By Maggie Koerth-Baker If an animal is smart enough, should we treat it like a human? An abstract question, but one that found its way into a courtroom recently. A case bidding for consideration by the New York State Court of Appeals sought to extend the legal concept of habeas corpus — which allows a person to petition a court for freedom from unlawful imprisonment — to cover two privately-owned chimpanzees. The case for giving the chimps a human right like freedom from unlawful incarceration is based on their similarity to humans — they can think, feel and plan, argue the people bringing the case on behalf of the chimpanzees, so shouldn’t they have some guarantees of liberty? The court declined to hear the case, but one judge did say that some highly intelligent animals probably should be treated more like people and less like property. It’s just one judge, but you hear this kind of thing a lot from animal rights activists. The Nonhuman Rights Project, the nonprofit behind the habeas corpus lawsuit, has a stated goal of securing increased, human-like rights for great apes, elephants, dolphins and whales — highly intelligent, charismatic mammals. So, does a chimpanzee deserve more rights than, say, a pigeon? The logic that leads to “yes” is clear enough, but putting it into practice would be tough, scientists say. Because when it comes to measuring intelligence, we’re actually a little dumb. One of the problems: Animals don’t stack up the way you’d expect. “[Pigeons have] knocked our socks off in our own lab and other people’s labs in terms of what they can do,” said Edward Wasserman, a professor of experimental psychology at the University of Iowa. “Pigeons can blow the doors off monkeys in some tasks.” Experts who study animal intelligence across species say we can’t rank animals by their smarts — scientists don’t even try anymore — which means there’s no objective way to determine which animals would deserve more human-like rights.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 1: Introduction: Scope and Outlook
Related chapters from MM:Chapter 20:
Link ID: 25047 - Posted: 06.01.2018

By Elizabeth Pennisi Three nearly identical genes could help explain how 0.5 liters of gray matter in early human ancestors became the 1.4-liter organ that has made our species so successful and distinctive. The newly identified genes could also help explain how brain development sometimes goes wrong, leading to neurological disorders. The genes, descendants of an ancient developmental gene that multiplied and changed in the course of evolution, add to a growing list of DNA implicated in human brain expansion. But they stand out because so much has been learned about how they work their magic, says James Noonan, an evolutionary genomicist at Yale University. Researchers have shown that this trio boosts the number of potential nerve cells in brain tissue, and one team even pinned down the protein interactions likely responsible. “These are new proteins that are potentially modifying a very important pathway in brain development in a very powerful way,” Noonan adds. Until now, the four genes were thought to be one, NOTCH2NL, itself a spinoff of the NOTCH gene family, which controls the timing of development in everything from fruit flies to whales. But two studies in the 31 May issue of Cell trace a series of genetic accidents in recent evolutionary history that have yielded four very closely related NOTCH2NL genes in humans (see graphic, below). David Haussler, a bioinformatician at the University of California, Santa Cruz, and his colleagues got on the trail of the genes after they discovered that the NOTCH pathway works differently in human and macaque brain organoids—test tube models of the developing brain. NOTCH2NL was missing in the macaque organoid and, later analyses showed, in other nonhuman apes as well. That suggested NOTCH2NL might have played a unique role in human evolution. © 2018 American Association for the Advancement of Science.

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 4: Development of the Brain
Link ID: 25046 - Posted: 06.01.2018

By Carl Zimmer Early inhabitants of the Americas split into two populations over 13,000 years ago, according to a new study of ancient DNA, and remained separated for thousands of years. Eventually, somewhere, the two groups met again and began commingling. Today, their descendants inhabit a vast region stretching from Mexico to the southern tip of South America. The research, published on Thursday in the journal Science, paints a complex picture of human migrations through the Americas. When people arrived in the Western Hemisphere from Asia, they didn’t just move to new territories and settle down. “This study is important because it begins to move us away from overly simplistic models of how people first spread throughout the Americas,” said Deborah A. Bolnick, a geneticist at the University of Texas at Austin, who was not involved in the study. The findings emerged from a study of 91 ancient genomes of people who lived as long as 4,800 years ago in what are now Alaska, California and Ontario. They represent a major addition to the catalog of ancient DNA in the Western Hemisphere. Until the 1990s, archaeological sites provided much of the evidence for the spread of people across the Americas. There’s firm archaeological evidence that people had reached southern Chile by 14,500 years ago, for example; some researchers even argue that people arrived several thousand years earlier. Yet archaeology alone has left many questions unanswered, such as who exactly lived in those early sites and how they were related to each other. Geneticists are seeking to answer some of those questions by looking at the DNA of living Native Americans. Early studies on small fragments of genes suggested that all Native Americans south of the Arctic descended from the same group of migrants, who may have traveled across the Bering Land Bridge connecting Asia to what is now Alaska at the end of the last ice age. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25044 - Posted: 06.01.2018

