Chapter 6. Evolution of the Brain and Behavior
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// by Jennifer Viegas Male species of a West African monkey communicate using at least these six main sounds: boom-boom, krak, krak-oo, hok, hok-oo and wak-oo. Key to the communication by the male Campbell's monkey is the suffix "oo," according to a new study, which is published in the latest issue of the Proceedings of the Royal Society B. By adding that sound to the end of their calls, the male monkeys have created a surprisingly rich "vocabulary" that males and females of their own kind, as well as a related species of monkey, understand. The study confirms prior suspected translations of the calls. For example, "krak" means leopard, while "krak-oo" refers to other non-leopard threats, such as falling branches. "Boom-boom-krak-oo" can roughly translate to, "Watch out for that falling tree branch." "Several aspects of communication in Campbell's monkeys allow us to draw parallels with human language," lead author Camille Coye, a researcher at the University of St. Andrews, told Discovery News. For the study, she and her team broadcast actual and artificially modified male Campbell's monkey calls to 42 male and female members of a related species: Diana monkeys. The latter's vocal responses showed that they understood the calls and replied in predicted ways. They freaked out after hearing "krak," for example, and remained on alert as they do after seeing a leopard. © 2015 Discovery Communications, LLC.
By Sid Perkins Imagine having a different accent from someone else simply because your house was farther up the same hill. For at least one species of songbird, that appears to be the case. Researchers have found that the mating songs of male mountain chickadees (Poecile gambeli, shown) differ in their duration, loudness, and the frequency ranges of individual chirps, depending in part on the elevation of their habitat in the Sierra Nevada mountains of the western United States. The songs also differed from those at similar elevations on a nearby peak. Young males of this species learn their breeding songs by listening to adult males during their first year of life, the researchers note. And because these birds don’t migrate as the seasons change, and young birds don’t settle far from where they grew up, it’s likely that the differences persist in each local group—the ornithological equivalent of having Southern drawls and Boston accents. Females may use the differences in dialect to distinguish local males from outsiders that may not be as well adapted to the neighborhood they’re trying to invade, the team reports today in Royal Society Open Science. © 2015 American Association for the Advancement of Science
By Ann Gibbons Nearly 42,000 years ago, ancient humans began wielding a new kind of Stone Age toolkit in southern Europe—one that included perforated shell ornaments and long, pointed stone bladelets that were thrown long distances atop spears. Now, after decades of speculation about who made the tools, scientists have finally shown that they were crafted by modern humans, rather than Neandertals. The technological breakthrough may have helped our species outcompete Neandertals, who went extinct shortly after the new tools appeared in Europe. The proof comes from a new state-of-the-art analysis of two baby teeth found in 1976 and 1992 at separate archaeological sites in northern Italy. At the time, researchers were unable to tell whether they belonged to modern humans or Neandertals. But in the new study, an international team of researchers led by Stefano Benazzi of the University of Bologna in Italy used three-dimensional digital imaging methods, including computerized tomography scans, to measure the thickness of the enamel of one of the teeth, found at the collapsed rock shelter of Riparo Bombrini in the western Ligurian Alps. The enamel was thick, as in modern humans, rather than relatively thin, as in Neandertals, the authors report online today in Science. And new radiocarbon dates on animal bones and charcoal from the site suggest this modern child lived there approximately 40,710 to 35,640 years ago. The researchers were also able to extract maternally inherited mitochondrial DNA (mtDNA) from the other child’s tooth from Grotta di Fumane, a cave in the western Lessini mountains, which dated between 41,110 and 38,500 years ago. When researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sequenced the mtDNA and compared it with that of 10 ancient modern humans and 10 Neandertals, they found it belonged to a known lineage of mtDNA, called haplogroup R, which has also been found in a 45,000-year-old modern human bone found in a riverbank near Ust’-Ishim, Siberia. © 2015 American Association for the Advancement of Science
Link ID: 20843 - Posted: 04.25.2015
By Felicity Muth One of the first things I get asked when I tell people that I work on bee cognition (apart from ‘do you get stung a lot?’) is ‘bees have cognition?’. I usually assume that this question shouldn’t be taken literally otherwise it would mean that whoever was asking me this thought that there was a possibility that bees didn’t have cognition and I had just been making a terrible mistake for the past two years. Instead I guess this question actually means ‘please tell me more about the kind of cognitive abilities bees have, as I am very much surprised to hear that bees can do more than just mindlessly sting people’. So, here it is: a summary of some of the more remarkable things that bees can do with their little brains. In the first part of two articles on this topic, I introduce the history and basics of bee learning. In the second article, I go on to discuss the more advanced cognitive abilities of bees. The study of bee cognition isn’t a new thing. Back in the early 1900s the Austrian scientist Karl von Frisch won the Nobel Prize for his work with honeybees (Apis mellifera). He is perhaps most famous for his research on their remarkable ability to communicate through the waggle dance but he also showed for the first time that honeybees have colour vision and learn the colours of the flowers they visit. Appreciating how he did this is perhaps the first step to understanding everything we know about bee cognition today. Before delving into the cognitive abilities of bees it’s important to think about what kinds of abilities a bee might need, given the environment she lives in (all foraging worker bees are female). Bees are generalists, meaning that they don’t have to just visit one particular flower type for food (nectar and pollen), but can instead visit hundreds of different types. However, not all flowers are the same. © 2015 Scientific American,
