Tag: Welfare

A long-term study of aggression in lemurs finds that infants born to older mothers are less likely to get hurt than those born to younger mothers. The researchers base their findings on an analysis of detailed medical records for more than 240 ring-tailed lemurs — cat-sized primates with long black-and-white banded tails — that were monitored daily from infancy to adulthood over a 35-year period at the Duke Lemur Center in North Carolina. The results suggest that infants born to older mothers are less likely to get bitten. It may be that older moms are better at fending off attackers or protecting their infants during fights, say researchers at Duke University and the National Center for Scientific Research in Montpellier, France. The study appeared online in the December 18 issue of the journal PLOS ONE. In most animal societies, males are the more aggressive sex. But in lemurs, females can be bullies too, explained co-author Marie Charpentier of the National Center for Scientific Research in France. Female lemurs compete with one another for first dibs on food and chase away males at mealtimes, sometimes lunging or snapping at each other with their sharp canine teeth.

To tease out the factors that influence who gets hurt when ring-tailed lemurs tussle, Charpentier and Christine Drea of Duke University combed the animals’ medical records for evidence of bite wounds. Animals at the Duke Lemur Center live outdoors for much of the year in large forested enclosures ranging in size from 1.5 to 14 acres. In these natural habitat enclosures, ring-tailed lemurs live in mixed groups of males and females who are free to forage, interact, play and move around as they would in the wild, providing a unique opportunity to study lemur social dynamics. Any victims of serial bullying are removed from the group to prevent additional injuries, and all wounds are recorded and treated by veterinarians. As a result, infant mortality for ring-tailed lemurs at the Lemur Center overall is about half of what it often is in the wild. Of the 237 ring-tailed lemur babies born at the Duke Lemur Center between 1971 and 2006, 15 were bitten before their first birthday, all of whom died from their wounds. The researchers examined a range of possible risk factors that might influence how the infants fared, including sex, weight, genetic diversity, group size, and whether the infant was a twin or a singleton. Of all the factors studied, the one that had the most significant impact on infant injury and survival rates was the age of the mother.

Infants that avoided injury were born to mothers who were two years older on average than the mothers of infants that were badly bitten. The results held up even when the mothers were first-time moms. “Whether the mother had had a kid before didn’t matter,” Drea said. The records don’t reveal who the perpetrators were, but in a separate behavioral study, the authors found that females — some of them related to the victims as sisters and aunts — were responsible for some of the biting. In some animal species, males are known to attack and kill the infants of nursing moms to bring the females back into heat. But the same mechanism is unlikely to be at work in ring-tailed lemurs because these animals only breed once a season, and because females wean their infants before the next breeding season begins. “Even if a female stopped nursing prematurely due to the death of an infant, she wouldn’t be ready to breed again until the next season anyway,” Drea said. Other researchers have found injured infants clinging to their mothers at the time of attack, rather than venturing out on their own. This suggests that the mother, not the baby, may be the intended target and infant injuries are a byproduct of skirmishes between adults.

Additional research is needed to determine why maternal age improves infant survival, but it is possible that older moms are better at protecting their infants or are less likely to pick fights. Older females could also be less frequent targets of aggression from their female peers. The study illustrates one of the ways that female aggression takes its toll, Drea added. For young female lemurs in particular, fighting for their place in the pecking order comes at a cost to their infants. “Female lemurs are more dominant and aggressive than females in other species, and that puts their kids at risk,” Drea said.

