In anthropology departments, the debate has long simmered: Was it an improvement in manual dexterity or intelligence that allowed our human ancestors to begin making sophisticated stone tools?

According to one group of scientists, figuring out the answer required only a pair of high-tech gloves and a trained craftsman who could make both simple stone knives and more complicated hand axes. The craftsman wore gloves studded with electronic sensors that tracked his his hand movements. Lead researcher Aldo Faisal of Imperial College London found that simple and complex tools required the same amount of dexterity to produce.

“From these results, dexterity can be ruled out, and we can infer it has something to do with the complexity of the task,” says Faisal. Axes are made in several stages, which requires switching between tasks, suggesting that a higher level of complexity is required in the brain. [New Scientist]

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A bountiful archaeological site in South Africa has given up another discovery showing humans becoming sophisticated tool users. According to a study out in the journal Science, 75,000-year-old artifacts in the Blombos Cave appear to show signs of pressure flaking, a process of finely shaping hard material. Before this, study author Paola Villa says, the oldest evidence of humans using the technique was dated to just 20,000 years ago.

Pressure flaking consists of trimming the edges of a finished tool by pressing with a bone point hard enough to remove thin slices of rock. This process creates the narrow, evenly spaced grooves found on flint tools from Europe’s 20,000-year-old Solutrean culture and prehistoric Native American groups. Wider, more irregular grooves characterize 36 pressure-flaked Blombos tools, which were made from silcrete, Villa says. This rock, a silica-rich material, is of lower quality than flint and requires heating to ready it for pressure flaking. [Science News]

It’s not easy to tell from these artifacts whether their makers simply hammered them into shape or used the more sophisticated flaking method to polish them off. So the team, led by Vincent Mourre, found silcrete around the cave site and tried to make their own.

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Over the past few years, studies have chipped away at the old-fashioned stereotype of dense and dumb Neanderthals. Archaeological excavations suggested the hominids made tools and weapons, fashioned jewelry, or possessed other mental faculties some presumed only early humans to have.

The Neanderthal renaissance may be in danger. For a study in the Proceedings of the National Academy of Sciences this week, radiocarbon dating expert Thomas Higham tested one of the most important Neanderthal sites in the world—Grotte du Renne in France—and found that all is not well in dating the artifacts that some archaeologists have connected to Neanderthals.

The key finding is that as you dig down through the layers of sediment in the Grotte du Renne, the age of the remains does not increase as you would expect. Instead, the ages of the different objects are all over the place, suggesting that remains from different eras have got mixed up together. [New Scientist]

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Humans didn’t begin major agriculture until about 10,000 years ago. But 20,000 years  before that they were grinding their own flour, a new study (in press) suggests, adding more proof that our forebears were eating the beginnings of a more balanced diet while still roving as hunter-gatherers.

Anna Revedin’s team says in today’s Proceedings of the National Academy of Sciences that they found traces evidence of flour still stuck in 30,000-year-old stones the team found in Russia, Italy, and the Czech Republic.

The flour, likely suitable for making flatbread or cakes, didn’t just give stone age people some dinnertime variety. Because it could be stored in dried form, flour would have given them greater independence from environmental and seasonal circumstance. [Wired.com]

The stones themselves appear to have been shaped for grinding, like an archaic mortar and pestle.

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Was Lucy a tool user and a meat eater?

Quite possibly, argues a new study in Nature. Archaeologist Shannon McPherron turned up animal bones at an Ethiopian site that he says show markings of stone tool cutting dating back nearly 3.4 million years. That would be a big jump in the record: Right now the oldest known evidence of tool use among our ancestral species dates back about 2.6 million years.

McPherron’s date falls in the time of Australopithecus afarensis, the species to which the famous Lucy find belongs. But thus far he’s found only the markings on bones—not the tools themselves. Perhaps not surprisingly, though, at least one scientist behind the 2.6 million-year-old find says the new study is not convincing evidence that tool use dates back all the way to 3.4 million years ago.

For plenty more about the find—and the differing opinions—check out DISCOVER blogger Ed Yong’s post.

