Chapter 6. Evolution of the Brain and Behavior
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By Sid Perkins Forget the phrase “blind as a bat.” New experiments suggest that members of one species of these furry flyers—Myotis myotis, the greater mouse-eared bat—can do something no other mammal is known to do: They detect and use polarized light to calibrate their long-distance navigation. Previous research hinted that these bats reset their magnetic compass each night based on cues visible at sunset, but the particular cue or cues hadn’t been identified. In the new study, researchers placed bats in boxes in which the polarization of light could be controlled and shifted. After letting the bats experience sundown at a site near their typical roost, the team waited until after midnight (when polarized light was no longer visible in the sky), transported the animals to two sites between 20 and 25 kilometers from the roost, strapped radio tracking devices to them, and then released them. In general, bats whose polarization wasn’t shifted took off for home in the proper direction. But those that had seen polarization shifted 90° at sunset headed off in directions that, on average, pointed 90° away from the true bearing of home, the researchers report online today in Nature Communications. It’s not clear how the bats discern the polarized light, but it may be related to the type or alignment of light-detecting pigments in their retinas, the team suggests. The bats may have evolved to reset their navigation system using polarized light because that cue persists long after sunset and is available even when skies are cloudy. Besides these bats (and it’s not known whether other species of bat can do this, too), researchers have found that certain insects, birds, reptiles, and amphibians can navigate using polarized light. © 2014 American Association for the Advancement of Science
Ewen Callaway One could be forgiven for mistaking anomalocaridids for creatures from another world. The spade-shaped predators, which lived in the seas during the Cambrian — the geological era stretching from 541 million to 485 million years ago — had eyes that protruded from stalks and a pair of giant appendages on the sides of their mouths. But three stunningly well-preserved fossils found in China now show that the anomalocaridid brain was wired much like that of modern creatures called velvet worms, or onychophorans. Both anomalocaridids and onychophorans belong to the arthropods, the group of invertebrates that includes spiders and insects and whose brain structures come in three main types. Two of those were already known to be very ancient, and the new fossils, described today in Nature1, suggest that the third type — the neural architecture found in onychophorans — also has changed little over more than half a billion years of evolution. Named Lyrarapax unguispinus, the three fossils reveal creatures that — at 8 centimetres long — are on the small side for anomalocaridids, some of which are thought to have been as long as 2 to 3 metres. But the fossils’ segmented bodies and frontal appendages are pure anomalocaridid, says Nicholas Strausfeld, a neuroscientist at the University of Arizona in Tucson, who co-led the study. What really grabbed Strausfeld’s attention was the creature’s brain, preserved flattened like a pressed flower: “I said, ‘Holy shit, that’s an onychophoran brain!’” he recalls. The animal’s frontal appendages are connected to nerve bundles, or ganglia, in front of optic nerves. Both the ganglia and the optic nerves lead to a segmented brain. The layout is an uncanny match to the wiring of the velvet worm’s brain, Strausfeld says: “It’s completely unlike anything else in any other arthropod.” © 2014 Nature Publishing Group
Link ID: 19851 - Posted: 07.19.2014
Sara Reardon For chimps, nature and nurture appear to contribute equally to intelligence. Smart chimpanzees often have smart offspring, researchers suggest in one of the first analyses of the genetic contribution to intelligence in apes. The findings, published online today in Current Biology1, could shed light on how human intelligence evolved, and might even lead to discoveries of genes associated with mental capacity. A team led by William Hopkins, a psychologist at Georgia State University in Atlanta, tested the intelligence of 99 chimpanzees aged 9 to 54 years old, most of them descended from the same group of animals housed at the Yerkes National Primate Research Center in Atlanta. The chimps faced cognitive challenges such as remembering where food was hidden in a rotating object, following a human’s gaze and using tools to solve problems. A subsequent statistical analysis revealed a correlation between the animals' performance on these tests and their relatedness to other chimpanzees participating in