Altruistic side of aggressive greed

In many group-living species, high-rank individuals bully their group-mates to get what they want, but their contribution is key to success in conflict with other groups, according to a study that sheds new light on the evolutionary roots of cooperation and group conflict.

In a series of mathematical models, researchers from the National Institute for Mathematical and Biological Synthesis and the University of Oxford uncovered a mechanism for explaining how between-group conflict influences within-group cooperation and how genes for this behavior might be maintained in the population by natural selection.

Humans are unique in their innate ability and willingness to cooperate within groups ranging in size from small-scale forager bands to nations of millions of individuals. Yet, cooperation has its downsides as it can lead to what scientists call “the collective action problem,” which says that if individual effort is costly and a group member can benefit from the action of group-mates, then there is an incentive to “free-ride,” whereby effort is reduced or withdrawn completely. If a number of group-mates follow this logic, the public good is not produced and all group members suffer. The collective action problem also occurs in conflicts between groups: everyone benefits from the group’s success, but achieving success requires costly contributions by members of the group.

The study, issued today as open access in the journal Nature Communications, shows that the collective action problem can be overcome in groups that have a hierarchical structure and high inequality. When within-group hierarchy and inequality are well established, high-rank individuals effectively spend their effort on competition with their peers in other groups. This competition then results in a seemingly altruistic behavior of the high-rank individuals as they make stronger effort, pay higher costs, and get smaller net benefit than their low-rank group mates who free-ride contributing nothing. The study also found that the total group effort that a group directs toward between-group conflict typically increases with the degree of hierarchy and inequality within the group.

The results are consistent with observations in nature across a range of species. The study cites chimpanzees, for example, whose high-rank males travel further into the periphery of the group during border patrols, and ring-tail lemurs and blue monkeys whose high-rank females participate more in the defense of communal feeding territories.

“As far as within-group interactions are concerned, the alpha males and females are ‘bad guys’ taking various resources from their group-mates. However, in between-group conflicts they become ‘good guys’ and their presence and effort benefit everybody else,” said Sergey Gavrilets, NIMBioS’ associate director for scientific activities and the study’s lead author.

While the study focuses on social instincts, those genetically-based biases affecting individual behavior in social interactions, the authors point out that human behavior is controlled not only by genes but also by other factors, including culture, the environment and rational choice. The study suggests that humans may have an innate preference for an egalitarian social structure when there is relatively little between-group conflict and, conversely, an innate preference for a hierarchical social structure when levels of between-group conflict are high. The study also predicts that humans who find themselves in a leadership position may exhibit seemingly altruistic behavior.

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No Monkeying Around for These Partners

For These Monkeys, Mother Knows Best

Sometimes less is more for hungry dogs

Hungry dogs would be expected to choose alternatives leading to more food rather than less food. But just as with humans and monkeys, they sometimes show a “less is more” effect. Thus conclude Kristina Pattison and Thomas Zentall of the University of Kentucky in the US, who tested the principle by feeding baby carrots and string cheese to ten dogs of various breeds. The findings are published in Springer’s journal Animal Cognition.

The research was conducted on dogs that would willingly eat cheese and baby carrots when offered, but showed a preference for the cheese. However, when given a choice between one slice of cheese, or the cheese together with a piece of carrot, nine of the ten dogs chose the cheese alone. That is, they chose less food over more food.The “less is more” effect is considered an affect heuristic or mental shortcut that sometimes shows a preference for the qualitative over the quantitative when considering different options.

It appears that the dogs averaged the quality of the cheese plus carrot, rather than sum up the quantity of food. This quick decision making was first demonstrated in humans, and later in monkeys. People, for instance, tend to place greater value on a set of six baseball cards that are in perfect condition, than on the same set of six perfect cards together with three more cards in fair condition. A similar effect was also reported in studies of monkeys where the animals would eat both grapes and cucumbers, but preferred one grape over one grape plus a slice of cucumber when given the option.

The researchers believe that this paradoxical choice occurs because in most cases it is easier to judge the average quality than the overall quantity of alternatives. In cases where rapid decisions must be made, quick solution-driven heuristics such as the “less is more” effect may therefore come in handy. For instance, it is helpful when members of the same species, such as a pack of dogs, feed together. The one that hesitates may lose food to faster-choosing competitors. Such heuristics may also help prey in the wild to make rapid decisions rather than become supper. But the fact that one in ten dogs did choose the cheese-and-carrot combination suggests that levels of motivation may play a role in this effect. The outlier dog, for instance, had a history of living in shelters and fending for himself.