Related Content:
Not Exactly Rocket Science: Human Ancestors Carved Meat with Stone Tools Almost a Million Years Earlier Than Expected
80beats: Lucy’s New Relative, “Big Man,” May Push Back the Origin of Walking
DISCOVER: How Loyal Was Lucy?

Image: Dikika Research Project

Dear male reader: Just so you know, your sperm isn’t that different from a sea anemone’s.

Sperm is so vital, a new study in PLoS Genetics found, that one of the genes responsible for it hasn’t changed in 600 million years. Insects, humans, marine invertebrates, other mammals, even fish—the males of all these creatures share a common sperm gene that dates back to before all those animals diverged all those millions of years ago, according to the team led by Eugene Xu.

From an evolutionary point of view, that longevity is simply stunning.

“It’s really surprising because sperm production gets pounded by natural selection,” Xu said. “It tends to change due to strong selective pressures for sperm-specific genes to evolve. There is extra pressure to be a super male to improve reproductive success. This is the one sex-specific element that didn’t change across species. This must be so important that it can’t change” [MSNBC].

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Perhaps you’re one of those people who get their dander up when you hear creationists saying “I’m not descended from some monkey” not only for the obvious reason, but also because you can’t help but blurt out, “No, you mean ‘ape!’ We’re apes, not monkeys.”

Indeed, our superfamily, Hominoidea, split from the group labeled “old world monkeys” millions of years ago—but perhaps not as many million as we thought. In Nature this week, a team of scientists report on a 28-29 million year old fossil that appears to predate the split, meaning the separation would have happened more recently than other studies suggested.

The partial skull of this new creature, which the team dubbed Saadanius hijazensis, turned up in Saudi Arabia in February 2009.

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It’s what happens to your brain after you’re born that makes you human.

Jason Hill and colleagues were comparing the structure of newborn brains to those of adults when they came upon a striking find, documented this week in the Proceedings of the National Academy of Sciences. Clearly, the brain expands greatly as you grow from baby to adult. But the researchers discovered not only that the brain grows in a non-uniform way, but also that the parts of the brain that change most rapidly as people grow up are the same parts that changed the most as humans evolved away from our primate relatives.

The research revealed that brain regions involved in higher cognitive and executive processes—such as language and reasoning—grow about twice as much as regions associated with basic senses such vision and hearing…. “The parts of the [brain] that have grown the most to make us uniquely humans are the same regions that tend to grow the most postnatally,” Hill said [National Geographic].

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Clearly, the people of Tibet must have evolved quickly to tolerate a life spent living at the top of the world. How quickly? A study out in this week’s Science, which compared Tibetans to Han Chinese to see the differences in their DNA, says that the two groups may have diverged no more than 3,000 years ago. If natural selection has changed Tibetans in such a short time, it would be the fastest known example of human evolution. But not everybody is buying this time line.

As DISCOVER noted when a similar study by another team came out in May, natives of the Tibetan plateau seem to survive the altitude because their bodies make less hemoglobin. It’s somewhat counter-intuitive:

In theory higher levels of haemoglobin would be beneficial, because this would improve oxygen transport. But high levels could make the blood thicker and less efficient at carrying oxygen, says Jay Storz of the University of Nebraska-Lincoln [New Scientist]. (Storz writes the accompanying commentary in Science.)

Looking at the differences in genes that regulate that, the team found vast differences between the Han and the Tibetans, with one version appearing in 87 percent of Tibetans studied but only 9 percent of Chinese. However, the assertion by the scientists at the Beijing Genome Institute—that their findings mean the two group broke apart just three millennia ago—has ruffled archaeologists who believe that the Tibetan plateau has been continuously occupied for much, much longer: more like 7,000 to 21,000 years.

For more about all of this, check out Razib Khan’s post at Gene Expression.