the study. About half of the difference in performance between individual apes was genetic, the researchers found. In humans, about 30% of intelligence in children can be explained by genetics; for adults, who are less vulnerable to environmental influences, that figure rises to 70%. Those numbers are comparable to the new estimate of the heritability of intelligence across a wide age range of chimps, says Danielle Posthuma, a behavioural geneticist at VU University in Amsterdam, who was not involved in the research. “This study is much overdue,” says Rasmus Nielsen, a computational biologist at the University of California, Berkeley. “There has been enormous focus on understanding heritability of intelligence in humans, but very little on our closest relatives.” © 2014 Nature Publishing Group
by Sarah Zielinski Would you recognize a stop sign if it was a different shape, though still red and white? Probably, though there might be a bit of a delay. After all, your brain has long been trained to expect a red-and-white octagon to mean “stop.” The animal and plant world also uses colorful signals. And it would make sense if a species always used the same pattern to signal the same thing — like how we can identify western black widows by the distinctive red hourglass found on the adult spiders’ back. But that doesn’t always happen. Even with really important signals, such as the ones that tell a predator, “Don’t eat me — I’m poisonous.” Consider the dyeing dart frog (Dendrobates tinctorius), which is found in lowland forests of the Guianas and Brazil. The backs of the 5-centimeter-long frogs are covered with a yellow-and-black pattern, which warns of its poisonous nature. But that pattern isn’t the same from frog to frog. Some are decorated with an elongated pattern; others have more complex, sometimes interrupted patterns. The difference in patterns should make it harder for predators to recognize the warning signal. So why is there such variety? Because the patterns aren’t always viewed on a static frog, and the different ways that the frogs move affects how predators see the amphibians, according to a study published June 18 in Biology Letters. Bibiana Rojas of Deakin University in Geelong, Australia, and colleagues studied the frogs in a nature reserve in French Guiana from February to July 2011. They found 25 female and 14 male frogs, following each for two hours from about 2.5 meters away, where the frog wouldn’t notice a scientist. As a frog moved, a researcher would follow, recording how far it went and in what direction. Each frog was then photographed. © Society for Science & the Public 2000 - 2013.
Karen Ravn To the west, the skies belong to the carrion crow. To the east, the hooded crow rules the roost. In between, in a narrow strip running roughly north to south through central Europe, the twain have met, and mated, for perhaps as long as 10,000 years. But although the crows still look very different — carrion crows are solid black, whereas hooded crows are grey — researchers have found that they are almost identical genetically. The taxonomic status of carrion crows (Corvus corone) and hooded crows (Corvus cornix) has been debated ever since Carl Linnaeus, the founding father of taxonomy, declared them to be separate species in 1758. A century later, Darwin called any such classification impossible until the term 'species' had been defined in a generally accepted way. But the definition is still contentious, and many believe it always will be. The crows are known to cross-breed and produce viable offspring, so lack the reproductive barriers that some biologists consider essential to the distinction of a species, leading to proposals that they are two subspecies of carrion crow. In fact, evolutionary biologist Jochen Wolf from Uppsala University in Sweden and his collaborators have now found that the populations living in the cross-breeding zone are so similar genetically that the carrion crows there are more closely related to hooded crows than to the carrion crows farther west1. Only a small part of the genome — less than 0.28% — differs between the populations, the team reports in this week's Science1. This section is located on chromosome 18, in an area associated with pigmentation, visual perception and hormonal regulation. It is no coincidence, the researchers suggest, that the main differences between carrion and hooded crows are in colouring, mating preferences (both choose mates whose colouring matches theirs), and hormone-influenced social behaviours (carrion crows lord it over hooded ones). © 2014 Nature Publishing Group,