“The present research indicates that the less is more effect is not unique to humans and other primates but can occur in other mammalian species, at least those that are socially organized such as carnivores like wolves, dogs and jackals,” says Pattison. She believes that further research is needed to find out if the “less is more” effect also occurs in less socially organized species such as rats, or non-mammalian species such as birds.

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Owl monkeys don’t cheat: Intensive fathering plays a role

True monogamy is rare in the animal kingdom. Even in species that appear to “mate for life,” genetic maternity and paternity tests have revealed that philandering often takes place.

Yet a new study by University of Pennsylvania researchers shows that Azara’s owl monkeys (Aotus azarae) are unusually faithful. The investigation of 35 offspring born to 17 owl monkey pairs turned up no evidence of cheating; the male and female monkeys that cared for the young were the infants’ true biological parents.

An additional analysis of 15 pair-living mammals by the Penn team found a strong connection between a species’ faithfulness and significant involvement of males in caring for their young.

“Our study is the first of any primate species, and only the fourth for a pair-living mammal, to show genetic monogamy, or real faithfulness, between partners,” said study author Eduardo Fernandez-Duque, an associate professor in Penn Arts and Sciences’ Department of Anthropology. “Paternal care in owl monkeys now makes sense. The males are making a huge investment in their own offspring.”

Fernandez-Duque collaborated on the work with lead author Maren Huck, who completed a postdoctoral fellowship in his lab and is now a lecturer at the University of Derby, as well as professor Theodore Schurr of Penn’s Department of Anthropology and Paul Babb, who completed his Ph.D. with Fernandez-Duque and Schurr and is now a postdoctoral research at Penn’s Perelman School of Medicine. The study will be published in Proceedings of the Royal Society B: Biological Sciences.

As part of the Owl Monkey Project, the Penn evolutionary anthropologists have been studying a population of these primates in Argentina’s Chaco region for 18 years. Previous work had shown that male and female owl monkeys form strong pair-bonds and that males contribute significantly to raising young by carrying them on their bodies, playing with them and feeding them solid foods.

Though the species was known to be socially monogamous, no one had tested whether the species was genetically monogamous — in other words, whether there were any cases of females reproducing with a male other than her mate, a behavior known as extra-pair paternity.

To test this, the researchers paired behavioral field observations with genetic tests to see whether the “social” mothers and fathers of infant monkeys were the biological parents. They collected samples from 128 individual monkeys living in 29 groups or as solitary “floaters.” This set included genetic samples from 35 infants born to 17 reproducing pairs.

By examining 14 different regions of the genome, the research team’s analysis strongly suggested that owl monkeys were completely faithful. They found no evidence of extra-pair paternity.

“In the 18 years of the Owl Monkey Project, we never witnessed a little sneaky copulation with a neighbor, or that one partner dashed off for some time,” Fernandez-Duque said. “So in that sense we were not very much surprised by our results. But true genetic monogamy is very rare. We would not have been surprised if there had been at least one non-pair infant, but there were none.”

Indeed, no other robust study of primates has demonstrated genetic monogamy. It has been shown in only four other mammal species, including coyotes and the California mouse.

Because the researchers were interested in how genetic monogamy has evolved and the conditions under which it occurs, they went on to perform an analysis of 15 mammal species that have been shown to live in socially monogamous pairs and for which paternity studies have been conducted. In addition to the owl monkeys, this group included birds, rodents and canines.

The results of this broader investigation showed that species in which males contribute significantly to infant care were more likely to be genetically monogamous. They also found an association between the strength of the bond between mates — that is, the percentage of time the male and female spent together — and low levels of extra-pair paternity, but this connection was not as strong.

Though their results underline the presence of a connection between intense male care for young and faithfulness, the researchers say they cannot yet tell which condition gives rise to the other. They also note that other factors, including the ecological conditions in which a species dwell, play a role.

“Male care is surely not the only factor explaining genetic monogamy,” Huck said. “Some of the species that show male care have, due for example to their foraging habits, much more opportunities for seeking extra-pair copulations than owl monkeys.”

