Chapter 6. Evolution of the Brain and Behavior
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By Erin Wayman Photographer Bill Wallauer was following a group of chimpanzees in Tanzania’s Gombe Stream National Park one March day when a young female caught his eye. She had climbed a tree, inserted a thin, peeled branch into a hole and was fishing out carpenter ants. Wallauer, of the Jane Goodall Institute, took out his video camera and filmed the chimp as she slurped up insects for several minutes. What Wallauer witnessed wasn’t supposed to happen. Though chimps in other areas use tools to collect carpenter ants, scientists studying the Kasekela chimp community at Gombe had rarely seen the behavior since Jane Goodall began her fieldwork there in 1960. Before Wallauer’s 1994 observation, researchers had seen only one other instance of the behavior, in 1978. This type of tool use was considered a fluke. But when Robert O’Malley, a primatologist now at Kenyon College in Gambier, Ohio, went to Gombe in the late 2000s, he noticed many of the Kasekela chimps regularly fishing for ants. He wondered why, after decades with only a couple of sporadic sightings, ant probing had become a widespread habit. Because of meticulous record keeping at Gombe, O’Malley and his colleagues had a rare opportunity to reconstruct the origin of this behavior. An adult female immigrant who joined the Kasekela group in the early 1990s, the team concluded, introduced ant fishing, a common practice in her previous community. The finding, reported late last year in Current Anthropology, marks the first time in the more than 50-year history of chimp field studies that anyone has documented the transfer of a cultural tradition from one wild chimp group to another. © Society for Science & the Public 2000 - 2013
by Gretchen Cuda Kroen A day in the life of a male dung beetle goes something like this: Fly to a heap of dung, sculpt a clump of it into a large ball, then roll the ball away from the pile as fast as possible. However, it turns out that the beetles, who work at night, need some sort of compass to prevent them from rolling around in circles. New research in Current Biology suggests that the insects use starlight to guide their way. Birds, seals, and humans also use starlight to navigate, but this is the first time it's been shown in an insect. The whole point of rolling dung is to impress the female beetle with provisions—i.e., excrement—for her future progeny and entice her to mate. She then lays an egg in the ball and buries it in a network of tunnels more than a meter deep, where it serves as food for the developing larvae inside. But rolling dung balls in a straight line is also key to the male dung beetle's reproductive success. Rival males have been known to overtake a slower moving insect and claim the hard-earned treasure as their own. Competition is fiercest near the dung heap, so making a quick and efficient getaway is crucial for mating success. The discovery that dung beetles use starlight "was an accident more than anything," explains study author Eric Warrant, professor of zoology at the Lund University in Sweden. His research group was studying how the beetles used the polarized light patterns of the moon to stay on their paths, when one moonless night they made a surprising observation—the beetles maintained straight trajectories. "Even without the moon—just with the stars—they were still able to navigate," Warrant says. "We were just flabbergasted." © 2010 American Association for the Advancement of Science
By Bruce Bower Chimpanzees often share and share alike when cooperating in pairs, suggesting that these apes come close to a human sense of fairness, a controversial new study finds. Like people, chimps tend to fork over half of a valuable windfall to a comrade in situations where the recipient can choose to accept the deal or turn it down and leave both players with nothing, say psychologist Darby Proctor of Yerkes National Primate Research Center in Lawrenceville, Ga., and her colleagues. And just as people do, chimps turn stingy when supplied with goodies that they can share however they like, the researchers report online January 14 in the Proceedings of the National Academy of Sciences. “Humans and chimpanzees show similar preferences in dividing rewards, suggesting a long evolutionary history to the human sense of fairness,” Proctor says. But psychologist Josep Call of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, considers the new results “far from convincing.” In Proctor’s experiments, pairs of chimps interacted little with each other and showed no signs of understanding that some offers were unfair and could be rejected, Call says. “If anything, Proctor’s study suggests that there is no fairness sensitivity in chimpanzees,” remarks psychologist Keith Jensen of the University of Manchester in England. © Society for Science & the Public 2000 - 2013