By Robert Dudley When we think about the origins of agriculture and crop domestication, alcohol isn’t necessarily the first thing that comes to mind. But our forebears may well have been intentionally fermenting fruits and grains in parallel with the first Neolithic experiments in plant cultivation. Ethyl alcohol, the product of fermentation, is an attractive and psychoactively powerful inebriant, but fermentation is also a useful means of preserving food and of enhancing its digestibility. The presence of alcohol prolongs the edibility window of fruits and gruels, and can thus serve as a means of short-term storage for various starchy products. And if the right kinds of bacteria are also present, fermentation will stabilize certain foodstuffs (think cheese, yogurt, sauerkraut, and kimchi, for example). Whoever first came up with the idea of controlling the natural yeast-based process of fermentation was clearly on to a good thing. Using spectroscopic analysis of chemical residues found in ceramic vessels unearthed by archaeologists, scientists know that the earliest evidence for intentional fermentation dates to about 7000 BCE. But if we look deeper into our evolutionary past, alcohol was a component of our ancestral primate diet for millions of years. In my new book, The Drunken Monkey, I suggest that alcohol vapors and the flavors produced by fermentation stimulate modern humans because of our ancient tendencies to seek out and consume ripe, sugar-rich, and alcohol-containing fruits. Alcohol is present because of particular strains of yeasts that ferment sugars, and this process is most common in the tropics where fruit-eating primates originated and today remain most diverse. © 1986-2014 The Scientist
by Colin Barras The Neanderthals knew how to make an entrance: teeth first. Our sister species' distinctive teeth were among the first unique aspects of their anatomy to evolve, according to a study of their ancestors. These early Neanderthals may have used their teeth as a third hand, gripping objects that they then cut with tools. The claim comes from a study of fossils from Sima de los Huesos in northern Spain. This "pit of bones" may be an early burial site, and 28 near-complete skeletons have been pulled from it, along with a large hand-axe that might be a funeral gift. The hominins in the pit look like Neanderthals, but are far too old. That suggests they are forerunners of the Neanderthals, and if that is the case they can tell us how the species evolved. To find out, Juan Luis Arsuaga Ferreras at the UCM-ISCIII Joint Centre for Research into Human Evolution and Behaviour in Madrid, Spain, and colleagues studied 17 of the skulls. They found that the brain case was still the same shape as in older species. But the skulls' protruding faces and small molar teeth were much more Neanderthal-like. This suggests the earliest Neanderthals used their jaws in a specialised way. It's not clear how, but it probably wasn't about food, says Ferreras. "There are no indications of any dietary specialisation in the Neanderthals and their ancestors. They were basically carnivores." © Copyright Reed Business Information Ltd.
Link ID: 19750 - Posted: 06.21.2014
Virginia Morell Teaching isn’t often seen in animals other than humans—and it’s even more difficult to demonstrate in animals living in the wild rather than in a laboratory setting. But researchers studying the Australian superb fairy-wren (Malurus cyaneus) in the wild think the small songbirds (a male is shown in the photo above) practice the behavior. They regard a female fairy-wren sitting on her nest and incubating her eggs as the teacher, and her embryonic chicks as her pupils. She must teach her unhatched chicks a password—a call they will use after emerging to solicit food from their parents; the better they learn the password, the more they will be fed. Since 1992, there’s been a well-accepted definition of teaching that consists of three criteria. First, the teacher must modify his or her behavior in the presence of a naive individual—which the birds do; the mothers increase their teaching (that is, the rate at which they make the call) when their chicks are in a late stage of incubation. Second, there must be a benefit to the pupil, which there clearly is. Scientists reported online yesterday in Behavioral Ecology that the fairy-wrens also pass the third criteria: There must be a cost to the teacher. And for the small birds, there can be a hefty price to pay. The more often a female repeats the password, the more likely she is to attract a parasitical cuckoo, which will sneak in and lay its eggs in her nest. From careful field observations, the scientists discovered that at nests that were parasitized, the females had recited their password 20 times an hour. But at nests that were not parasitized, the females had called only 10 times per hour. Superb fairy-wrens thus join a short but growing list of animal-teachers, such as rock ants, meerkats, and pied babblers. © 2014 American Association for the Advancement of Science.