Related Content:
Gene Expression: Very Recent Altitude Adaptation in Tibet
Gene Expression: Tibet & Tibetans, Not Coterminus
80beats: Found: The Genes That Help Tibetans Live at the Top of the World
DISCOVER: High-Altitude Determines Who Survives in Tibet

Image: Wikimedia Commons

Chimps kill chimps. And according to a 10-year study of Ngogo chimps in Uganda, they do it to defend and extend their territory. John Mitani documented 21 chimp-on-chimp killings during the study, 18 of which his team witnessed. And when the chimps kill another, they take over its land.

Because of the 1 percent difference of DNA between us and our ape cousins, it can be irresistible to anthropomorphize them, referring to their deadly attacks upon each other with terms like “murder” or “crime.” And given the murders over territory that litter human history books, it’s hard not to see echoes of our ourselves in chimp “warfare.”

Chimpanzee warfare is of particular interest because of the possibility that both humans and chimps inherited an instinct for aggressive territoriality from their joint ancestor who lived some five million years ago. Only two previous cases of chimp warfare have been recorded, neither as clear-cut as the Ngogo case [The New York Times].

But not so fast, says DISCOVER’s own award-winning blogger Ed Yong. He contacted chimp expert Frans de Waal, who would like to dissent:

“There are many problems with this idea, not the least of which is that firm archaeological evidence for human warfare goes back only about 10-15 thousand years. And apart from chimpanzees, we have an equally close relative, the bonobo, that is remarkably peaceful… The present study provides us with a very critical piece of information of what chimpanzees may gain from attacking neighbours. How this connects with human warfare is a different story” [Not Exactly Rocket Science].

For much more, check out Yong’s full post on the study.

Related Content:
Not Exactly Rocket Science: Chimpanzees Murder for Land
80beats: How Chimps Mourn Their Dead: Reactions to Death Caught on Video
DISCOVER: Chimps Show Altruistic Streak

Image: John Mitani

No offense, Lucy, but at three feet, six inches you were kind of short. Your diminutive, 3.2 million-year-old bones made it difficult to tell whether your species could even walk like us. Fortunately, researchers in Ethiopia have uncovered an older, bigger relative. As described in Proceedings of the National Academy of Sciences, some researchers believe that these new bones show that members of Lucy’s species, Australopithecus afarensis, could walk like modern humans. 

The paper’s authors call him Kadanuumuu (kah-dah-nuu-muu)–”big man” in the Afar language. Big Man still isn’t really that big by today’s standard: His 3.6 million-year-old bones show that he stood at around five feet.

The fossilized remains don’t include a head, but Big Man has many of the same bones as Lucy, and also others previously missing: a shoulder blade and a rib cage bits. Lead researcher Yohannes Haile-Selassie argues that Big Man’s skeleton upends previous beliefs about Lucy’s love of tree climbing and more primitive walk.

“This individual was fully bipedal and had the ability to walk almost like modern humans,” said Haile-Selassie. “As a result of this discovery, we can now confidently say that ‘Lucy’ and her relatives were almost as proficient walking on two legs as we are, and that the elongation of our legs came earlier in our evolution that previously thought.” [Cleveland Museum of Natural History]

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Your brain is hungry. That big gray calculating machine in your head is an energy hog that needs lots of calories—more than the diet of fruits and plants that our distant hominin ancestors probably ate could provide. It’s a mystery, then, just how human ancestors like Homo erectus—who were around when our craniums started to expand in a hurry—ate enough to start growing big brains. But buried in Kenya, a two-million-year-old hint has emerged: Those hominins started eating seafood way back then, archaeologists say.

Near a place called Lake Turkana, archaeologists David Braun found two intriguing groups of items: The bones of fish, turtles, and even crocodiles with the scars of stone tools still showing, and stone fragments that Braun says come from the simple tools these hominins used to carve up the marine animals. He and his colleagues report the find of our ancestors’ ancient feast in the Proceedings of the National Academy of Sciences.

Today, their leftovers—in the form of hundreds of bones and several thousand stone tools—are the earliest “definitive evidence” of hominins butchering and eating aquatic animals, which are rich in fatty acids essential for growing bigger brains [ScienceNOW].

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The bones of our ancestors do not speak across time with ultimate clarity. The fossils with which scientists reconstruct our family tree are often fragments that offer hints and clues to where we came from. So it comes as no surprise when, as part of the flow of science, researchers offer counter-interpretations to even the most famous of finds.