By Virginia Morell Baby common marmosets, small primates found in the forests of northeastern Brazil, must learn to take turns when calling, just as human infants learn not to interrupt. Even though the marmosets (Callithrix jacchus) don’t have language, they do exchange calls. And the discovery that a young marmoset (as in the photo above) learns to wait for another marmoset to finish its call before uttering its own sound may help us better understand the origins of human language, say scientists online today in the Proceedings of the Royal Society B. No primate, other than humans, is a vocal learner, with the ability to hear a sound and imitate it—a talent considered essential to speech. But the marmoset researchers say that primates still exchange calls in a manner reminiscent of having a conversation because they wait for another to finish calling before vocalizing—and that this ability is often overlooked in discussions about the evolution of language. If this skill is learned, it would be even more similar to that of humans, because human babies learn to do this while babbling with their mothers. In a lab, the researchers recorded the calls of a marmoset youngster from age 4 months to 12 months and those of its mother or father while they were separated by a dark curtain. In adult exchanges, a marmoset makes a high-pitched contact call (listen to a recording here), and its fellow responds within 10 seconds. The study showed that the youngster’s responses varied depending on who was calling to them. They were less likely to interrupt their mothers, but not their dads—and both mothers and fathers would give the kids the “silent treatment” if they were interrupted. Thus, the youngster learns the first rule of polite conversation: Don’t interrupt! © 2015 American Association for the Advancement of Science.
By JAMES GORMAN Studies of hunters and gatherers — and of chimpanzees, which are often used as stand-ins for human ancestors — have cast bigger, faster and more powerful males in the hunter role. Now, a 10-year study of chimpanzees in Senegal shows females playing an unexpectedly big role in hunting and males, surprisingly, letting smaller and weaker hunters keep their prey. The results do not overturn the idea of dominant male hunters, said Jill D. Pruetz of Iowa State University, who led the study. But they may offer a new frame of reference on hunting, tools and human evolution. “We need to broaden our perspective,” she said. Among the 30 or so chimps Dr. Pruetz and her colleagues observed, called the Fongoli band, males caught 70 percent of the prey, mostly by chasing and running it down. But these chimps are very unusual in one respect. They are the only apes that regularly hunt other animals with tools — broken tree branches. And females do the majority of that hunting for small primates called bush babies. Craig Stanford, an anthropologist at the University of Southern California who has written extensively on chimp hunting and human evolution, said the research was “really important” because it solidified the evidence for chimps hunting with tools, which Dr. Pruetz had reported in earlier papers. It also clearly shows “the females are more involved than in other places,” he said, adding that it provides new evidence to already documented observations that female chimps are “much more avid tool users than males are.” All chimpanzees eat a variety of plant and animal foods, including insects like termites. And all chimpanzees eat some other animals. The most familiar examples of chimpanzee hunting are bands of the apes chasing red colobus monkeys through the trees in the rain forests of East Africa. © 2015 The New York Times Company
by Catherine Brahic TRANSLUCENT comb jellies are some of the most primitive animals on Earth, yet they have remarkable nervous systems. Controversial data discussed at a meeting in London last month proposes that their neurons are unlike any others on Earth. This could be evidence that neurons evolved more than once in the history of animal life. The suggestion that neurons evolved in parallel multiple times has divided biologists for over a century. Ultimately, Erich Jarvis of Duke University in North Carolina told a Royal Society conference in March, the question relates to how special we are. If neurons evolved several times on our planet, then it becomes more likely that they could evolve elsewhere in the universe. Until recently, the consensus has leaned towards a very Darwinian story. In this scenario, sometime around 600 million years ago, the common ancestor to all animals gave rise to some organisms with simple neural networks. Central nervous systems arose later, allowing for greater coordination and more complex behaviours. These perhaps started out as tight balls of neurons, but eventually gave rise to the magnificently complex primate brain. This single origin scenario offers a tidy explanation for why some animals, like sponges and flat, simple placozoans, still don't have neurons: they must have branched off before these evolved and are relics of ancestral animals (see diagram). The story was somewhat turned on its head by the recent whole genome sequence of comb jellies. These small marine animals look like jellyfish but in fact seem to be only distantly related. They use a neural network just beneath their skin and a brain-like knot of neurons at one end to catch food, respond to light, sense gravity and escape predators. © Copyright Reed Business Information Ltd.