By Jonathan Webb Science reporter, BBC News A new theory suggests that our male ancestors evolved beefy facial features as a defence against fist fights. The bones most commonly broken in human punch-ups also gained the most strength in early "hominin" evolution. They are also the bones that show most divergence between males and females. The paper, in the journal Biological Reviews, argues that the reinforcements evolved amid fighting over females and resources, suggesting that violence drove key evolutionary changes. For many years, this extra strength was seen as an adaptation to a tough diet including nuts, seeds and grasses. But more recent findings, examining the wear pattern and carbon isotopes in australopith teeth, have cast some doubt on this "feeding hypothesis". "In fact, [the australopith] boisei, the 'nutcracker man', was probably eating fruit," said Prof David Carrier, the new theory's lead author and an evolutionary biologist at the University of Utah. Masculine armour Instead of diet, Prof Carrier and his co-author, physician Dr Michael Morgan, propose that violent competition demanded the development of these facial fortifications: what they call the "protective buttressing hypothesis". In support of their proposal, Carrier and Morgan offer data from modern humans fighting. Several studies from hospital emergency wards, including one from the Bristol Royal Infirmary, show that faces are particularly vulnerable to violent injuries. BBC © 2014
Carl Zimmer All animals do the same thing to the food they eat — they break it down to extract fuel and building blocks for growing new tissue. But the metabolism of one species may be profoundly different from another’s. A sloth will generate just enough energy to hang from a tree, for example, while some birds can convert their food into a flight from Alaska to New Zealand. For decades, scientists have wondered how our metabolism compares to that of other species. It’s been a hard question to tackle, because metabolism is complicated — something that anyone who’s stared at a textbook diagram knows all too well. As we break down our food, we produce thousands of small molecules, some of which we flush out of our bodies and some of which we depend on for our survival. An international team of researchers has now carried out a detailed comparison of metabolism in humans and other mammals. As they report in the journal PLOS Biology, both our brains and our muscles turn out to be unusual, metabolically speaking. And it’s possible that their odd metabolism was part of what made us uniquely human. When scientists first began to study metabolism, they could measure it only in simple ways. They might estimate how many calories an animal burned in a day, for example. If they were feeling particularly ambitious, they might try to estimate how many calories each organ in the animal’s body burned. Those tactics were enough to reveal some striking things about metabolism. Compared with other animals, we humans have ravenous brains. Twenty percent of the calories we take in each day are consumed by our neurons as they send signals to one another. Ten years ago, Philipp Khaitovich of the Max Planck Institute of Evolutionary Anthropology and his colleagues began to study human metabolism in a more detailed way. They started making a catalog of the many molecules produced as we break down food. “We wanted to get as much data as possible, just to see what happened,” said Dr. Khaitovich. To do so, the scientists obtained brain, muscle and kidney tissues from organ donors. They then extracted metabolic compounds like glucose from the samples and measured their concentrations. All told, they measured the levels of over 10,000 different molecules. © 2014 The New York Times Company
Link ID: 19670 - Posted: 05.28.2014
|By Isaac Bédard Very few animals have revealed an ability to consciously think about the future—behaviors such as storing food for the winter are often viewed as a function of instinct. Now a team of anthropologists at the University of Zurich has evidence that wild orangutans have the capacity to perceive the future, prepare for it and communicate those future plans to other orangutans. The researchers observed 15 dominant male orangutans in Sumatra for several years. These males roam through immense swaths of dense jungle, emitting loud yells every couple of hours so that the females they mate with and protect can locate and follow them. The shouts also warn away any lesser males that might be in the vicinity. These vocalizations had been observed by primatologists before, but the new data reveal that the apes' last daily call, an especially long howl, is aimed in the direction they will travel in the morning—and the other apes take note. The females stop moving when they hear this special 80-second call, bed down for the night, and in the morning begin traveling in the direction indicated the evening before. The scientists believe that the dominant apes are planning their route in advance and communicating it to other orangutans in the area. They acknowledge, however, that the dominant males might not intend their long calls to have such an effect on their followers. Karin Isler, a Zurich anthropologist who co-authored the study in PLOS ONE last fall, explains, “We don't know whether the apes are conscious. This planning does not have to be conscious. But it is also more and more difficult to argue that they [do not have] some sort of mind of their own.” © 2014 Scientific American