That’s what happening to Ardi.

Last October Ardipithecus ramidus hit the main stage when, after 17 years of study, a large team led by paleoanthropologist Tim White published its work in the journal Science. The 4.4-million-year-old find shakes up our understanding of our own history, White said—primarily the story of how and when we learned to walk.

Ardi cast doubt on the widely accepted view that our ancestors became bipeds because they left the forest and entered a flatland savanna habitat that demanded it. But Ardi appeared to be a kind of hybrid, comfortable in the trees and on the ground. And, White said, analysis of the site where the fossil was found indicated that Ardi lived in a woodland habitat. If it’s true that early humans walked in the woods, then the “savanna hypothesis” would be swept away.

But not so fast. In today’s edition of Science, two teams of scientists respond (1, 2) with doubts about the story of Ardi.

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Ever since anthropologists figured out that early humans and Neanderthals coexisted for a span of prehistory, they’ve wondered–did the two species, you know, make friends? Now a fascinating new genetics study reveals that Homo sapiens and Neanderthals did indeed interbreed, and the evidence is still to be found in the human genome.

Researchers from Germany’s Max Planck Institute for Evolutionary Anthropology first sequenced the entire Neanderthal genome from powdered bone fragments found in Europe and dating from 40,000 years ago–a marvelous accomplishment in itself. Then, they compared the Neanderthal genome to that of five modern humans, including Africans, Europeans, and Asians. The researchers found that between 1 percent and 4 percent of the DNA in modern Europeans and Asians was inherited from Neanderthals, which suggests that the interbreeding took place after the first groups of humans left Africa.

Anthropologists have long speculated that early humans may have mated with Neanderthals, but the latest study provides the strongest evidence so far, suggesting that such encounters took place around 60,000 years ago in the Fertile Crescent region of the Middle East [The Guardian].

The study, published in Science and made available to the public for free, opens up new areas for research. Geneticists will now probe the function of the Neanderthal genes that humans have hung on to, and can also look for human genes that may have given us a competitive edge over Neanderthals.

Erik Trinkaus, an anthropologist at Washington University in St. Louis, who has long argued that Neanderthals contributed to the human genome, welcomed the study, commenting that now researchers “can get on to other things than who was having sex with who in the Pleistocene” [AP].

For a much deeper dive into these issues, head to Carl Zimmer’s post at The Loom and Razib Khan’s post at Gene Expression.

Related Content:
The Loom: Skull Caps and Genomes
Gene Expression: Breaking: There’s a Little Bit of Neandertal in All of Us
80beats: We May Soon Be Able to Clone Neanderthals. But Should We?
80beats: Crafty & Clever Neanderthals Made Jewelry 50,000 Years Ago
80beats: Did Spear-Throwing Humans Kill Neanderthals?
80beats: Rough Draft of the Neanderthal Genome is Complete!
DISCOVER: Works in Progress asks whether we rubbed out Neanderthals, or rubbed off on them

Image: Max Planck Institute EVA. The researchers hang out with their Neanderthal relation.

Last week, Lee Berger unveiled for the world the stunningly intact fossil finds (that his 9-year-old son actually made while with his dad in South Africa) from what he is calling a new hominid species, Australopithecus sediba. Yesterday, he announced another surprise: Berger says that brain scans just finished in France show that insects that might have feasted on the person after death, and even possibly a piece of the hominid’s brain, may be preserved inside the recovered skull.

Experts at the European Synchrotron Radiation Facility (ESRF) in France have been analyzing the find. The ESRF uses a technique known as micro-tomography to assemble its images. This involves taking a series of a high-contrast, high-resolution X-ray radiographs of the target fossil in rotation to build up a 3D representation [BBC News]. The scientists were trying to study the teeth; the skull comes from a young boy, Berger says, and they hoped tooth analysis could help them pin down his exact age at death. But the 3-D representation revealed these other unexpected finds, including a low-density cavity in the skull that could—could—represent a brain remnant.

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