Primate Win

When a new male gelada monkey takes control of a reproductive group, he will typically kill off the babies of his predecessor. Now, new research shows that pregnant females have an adaptive strategy to minimize their losses: They spontaneously miscarry.

In 1959, biologist Hilda Bruce first demonstrated the so-called Bruce effect in mice, where recently pregnant females miscarry after being exposed to novel males. Since then, researchers have documented the phenomena in other rodent species. However, until now, the Bruce effect seemed to be something restricted to the laboratory, as nobody had conclusively shown that it exists in wild animal populations. Moreover, studies have not shown that there is any evolutionary advantage to miscarrying when confronted with new males.

To see if the Bruce effect exists in gelada monkeys (Theropithecus gelada), Jacinta Beehner, an anthropologist at the University of Michigan, and her colleagues tracked 110 females across 21 groups of wild geladas living in the Simien Mountains National Park in Ethiopia.

“We saw that as soon as a new male came into a group, there were no births for the next six months,” Beehner told LiveScience. In fact, the researchers documented only two births in these replacement groups in the five years of the study. “We get this big gap, screaming out that something is going on — it’s statistically almost impossible to get this by chance.”

To be sure what they were seeing was indeed the Bruce effect, the researchers also took hormonal data from the fecal samples of females before and after a new male arrived. Out of the 10 cases of pregnancies the researchers looked at, eight of the females miscarried within two weeks of a new male coming on to the scene. Most surprising to the researchers, the miscarriages happened the same day the male took over. Of the two females that didn’t miscarry, one quickly showed signs of fertility swelling and eventually mated with the new male while still pregnant. The other didn’t, and probably as a result, the male killed her infant, but didn’t kill the infant of the female with whom he mated. This behavior suggests that the males figure out which babies are theirs simply by knowing which females they mated with, Beehner said. Females that miscarried as soon as new males arrived also became pregnant again, and the researchers saw a twofold increase in births during the seven to 12 months after new males took over. They also found that females that experienced such primate infanticide took longer to become pregnant again, suggesting these miscarriages are evolutionarily advantageous to the mama monkeys. Peter Brennan, a physiologist at the University of Bristol in the United Kingdom who was not involved in the research, said that the study was quite convincing. “It’s a great example of pregnancy block being demonstrated quite convincingly in the wild,” said Brennan, who has studied the Bruce effect in lab mice. “And there’s good evidence that it’s adaptive in evolutionary terms.” Brennan is curious as to exactly how the females miscarry. In lab mice, he notes, females miscarry after picking up on chemical signals put off by the new males. “The actual physiological mechanism (in geladas) may be different,” he said, adding that the miscarriages might be a response to social stress. Beehner said that the next step is to pinpoint this mechanism, though this research cannot be conducted on a threatened wild primate like the gelada. Domestic horses may be good candidates for further research, as scientists have seen the Bruce effect in the species before, she said. From msnbc.com

Authorities in North Sumatra, Indonesia, have sentenced an illegal owner and trader of orangutans to a seven-month prison sentence, the first time an actual prosecution has taken place since orangutans were deemed a protected species in 1924, according to a press release issued today by the Wildlife Conservation Society (WCS).

The illegal trader, a man from Mardinding in the province of North Sumatra, was allegedly trying to sell a three-year-old orangutan named Julius, according to the release.

Last July, wildlife rescuers from a number of a conservation organizations teamed up with the Indonesian Ministry of Forestry to conduct a raid on the man’s home and confiscate Julius, who is now being cared for at an orangutan quarantine center along with 50 others.

The rescue effort was part of the National Orangutan Conservation Strategy and Action plan, launched in 2007 by President Susilo Bambang Yudhoyono.

According to the Wildlife Conservation Society, the majority of Indonesia’s illegal pet orangutans were captured after the forests they called home were cleared to make way for palm oil plantations. Others were sold by agriculture workers who caught them raiding crops in areas that had been converted to farmland.