The team also noted that being a good dad can also be a mating strategy in and of itself; females might be attracted to males that appear to be good dads.

These findings in the owl monkey and other species can begin to help explain the evolution of pair-bonds in another primate species: human beings.

“Pair bonding, love if you want, is prevalent in all human societies, whereas fathering is much more variable,” Fernandez-Duque said. “The owl monkey story is suggesting that, under very specific ecological settings, this preference for each other leads to the pair spending a lot of time in close proximity, thus facilitating paternal care and increasing paternity certainty. Genetic monogamy is the result.”

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Personality predicts social learning in wild monkeys: Bold or anxious baboons learn to solve tasks from other baboons

Baboons learn from other baboons about new food sources — but only if they are bold or anxious — according to a new study published in the journal PeerJ). The results suggest that personality plays a key role in social learning in animals, something previously ignored in animal cognition studies.

Studying animals at the Zoological Society of London’s Institute of Zoology Tsaobis Baboon Project in Namibia, the researchers examined how personality influenced whether baboons solved foraging tasks and whether they then demonstrated to others how to solve the tasks. They found bolder baboons did both.

Over three years, the researchers performed two types of experiment in which the baboons could learn about a novel food source by watching another baboon with it.

According to lead author Dr Alecia Carter of the University of Cambridge: “Though bolder baboons learnt, the shy ones watched the baboon with the novel tasks just as long as the bold ones did, but did not learn the task. In effect, despite being made aware of what to do with the tasks they were still too shy to do anything with it afterwards.”

This means there was a mismatch between collecting social information and using social information.

The authors found a similar mismatch for anxiety: calm baboons watched a demonstrator for longer than anxious individuals, but it was the anxious individuals which learnt the task.

“These results are significant, because they suggest that in cognitive tasks animals may perform poorly not because they aren’t clever enough to solve the task, they may just be too shy or nervous to interact with it. Individual differences in social learning that are related to personality may thus have to be taken into account systematically when studying animal cognition,” she said.

The results also suggest that the baboons’ social networks may prevent them from learning from others. “I couldn’t test some individuals no matter how hard I tried,” explained Dr Carter, “because although they were given the opportunity to watch a knowledgeable individual who knew how to solve the task some baboons simply never went near a knowledgeable individual and thus never had the opportunity to learn from others.”

The findings may impact how we understand the formation of culture in societies through social learning. If some individuals are unable to get information from others because they don’t associate with the knowledgeable individuals, or they are too shy to use the information once they have it, information may not travel between all group members, stopping the formation of a culture based on social learning.

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Novel drug treatment protects primates from deadly Marburg virus

For the first time, scientists have demonstrated the effectiveness of a small-molecule drug in protecting nonhuman primates from the lethal Marburg virus. Their work, published online in the journal Nature, is the result of a continuing collaboration between Army scientists and industry partners that also shows promise for treating a broad range of other viral diseases.

According to senior author Sina Bavari, the drug, known as BCX4430, protected cynomolgous macaques from Marburg virus infection when administered by injection as long as 48 hours post-infection. Bavari and his team at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) also found that BCX4430 protected guinea pigs exposed to Marburg virus by the inhalation route.

Developed by BioCryst Pharmaceuticals, Inc., BCX4430 also demonstrated activity against a broad range of other RNA viruses, including the emerging viral pathogen Middle East respiratory syndrome coronavirus (MERS-CoV), when tested in cell culture.

“This study demonstrates the importance of government-industry collaboration,” said COL Erin P. Edgar, commander of USAMRIID. “Developing filovirus medical countermeasures is a top biodefense priority for the United States. When federal assets like USAMRIID team up with cutting-edge partners in private industry, we can make real progress toward achieving that goal.”

The paper’s first author, Travis K. Warren of USAMRIID, said findings from the work show the drug acts by interfering with the internal “machinery” of the Marburg virus, preventing it from replicating its genetic material. He said the team is currently planning additional studies to determine whether the therapeutic window can be extended beyond 48 hours. In addition, BioCryst plans to file investigational new drug (IND) applications for intravenous and intramuscular BCX4430 for the treatment of Marburg virus disease, and to conduct Phase 1 human clinical trials, according to Warren.

