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By Michael Balter For much of the time dinosaurs were lording over the land, sleek marine reptiles called ichthyosaurs were the masters of the sea. The dolphinlike predators had enormous eyes for hunting and grew as long as 20 meters. But paleontologists have long been baffled by their brain structure, because most fossil specimens have been squished flat by marine sediments. One rare exception—discovered in the 1800s in southern England’s Bristol Channel—is a spectacularly preserved, 180-million-year-old ichthyosaur named Hauffiopteryx. Now, using computerized tomography (CT) scanning, researchers have created a 3D digital reconstruction of Hauffiopteryx’s skull, making a “ghost image” of its brain known as a digital endocast (above). The team, which reported its findings online earlier this month in Palaeontology, found that the brain’s optic lobes were particularly large; so were the cerebellum, which controls motor functions, and the olfactory region, where odors are processed. Taken together, the team concludes these features show ichthyosaurs were highly mobile predators with a keen sense of sight and smell. © 2015 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 21097 - Posted: 06.27.2015

By David Shultz Not usually lauded for their cuddly appearance, opossums were long thought to have a social inclination to match their looks; the marsupials have mostly been observed lurking alone and hissing at others who encroach on their personal space. However, a new study published online today in Biology Letters suggests that opossums sometimes live in groups and may form pair bonds with mates before the mating season starts. Based on 17,127 observations of 312 artificial nests over 8 years, scientists at the Federal University of Pernambuco in Recife, Brazil, discovered 10 instances of multiple opossums sharing the same den with no signs of hostility or ongoing reproductive activity. An additional observation made on the university campus revealed a group of 13 opossums from three separate age groups all sharing a single den. The researchers speculate that this type of “gregarious denning” may be relatively common in the wild and that males and females may work cooperatively to build a nest—a ritual that could trigger the onset of an estrous cycle in females. Furthermore, the group of 13 animals was discovered in a large concrete box housing electrical equipment, much bigger than the typical artificial dens used by scientists studying opossums. The team suspects that building larger artificial dens may promote more social interactions like the ones they observed. © 2015 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 21059 - Posted: 06.17.2015

James Gorman Chimpanzees have the cognitive ability to cook, according to new research, if only someone would give them ovens. It’s not that the animals are ready to go head-to-head with Gordon Ramsay, but scientists from Harvard and Yale found that chimps have the patience and foresight to resist eating raw food and to place it in a device meant to appear, at least to the chimps, to cook it. That is no small achievement. In a line that could easily apply to human beings, the researchers write, “Many primate species, including chimpanzees, have difficulty giving up food already in their possession and show limitations in their self-control when faced with food.” But they found that chimps would give up a raw slice of sweet potato in the hand for the prospect of a cooked slice of sweet potato a bit later. That kind of foresight and self-control is something any cook who has eaten too much raw cookie dough can admire. The research grew out of the idea that cooking itself may have driven changes in human evolution, a hypothesis put forth by Richard Wrangham, an anthropologist at Harvard and several colleagues about 15 years ago in an article in Current Anthropology, and more recently in his book, “Catching Fire: How Cooking Made Us Human.” He argued that cooking may have begun something like two million years ago, even though hard evidence only dates back about one million years. For that to be true, some early ancestors, perhaps not much more advanced than chimps, had to grasp the whole concept of transforming the raw into the cooked. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 21016 - Posted: 06.03.2015

By Sarah C. P. Williams Bonobos, endangered great apes considered—along with chimpanzees—the closest living relative to humans, spend most of each day climbing through trees, collecting fruit and leaves. Compare that with the lives of early humans who traversed hot, barren landscapes and it begins to make sense why we’re the fattier, less muscular primate. Over the past 3 decades, two researchers analyzed the hard-to-come-by bodies of 13 bonobos that had died in captivity and compared them with already collected data on 49 human bodies donated by means of autopsy to help understand how evolution drove this change. Although some captive bonobos have become obese, the researchers found that, on average, the apes’ body mass—which is thought to resemble that of the closest common ancestor we share with them—is composed of 10% to 13% skin, whereas humans have only 6% skin. This thinner skin, the team hypothesizes, probably arose around the same time that Homo sapiens gained the ability to sweat, allowing more time spent in hot, open areas. The scientists also found that we pack on more fat than our ape relatives: Female and male humans average 36% and 20% body fat, whereas female and male bonobos average 4% and close to 0% body fat, respectively. Increased fat, the researchers hypothesize, allowed our species to survive—and reproduce—during times of low food availability. As for muscle, the team reports online today in the Proceedings of the National Academy of Sciences, bonobos come out on top, especially when it comes to upper body muscles needed for tree climbing and swinging, which became unnecessary when humans went strictly bipedal. The new findings, the researchers say, help illustrate the forces of natural selection that may have affected H. sapiens’s soft tissues even before our brains started expanding in size and tool use shaped the species. © 2015 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 21007 - Posted: 06.02.2015