Science Daily
January 21, 2014

Original web page at Science Daily

Chimpanzees are sensitive to social influences but they maintain their own strategy to solve a problem rather than conform to what the majority of group members are doing. However, chimpanzees do change their strategy when they can obtain greater rewards, MPI researchers found. The study was published in PLOS ONE on November 28, 2013. Chimpanzees are known for their curious nature. They show a rich palette of learning behaviour, both individually and socially. But they are also rather hesitant to abandon their personal preferences, even when that familiar behaviour becomes extremely ineffective. Under which circumstances would chimpanzees flexibly adjust their behaviour? Edwin van Leeuwen and colleagues from the MPI’s for Psycholinguistics and Evolutionary Anthropology conducted a series of experiments in Germany and Zambia to answer this question. The researchers studied 16 captive chimpanzees at the Wolfgang Kohler Primate Research Center in Germany (Leipzig) and 12 semi-wild chimpanzees at the Chimfunshi Wildlife Orphanage Trust, a sanctuary that houses more than a hundred chimpanzees under nearly natural conditions in the north-western part of Zambia. Chimpanzees were trained on two different vending machines. A minority of the group was made familiar with one machine and the majority of group members with the other machine. Wooden balls were thrown into their enclosure; the chimpanzees could insert these balls into the machines to receive one peanut for each ball.

Van Leeuwen and his colleagues first aimed to replicate previous research and looked whether the chimpanzees in the minority group would change their behaviour toward using the vending machine that the majority of group members used. However, neither the German nor the Zambian chimpanzees gave up their strategy to join the majority. In the second study, the profitability of the vending machines was changed so that the vending machine that the minority used became more profitable, now spitting out five rewards for every ball inserted. Over time, the majority chimpanzees observed that the minority chimpanzees received more peanuts for the same effort and all but one gradually switched to using this more profitable machine. “Where chimpanzees do not readily change their behaviour under majority influences, they do change their behaviour when they can maximise their payoffs,” Van Leeuwen says. “We conclude that chimpanzees may prefer persevering in successful and familiar strategies over adopting the equally effective strategy of the majority, but that chimpanzees find sufficient incentive in changing their behaviour when they can obtain higher rewards somewhere else.” “So, it’s peanuts over popularity” he jokingly adds. The researchers emphasise that these results may be dependent upon the specific trade-offs that were created by the experimental design and that chimpanzees could act differently under the pressures of life in the wild. Van Leeuwen: “Conformity could still be a process guiding chimpanzees’ behaviour. Chimpanzee females, for instance, disperse to other groups in the wild. For these females, it is of vital importance to integrate into the new group. Conformity to local (foraging) customs might help them to achieve this integration.”

Science Daily
January 7, 2014

Original web page at Science Daily

Why do the faces of some primates contain so many different colors — black, blue, red, orange and white — that are mixed in all kinds of combinations and often striking patterns while other primate faces are quite plain? UCLA biologists reported last year on the evolution of 129 primate faces in species from Central and South America. This research team now reports on the faces of 139 Old World African and Asian primate species that have been diversifying over some 25 million years. With these Old World monkeys and apes, the species that are more social have more complex facial patterns, the biologists found. Species that have smaller group sizes tend to have simpler faces with fewer colors, perhaps because the presence of more color patches in the face results in greater potential for facial variation across individuals within species. This variation could aid in identification, which may be a more difficult task in larger groups. Species that live in the same habitat with other closely related species tend to have more complex facial patterns, suggesting that complex faces may also aid in species recognition, the life scientists found.

“Humans are crazy for Facebook, but our research suggests that primates have been relying on the face to tell friends from competitors for the last 50 million years and that social pressures have guided the evolution of the enormous diversity of faces we see across the group today,” said Michael Alfaro, an associate professor of ecology and evolutionary biology in the UCLA College of Letters and Science and senior author of the study. “Faces are really important to how monkeys and apes can tell one another apart,” he said. “We think the color patterns have to do both with the importance of telling individuals of your own species apart from closely related species and for social communication among members of the same species.” Most Old World monkeys and apes are social, and some species, like the mandrills, can live in groups with up to 800 members, said co-author Jessica Lynch Alfaro, an adjunct assistant professor in the UCLA Department of Anthropology and UCLA’s Institute for Society and Genetics. At the other extreme are solitary species, like the orangutans. In most orangutan populations, adult males travel and sleep alone, and females are accompanied only by their young, she said. Some primates, like chimpanzees, have “fission-fusion societies,” where they break up into small sub-groups and come together occasionally in very large communities. Others, like the hamadryas baboons, have tiered societies with harems, clans, bands and troops, she said.