By Ashley Yeager Finding food and lighting fires might explain why humans have such big brains, researchers report yesterday (May 23) in Nature. Humans’ brains are six times as large as those of similarly sized mammals, an observation that has led scientists to ponder for decades what led to such big noodles. Studies suggest social challenges, such as cooperating to hunt, or sharing cultural knowledge spurred the expansion, but a mathematical model to explain human brain evolution finds the environment had a stronger influence. Study coauthors Mauricio González-Forero and Andy Gardner of the University of St. Andrews developed a computer model to simulate the effects of social, environmental, and cultural challenges on brain size over time. “We were expecting social challenges to be a strong promoter of brain size,” González-Forero tells New Scientist. Surprisingly, environmental challenges won out. About 60 percent of the increase in brain size over our ape ancestors came as a result of surviving in the environment, finding and caching food, for example. Another 30 percent came from banding together to survive, and the final 10 percent came from competing with other human groups, the researchers report. If left alone to survive, humans’ brains would be even bigger, according to the model, González-Forero tells The Los Angeles Times. Increasing the cooperative challenges in the model to greater than 30 percent decreased brain size, the team found. “Cooperation decreases brain size because you can rely on the brain of other individuals and you don’t need to invest in such a large and expensive brain,” González-Forero says. The Scientist

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 1: Introduction: Scope and Outlook
Related chapters from MM:Chapter 20:
Link ID: 25019 - Posted: 05.25.2018

By Matthew Hutson Parents tend to favor children of one gender in certain situations—or so evolutionary biologists tell us. A new study used data on colored backpack sales to show that parental wealth may influence spending on sons versus daughters. In 1973 biologist Robert Trivers and computer scientist Dan Willard published a paper suggesting that parents invest more resources, such as food and effort, in male offspring when times are good and in female offspring when times are bad. According to the Trivers-Willard hypothesis, a son given lots of resources can outcompete others for mates—but when parents have few resources, they are more inclined to invest them in daughters, who generally find it easier to attract reproductive partners. Trivers and Willard further posited that parental circumstances could even influence the likelihood of having a boy or girl, a concept widely supported by research across vertebrate species. Studying parental investment after birth is difficult, however, and has produced conflicting results. The new study looked for a metric of such investment that met several criteria: it should be immune to inherent sex differences in the need for resources; it should measure investment rather than outcomes; and it should be objective rather than rely on self-reporting. Study author Shige Song, a sociologist at Queens College, City University of New York, examined spending on pink and blue backpacks purchased in China in 2015 from a large retailer, JD.com. He narrowed the data to about 5,000 bags: blue backpacks bought by households known to have at least one boy and pink ones bought by households known to have at least one girl. The results showed that wealthier families spent more on blue versus pink backpacks—suggesting greater investment in sons. Poorer families spent more on pink packs than blue ones. The findings were published online in February in Evolution and Human Behavior. © 2018 Scientific American