By Susan Milius Imagining tiny creatures infiltrating human brains is creepy enough. But Marion Vittecoq knows she has been invaded. Her inner companions may be just hanging out — or they may be subtly changing her personality, manipulating her behavior or altering her risk of disease. Yet she doesn’t sound particularly upset. Not once in the course of a phone conversation and many e-mails did Vittecoq recommend wearing tinfoil hats or mention mind control by the CIA, the United Nations or little green men beaming rays from the moons of Uranus. She studies the ecology of parasites, especially the one-celled Toxoplasma gondii, which coincidentally is the creature that has invaded her brain. She doesn’t see it as an extra-ordinary intrusion. The parasite has wormed its way into an estimated one-third of people on the planet. In France, where Vittecoq works at both a CNRS national research lab in Montpellier and the Tour du Valat research center in Arles, nearly one-third to about one-half of adults carry hitchhiking T. gondii. CNRS research colleague Frédéric Thomas is also infected, and also doesn’t fret about it. In the United States, almost one in four residents over the age of 12 has the infection. In other parts of the world, rates are as high as 95 percent. An unlucky minority of these infected people become quite ill. Most, however, don’t even know that their muscles and brains carry the parasite. © Society for Science & the Public 2000 - 2013
Sujata Gupta Two things are thought to be crucial for evolutionary adaptation: genetic diversity and long periods of time, in which advantageous mutations accumulate. So how do invasive species, which often lack genetic diversity, succeed so quickly? Some ecologists are beginning to think that environmental, or ‘epigenetic’, factors might be modifying genes while leaving the genome intact. “There are a lot of different ways for invasive species to do well in novel environments and I think epigenetics is one of those ways,” says Christina Richards, an evolutionary ecologist at the University of South Florida in Tampa. Although biomedical researchers have been investigating the links between epigenetics and human health for some time, evolutionary biologists are just beginning to take up the subject. Richards, who helped to organize a special symposium on ecological epigenetics at a meeting of the Society for Integrative and Comparative Biology (SICB) in San Francisco this month, says that the field has the potential to revolutionize the study of evolutionary biology. The nascent field of ecological epigenetics has plenty of challenges standing in its way. The genomes of most wild animals and plants have not been sequenced so ecologists can’t pinpoint which genes have been modified. And, because they tend to work outside of controlled laboratory conditions, researchers have trouble linking those gene modifications to behavioural changes. © 2013 Nature Publishing Group
by Michael Balter Are crows mind readers? Recent studies have suggested that the birds hide food because they think others will steal it -- a complex intuition that has been seen in only a select few creatures. Some critics have suggested that the birds might simply be stressed out, but new research reveals that crows may be gifted after all. Cracks first began forming in the crow mind-reading hypothesis last year. One member of a research team from the University of Groningen in the Netherlands spent 7 months in bird cognition expert Nicola Clayton's University of Cambridge lab in the United Kingdom studying Western scrub jays, a member of the crow family that is often used for these studies. The Groningen team then developed a computer model in which "virtual jays" cached food under various conditions. In PLOS ONE, they argued that the model showed the jays' might be moving their food—or recaching it—not because they were reading the minds of their competitors, but simply because of the stress of having another bird present (especially a more dominant one) and of losing food to thieves. The result contradicted previous work by Clayton's group suggesting that crows might have a humanlike awareness of other creatures' mental states—a cognitive ability known as theory of mind that has been claimed in dogs, chimps, and even rats. In the new study, Clayton and her Cambridge graduate student James Thom decided to test the stress hypothesis. First, they replicated earlier work on scrub jays by letting the birds hide peanuts in trays of ground corn cobs—either unobserved or with another bird watching—and later giving them a chance to rebury them. As in previous studies, the jays recached a much higher proportion of the peanuts if another bird could see them: nearly twice as much as in private, the team reports online today in PLOS ONE. © 2010 American Association for the Advancement of Science
Some animals are more eloquent than previously thought and have a communication structure similar to the vowel and consonant system of humans, according to new research. Studying the abbreviated call of the mongoose, researchers at the University of Zurich have found they are the first animals to communicate with sound units that are even smaller than syllables and yet still contain information about who is calling and why. Usually, animals can only produce a limited number of distinguishable sounds and calls due to their anatomy. While whale and bird songs are a little more complex than most animal sounds — in that they are repeatedly combined with new arrangements — they don’t pattern themselves after human syllables with their combination of vowels and consonants. Studying wild banded mongooses in Uganda, behavioural biologists discovered that the calls of the animals are structured and contain different information — a sound structure that has some similarities to the vowel and consonant system of human speech. Banded mongooses live in the savannah regions of the Sahara. They are small predators that live in groups of around 20 and are related to the meerkat. The scientists recorded calls of the mongoose and made acoustic analyses of them. The calls, which last between 50 and 150 milliseconds, could be compared to one "syllable," the researchers found. © CBC 2013