Link ID: 20786 - Posted: 04.11.2015
By Jonathan Webb Science reporter, BBC News Living in total darkness, the animals' eyes have disappeared over millions of years A study of blind crustaceans living in deep, dark caves has revealed that evolution is rapidly withering the visual parts of their brain. The findings catch evolution in the act of making this adjustment - as none of the critters have eyes, but some of them still have stumpy eye-stalks. Three different species were studied, each representing a different subgroup within the same class of crustaceans. The research is published in the journal BMC Neuroscience. The class of "malocostracans" also includes much better-known animals like lobsters, shrimps and wood lice, but this study focussed on three tiny and obscure examples that were only discovered in the 20th Century. It is the first investigation of these mysterious animals' brains. "We studied three species. All of them live in caves, and all of them are very rare or hardly accessible," said lead author Dr Martin Stegner, from the University of Rostock in Germany. Specifically, his colleagues retrieved the specimens from the coast of Bermuda, from Table Mountain in South Africa, and from Monte Argentario in Italy. One of the species was retrieved from caves on the coast of Bermuda The animals were preserved rather than living, so the team could not observe their tiny brains in action. But by looking at the physical shape of the brain, and making comparisons with what we know about how the brain works in their evolutionary relatives, the researchers were able to assign jobs to the various lobes, lumps and spindly structures they could see under the microscope. © 2015 BBC.
Tom Bawden Scientists have deciphered the secrets of gibbon “speech” – discovering that the apes are sophisticated communicators employing a range of more than 450 different calls to talk to their companions. The research is so significant that it could provide clues on the evolution of human speech and also suggests that other animal species could speak a more precise language than has been previously thought, according to lead author Dr Esther Clarke of Durham University. Her study found that gibbons produce different categories of “hoo” calls – relatively quiet sounds that are distinct from their more melodic “song” calls. These categories of call allow the animals to distinguish when their fellow gibbons are foraging for food, alerting them to distant noises or warning others about the presence of predators. In addition, Dr Clarke found that each category of “hoo” call can be broken down further, allowing gibbons to be even more specific in their communication. A warning about lurking raptor birds, for example, sounds different to one about pythons or clouded leopards – being pitched at a particularly low frequency to ensure it is too deep for the birds of prey to hear. The warning call denoting the presence of tigers and leopards is the same because they belong to the same class of big cats, the research found. © independent.co.uk
by Jan Piotrowski It's not the most charismatic fossil ever found, but it may reveal secrets of our earliest evolution. Unearthed in Ethiopia, the broken jaw with greying teeth suggests that the Homo lineage – of which modern humans are the only surviving member – existed up to 400,000 years earlier than previously thought. The fragment dates from around 2.8 million years ago, and is by far the most ancient specimen to bear the Homo signature. The earliest such fossil was one thought to be up to 2.4 million years ages old. Showing a mixture of traits, the new find pinpoints the time when humans began their transition from primitive, apelike Australopithecus to the big-brained conquerer of the world, says Brian Villmoare from the University of Nevada, Las Vegas, whose student made the find. Geological evidence from the same area, also reported this week in a study led by Erin DiMaggio from Pennsylvania State University, shows that the jaw's owner lived just after a major climate shift in the region: forests and waterways rapidly gave way to arid savannah, leaving only the occasional crocodile-filled lake. Except for the sabre-toothed big cat that once roamed these parts, the environment ended up looking much like it does today. It was probably the pressure to adapt to this new world that jump-started our evolution into what we see looking back at us in the mirror today, according to Villmoare. © Copyright Reed Business Information Ltd.