“Our research suggests increasing group size puts more pressure on the evolution of coloration across different sub-regions of the face,” Michael Alfaro said. This allows members of a species to have “more communication avenues, a greater repertoire of facial vocabulary, which is advantageous if you’re interacting with many members of your species,” he said. The research, federally funded by the National Science Foundation and supported through a postdoctoral fellowship from the UCLA Institute for Society and Genetics, was published Nov. 11 in the journal Nature Communications. Lead study author Sharlene Santana used photographs of primate faces for her analysis and devised a new method to quantify the complex patterns of primate faces. She divided each face into several regions; classified the color of each part of the face, including the hair and skin; and assigned a score based on the total number of different colors across the facial regions. This numerical score is called the “facial complexity” score. The life scientists then studied how the complexity scores of primate faces were related to primates’ social systems. The habitat where species live presents many potential pressures that could have influenced the evolution of facial coloration. To assess how facial colors are related to physical environments, the researchers analyzed environmental variables such as geographic location, canopy density, rainfall and temperature. They also used statistical methods that took into account the evolutionary history and relationships among the primate groups to better understand the evolution of facial diversity and complexity.

While facial complexity was related to social variables, such as group size and the number of closely related species in the same habitat, facial pigmentation was best explained by ecological and spatial factors. Where a species lives is a good predictor of its degree of facial pigmentation — how light or dark the face is. “Our map shows clearly the geographic trend in Africa of primate faces getting darker nearer to the equator and lighter as we move farther away from the equator,” Lynch Alfaro said. “This is the same trend we see on an intra-species level for human skin pigmentation around the globe.” Species living in more tropical and more densely forested habitats also tend to have darker, more pigmented faces. But the complexity of facial color patterns is not related to habitat type. “We found that for African primates, faces tend to be light or dark depending on how open or closed the habitat is and on how much light the habitat receives,” Alfaro said. “We also found that no matter where you live, if your species has a large social group, then your face tends to be more complex. It will tend to be darker and more complex if you’re in a closed habitat in a large social group, and it will tend to be lighter and more complex if you’re in an open habitat with a large social group. Darkness or lightness is explained by geography and habitat type. Facial complexity is better explained by the size of your social group.” In their research on primates from Central and South America published last year, the scientists were surprised to find a different pattern. For these primates, species that lived in larger groups had more plain facial patterns.

“We expected to find similar trends across all primate radiations — that is, that the faces of highly social species would have more complex patterning,” said Santana, who conducted the research as a postdoctoral fellow with the UCLA Department of Ecology and Evolutionary Biology and UCLA’s Institute for Society and Genetics and who is now an assistant professor at the University of Washington and curator of mammals at the Burke Museum of Natural History and Culture. “We were surprised by the results in our original study on neotropical (Central and South American) primates.” In the new study, they did find the predicted trends, but they also found differences across primate groups — differences they said they found intriguing. Are primate groups using their faces differently? “In the present study, great apes had significantly lower facial complexity compared to monkeys,” Lynch Alfaro said. “This may be because apes are using their faces for highly complex facial expressions and these expressions would be obscured by more complex facial color patterns. There may be competing pressures for and against facial pattern complexity in large groups, and different lineages may solve this problem in different ways.”

“Our research shows that being more or less social is a key explanation for the facial diversity that we see,” Alfaro said. “Ecology is also important, such as camouflage and thermal regulation, but our research suggests that faces have evolved along with the diversity of social behaviors in primates, and that is the big cause of facial diversity.” Alfaro and his colleagues serve as “evolutionary detectives,” asking what factors produced the patterns of species richness and diversity of traits. “When evolutionary biologists see these striking patterns of richness, we want to understand the underlying causes,” he said. Human faces were not part of the analysis, although humans also belong to the clade catarrhini, which includes Old World monkeys and apes. Andrew Noonan, a former UCLA undergraduate student who conducted research in Alfaros laboratory, was also a co-author of this research.