by Sara Reardon In the dark expanses of the Sonoran desert in the US, a terrifying creature stalks the night, searching for fresh meat. Anything will do: crickets, rodents, tarantulas – the nastier the better. Even the poisonous scorpion cannot escape the savage monster's little pink paws. It fights bravely, stinging its attacker on the nose. To no avail. The mouse ignores the painful venom and cruelly breaks the scorpion's tail by pummelling it into the ground, then bites its head and feasts on its flesh. Throwing its head back, the murderous animal howls at the moon. No, it's not the mythical Chupacabra. It's the southern grasshopper mouse (Onychomys torridus), the only carnivorous mouse in North America. Its unique biology and resistance to scorpion venom may one day help researchers treat human pain disorders. But for now, it's just after blood. Natural born killer From the day they are born, grasshopper mice are natural killers. Even pups born and raised in captivity quickly figure out how to take down prey much larger than themselves. They appear to learn some of their aggression from their fathers: pups raised with two parents are more likely to bully other mice and attack insects more viciously than those raised by single mothers (Behavioral Biology, DOI: 10.1016/S0091-6773(77)91933-2) © Copyright Reed Business Information Ltd.
By Christie Wilcox There’s a lot to be said for smarts—at least we humans, with some of the biggest brains in relation to our bodies in the animal kingdom, certainly seem to think so. The size of animal brains is extravagantly well-studied, as scientists have long sought to understand why our ancestors developed such complex and energetically costly neural circuitry. One of the most interesting evolutionary hypotheses about brain size is The Expensive Tissue Hypothesis. Back in the early 1990s, scientists were looking to explain how brain size evolves. Brains are exceedingly useful organs; more brain cells allows for more behavioral flexibility, better control of larger bodies, and, of course, intelligence. But if bigger brains were always better, every animal would have them. Thus, scientists reasoned, there must be a downside. The hypothesis suggests that while brains are great and all, their extreme energetic cost limits their size and tempers their growth. When it comes to humans, for example, though our brains are only 2% of our bodies, they take up a whopping 20% of our energy requirements. And you have to wonder: with all that energy being used by our brains, what body parts have paid the price? The hypothesis suggested our guts took the hit, but that intelligence made for more efficient foraging and hunting, thus overcoming the obstacle. This makes sense, but despite over a century of research on the evolution of brain size, there is still controversy, largely stemming from the fact that evidence for the expensive tissue hypothesis is based entirely on between species comparisons and correlations, with no empirical tests. © 2013 Scientific American
By Susan Lunn, CBC News It's the time of year when people take stock of the past 12 months, and make resolutions for the New Year. That's kind of what Svante Paabo is doing — but the Swedish archeological geneticist is looking over a time span of 30,000 years. He's almost finished mapping the DNA of neanderthal man, a distant cousin of modern humans. Paabo has found that many people today carry within their DNA about 3 to 5 per cent in common with neanderthals. Paabo says it's important to learn more about our caveman cousins' DNA to reveal the differences between us and them, differences that have seen modern humans surive and thrive over the millennia, while neanderthals have become extinct. "I really hope that over the next 10 years we will understand much more of those things that set us apart. Which changes in our genome made human culture and technology possible? And allowed us to expand and become 7, 8, 9 billion people and spread all over the world?," he asked at a recent genetic conference in Ottawa. The room was packed with people from across North America who wanted to hear Paabo speak. He's recognized as the inspiration for Michael Crichton's Jurassic Park. © CBC 2012
by Carrie Arnold ‘Tis the season for twinkling lights, wrapping paper, and virgin birth. For billions of Christians around the world, the holidays are a time to celebrate Jesus’s birth to the Virgin Mary. But for many animals, virgin birth is far from a miraculous event. Researchers have discovered a growing number of species that reproduce without assistance from the opposite sex. Known formally as parthenogenesis, virgin birth occurs when an embryo develops from an unfertilized egg cell. The development of an embryo usually requires genetic material from sperm and egg, as well as a series of chemical changes sparked by fertilization. In some parthenogenetic species, egg cells don’t undergo meiosis, the typical halving of the cell’s chromosomes, before dividing into new cells. These offspring are generally all female and clones of their mother. Other forms of parthenogenesis occur when two egg cells fuse after meiosis. Biologists think that sexual reproduction evolved as a way to mix the gene pool and reduce the impact of harmful mutations. Still, parthenogenesis can be beneficial if the mother is particularly well adapted to her environment, since all of her offspring will be just as well adapted. © 2010 American Association for the Advancement of Science.