By David Grimm, A shaggy brown terrier approaches a large chocolate Labrador in a city park. When the terrier gets close, he adopts a yogalike pose, crouching on his forepaws and hiking his butt into the air. The Lab gives an excited bark, and soon the two dogs are somersaulting and tugging on each other’s ears. Then the terrier takes off and the Lab gives chase, his tail wagging wildly. When the two meet once more, the whole thing begins again. Watch a couple of dogs play, and you’ll probably see seemingly random gestures, lots of frenetic activity and a whole lot of energy being expended. But decades of research suggest that beneath this apparently frivolous fun lies a hidden language of honesty and deceit, empathy and perhaps even a humanlike morality. Take those two dogs. That yogalike pose is known as a “play bow,” and in the language of play it’s one of the most commonly used words. It’s an instigation and a clarification, a warning and an apology. Dogs often adopt this stance as an invitation to play right before they lunge at another dog; they also bow before they nip (“I’m going to bite you, but I’m just fooling around”) or after some particularly aggressive roughhousing (“Sorry I knocked you over; I didn’t mean it.”). All of this suggests that dogs have a kind of moral code — one long hidden to humans until a cognitive ethologist named Marc Bekoff began to crack it. A wiry 68-year-old with reddish-gray hair tied back in a long ponytail, Bekoff is a professor emeritus at the University of Colorado at Boulder, where he taught for 32 years. He began studying animal behavior in the early 1970s, spending four years videotaping groups of dogs, wolves and coyotes in large enclosures and slowly playing back the tapes, jotting down every nip, yip and lick. “Twenty minutes of film could take a week to analyze,” he says. © 1996-2014 The Washington Post
Tastes are a privilege. The oral sensations not only satisfy foodies, but also on a primal level, protect animals from toxic substances. Yet cetaceans—whales and dolphins—may lack this crucial ability, according to a new study. Mutations in a cetacean ancestor obliterated their basic machinery for four of the five primary tastes, making them the first group of mammals to have lost the majority of this sensory system. The five primary tastes are sweet, bitter, umami (savory), sour, and salty. These flavors are recognized by taste receptors—proteins that coat neurons embedded in the tongue. For the most part, taste receptor genes present across all vertebrates. Except, it seems, cetaceans. Researchers uncovered a massive loss of taste receptors in these animals by screening the genomes of 15 species. The investigation spanned the two major lineages of cetaceans: Krill-loving baleen whales—such as bowheads and minkes—were surveyed along with those with teeth, like bottlenose dolphins and sperm whales. The taste genes weren’t gone per se, but were irreparably damaged by mutations, the team reports online this month in Genome Biology and Evolution. Genes encode proteins, which in turn execute certain functions in cells. Certain errors in the code can derail protein production—at which point the gene becomes a “pseudogene” or a lingering shell of a trait forgotten. Identical pseudogene corpses were discovered across the different cetacean species for sweet, bitter, umami, and sour taste receptors. Salty tastes were the only exception. © 2014 American Association for the Advancement of Science.
|By Andrea Anderson Our knack for language helps us structure our thinking. Yet the ability to wax poetic about trinkets, tools or traits may not be necessary to think about them abstractly, as was once suspected. A growing body of evidence suggests nonhuman animals can group living and inanimate things based on less than obvious shared traits, raising questions about how creatures accomplish this task. In a study published last fall in the journal PeerJ, for example, Oakland University psychology researcher Jennifer Vonk investigated how well four orangutans and a western lowland gorilla from the Toronto Zoo could pair photographs of animals from the same biological groups. Vonk presented the apes with a touch-screen computer and got them to tap an image of an animal—for instance, a snake—on the screen. Then she showed each ape two side-by-side animal pictures: one from the same category as the animal in the original image and one from another—for example, images of a different reptile and a bird. When they correctly matched animal pairs, they received a treat such as nuts or dried fruit. When they got it wrong, they saw a black screen before beginning the next trial. After hundreds of such trials, Vonk found that all five apes could categorize other animals better than expected by chance (although some individuals were better at it than others). The researchers were impressed that the apes could learn to classify mammals of vastly different visual characteristics together—such as turtles and snakes—suggesting the apes had developed concepts for reptiles and other categories of animals based on something other than shared physical traits. Dogs, too, seem to have better than expected abstract-thinking abilities. They can reliably recognize pictures of other dogs, regardless of breed, as a study in the July 2013 Animal Cognition showed. The results surprised scientists not only because dog breeds vary so widely in appearance but also because it had been unclear whether dogs could routinely identify fellow canines without the advantage of smell and other senses. Other studies have found feats of categorization by chimpanzees, bears and pigeons, adding up to a spate of recent research that suggests the ability to sort things abstractly is far more widespread than previously thought. © 2014 Scientific American
By NATALIE ANGIER Of the world’s 43,000 known varieties of spiders, an overwhelming majority are peevish loners: spinning webs, slinging lassos, liquefying prey and attacking trespassers, each spider unto its own. But about 25 arachnid species have swapped the hermit’s hair shirt for a more sociable and cooperative strategy, in which dozens or hundreds of spiders pool their powers to exploit resources that would elude a solo player. And believe it or not, O ye of rolled-up newspaper about to dispatch the poor little Charlotte dangling from your curtain rod for no better reason than your purported “primal fear,” these oddball spider socialites may offer fresh insight into an array of human mysteries: where our personalities come from, why some people can’t open their mouths at a party while others can’t keep theirs shut and, why, no matter our age, we can’t seem to leave high school behind. “It’s very satisfying to me that the most maligned of organisms may have something to tell us about who we are,” said Jonathan N. Pruitt, a biologist at the