Science Daily
December 10, 2013

Original web page at Science Daily

At least 441 new species of animals and plants have been discovered over a four year period in the vast, underexplored rainforest of the Amazon, including a monkey that purrs like a cat. Found between 2010 and 2013, the species include a flame-patterned lizard, a thumbnail-sized frog, a vegetarian piranha, a brightly coloured snake, and a beautiful pink orchid, according to World Wildlife Fund (WWF). Discovered by a group of scientists and compiled by WWF, the new species number 258 plants, 84 fish, 58 amphibians, 22 reptiles, 18 birds and one mammal. This total does not include countless discoveries of insects and other invertebrates. “These species form a unique natural heritage that we need to conserve. This means protecting their home — the amazing Amazon rainforest — which is under threat from deforestation and dam development,” said Claudio Maretti, Leader of Living Amazon Initiative, WWF. Some of the most remarkable species outlined in the report include:

• Flame-patterned lizard: This beautiful lizard was found from the hatchlings of eggs collected by scientists in the Colombian Amazon. An elusive species, Cercosaura hypnoides, has not been seen in the wild since the original eggs were collected, raising the prospect that it could potentially be endangered.
• Thumbnail-sized frog: This amphibian is already believed to be highly endangered. In fact, its Latin name, Allobates amissibilis, meaning “that may be lost,” alludes to this as the area where it thrives could soon be opened to tourism. This is now the third Allobates species found in Guyana.
• Vegetarian piranha: This new species of piranha, Tometes camunani, can span 20 inches wide and weigh up to 9 pounds, and is strictly herbivorous. The freshwater fish inhabits rocky rapids associated with seedlings of plants that grow among the rocks, its main source of food. Tometes is described from the upper drainages of the Trombetas River basin, Para, Brazilian Amazon.
• A brightly coloured snake from the “Lost World”: Found in the mountains of Guyana, this brightly-colored snake species was named Chironius challenger after Arthur C. Doyle’s fictional character Professor George Edward Challenger in the novel, The Lost World.
• A beautiful pink orchid: Among the new plant species are a large number of new orchid species, including this splendid pink species, Sobralia imavieirae, officially described by scientists from Roraima in the Brazilian Amazon.
• Caqueta titi monkey: This new species, Callicebus caquetensis, is one of about 20 species of titi monkey, which all live in the Amazon basin. The babies have an endearing trait, “When they feel very content they purr towards each other,” explained scientist Thomas Defler.

Many of the new discoveries are believed to be endemic to the Amazon rainforest and are found nowhere else in the world. This makes them even more vulnerable to rainforest destruction that occurs every minute across the Amazon. “Compiling and updating data on new species discovered in the vast extension of the Amazon over the last four years has shown us just how important the region is for humanity and how fundamentally important it is to research it, understand it and conserve it. The destruction of these ecosystems is threatening biodiversity and the services it provides to societies and economies. We cannot allow this natural heritage to be lost forever,” Maretti said.

Science Daily
November 12, 2013

Original web page at Science Daily

Male orangutans plan their travel route up to one day in advance and communicate it to other members of their species. In order to attract females and repel male rivals, they call in the direction in which they are going to travel. Anthropologists at the University of Zurich have found that not only captive, but also wild-living orangutans make use of their planning ability. For a long time it was thought that only humans had the ability to anticipate future actions, whereas animals are caught in the here and now. But in recent years, clever experiments with great apes in zoos have shown that they do remember past events and can plan for their future needs. Anthropologists at the University of Zurich have now investigated whether wild apes also have this skill, following them for several years through the dense tropical swamplands of Sumatra. Orangutans generally journey through the forest alone, but they also maintain social relationships. Adult males sometimes emit loud ‘long calls’ to attract females and repel rivals. Their cheek pads act as a funnel for amplifying the sound in the same way as a megaphone. Females that only hear a faint call come closer in order not to lose contact. Non-dominant males on the other hand hurry in the opposite direction if they hear the call coming loud and clear in their direction.