Fighting may have shaped the evolution of the human hand, according to a new study by a US team. The University of Utah researchers used instruments to measure the forces and acceleration when martial artists hit a punch bag. They found that the structure of the fist provides support that increases the ability of the knuckles to transmit "punching" force. Details have been published in the Journal of Experimental Biology. "We asked the question: 'can you strike harder with a fist than with an open palm?'," co-author David Carrier told BBC News. "We were surprised because the fist strikes were not more forceful than the strikes with the palm. In terms of the work on the bag there is really no difference." Of course, the surface that strikes the target with a fist is smaller, so there is more stress from a fist strike. "The force per area is higher in a fist strike and that is what causes localised tissue damage," said Prof Carrier. BBC © 2012
by Emily Underwood On the reality television show Extreme Makeover: Home Edition, the lucky recipient gets a first look at his newly renovated home. For a split second, his face contorts with—shock? Joy? During intense emotional experiences, there's a fleeting moment when expressions of pleasure and pain are hard to distinguish. In fact, others read intense emotion more effectively by looking at a person's body language than by watching his facial expressions, a new study suggests. Most studies of facial cues rely on a set of stylized, recognizable expressions—perhaps made by actors in photographs. The actors make expressions meant to be obvious enough to translate across cultures: anger, disgust, fear, joy, sadness, and surprise. But these stylized images don't necessarily reflect the expressions that people make in the real world, says Hillel Aviezer, a neuropsychologist at who is now at The Hebrew University of Jerusalem and lead author of the new study, published online today in Science. Moreover, when emotions get particularly extreme, people undergoing fleeting peaks of intense pain, joy, grief, or anger look surprisingly similar, Aviezer says. From the face, at least, "when you compare extreme pain to extreme pleasure, you really can't tell them apart," he says. And yet most people are rarely confused about whether someone is experiencing grief or joy. To figure out what tips us off, Aviezer and his colleagues showed photos of professional tennis players to 45 Princeton University students, randomly divided into three groups of 15. Each tennis player had just won or lost an important match, and the participants rated the players' contorted facial expressions from negative to positive on a scale from 1 to 9, with 5 marking the neutral midway point. One group of participants looked at head-to-toe photos of the players, the second group looked at only the players' bodies, and the third group looked at only their heads. Only the final group had trouble making the correct identification, suggesting that facial expressions alone didn't tell them whether the players were joyous or in despair. © 2010 American Association for the Advancement of Science
By David P. Barash Critics claim that evolutionary biology is, at best, guesswork. The reality is otherwise. Evolutionists have nailed down how an enormous number of previously unexplained phenomena—in anatomy, physiology, embryology, behavior—have evolved. There are still mysteries, however, and one of the most prominent is the origins of homosexuality. The mystery is simple enough. Its solution, however, has thus far eluded our best scientific minds. The sine qua non for any trait to have evolved is for it to correlate positively with reproductive success, or, more precisely, with success in projecting genes relevant to that trait into the future. So, if homosexuality is in any sense a product of evolution—and it clearly is, for reasons to be explained—then genetic factors associated with same-sex preference must enjoy some sort of reproductive advantage. The problem should be obvious: If homosexuals reproduce less than heterosexuals—and they do—then why has natural selection not operated against it? The paradox of homosexuality is especially pronounced for individuals whose homosexual preference is exclusive; that is, who have no inclination toward heterosexuality. But the mystery persists even for those who are bisexual, since it is mathematically provable that even a tiny difference in reproductive outcome can drive substantial evolutionary change. Copyright 2012.