Carl Zimmer For scientists who study human evolution, the last few months have been a whirlwind. Every couple of weeks, it seems, another team pulls back the curtain on newly discovered bones or stone tools, prompting researchers to rethink what we know about early human history. On Wednesday, it happened again. Yohannes Haile-Selassie of the Cleveland Museum of Natural History and his colleagues reported finding a jaw in Ethiopia that belonged to an ancient human relative that lived some time between 3.3 and 3.5 million years. They argue that the jaw belongs to an entirely new species, which they dubbed Australopithecus deyiremeda. While some experts agree, skeptics argued that the jaw belongs to a familiar hominid species, known as Australopithecus afarensis, that existed from about 3.9 to 3 million years ago. Studies like this one are adding fresh fuel to the debate over the pace of human evolution. Some researchers now believe the human family tree bore exuberant branches early on. “I’m so excited about these discoveries, I’m driving my friends crazy,” said Carol V. Ward, a paleoanthropologist at the University of Missouri. “It makes us stop and rethink everything.” In the 1990s, the broad outlines of human evolution seemed fairly clear. Early human ancestors — known as hominids — evolved from an ancestor shared with chimpanzees about six or seven million years ago. These hominids were short, bipedal apes with small brains and arms and legs still adapted for climbing trees. Until about three million years ago, experts thought, there weren’t a lot of hominid species. In fact, some researchers argued that most hominid fossils represented just a single species. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20993 - Posted: 05.28.2015

By James Gorman and Robin Lindsay Before human ancestors started making stone tools by chipping off flakes to fashion hand axes and other implements, their ancestors may have used plain old stones, as animals do now. And even that simple step required the intelligence to see that a rock could be used to smash open a nut or an oyster and the muscle control to do it effectively. Researchers have been rigorous in documenting every use of tools they have found find in animals, like crows, chimpanzees and dolphins. And they are now beginning to look at how tools are used by modern primates — part of the scientists’ search for clues about the evolution of the kind of delicate control required to make and use even the simplest hand axes. Monkeys do not exhibit human dexterity with tools, according to Madhur Mangalam of the University of Georgia, one of the authors of a recent study of how capuchin monkeys in Brazil crack open palm nuts. “Monkeys are working as blacksmiths,” he said, “They’re not working as goldsmiths.” But they are not just banging away haphazardly, either. Mr. Mangalam, a graduate student who is interested in “the evolution of precise movement,” reported in a recent issue of Current Biology on how capuchins handle stones. His adviser and co-author was Dorothy M. Fragaszy, the director of the Primate Behavior Laboratory at the university. Using video of the capuchins’ lifting rocks with both hands to slam them down on the hard palm nuts, he analyzed how high a monkey lifted a stone and how fast it brought it down. He found that the capuchins adjusted the force of a strike according to the condition of the nut after the previous strike. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 20952 - Posted: 05.19.2015

By Rachel Feltman Animals didn't always have heads. We know that sometime during the Cambrian Period -- around 500 million years ago, as animals transitioned from the squishy likes of the penis worm to hard-bodied arthropods -- body segments started transitioning into something like the head/body differentiation we see today. But figuring out just how that transition went can be tricky. A study published on Thursday in Current Biology looks to one of the oldest-ever brain fossils for clues. Brains, being all squishy and stuff, aren't commonly found in fossilized form, especially not 500 million years after the fact. But the new study compares two specimens: A trilobite with a squishy body and Odaraia alata, a creature said to resemble a submarine. Cute, yeah? The Cambrian was such a great time. Lead author Javier Ortega-Hernández, a postdoctoral researcher from Cambridge's Department of Earth Sciences, found that the front portions of both creatures' brains had nerve connections to their eye stalks and a hard plate called the anterior sclerite. In modern arthropods, that brain region controls the eyes. Ortega-Hernández believes that this anterior sclerite was a bridge between ancient arthropods and more modern ones. Anomalocaridids, which lived at the same time but looked very different, have a plate that Ortega-Hernández thinks came from the same ancestral anatomy that went on to form anterior sclerites in the animals he examined (and, eventually, a more modern head structure today).