University of Pittsburgh who studies social spiders. The new work on social spiders is part of the expanding field of animal personality research, which seeks to delineate, quantify and understand the many stylistic differences that have been identified in a vast array of species, including monkeys, minks, bighorn sheep, dumpling squid, zebra finches and spotted hyenas. Animals have been shown to differ, sometimes hugely, on traits like shyness, boldness, aggressiveness and neophobia, or fear of the new. Among the big questions in the field are where those differences come from, and why they exist. Reporting recently in The Proceedings of the Royal Society B, Dr. Pruitt and Kate L. Laskowski, of the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin, have determined that character-building in social spiders is a communal affair. While they quickly display the first glimmerings of a basic predisposition — a relative tendency toward shyness or boldness, tetchiness or docility — that personality is then powerfully influenced by the other spiders in the group. © 2014 The New York Times Company
by Colin Barras PICTURE the scene: a weak leader is struggling to hold onto power as ambitious upstarts plot to take over. As tensions rise, the community splits and the killing begins. The war will last for years. No, this isn't the storyline of an HBO fantasy drama, but real events involving chimps in Tanzania's Gombe Stream National Park. A look at the social fragmentation that led to a four-year war in the 1970s now reveals similarities between the ways chimpanzee and human societies break down. Jane Goodall has been studying the chimpanzees of Gombe for over 50 years. During the early 1970s the group appeared to split in two, and friendliness was replaced by fighting. So extreme and sustained was the aggression that Goodall dubbed it a war. Joseph Feldblum at Duke University in Durham, North Carolina, and colleagues have re-examined Goodall's field notes from the chimp feeding station she established at Gombe to work out what led to the conflict. In the past, researchers have estimated the strength of social ties based on the amount of time two chimps spent together at the station. But the notes are so detailed that Feldblum could get a better idea of each chimp's social ties, for instance, by considering if the chimps arrived at the same time and from the same direction. His team then plugged this data into software that can describe the chimps' social network. They did this for several periods between 1968 and 1972, revealing when the nature of the network changed. © Copyright Reed Business Information Ltd.
By Felicity Muth Imagine that you walk into a room, where three people are sitting, facing you. Their faces are oriented towards you, but all three of them have their eyes directed towards the left side of the room. You would probably follow their gaze to the point where they were looking (if you weren’t too unnerved to take your eyes off these odd people). As a social species, we are particularly cued in to social cues like following others’ gazes. However, we’re not the only animals that follow the gazes of members of our species: great apes, monkeys, lemurs, dogs, goats, birds and even tortoises follow each other’s gazes too. However, we don’t all follow gazes to the same extent. One species of macaque monkey (the stumptailed macaque) follows gazes a lot more than other macaque species, bonobos do it more than chimpanzees and human children follow gazes a lot more than other great ape species do. Species also differ in their understanding of what the other animal is looking at. For example, if we saw a person gazing at a point, and between them and this point was a barrier, whether the barrier was solid or transparent would affect how far we followed their gaze. This is because we imagine ourselves in their physical position and what they might be able to see. Bonobos and chimpanzees can also do this, but not the orang-utan. Like us, great apes and old world monkeys also will follow a gaze, but then look back at the individual gazing if they don’t see what the individual is gazing at (‘are you going crazy or am I just not seeing what you’re seeing?’). Capuchin and spider monkeys don’t seem to do this. So, even though a lot of animals are capable of following the gazes of others, there is a lot of variation in the extent and flexibility of this behaviour. A recent study looked to see whether chimpanzees, bonobos, orang-utans and humans would be more likely to follow their own species’ gazes than another species. © 2014 Scientific American
by Colin Barras Enough of the cheap jibes: Neanderthals may have been just as clever as modern humans. Anthropologists have already demolished the idea that Neanderthals were dumb brutes, and now a review of the archaeological record suggests they were our equals. Neanderthals were one of the most successful of all hominin species, occupying much of Europe and Asia. Their final demise about 40,000 years ago, shortly after Homo sapiens walked into their territory, is often put down to the superiority of our species. It's time to lay that idea to rest, say Paola Villa at the University of Colorado in Boulder and Wil Roebroeks at Leiden University in the Netherlands. Just as smart as you For instance, there is evidence that Homo sapiens could use fire to chemically transform natural materials into glue 70,000 years ago, but Neanderthals were performing similarly complex chemical syntheses at least 200,000 years ago. And although 70,000-year-old engraved ochre from South Africa is seen as evidence that our species had developed sophisticated symbolism and perhaps even language, similar artefacts have been found at 50,000-year-old Neanderthal sites in Spain. What's more, Neanderthals might have been able to talk. Late last year we learned that our extinct cousins had a hyoid, a small bone in the neck that plays a big role in speech, very like ours. Evidence has even emerged that Homo sapiens may have learned some skills by copying Neanderthals. Yet despite all of this evidence, the idea that Neanderthals were our inferiors still persists. © Copyright Reed Business Information Ltd.