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 25000 - Posted: 05.21.2018

By Nicholas St. Fleur What makes humans so smart? For a long time the answer was simple: our big brains. But new research into the tiny noggins of a recently discovered human relative called Homo naledi may challenge that notion. The findings, published Monday, suggest that when it comes to developing complex brains, size isn’t all that matters. In 2013 scientists excavating a cave in South Africa found remains of Homo naledi, an extinct hominin now thought to have lived 236,000 to 335,000 years ago. Based on the cranial remains, the researchers concluded it had a small brain only about the size of an orange or your fist. Recently, they took another look at the skull fragments and found imprints left behind by the brain. The impressions suggest that despite its tiny size, Homo naledi’s brain shared a similar shape and structure with that of modern human brains, which are three times as large. “We’ve now seen that you can package the complexity of a large brain in a tiny packet,” said Lee Berger, a paleoanthropologist at Wits University in South Africa and an author of the paper published in the journal Proceedings of the National Academy of Sciences. “Almost in one fell swoop we slayed the sacred cow that complexity in the hominid brain was directly associated with increasing brain size.” Not every scientist agrees with their interpretation. Since its remains were first retrieved, Homo naledi has puzzled scientists. From head to toe the ancient hominin displays a medley of primitive, apelike features and more advanced, humanlike characteristics. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24977 - Posted: 05.15.2018

Carl Zimmer Nine years later, Erin Wessling can still remember the first time she visited Fongoli, a savanna in southeast Senegal. “You feel like you walk into an oven,” she said. Temperatures at Fongoli can reach 110 degrees Fahrenheit or more. During every dry season, brush fires sweep across the parched landscape, leaving behind leafless trees and baked, orange soil. “It’s really nuts,” said Ms. Wessling, now a graduate student at the Max Planck Institute for Evolutionary Anthropology. Yet Ms. Wessling and her colleagues keep coming back to Fongoli, despite the harsh conditions. That’s because it’s home to some remarkable residents: chimpanzees. To study them, scientists have mostly traveled to African rain forests and woodlands, where the apes live in dense groups. The sparse populations of chimpanzees that live on savannas in western and central Africa are far less understood. Ms. Wessling and her colleagues think there are important lessons to be learned from chimps like the ones at Fongoli. Because they are our closest living relatives, they may even tell us something about our own deep history. Millions of years ago, our apelike ancestors gradually moved from woodlands to savannas and began walking upright at some point. The Fongoli chimpanzees demonstrate just how difficult that transition would have been — and how that challenge may have driven some major changes in our evolution, from evolving sweat glands to losing fur and walking upright. The savanna became the subject of long-term research in 2000, when Ms. Wessling’s undergraduate adviser at Iowa State University, Jill D. Pruetz, first paid a visit. Surveying Fongoli, Dr. Pruetz decided it would be a good place to observe the differences between chimpanzee life on a savanna compared to forests. In forests, for example, chimpanzees typically thrive on a diet of ripe fruit. That’s a rare treat on a savanna. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24920 - Posted: 04.28.2018

By Ann Gibbons With their opposable toes and flat feet, early human ancestors have often been portrayed as weird walkers, swaying from side to side or rolling off the outside edges of their feet. Now, a new study finds that this picture of awkward upright locomotion is wrong: Early members of the human family, or hominins, were already walking upright with an efficient, straight-legged gait some 4.4 million years ago. The study helps settle a long-standing debate about how quickly our ancestors developed a humanlike gait, and shows that ancient hominins didn’t have to sacrifice climbing agility to walk upright efficiently. For years, some paleoanthropologists argued that hominins like the famous 3.1-million-year-old Lucy weren’t graceful on the ground because they retained traits for climbing trees, such as long fingers and toes. In one famous experiment, researchers donned extra-long shoes—one critic called them clown shoes—to mimic walking with longer toes. The scientists stumbled over their long feet and concluded that early hominins would have been just as clumsy. But other researchers argued that natural selection would have quickly favored adaptations for efficient walking given the dangers on the ground, even while hominins were still scurrying up trees. To test these hypotheses, evolutionary anthropologist Herman Pontzer of the City University of New York (CUNY) in New York City and his team compared how humans, living apes, and monkeys use their hips, leg bones, and muscles when they walk and climb. CUNY graduate student Elaine Kozma filmed chimps, bonobos, gorillas, gibbons, and other primates in zoos so she could measure the precise angles of their legs and hips when they walked upright. She then calculated the stresses on their bones during maximum extension and found that apes put a lot of force on their massive thighs, hamstrings, and knees—forces that also help them power up trees. © 2018 American Association for the Advancement of Science.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24816 - Posted: 04.03.2018