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20899 - Posted: 05.08.2015

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

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20843 - Posted: 04.25.2015

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

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 20800 - Posted: 04.15.2015

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.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
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.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 7: Vision: From Eye to Brain
Link ID: 20769 - Posted: 04.08.2015

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.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20654 - Posted: 03.05.2015

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.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20512 - Posted: 01.23.2015

By Christie Aschwanden Maybe it’s their famously protruding brow ridge or perhaps it’s the now-discredited notion that they were primitive scavengers too dumb to use language or symbolism, but somehow Neanderthals picked up a reputation as brutish, dim and mannerless cretins. Yet the latest research on the history and habits of Neanderthals suggests that such portrayals of them are entirely undeserved. It turns out that Neanderthals were capable hunters who used tools and probably had some semblance of culture, and the DNA record shows that if you trace your ancestry to Europe or Asia, chances are very good that you have some Neanderthal DNA in your own genome. The bad rap began when the first Neanderthal skull was discovered around 1850 in Germany, says Paola Villa, an archaeologist at the University of Colorado. “The morphological features of these skulls — big eyebrows, no chin — led to the idea that they were very different from us, and therefore inferior,” she says. While the majority of archaeologists no longer believe this, she says, the idea that Neanderthals were inferior, brutish or stupid remains in popular culture. Neanderthals first appeared in Europe and western Asia between 300,000 and 400,000 years ago. They are our closest (extinct) relative, and their species survived until 30,000 to 40,000 years ago, when they vanish from the fossil record, says Svante Paabo, director of the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, and author of “Neanderthal Man: In Search of Lost Genomes.” Why these relatives of ours thrived for so long and then ended their long, successful run about the same time that modern humans began to spread remains a point of debate and speculation.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20498 - Posted: 01.20.2015

by Clare Wilson Could a lopsided gap help set us apart from our primate cousins? Our brains and chimps' are built differently in the areas that give us our social skills and language. The human brain has a 4.5-centimetre-long groove running deeper along the right side than the left. Chimp brains lack this asymmetry, as François Leroy of the French National Institute of Health and Medical Research in Saclay, and colleagues, have discovered. The groove's function is unknown, but its location suggests it played a role in the evolution of our communication abilities. "One day this will help us understand what makes us tick," says Colin Renfrew of the University of Cambridge, who was not involved in the study. Although our brain is about three times the size of a chimp's, anatomical features that only the human brain possesses are surprisingly hard to find. One known difference is in a region called Broca's area, which is also involved in speech and is larger in humans than chimps. The asymmetrical groove in humans was also known, but the new study, in which 177 people and 73 chimps had brain scans, revealed it is almost completely absent in the other primates. In humans, the deeper groove in the right brain lies in the region that controls voice and face recognition and working out what other people are thinking – our so-called theory of mind. The shallower groove on the left is at the heart of the areas associated with language. The lack of symmetry could signify that tissue layers in the right brain have been reorganised, says Leroy. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 20475 - Posted: 01.13.2015

By Virginia Morell Animals that live in larger societies tend to have larger brains. But why? Is it because a larger group size requires members to divide up the labor on tasks, thus causing some individuals to develop specialized brains and neural anatomy? (Compared with most humans, for instance, taxicab drivers have brains that have larger areas that are involved with spatial memory.) Or is it because the challenges of group living—needing to know all the foibles of your neighbors—cause the brains of all members to grow larger? Scientists tested the two hypotheses with wild colonies of acacia ants (Pseudomyrmex spinicola), which make their nests in the hollow spines of acacia trees in Panama. Ant workers at the base of the tree wait to attack intruders, while workers foraging on the leaves (as in the photo above), aren’t as aggressive but are faster at managing the colony’s brood. This division of labor is most marked in larger colonies (those found on larger trees), while workers in smaller colonies do both jobs. The scientists studied 17 colonies of ants and measured the brain volumes of 29 of the leaf ants and 34 of the trunk ants. As the colony size increased, the leaf ants showed a marked increase in the regions of the brain concerned with learning and memory, the scientists report today in the Proceedings of the Royal Society B. But the same neural areas decreased in the trunk ants. Thus, larger societies’ need for specialized workers, some strictly for defense, others for foraging and brood tending—rather than for social masters—seems to be the key to the expanding brain, at least in ants.

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20457 - Posted: 01.08.2015

Carl Zimmer For thousands of years, fishermen knew that certain fish could deliver a painful shock, even though they had no idea how it happened. Only in the late 1700s did naturalists contemplate a bizarre possibility: These fish might release jolts of electricity — the same mysterious substance as in lightning. That possibility led an Italian physicist named Alessandro Volta in 1800 to build an artificial electric fish. He observed that electric stingrays had dense stacks of muscles, and he wondered if they allowed the animals to store electric charges. To mimic the muscles, he built a stack of metal disks, alternating between copper and zinc. Volta found that his model could store a huge amount of electricity, which he could unleash as shocks and sparks. Today, much of society runs on updated versions of Volta’s artificial electric fish. We call them batteries. Now a new study suggests that electric fish have anticipated other kinds of technology. The research, by Kenneth C. Catania, a biologist at Vanderbilt University, reveals a remarkable sophistication in the way electric eels deploy their shocks. Dr. Catania, who published the study on Thursday in the journal Science, found that the eels use short shocks like a remote control on their victims, flushing their prey out of hiding. And then they can deliver longer shocks that paralyze their prey at a distance, in precisely the same way that a Taser stops a person cold. “It shows how finely adapted eels are to attack prey,” said Harold H. Zakon, a biologist at the University of Texas at Austin, who was not involved in the study. He considered Dr. Catania’s findings especially impressive since scientists have studied electric eels for more than 200 years. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 5: The Sensorimotor System
Link ID: 20400 - Posted: 12.06.2014