Fork-tailed drongos, glossy black African songbirds with ruby-colored eyes, are the avian kingdom’s masters of deception. They mimic the alarm calls of other species to scare animals away and then swipe their dupes’ dinner. But like the boy who cried wolf, drongos can raise the alarm once too often. Now, scientists have discovered that when one false alarm no longer works, the birds switch to another species’ warning cry, a tactic that usually does the trick. “The findings are astounding,” says John Marzluff, a wildlife biologist at the University of Washington, Seattle, who was not involved in the work. “Drongos are exceedingly deceptive; their vocabularies are immense; and they match their deception to both the target animal and [its] past response. This level of sophistication is incredible.” Since 2008, Tom Flower, an evolutionary biologist at the University of Cape Town, has followed drongos in the Kuruman River Reserve in the Kalahari Desert. He’s habituated and banded about 200 of the robin-sized birds, and, using food rewards, has trained individuals to come to him when he calls. After getting its snack, the drongo quickly returns to its natural behavior—catching insects and following other bird species or meerkats—while Flower tags along. Drongos also keep an eye out for raptors and other predators. When they spot one, they utter metallic alarm cries. Meerkats and pied babblers, a highly social bird, pay attention to the drongos and dash for cover when the drongos raise an alarm—just as they do when one of their own calls out a warning. Studies have shown that having drongos around benefits animals of other species, which don’t have to be as vigilant and can spend more time foraging. But there’s a trade-off: The drongos’ cries aren’t always honest. When a meerkat has caught a fat grub or gecko, a drongo is apt to change from trustworthy sentinel to wily deceiver. © 2014 American Association for the Advancement of Science.
Intelligence is hard to test, but one aspect of being smart is self-control, and a version of the old shell game that works for many species suggests that brain size is very important. When it comes to animal intelligence, says Evan MacLean, co-director of Duke University’s Canine Cognition Center, don’t ask which species is smarter. “Smarter at what?” is the right question. Many different tasks, requiring many different abilities, are given to animals to measure cognition. And narrowing the question takes on particular importance when the comparisons are across species. So Dr. MacLean, Brian Hare and Charles Nunn, also Duke scientists who study animal cognition, organized a worldwide effort by 58 scientists to test 36 species on a single ability: self-control. This capacity is thought to be part of thinking because it enables animals to override a strong, nonthinking impulse, and to solve a problem that requires some analysis of the situation in front of them. The testing program, which took several international meetings to arrange, and about seven years to complete, looked at two common tasks that are accepted ways to judge self-control. It then tried to correlate how well the animals did on the tests with other measures, like brain size, diet and the size of their normal social groups. Unsurprisingly, the great apes did very well. Dogs and baboons did pretty well. And squirrel monkeys, marmosets and some birds were among the worst performers. Surprisingly, absolute brain size turned out to be a much better predictor of success than relative brain size, which has been thought to be a good indication of intelligence. Social group size was not significant, but variety of diet was. The paper, published last week in the journal Proceedings of the National Academy of Sciences, is accompanied online by videos showing the animals doing what looks for all the world like the shell game in which a player has to guess where the pea is. © 2014 The New York Times Company