Bruce Bower Groove patterns on the surface of modern chimpanzee brains throw a monkey wrench into proposals that some ancient southern African hominids evolved humanlike brain characteristics, a new study suggests. MRIs of eight living chimps reveal substantial variability in the shape and location of certain features on the brain surface. Some of these brains showed surface creases similar to ones that were thought to have signaled a turn toward humanlike brain organization in ancient hominids hundreds of thousands, if not millions, of years ago. Paleoanthropologist Dean Falk of Florida State University in Tallahassee and colleagues report their findings online March 13 in Brain, Behavior and Evolution. The study casts doubt on a 2014 paper by Falk that was based on casts of the inside of fossil braincases, called endocasts, which preserve impressions of these surface features. At the time, Falk argued that four endocasts from southern African hominids — three Australopithecus africanus and one Australopithecus sediba — showed folding patterns that suggested that brain reorganization was underway as early as 3 million years ago in a frontal area involved in human speech production. But MRIs of three of the chimp brains reveal comparable creases, the researchers found. Two other chimps display other frontal tissue furrows that Falk had also previously described as distinctly humanlike. |© Society for Science & the Public 2000 - 2018

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24786 - Posted: 03.27.2018

Jeff Tollefson Early humans in eastern Africa crafted advanced tools and displayed other complex behaviours tens of thousands of years earlier than previously thought, according to a trio of papers published on 15 March in Science1,2,3. Those advances coincided with — and may have been driven by — major climate and landscape changes. The latest evidence comes from the Olorgesailie Basin in Southern Kenya, where researchers have previously found traces of ancient relatives of modern human as far back as 1.2 million years ago. Evidence collected at sites in the basin suggests that early humans underwent a series of profound changes at some point before roughly 320,000 years ago. They abandoned simple hand axes in favour of smaller and more advanced blades made from obsidian and other materials obtained from distant sources. That shift suggests the early people living there had developed a trade network — evidence of growing sophistication in behaviour. The researchers also found gouges on black and red rocks and minerals, which indicate that early Olorgesailie residents used those materials to create pigments and possibly communicate ideas. All of these changes in human behaviour occurred during an extended period of environmental upheaval, punctuated by strong earthquakes and a shift towards a more variable and arid climate. These changes occurred at the same time as larger animals disappeared from the site and were replaced by smaller creatures. “It’s a one-two punch combining tectonic shifts and climate shifts,” says Rick Potts, who led the work as director of the human origins programme at the Smithsonian Institution in Washington DC. “That’s the kind of stuff out of which evolution arises.” Researchers from the Smithsonian Institution digging in the Olorgesailie Basin in Kenya. © 2018 Macmillan Publishers Limited

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24759 - Posted: 03.16.2018

By Elizabeth Pennisi Although it’s hard to believe that delicate nervous tissues could persist for hundreds of millions of years, that’s exactly what happened to the brains and eyes of some 15 ancestors of modern-day spiders and lobsters, called Kerygmachela kierkegaardi (after the famous philosopher Søren Kierkegaard). Found along the coast of north Greenland, the 518-million-year-old fossils contained enough preserved brains and eyes to help researchers write a brand-new history of the arthropod nervous system. Until now, many biologists had argued that ancient arthropods—which gave rise to today’s insects, spiders, and crustaceans—had a three-part brain and very simple eyes. Compound eyes, in which the “eye” is really a cluster of many smaller eyes, supposedly evolved later from a pair of legs that moved into the head and was modified to sense light. But these new fossils, which range from a few centimeters to 30 centimeters long, had a tiny, unsegmented brain, akin to what’s seen in modern velvet worms, researchers report today in Nature Communications. Despite the simple brain, Kerygmachela’s eyes were probably complex, perhaps enough to form rudimentary images. The eyes, indicated by shiny spots in the fossil’s small head, appear to be duplicated versions of the small, simple eyes seen today in soft, primitive arthropods called water bears and velvet worms. © 2018 American Association for the Advancement of Science.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24734 - Posted: 03.10.2018