Ewen Callaway A shell found on Java in the late 1800s was recently found to bear markings that seem to have been carved intentionally half a million years ago. The photograph is about 15 millimetres wide. Expand A zigzag engraving on a shell from Indonesia is the oldest abstract marking ever found. But what is most surprising about the half-a-million-year-old doodle is its likely creator — the human ancestor Homo erectus. "This is a truly spectacular find and has the potential to overturn the way we look at early Homo," says Nick Barton, an archaeologist at the University of Oxford, UK, who was not involved in the discovery, which is described in a paper published online in Nature on 3 December1. By 40,000 years ago, and probably much earlier, anatomically modern humans — Homo sapiens — were painting on cave walls in places as far apart as Europe2 and Indonesia3. Simpler ochre engravings found in South Africa date to 100,000 years ago4. Earlier this year, researchers reported a 'hashtag' engraving in a Gibraltar cave once inhabited by Neanderthals5. That was the first evidence for drawing in any extinct species. But until the discovery of the shell engraving, nothing approximating art has been ascribed to Homo erectus. The species emerged in Africa about 2 million years ago and trekked as far as the Indonesian island of Java, before going extinct around 140,000 years ago. Most palaeoanthropologists consider the species to be the direct ancestor of both humans and Neanderthals. © 2014 Nature Publishing Group

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20390 - Posted: 12.04.2014

By John Edward Terrell We will certainly hear it said many times between now and the 2016 elections that the country’s two main political parties have “fundamental philosophical differences.” But what exactly does that mean? At least part of the schism between Republicans and Democrats is based in differing conceptions of the role of the individual. We find these differences expressed in the frequent heated arguments about crucial issues like health care and immigration. In a broad sense, Democrats, particularly the more liberal among them, are more likely to embrace the communal nature of individual lives and to strive for policies that emphasize that understanding. Republicans, especially libertarians and Tea Party members on the ideological fringe, however, often trace their ideas about freedom and liberty back to Enlightenment thinkers of the 17th and 18th centuries, who argued that the individual is the true measure of human value, and each of us is naturally entitled to act in our own best interests free of interference by others. Self-described libertarians generally also pride themselves on their high valuation of logic and reasoning over emotion. The basic unit of human social life is not and never has been the selfish and self-serving individual. Philosophers from Aristotle to Hegel have emphasized that human beings are essentially social creatures, that the idea of an isolated individual is a misleading abstraction. So it is not just ironic but instructive that modern evolutionary research, anthropology, cognitive psychology and neuroscience have come down on the side of the philosophers who have argued that the basic unit of human social life is not and never has been the selfish, self-serving individual. Contrary to libertarian and Tea Party rhetoric, evolution has made us a powerfully social species, so much so that the essential precondition of human survival is and always has been the individual plus his or her relationships with others. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 20371 - Posted: 12.01.2014

Christopher Stringer Indeed, skeletal evidence from every inhabited continent suggests that our brains have become smaller in the past 10,000 to 20,000 years. How can we account for this seemingly scary statistic? Some of the shrinkage is very likely related to the decline in humans' average body size during the past 10,000 years. Brain size is scaled to body size because a larger body requires a larger nervous system to service it. As bodies became smaller, so did brains. A smaller body also suggests a smaller pelvic size in females, so selection would have favored the delivery of smaller-headed babies. What explains our shrinking body size, though? This decline is possibly related to warmer conditions on the earth in the 10,000 years after the last ice age ended. Colder conditions favor bulkier bodies because they conserve heat better. As we have acclimated to warmer temperatures, the way we live has also generally become less physically demanding, which overall serves to drive down body weights. Another likely reason for this decline is that brains are energetically expensive and will not be maintained at larger sizes unless it is necessary. The fact that we increasingly store and process information externally—in books, computers and online—means that many of us can probably get by with smaller brains. Some anthropologists have also proposed that larger brains may be less efficient at certain tasks, such as rapid computation, because of longer connection pathways. © 2014 Scientific American

Related chapters from BP7e: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 20345 - Posted: 11.24.2014