“To optimize the effect of these calls, it thus would make sense for the male to call in the direction of his future whereabouts, if he already knew about them,” explains Carel van Schaik. “We then actually observed that the males traveled for several hours in approximately the same direction as they had called.” In extreme cases, long calls made around nesting time in the evening predicted the travel direction better than random until the evening of the next day. Carel van Schaik and his team conclude that orangutans plan their route up to a day ahead. In addition, the males often announced changes in travel direction with a new, better-fitting long call. The researchers also found that in the morning, the other orangutans reacted correctly to the long call of the previous evening, even if no new long call was emitted. “Our study makes it clear that wild orangutans do not simply live in the here and now, but can imagine a future and even announce their plans. In this sense, then, they have become a bit more like us,” concludes Carel van Schaik.

Science Daily
October 1, 2013

Original web page at Science Daily

“Should I say something or not?” Human beings are not alone in pondering this dilemma — animals also face decisions when they communicate by voice. University of Tübingen neurobiologists Dr. Steffen Hage and Professor Andreas Nieder have now demonstrated that nerve cells in the brain signal the targeted initiation of calls — forming the basis of voluntary vocal expression. When we speak, we use the sounds we make for a specific purpose — we intentionally say what we think, or consciously withhold information. Animals, however, usually make sounds according to what they feel at that moment. Even our closest relations among the primates make sounds as a reflex based on their mood. Now, Tübingen neuroscientists have shown that rhesus monkeys are able to call (or be silent) on command. They can instrumentalize the sounds they make in a targeted way, an important behavioral ability which we also use to put language to a purpose. To find out how the neural cells in the brain catalyse the production of controled vocal noises, the researchers taught rhesus monkeys to call out quickly when a spot appeared on a computer screen. While the monkeys solved puzzles, measurements taken in their prefrontal cortex revealed astonishing reactions in the cells there. The nerve cells became active whenever the monkey saw the spot of light which was the instruction to call out. But if the monkey simply called out spontaneously, these nerve cells were not activated. The cells therefore did not signal for just any vocalisation — only for calls that the monkey actively decided to make.

The results published in Nature Communications provide valuable insights into the neurobiological foundations of vocalization. “We want to understand the physiological mechanisms in the brain which lead to the voluntary production of calls,” says Dr. Steffen Hage of the Institute for Neurobiology, “because it played a key role in the evolution of human ability to use speech.” The study offers important indicators of the function of part of the brain which in humans has developed into one of the central locations for controlling speech. “Disorders in this part of the human brain lead to severe speech disorders or even complete loss of speech in the patient,” Professor Andreas Nieder explains. The results — giving insights into how the production of sound is initiated — may help us better understand speech disorders.

Science Daily
September 17, 2013

Original web page at Science Daily

Human infants’ responses to the vocalizations of non-human primates shed light on the developmental origin of a crucial link between human language and core cognitive capacities, a new study reports. Previous studies have shown that even in infants too young to speak, listening to human speech supports core cognitive processes, including the formation of object categories. Alissa Ferry, lead author and currently a postdoctoral fellow in the Language, Cognition and Development Lab at the Scuola Internationale Superiore di Studi Avanzati in Trieste, Italy, together with Northwestern University colleagues, documented that this link is initially broad enough to include the vocalizations of non-human primates. “We found that for 3- and 4-month-old infants, non-human primate vocalizations promoted object categorization, mirroring exactly the effects of human speech, but that by six months, non-human primate vocalizations no longer had this effect — the link to cognition had been tuned specifically to human language,” Ferry said. In humans, language is the primary conduit for conveying our thoughts. The new findings document that for young infants, listening to the vocalizations of humans and non-human primates supports the fundamental cognitive process of categorization. From this broad beginning, the infant mind identifies which signals are part of their language and begins to systematically link these signals to meaning.