By Alexandra Rosati The shift to a cooked-food diet was a decisive point in human history. The main topic of debate is when, exactly, this change occurred. All known human societies eat cooked foods, and biologists generally agree cooking could have had major effects on how the human body evolved. For example, cooked foods tend to be softer than raw ones, so humans can eat them with smaller teeth and weaker jaws. Cooking also increases the energy they can get from the food they eat. Starchy potatoes and other tubers, eaten by people across the world, are barely digestible when raw. Moreover, when humans try to eat more like chimpanzees and other primates, we cannot extract enough calories to live healthily. Up to 50 percent of women who exclusively eat raw foods develop amenorrhea, or lack of menstruation, a sign the body does not have enough energy to support a pregnancy—a big problem from an evolutionary perspective. Such evidence suggests modern humans are biologically dependent on cooking. But at what point in our evolutionary history was this strange new practice adopted? Some researchers think cooking is a relatively recent innovation—at most 500,000 years old. Cooking requires control of fire, and there is not much archaeological evidence for hearths and purposefully built fires before this time. The archaeological record becomes increasingly fragile farther back in time, however, so others think fire may have been controlled much earlier. Anthropologist Richard Wrangham has proposed cooking arose before 1.8 million years ago, an invention of our evolutionary ancestors. If the custom emerged this early, it could explain a defining feature of our species: the increase in brain size that occurred around this time. © 2018 Scientific American,

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 24698 - Posted: 02.26.2018

Emma Marris Neanderthals painted caves in what is now Spain before their cousins, Homo sapiens, even arrived in Europe, according to research published today in Science1. The finding suggests that the extinct hominids, once assumed to be intellectually inferior to humans, may have been artists with complex beliefs. Ladder-like shapes, dots and handprints were painted and stenciled deep in caves at three sites in Spain. Their precise meaning may forever be unknowable, says Alistair Pike, an archaeologist at the University of Southampton, UK, who co-authored the study, but they were almost certainly meaningful to our lost kin. “It wasn’t simply decorating your living space,” Pike says. “People were making journeys into the darkness.” Humans are thought to have arrived in Europe from Africa around 40,000–45,000 years ago. The three caves in different parts of Spain yielded artworks that are at least 65,000 years old, according to uranium-thorium dating of calcium carbonate that had formed on top of the art. These mineral deposits develop slowly, as water containing calcium comes into contact with cave surfaces. The water also contains trace levels of uranium from the rock. After the calcium carbonate has precipitated out of the water, a clock of sorts begins to tick, as uranium decays into thorium at a steady, known rate. Uranium-thorium dating has been used in geology for decades, but has seldom been employed to estimate the age of cave art. Some archaeologists are sceptical of the approach. They suggest that the calcium carbonate could have dissolved and re-crystallized after it was first formed — a process that could have also washed away some uranium, making a sample of the mineral appear older than it is. 2018 Macmillan Publishers Limited,

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24693 - Posted: 02.23.2018

By C. CLAIBORNE RAY Q. Does an octopus have a brain? Where is it? And just how smart is an octopus? A. In a sense, an octopus has several brains, collections of neurons that control each arm. A famous 2001 study in the journal Science described how the commands that control one arm’s movement continue even when connections to the walnut-sized central processing system in the head are severed. Since then, more has been found about why the octopus is so much smarter than the average seafood. Even the relatively small central brain of an octopus is the largest among all invertebrates — proportionally, that is. A review article in 2015 in the journal Current Opinion in Neurobiology summarized the complexity of learning processes in the octopus and its remarkable adaptability. Some studies have examined the cephalopod’s ability to discern objects of different sizes, shapes, colors, brightnesses and textures; and its problem-solving, including the ability to navigate mazes and open jars. The creature also displays both short-term and long-term memory and recall over periods of weeks and even months. A possible explanation of the advanced abilities of the octopus lies in its very large genome, decoded in 2015 in a study in the journal Nature. The researchers surmised that the vast expansion of certain gene families in the octopus, and the network of linkages among the genes, could account for the development of its neurological complexity. © 2018 The New York Times Company

