outcroppings and steep gorges offered shelter and opportunities to trap prey, but also required the hominids to perform more upright scrambling and climbing gaits.

“The broken, disrupted terrain offered benefits for hominins in terms of security and food, but it also proved a motivation to improve their locomotor skills by climbing, balancing, scrambling and moving swiftly over broken ground – types of movement encouraging a more upright gait,” said Dr Isabelle Winder, from the Department of Archaeology at York and one of the paper’s authors.

The varied terrain didn’t only prompt upright locomotion, but also helped develop cognitive abilities, such as navigation and communication abilities, accounting for the continued evolution of our brains and social functions such as co-operation and team work, the researchers claim.  With their upright limbs free, the hominids could now evolve more dexterous hands and arms for more refined tool use, supporting a further key stage in the evolutionary story.

“Our hypothesis offers a new, viable alternative to traditional vegetation or climate change hypotheses. It explains all the key processes in hominin evolution and offers a more convincing scenario than traditional hypotheses,” Dr. Winder said.

Findings were reported in the journal Antiquity.