Link ID: 20654 - Posted: 03.05.2015
By Nicholas Weiler The grizzled wolf stalks from her rival’s den, her mouth caked with blood of the pups she has just killed. It’s a brutal form of birth control, but only the pack leader is allowed to keep her young. For her, this is a selfish strategy—only her pups will carry on the future of the pack. But it may also help the group keep its own numbers in check and avoid outstripping its resources. A new survey of mammalian carnivores worldwide proposes that many large predators have the ability to limit their own numbers. The results, though preliminary, could help explain how top predators keep the food chains beneath them in balance. Researchers often assume that predator numbers grow and shrink based on their food supply, says evolutionary biologist Blaire Van Valkenburgh of the University of California, Los Angeles, who was not involved in the new study. But several recent examples, including an analysis of the resurgent wolves of Yellowstone National Park, revealed that some large predators keep their own numbers in check. The new paper is the first to bring all the evidence together, Van Valkenburgh says, and presents a “convincing correlation.” Hunting and habitat loss are killing off big carnivores around the world, just as ecologists are discovering how important they are for keeping ecosystems in balance. Mountain lions sustain woodlands by hunting deer that would otherwise graze the landscape bare. Coyotes protect scrub-dwelling birds by keeping raccoons and foxes in line. Where top carnivores disappear, these smaller predators often explode in numbers, with potentially disastrous consequences for small birds and mammals. © 2015 American Association for the Advancement of Science
By Elizabeth Pennisi Last week, researchers expanded the size of the mouse brain by giving rodents a piece of human DNA. Now another team has topped that feat, pinpointing a human gene that not only grows the mouse brain but also gives it the distinctive folds found in primate brains. The work suggests that scientists are finally beginning to unravel some of the evolutionary steps that boosted the cognitive powers of our species. “This study represents a major milestone in our understanding of the developmental emergence of human uniqueness,” says Victor Borrell Franco, a neurobiologist at the Institute of Neurosciences in Alicante, Spain, who was not involved with the work. The new study began when Wieland Huttner, a developmental neurobiologist at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, and his colleagues started closely examining aborted human fetal tissue and embryonic mice. “We specifically wanted to figure out which genes are active during the development of the cortex, the part of the brain that is greatly expanded in humans and other primates compared to rodents,” says Marta Florio, the Huttner graduate student who carried out the main part of the work. That was harder than it sounded. Building a cortex requires several kinds of starting cells, or stem cells. The stem cells divide and sometimes specialize into other types of “intermediate” stem cells that in turn divide and form the neurons that make up brain tissue. To learn what genes are active in the two species, the team first had to develop a way to separate out the various types of cortical stem cells. © 2015 American Association for the Advancement of Science
By Elizabeth Pennisi Researchers have increased the size of mouse brains by giving the rodents a piece of human DNA that controls gene activity. The work provides some of the strongest genetic evidence yet for how the human intellect surpassed those of all other apes. "[The DNA] could easily be a huge component in how the human brain expanded," says Mary Ann Raghanti, a biological anthropologist at Kent State University in Ohio, who was not involved with the work. "It opens up a whole world of possibilities about brain evolution." For centuries, biologists have wondered what made humans human. Once the human and chimp genomes were deciphered about a decade ago, they realized they could now begin to pinpoint the molecular underpinnings of our big brain, bipedalism, varied diet, and other traits that have made our species so successful. By 2008, almost two dozen computerized comparisons of human and ape genomes had come up with hundreds of pieces of DNA that might be important. But rarely have researchers taken the next steps to try to prove that a piece of DNA really made a difference in human evolution. "You could imagine [their roles], but they were just sort of 'just so' stories,” says Greg Wray, an evolutionary biologist at Duke University in Durham, North Carolina. Wray is particularly interested in DNA segments called enhancers, which control the activity of genes nearby. He and Duke graduate student Lomax Boyd scanned the genomic databases and combed the scientific literature for enhancers that were different between humans and chimps and that were near genes that play a role in the brain. Out of more than 100 candidates, they and Duke developmental neurobiologist Debra Silver tested a half-dozen. They first inserted each enhancer into embryonic mice to learn whether it really did turn genes on. Then for HARE5, the most active enhancer in an area of the brain called the cortex, they made minigenes containing either the chimp or human version of the enhancer linked to a “reporter” gene that caused the developing mouse embryo to turn blue wherever the enhancer turned the gene on. Embryos’ developing brains turned blue sooner and over a broader expanse if they carried the human version of the enhancer, Silver, Wray, and their colleagues report online today in Current Biology. © 2015 American Association for the Advancement of Science