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 24602 - Posted: 02.02.2018

Ewen Callaway The oldest human fossils ever found outside Africa suggest that Homo sapiens might have spread to the Arabian Peninsula around 180,000 years ago — much earlier than previously thought. The upper jaw and teeth, found in an Israeli cave and reported in Science on 25 January1, pre-date other human fossils from the same region by at least 50,000 years. But scientists say that it is unclear whether the fossils represent a brief incursion or a more-lasting expansion of the species. Researchers originally thought that H. sapiens emerged in East Africa 200,000 years ago then moved out to populate the rest of the world. Until discoveries in the past decade countered that story, scientists thought that a small group left Africa some 60,000 years ago and that signs of earlier travels, including 80,000–120,000 year-old skulls and other remains from Israel discovered in the 1920s and 1930s, were from failed migrations. However, recent discoveries have muddied that simple narrative. Some H. sapiens-like fossils from Morocco that are older than 300,000 years, reported last year2, have raised the possibility that humans evolved earlier and perhaps elsewhere in Africa. Teeth from southern China, described in 20153, hint at long-distance migrations some 120,000 years ago. And genome studies have sown more confusion, with some comparisons of global populations pointing to just one human migration from Africa4,5, and others suggesting multiple waves6. © 2018 Macmillan Publishers Limited,

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24570 - Posted: 01.26.2018

By Bret Stetka Fossil records can tell us a lot about our evolutionary past: what our ancestors looked like, how they walked, what they ate. But what bits of bone don’t typically reveal is why humans evolved the way we did—why, compared with all other known species, we wound up capable of such complex thought, emotion and behavior. A team of researchers has now used a novel technique to form a hypothesis on the origins of our rich cognitive abilities. They did so by profiling the chemicals buzzing around our brains. These compounds, known as neurotransmitters, are the signaling molecules responsible for key brain functions. Their research reveals that in comparison with other higher primates, our brains have unique neurotransmitter profiles that probably resulted in our enhanced cognition. The authors of the new study—a multicenter effort led by Kent State University anthropologists C. Owen Lovejoy and Mary Ann Raghanti and published January 22 in PNAS—began by measuring neurotransmitter levels in brain samples from humans, chimpanzees, gorillas, baboons and monkeys, all of whom had died of natural causes. Specifically, they tested levels in the striatum, a brain region involved in social behaviors and interactions. Compared with the other species tested, humans had markedly increased striatal dopamine activity. Among other functions, dopamine helps drive reward activity and social behaviors. In the striatum in particular it contributes to uniquely human abilities and behaviors like complicated social group formation and, in part, speech and language. © 2018 Scientific American,

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24567 - Posted: 01.25.2018

Bruce Bower Big brains outpaced well-rounded brains in human evolution. Around the time of the origins of our species 300,000 years ago, the brains of Homo sapiens had about the same relatively large size as they do today, new research suggests. But rounder noggins rising well above the forehead — considered a hallmark of human anatomy — didn’t appear until between about 100,000 and 35,000 years ago, say physical anthropologist Simon Neubauer and his colleagues. Using CT scans of ancient and modern human skulls, the researchers created digital brain reconstructions, based on the shape of the inner surface of each skull’s braincase. Human brains gradually evolved from a relatively flatter and elongated shape — more like that of Neandertals’ — to a globe shape thanks to a series of genetic tweaks to brain development early in life, the researchers propose January 24 in Science Advances. A gradual transition to round brains may have stimulated considerable neural reorganization by around 50,000 years ago. That cognitive reworking could have enabled a blossoming of artwork and other forms of symbolic behavior among Stone Age humans, the team suspects. Other researchers have argued, however, that abstract and symbolic thinking flourished even before H. sapiens emerged (SN: 12/27/14, p. 6). Ancient DNA studies indicate that genes involved in brain development changed in H. sapiens following a split from Neandertals more than 600,000 years ago (SN Online: 3/14/16). “Those genetic changes might be responsible for differences in neural wiring and brain growth that led to brain [rounding] in modern humans, but not in Neandertals,” says Neubauer of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. |© Society for Science & the Public 2000 - 2017