Furthermore, the researchers found that infants’ response to non-human primate vocalizations at three and four months was not just due to the sounds’ acoustic complexity, as infants who heard backward human speech segments failed to form object categories at any age. Susan Hespos, co-author and associate professor of psychology at Northwestern said, “For me, the most stunning aspect of these findings is that an unfamiliar sound like a lemur call confers precisely the same effect as human language for 3- and 4-month-old infants. More broadly, this finding implies that the origins of the link between language and categorization cannot be derived from learning alone.” “These results reveal that the link between language and object categories, evident as early as three months, derives from a broader template that initially encompasses vocalizations of human and non-human primates and is rapidly tuned specifically to human vocalizations,” said Sandra Waxman, co-author and Louis W. Menk Professor of Psychology at Northwestern. “Is this link sufficiently broad to include vocalizations beyond those of our closest genealogical cousins,” asks Waxman, “or is it restricted to primates, whose vocalizations may be perceptually just close enough to our own to serve as early candidates for the platform on which human language is launched?”

Science Daily
September 17, 2013

Original web page at Science Daily

Two researchers have provided the first video-based observation of swimming and diving apes. Instead of the usual dog-paddle stroke used by most terrestrial mammals, these animals use a kind of breaststroke. The swimming strokes peculiar to humans and apes might be the result of an earlier adaptation to an arboreal life. For many years, zoos have used water moats to confine chimpanzees, gorillas or orangutans. When apes ventured into deep water, they often drowned. Some argued that this indicated a definitive difference between humans and apes: people enjoy the water and are able to learn to swim, while apes prefer to stay on dry land. But it turns out that this distinction is not absolute. Renato Bender, who is working on a PhD in human evolution at the School of Anatomical Sciences at Wits University, and Nicole Bender, who works as an evolutionary physician and epidemiologist at the Institute of Social and Preventive Medicine at the University of Bern, have studied a chimpanzee and an orangutan in the US. These primates were raised and cared for by humans and have learned to swim and to dive. ‘We were extremely surprised when the chimp Cooper dived repeatedly into a swimming pool in Missouri and seemed to feel very comfortable,’ said Renato Bender.

To prevent the chimp from drowning, the researchers stretched two ropes over the deepest part of the pool. Cooper became immediately interested in the ropes and, after a few minutes, he started diving into the two-meter-deep water to pick up objects on the bottom of the pool. ‘It was very surprising behavior for an animal that is thought to be very afraid of water,’ said Renato Bender. Some weeks later, Cooper began to swim on the surface of the water. The orangutan Suryia, who was filmed in a private zoo in South Carolina, also possesses this rare swimming and diving ability. Suryia can swim freely up to twelve meters. Both animals use a leg movement similar to the human breaststroke ‘frog kick’. While Cooper moves the hind legs synchronous, Suryia moves them alternatively. The researchers believe that this swimming style might be due to an ancient adaptation to an arboreal life. Most mammals use the so-called dog-paddle, a mode of locomotion that they employ instinctively. Humans and apes, on the other hand, must learn to swim. The tree-dwelling ancestors of apes had less opportunity to move on the ground. They thus developed alternative strategies to cross small rivers, wading in an upright position or using natural bridges. They lost the instinct to swim. Humans, who are closely related to the apes, also do not swim instinctively. But unlike apes, humans are attracted to water and can learn to swim and to dive.

‘The behavior of the great apes in water has been largely neglected in anthropology. That’s one of the reasons why swimming in apes was never before scientifically described, although these animals have otherwise been studied very thoroughly. We did find other well-documented cases of swimming and diving apes, but Cooper and Suryia are the only ones we were able to film. We still do not know when the ancestors of humans began to swim and dive regularly,’ said Nicole Bender. ‘This issue is becoming more and more the focus of research. There is still much to explore,’ said Renato Bender.

Science Daily
September 3, 2013

Original web page at Science Daily