By Warren Cornwall The green wings of the luna moth, with their elegant, long tails, aren’t just about style. New research finds they also help save the insect from becoming a snack for a bat. The fluttering tails appear to create an acoustic signal that is attractive to echolocating bats, causing the predators to zero in on the wings rather than more vital body parts. Scientists pinned down the tails’ lifesaving role by taking 162 moths and plucking the tails off 75 of them. They used fishing line to tether two moths—one with tails, the other without—to the ceiling of a darkened room. Then, they let loose a big brown bat. The bats caught 81% of the tailless moths, but just 35% of those with fully intact wings, they report in a study published online today in the Proceedings of the National Academy of Sciences. High-speed cameras helped show why. In 55% of attacks on moths with tails, the bats went after the tails, often missing the body. It’s the first well-documented example of an organism using body shape to confuse predators that use echolocation, the researchers say—the equivalent of fish and insects that display giant eyespots for visual trickery. © 2015 American Association for the Advancement of Science
Madeline Bonin Bats and moths have been evolving to one-up each other for 65 million years. Many moths can hear bats’ ultrasonic echolocation calls, making it easy for the insects to avoid this predator. A few species of bat have developed echolocation calls that are outside the range of the moths’ hearing, making it harder for the moths to evade them1. But humans short-circuit this evolutionary arms race every time they turn on a porch light, according to a study in the Journal of Applied Ecology2. In field experiments, ecologist Corneile Minnaar of the University of Pretoria and his colleagues examined the diet of Cape serotine bats (Neoromicia capensis) both in the dark and under artificial light in a national park near Pretoria. The bat, an insect-eating species common in South Africa, has an echolocation call that moths can hear. Minnaar and his team determined both the species and quantity of available insect prey at the test sites using a hand-held net and a stationary trap. Cape serotine bats do not normally eat many moths. As the scientists expected, they caught more during the lighted trials than in the dark. What was surprising, however, was the discovery that the insects formed a greater share of the bats' diet during the lighted trials. The percentage of moths eaten in bright areas was six times larger than in dark zones, even though moths represented a smaller share of the total insect population under the lights than in the shade. But surprisingly, though moths represented a smaller share of the total insect population in the lighted areas, they played a larger role in the bats' diet. © 2015 Nature Publishing Group
by Andy Coghlan Apple's the word. Chimpanzees can learn to grunt "apple" in two chimp languages – a finding that questions how unique our own language abilities are. Researchers have kept records of vocalisations of a group of adult chimps from the Netherlands before and after the move to Edinburgh zoo. Three years later, recordings show, the Dutch chimps had picked up the pronunciation of their Scottish hosts. The finding challenges the prevailing theory that chimp words for objects are fixed because they result from excited, involuntary outbursts. Humans can easily learn foreign words that refer to a specific object, and it was assumed that chimps and other animals could not, perhaps owing to their different brain structure. This has long been argued to be one of the talents making humans unique. The assumption has been that animals do not have control over the sounds they make, whereas we socially learn the labels for things – which is what separates us from animals, says Katie Slocombe of the University of York, UK. But this may be wrong, it seems. "The important thing we've now shown is that with the food calls, they changed the structure to fit in with their new group members, so the Dutch calls for 'apple' changed to the Edinburgh ones," says Slocombe. "It's the first time call structure has been dissociated from emotional outbursts." © Copyright Reed Business Information Ltd.
by Sandrine Ceurstemont Malte Andersson from the University of Gothenburg in Sweden has been testing whether Norwegian lemmings (Lemmus lemmus), like the one in the video above, deter predators by warning them of their aggressive nature with their shrieks. The vivid markings on the fur also indicate to predators that this critter isn't for eating. Having such warning colours – a phenomenon known as aposematism – is common in insects, snakes and frogs, but unusual in herbivorous mammals. This combination of hues made the lemmings easier to spot than their plain-looking neighbours, grey-sided voles. When a predator, played by humans in Andersson's test, is far away, these lemmings prefer to go unnoticed, he found. But when predators get closer, to within a few metres, these lemmings were much more likely to give out a warning call than their browner relatives. The conspicuous colours, aggressive calls and threatening postures together let predators know to expect a fight, and potentially damage, if they attempt to eat a Norwegian lemming. In contrast with the voles, these lemmings aggressively resist attacks by predatory birds. © Copyright Reed Business Information Ltd.