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24566 - Posted: 01.25.2018

Hanneke Meijer Even though I am better with dead birds than with living ones, I do enjoy watching them. Their behaviour is fascinating, and as Jennifer Ackerman points out in her book, birds are a lot more intelligent than we often give them credit for. But what do we know about the evolution of bird intelligence? How did the bird brain evolve, and when did it take on its “birdiness”? The fossil record isn’t particularly well-suited for the preservation of soft tissue such as brains – and behaviour doesn’t fossilise at all. However, some inferences regarding behaviour can be made based on anatomy, something the fossil record is rife with. When we look at the anatomical evidence of bird behaviour in the fossil record (Naish, 2014), it becomes clear that certain types of behaviour we see in modern birds – such as colonial nesting, parental care and plumage display – evolved a long time ago, and are likely dinosaurian in origin. The avian brain itself is a modified version of the basic archosaur brain (archosaurs are the group of reptiles that gave rise to crocodiles and dinosaurs). The archosaur brain, as seen in living crocodiles, is a relatively simple, tube-like structure consisting of the hindbrain, mid-brain and forebrain along a central axis. The bird brain has undergone significant enlargement of the forebrain and has folded along its main axis, resulting in a distinctive shape. Unfortunately, no fossilised bird brain has yet been found, but the shape and size of the inner brain cavity in fossilised skulls provides some information about brain shape and maximal brain dimensions. It should be noted here that the brain cavity is never an exact representation of the brain itself, as a significant portion of the endocranial space can be taken up by blood vessels, other soft tissues and fluid. © 2018 Guardian News and Media Limited

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:None
Link ID: 24539 - Posted: 01.19.2018

Laura Sanders If more nerve cells mean more smarts, then dogs beat cats, paws down, a new study on carnivores shows. That harsh reality may shock some friends of felines, but scientists say the real surprises are inside the brains of less popular carnivores. Raccoon brains are packed with nerve cells, for instance, while brown bear brains are sorely lacking. By comparing the numbers of nerve cells, or neurons, among eight species of carnivores (ferret, banded mongoose, raccoon, cat, dog, hyena, lion and brown bear), researchers now have a better understanding of how different-sized brains are built. This neural accounting, described in an upcoming Frontiers in Neuroanatomy paper, may ultimately help reveal how brain features relate to intelligence. For now, the multispecies tally raises more questions than it answers, says zoologist Sarah Benson-Amram of the University of Wyoming in Laramie. “It shows us that there’s a lot more out there that we need to study to really be able to understand the evolution of brain size and how it relates to cognition,” she says. Neuroscientist Suzana Herculano-Houzel of Vanderbilt University in Nashville and colleagues gathered brains from the different species of carnivores. For each animal, the researchers whipped up batches of “brain soup,” tissue dissolved in a detergent. Using a molecule that attaches selectively to neurons in this slurry, researchers could count the number of neurons in each bit of brain real estate. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 24430 - Posted: 12.16.2017

Amy Maxmen A study of some of the world’s most obscure marine life suggests that the central nervous system evolved independently several times — not just once, as previously thought1. The invertebrates in question belong to families scattered throughout the animal evolutionary tree, and they display a diversity of central nerve cord architectures. The creatures also activate genes involved with nervous system development in other, well-studied animals — but they often do it in non-neural ways, report the authors of the paper, published on 13 December in Nature. “This puts a stake in the heart of the idea of an ancestor with a central nerve cord,” says Greg Wray, an evolutionary developmental biologist at Duke University in Durham, North Carolina. “That opens up a lot of questions we don’t have answers to — like, if central nerve cords evolved independently in different lineages, why do they have so many similarities?” In 1875, German zoologist Anton Dohrn noted anatomical similarities between the central nerve cord that runs length-wise through the bodies of annelids — a group of invertebrates that includes earthworms — and the nerve cord in the spine of vertebrates. He proposed that the groups’ ancient common ancestor had a nerve cord that ran along its belly-side, as seen in annelids. He also suggested that this cord flipped to the back of the body in a more recent animal that gave rise to all vertebrates. © 2017 Macmillan Publishers Limited,

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 4: Development of the Brain
Link ID: 24424 - Posted: 12.14.2017