By Bruce Bower MINNEAPOLIS — Baboons use the order of regularly appearing letter pairs to tell words from nonwords, new evidence suggests. Psychologist Jonathan Grainger of the University of Aix-Marseille reported earlier this year that baboons can learn to tell real four-letter words from nonsense words (SN: 5/5/12, p. 5). But whether these animals detect signature letter combinations that enable their impressive word feats has been tough to demonstrate. Monkeys that previously learned to excel on this task are more likely to mistake nonwords created by reversing two letters of a word they already recognize as real, much as literate people do, Grainger reported November 16 at the Psychonomics Society annual meeting. “Letters played a role in baboons’ word knowledge,” Grainger concluded. “This is a starting point for determining how they discriminate words from nonwords.” Grainger’s team tested the six baboons in their original investigation. Some of the monkeys had previously learned to recognize many more words than others. In new trials, the best word identifiers made more errors than their less successful peers when shown nonwords that differed from known words by a reversed letter combination, such as WSAP instead of WASP and KTIE instead of KITE. Grainger’s team fed the same series of words and nonwords into a computer simulation of the experiment. The computer model best reproduced the animals’ learning curves when endowed with a capacity for tracking letter combinations. © Society for Science & the Public 2000 - 2012
by Douglas Heaven All the better to hear you with, my dear. A chance discovery has revealed that some insects have evolved mammal-like ears, with an analogous three-part structure that includes a fluid-filled vessel similar to the mammalian cochlea. Fernando Montealegre-Z at the University of Lincoln, UK, and colleagues were studying the vibration of the tympanal membrane – a taut membrane that works like an eardrum – in the foreleg of Copiphora gorgonensis, a species of katydid from the South American rainforest, when they noticed tiny vibrations in the rigid cuticle behind the membrane. When they dissected the leg behind that membrane, they unexpectedly burst a vessel filled with high-pressure fluid. The team analysed the fluid to confirm that it was not part of the insect's circulatory system and concluded instead that it played a cochlea-like role in sound detection. In most insects, sound vibrations transmit directly to neuronal sensors which sit behind the tympanal membrane. Mammals have evolved tiny bones called ossicles that transfer vibrations from the eardrum to the fluid-filled cochlea. The analogous structure in the katydid is a vibrating plate, exposed to the air on one side and fluid on the other. Smallest ear In mammals, the cochlea analyses a sound's frequency – how high or low it is – and the new structure found by the team appears to do the same job. Spanning only 600 micrometres, it is the smallest known ear of its kind in nature. © Copyright Reed Business Information Ltd.
By MICHAEL TRIMBLE IN 2008, at a zoo in Münster, Germany, a gorilla named Gana gave birth to a male infant, who died after three months. Photographs of Gana, looking stricken and inconsolable, were ubiquitous. “Heartbroken gorilla cradles her dead baby,” Britain’s Daily Mail declared. Crowds thronged the zoo to see the grieving mother. Sad as the scene was, the humans, not Gana, were the only ones crying. The notion that animals can weep — apologies to Dumbo, Bambi and Wilbur — has no scientific basis. Years of observations by the primatologists Dian Fossey, who observed gorillas, and Jane Goodall, who worked with chimpanzees, could not prove that animals cry tears from emotion. In his book “The Emotional Lives of Animals,” the only tears the biologist Marc Bekoff were certain of were his own. Jeffrey Moussaieff Masson and Susan McCarthy, the authors of “When Elephants Weep,” admit that “most elephant watchers have never seen them weep.” It’s true that many mammals shed tears, especially in response to pain. Tears protect the eye by keeping it moist, and they contain antimicrobial proteins. But crying as an embodiment of empathy is, I maintain, unique to humans and has played an essential role in human evolution and the development of human cultures. Within two days an infant can imitate sad and happy faces. If a newborn mammal does not cry out (typically, in the first few weeks of life, without tears) it is unlikely to get the attention it needs to survive. Around three to four months, the relationship between the human infant and its environment takes on a more organized communicative role, and tearful crying begins to serve interpersonal purposes: the search for comfort and pacification. As we get older, crying becomes a tool of our social repertory: grief and joy, shame and pride, fear and manipulation. © 2012 The New York Times Company