Ebola and Marburg cause hemorrhagic fever with case fatality rates as high as 90 percent in humans. The viruses, which are infectious by aerosol (although more commonly spread through blood and bodily fluids of infected patients), are of concern both as global health threats and as potential agents of biological warfare or terrorism. Currently there are no available vaccines or therapies. Research on both viruses is conducted in Biosafety Level 4, or maximum containment, laboratories, where investigators wear positive-pressure “space suits” and breathe filtered air as they work.

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Testis size matters for genome evolution

In many primates, females mate with multiple partners, causing an often-intense competition amongst males to pass along their DNA to be king of the genome as well as the jungle.

In the advanced online edition of Molecular Biology and Evolution, author Alex Wong used a published sequence dataset from 55 species of primates to test for a correlation between molecular evolutionary rates across a genome (substitution rates) and testes weights, used in the study as a proxy for increased sperm production and competition. It is widely thought that the production of increased numbers of sperm results from more rounds of cell division — -and with more cell division, more mutations arise during sperm production.

“In general, the speed of genome evolution is higher for species in which males have large testes in comparison to species in which males have small testes,” said Wong. “This finding helps us to understand why genomes evolve at different rates in different species, and has implications for our understanding of the relationship between female mate choice and the overall fitness of a population.”

Wong applied a sophisticated evolutionary method to detect a correlation between testes size and substitution rate in primates, and found a positive correlation when accounting for other confounding factors. This finding could provide support for the general prediction that sperm competition should result in higher substitution rates as a consequence of higher spermatogenic activity in species that mate with more than one male.

“The current finding of covariance between sperm competition intensity and substitution rates adds to a growing body of knowledge concerning the sources of substitution rate variation,” said Wong. “The extent to which this covariance is widespread is not yet clear; application of robust comparative methods to large phylogenetic datasets in other taxa, such as birds and insects, will help to establish its generality.”

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Injections Providing Protection Against AIDS in Monkeys, Studies Find

Famed Milwaukee County Zoo orangutan’s death caused by strange infection

Mahal, the young orangutan who became a star of the Milwaukee County Zoo and an emblem of survival for a dwindling species, led an extraordinary life. It turns out, the young ape died an extraordinary death, too.

Rejected by his biological mother at the Cheyenne Mountain Zoo in Colorado Springs, Colo., and eventually flown to Milwaukee aboard a private jet to live with a surrogate mother, Mahal became one of the Milwaukee County Zoo’s star attractions. His unexpected death at age 5 in late December 2012 was a shock to the community that came to know him through a popular newspaper feature series in the Milwaukee Journal Sentinel and a book that recounted his difficult start in life.

Now, thanks to cutting-edge genetic diagnostics, a team of researchers led by Tony Goldberg at the University of Wisconsin-Madison’s School of Veterinary Medicine has documented the cause of Mahal’s death in the scientific literature, identifying a species of tapeworm unknown to science and newly recognized as a threat to primates.

“At the beginning, all we had were Mahal’s clinical condition and a tissue sample,” says Goldberg, professor in the Department of Pathobiological Sciences and associate director for research in the UW-Madison Global Health Institute. “We knew there was some type of infection in there. It could have been nearly anything. The list of potential agents was enormous.”

Goldberg, a veterinarian and expert in the identification of emerging and rare diseases in humans and other primates, worked with Annette Gendron of the UW-Madison Research Animal Resources Center, David O’Connor of the UW-Madison Department of Pathology and Laboratory Medicine, and veterinarians Roberta Wallace and Victoria Clyde from the Milwaukee County Zoo, as well as UW-Madison students and colleagues at the University of Florida, to identify the agent. The team pinned Mahal’s death on an unrecognized species of tapeworm in the genus Versteria. Their findings were published online in a recent (December, 2013) edition of the journal Emerging Infectious Diseases.

Tapeworms, notes Goldberg, are a large and diverse group of parasites. There are estimated to be more than 1,500 known species of the pathogenic flatworms, many of which are adapted to specific animal hosts. Of those, perhaps a few dozen can infect humans and other primates.

According to Goldberg, the tapeworm found in Mahal is an unknown species in the newly categorized Versteria genus, which has been found in weasels in either Africa or North America. Furthermore, Mahal’s tapeworm was in its larval form. “Larval tapeworms infect the tissues of animals,” says Goldberg. “This life stage is different from the adult form, which is the long, wormlike stage we usually think of.”