Link ID: 20558 - Posted: 02.07.2015
By Monique Brouillette When the first four-legged creatures emerged from the sea roughly 375 million years ago, the transition was anything but smooth. Not only did they have to adjust to the stress of gravity and the dry environment, but they also had to wait another 100 million years to evolve a fully functional ear. But two new studies show that these creatures weren’t deaf; instead, they may have used their lungs to help them hear. Fish hear easily underwater, as sound travels in a wave of vibration that freely passes into their inner ears. If you put a fish in air, however, the difference in the density of the air and tissue is so great that sound waves will mostly be reflected. The modern ear adapted by channeling sound waves onto an elastic membrane (the eardrum), causing it to vibrate. But without this adaptation, how did the first land animals hear? To answer this question, a team of Danish researchers looked at one of the closest living relatives of early land animals, the African lungfish (Protopterus annectens). As its name suggests, the lungfish is equipped with a pair of air-breathing lungs. But like the first animals to walk on land, it lacks a middle ear. The researchers wanted to determine if the fish could sense sound pressure waves underwater, so they filled a long metal tube with water and placed a loudspeaker at one end. They played sounds into the tube in a range of frequencies and carefully positioned the lungfish in areas of the tube where the sound pressure was high. Monitoring the brain stem and auditory nerve activity in the lungfish, the researchers were surprised to discover that the fish could detect pressure waves in frequencies above 200 Hz. © 2015 American Association for the Advancement of Science
David Cox Bernd Heinrich was on a hike through the woods of New England when he observed something which would go on to change our perception of animal psychology. A group of ravens had gathered to feed on a dead moose. But rather than choosing to keep the bounty for themselves, they were making a strange call, one which seemed to be deliberately attracting more ravens to the feast. A biologist at the University of Vermont, Heinrich was initially confused. By helping their competitors, the ravens appeared to be defying all natural biological instinct. But as it transpired, their motivation was actually deeply selfish. The birds were juveniles who had discovered the moose in an adult raven’s territory. By inviting other ravens to join them, their intrusion was more likely to go unchallenged. Last month, an astonishing video emerged of a rhesus macaque successfully resuscitating another of its species which had been electrocuted at a train station in India. It is tempting to describe the sustained display of persistence and apparent concern as almost human. But there is a danger in viewing animal behaviour through the misty lens of human emotion. What both Heinrich’s “sharing ravens’ and the macaques of Kampur do provide is a window into the gradual evolution of one of the most human of traits – altruism. Altruism in its purest form should be an entirely selfless action. “If there’s any kind of selfish interest at stake, like secretly hoping for a return favour or even doing it deliberately because you know it will make you feel good, then that doesn’t really count at all,” says psychologist Michael Platt of the Center for Cognitive Neuroscience at Duke University, North Carolina.
by Catherine Brahic Move over Homo habilis, you're being dethroned. A growing body of evidence – the latest published this week – suggests that our "handy" ancestor was not the first to use stone tools. In fact, the ape-like Australopithecus may have figured out how to be clever with stones before modern humans even evolved. Humans have a way with flint. Sure, other animals use tools. Chimps smash nuts and dip sticks into ant nests to pull out prey. But humans are unique in their ability to apply both precision and strength to their tools. It all began hundreds of thousands of years ago when a distant ancestor began using sharp stone flakes to scrape meat off skin and bones. So who were those first toolmakers? In 2010, German researchers working in Ethiopia discovered markings on two animal bones that were about 3.4 million years old. The cut marks had clearly been made using a sharp stone, and they were at a site that was used by Lucy's species, Australopithecus afarensis. The study, led by Shannon McPherron of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, was controversial. The bones were 800,000 years older than the oldest uncontested stone tools, and at the time few seriously thought that australopithecines had been tool users. Plus, McPherron hadn't found the tool itself. The problem, says McPherron, is that if we just go on tools that have been found, we must conclude that one day somebody made a beautifully flaked Oldowan hand axe, completely out of the blue. That seems unlikely. © Copyright Reed Business Information Ltd.
Link ID: 20512 - Posted: 01.23.2015