by Virginia Morell Figaro may not be as talented an inventor as Leonardo da Vinci, but among Goffin's cockatoos, he's a prodigy. In their natural habitat—the forests of Indonesia these cockatoos have never been seen making or using tools. But researchers report today—that Figaro, a member of a captive colony of the birds in Austria, invents and uses stick tools of his own design. Although toolmaking and use is not uncommon in animals, this type of spontaneous innovation and individual creativity is "exceedingly rare" among nonhuman animals, the scientists note, and opens up many questions about the cognitive skills required. Understanding these processes, they say, may help unlock many of the questions about the evolution of intelligence. Many species of birds, such as woodpecker finches of the Galapagos Islands, ravens, crows, and herons, are natural toolmakers and users. New Caledonian crows are especially talented, shaping bits of wood and stiff palm leaves into spears and hooks to forage for grubs. One captive New Caledonian crow displayed an inventiveness similar to Figaro's by fashioning hooks (a shape she had not previously seen) out of wire. And captive Northern blue jays, which are not tool-users in the wild, have shredded newspaper to use as rakes for retrieving food pellets. Such talents haven't been seen before in cockatoos—and although tool use is seen in many species, innovative tool manufacture is rare. But even if Figaro is a standalone talent among his species, says Frans de Waal, a primatologist at Emory University in Atlanta, the discovery of such skills in even one individual shows that "general intelligence can lead to innovative behavior." Inventiveness is thus not tied to some type of mental specialization, such as being a natural tool-user, as has been argued previously, he explains. © 2010 American Association for the Advancement of Science.
by Virginia Morell Alex, an African grey parrot who died 5 years ago and was known for his ability to use English words, also understood a great deal about numbers. In a new study in this month's Cognition, scientists show that Alex correctly inferred the relationship between cardinal and ordinal numbers, an ability that has not previously been found in any species other than humans. After learning the cardinal numbers—or exact values—of one to six, Alex was taught the ordinal values (the position of a number in a list) of seven and eight—that is, he learned that six is less than seven, and seven is less than eight. He was never taught the cardinal values of seven and eight—but when tested on this, he passed with flying colors, apparently inferring, for instance, that the sound "seven" meant six plus one. In the video above of one of these experiments, comparative psychologist Irene Pepperberg of Harvard University asks Alex to pick out the set of colored blocks that equal the number seven. Play the video to hear his answer. © 2010 American Association for the Advancement of Science.
By Maureen McCarthy October 30th marked the five-year anniversary of the death of my friend Washoe. Washoe was a wonderful friend. She was confident and self-assured. She was a matriarch, a mother figure not only to her adopted son but to others as well. She was kind and caring, but she didn’t suffer fools. Washoe also happened to be known around the world as the first nonhuman to acquire aspects of a human language, American Sign Language. You see, my friend Washoe was a chimpanzee. Washoe was born somewhere in West Africa around September 1965. Much like the chimpanzees I study here in Uganda, Washoe’s mother cared for her during infancy, nursing her, carrying her, and sharing her sleeping nests with her. That changed when her mother was killed so baby Washoe could be taken from her forest home, then bought by the US Air Force for use in biomedical testing. Washoe was not used in this sort of testing, however. Instead, Drs. Allen and Beatrix Gardner of the University of Nevada chose her among the young chimpanzees at Holloman Aeromedical Laboratory to be cross-fostered. Cross-fostering occurs when a youngster of one species is reared by adults of a different species. In this case, humans raised Washoe exactly as if she were a deaf human child. She learned to brush her teeth, drink from cups, and dress herself, in the same way a human child learns these behaviors. She was also exposed to humans using sign language around her. In fact, humans used only American Sign Language (ASL) to communicate in Washoe’s presence, avoiding spoken English so as to replicate as accurately as possible the learning environment of a young human exposed to sign language. © 2012 Scientific American