When certain tapeworm larvae in the tissues of an “intermediate” host are eaten by a predator, they grow into the more familiar adult form, which live in the intestine and produce eggs.

Sometimes, Goldberg explains, parasites like larval tapeworms infect animals they are not supposed to, as seems to be the case with Mahal. “It’s possible the parasite was expecting to be in a mouse but found itself inside an orangutan,” says Goldberg, noting that tapeworm eggs can move through the environment in complex ways. Mahal was therefore probably an “aberrant” host, and the larval form of the tapeworm infected practically every organ in his body.

“For reasons we don’t understand, tapeworms sometimes go haywire,” Goldberg says, adding that how and when Mahal became infected remain mysteries. “It is possible he was infected a few weeks before he died. Or he may have been infected several years ago and the tapeworm was dormant and suddenly started to multiply out of control.”

To identify the culprit, Goldberg and his team used a technique known as “deep sequencing” to characterize all of the DNA in Mahal’s tissue samples. Ninety-seven percent of the genetic material, explains Goldberg, belonged to Mahal, of course. But because the orangutan genome is known and sequenced, Goldberg’s team was able to pick out DNA from the parasite.

The work, Goldberg says, was possible because of unique facilities at the Wisconsin National Primate Research Center AIDS Vaccine Research Laboratory.

What was left after the orangutan DNA was filtered out was a small percentage of DNA sequences roughly similar to Torenia solium, also known as the pork tapeworm, a parasite that afflicts humans. By doing additional genetic testing and comparing the results to banked DNA sequences of known tapeworm species, Goldberg and his group were able to place the tapeworm in the newly proposed genus Versteria.

“This was an unknown species and a very unusual presentation,” says Goldberg. “On hindsight, there was nothing that could have been done to prevent it by anyone at the zoo or anywhere else, and by the time the infection made Mahal sick it had already gotten out of control. This was an unfortunate quirk with very sad consequences.”

The abstract to the article can be found at: http://ift.tt/1kUKm24

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Bisphenol A (BPA) at very low levels can adversely affect developing organs in primates

Bisphenol A (BPA) is a chemical that is used in a wide variety of consumer products, such as resins used to line metal food and beverage containers, thermal paper store receipts, and dental composites. BPA exhibits hormone-like properties, and exposure of fetuses, infants, children or adults to the chemical has been shown to cause numerous abnormalities, including cancer, as well as reproductive, immune and brain-behavior problems in rodents. Now, researchers at the University of Missouri have determined that daily exposure to very low concentrations of BPA by pregnant females also can cause fetal abnormalities in primates.

“BPA is an endocrine disrupting chemical that has been demonstrated to alter signaling mechanisms involving estrogen, androgen and thyroid hormones,” said Frederick vom Saal, Curators Professor of Biological Sciences in the College of Arts and Science at MU. “Previous studies in rodents have demonstrated that maternal exposure to very low doses of BPA can significantly alter fetal development, resulting in a variety of adverse outcomes in the fetus. Our study is one of the first to show this also happens in primates.”

Although BPA is considered a toxic chemical in other countries such as Canada, the U.S. has been slow to address the issue, said vom Saal. Until now, most studies involving BPA have been conducted on laboratory mice and rats, leading U.S. regulatory agencies to call for studies in primates. With funding provided by the National Institute of Environmental Health Sciences (NIEHS), a research institute of the National Institutes of Health, vom Saal and his colleagues studied the chemical’s blood levels in pregnant female rhesus monkeys and their fetuses, which are considered to be very similar to human fetuses.

After collecting tissue samples, other researchers analyzed the tissues to determine if BPA exposure was harmful to fetal development. Researchers found evidence of significant adverse effects in mammary glands, ovaries, brain, uterus, lung and heart tissues in BPA exposed fetus when compared to fetuses not exposed to BPA. The abnormalities were caused by levels of BPA in the monkey fetuses that were very similar to levels reported in previous studies of BPA in human fetuses.

“The very low-level exposure to BPA we delivered once a day to the rhesus monkeys is far less than the BPA levels humans are exposed to each day, which reflects multiple exposures,” vom Saal said. “Our findings suggest that traditional toxicological studies likely underestimate actual human exposure and show, unequivocally, that biologically active BPA passes from the mother to the fetus. Additionally, our latest study shows that BPA causes damage to developing systems of monkey fetuses, and this is of great concern for human fetuses.”

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