There are only about 9,200 Sumatran orangutans left in their natural habitat, and experts believe that if current trends continue, the endangered species could become extinct from the wild within a decade, according to data from the Denver Zoo.

Overall, about 80 percent of the world’s 50,000 to 60,000 wild orangutans live in Indonesia, according to the Jakarta Globe. But an increase in illegal logging over recent years has critically threatened their survival.

Much of the logging is being done to make way for Indonesia’s palm oil industry, which is experiencing rapid growth. According to Bloomberg, output expected to reach 25 million tons this year, up from around 23.5 million tons in 2011.

In response to the deforestation, a number of international organizations have called for a boycott on Indonesian palm oil. But President Yudhoyono has told the country’s diplomats to push back against those mandating reform in the palm oil business, according to the Jakarta Globe.

From huffingtonpost.com

Chimpanzees have a bad reputation. Maybe it’s because humans have a thing about wanting to feel unique among primates. Some have argued that humans are the only species that truly behaves altruistically, the only species that actively helps out other individuals even when there is no direct benefit. Despite mounting evidence that other animals, including non-human primates, have various forms of theory of mind, many still believe that human altruism exists because we – and we alone among all the animal kingdom – can understand the goals of others. Or, if there are other animals that can understand the goals of others, perhaps we somehow do it more readily.

In a new paper just published in PNAS, primatologist Shinya Yamamotoa and colleagues point out that while chimpanzees are known to help others, they don’t usually help when it would mean giving up things like food, even if they’ve got more food than they need. Even between a mother and her infant!

Why do chimpanzees seem so reluctant to help others? One possible explanation is that they’re unable to understand the goals of another individual, resulting in an inability to create any sort of shared intentionality between two individuals. To that end, the researchers write, “many still believe that humans are unique in this respect because we are the only animal species endowed with unique ‘theory of mind’ abilities enabling us to understand the goals and to share the intentions of others.”

Yamamotoa and the other researchers set up an experiment designed explicitly to address this possibility. The first chimpanzee was given a task to accomplish in order to receive a juice reward. The task required the use of one of two types of tools: a stick or a straw. The stick and the straw, however, as well as five other items were found not in the first chimpanzee’s booth, but in the second chimp’s booth. There was a small opening between the two booths where the second chimp could pass the necessary tool to the first. By itself, this could test whether or not the second chimp was willing to help the first chimp.

But to see whether the ability to understand the goal of another individual modulates the potential to help, the researchers created two further conditions: half the time, the barrier separating the two booths was a transparent window, and half the time it was a completely opaque wall. If chimpanzees modulate their responses to a help request based on whether or not they can see the goal of another individual, then they should give the appropriate tool more often when in the transparent window condition.

During the transparent window condition, the chimpanzees were more likely to offer up the appropriate tool (e.g. a stick during the stick condition, or a straw during the straw condition) than any of the other tools. This result itself shows that the chimpanzees were able to understand which tool their partner would need in order to solve a given task. Importantly, ninety percent of tool offers occurred only after a request was given by the first chimpanzee, suggesting that while chimpanzees may not spontaneously engage in helping behaviors, direct requests are effective in soliciting assistance.

Read More at Scientific American

/cringe

Scientists from Durham University, UK, filmed the mandrill stripping a twig and using the resulting tool to clean under its toenails.

They published the findings in the journal Behavioural Processes.

Mandrills are the fifth species of Old World monkey seen deliberately modifying tools.

Non-human apes, including chimpanzees and orangutans, can adapt basic tools for specific jobs.

One well-known example of this behaviour is termite fishing in chimpanzees, where the animals strip down grasses to make fishing rods that they then poke into termite mounds to snag the nutritious insects.

“It is an ability that, up until a few years ago, was thought to be unique to humans,” said Dr Riccardo Pansini, who led the research. The new findings, he said, indicate that monkeys’ intelligence may too have been underestimated. “The gap between monkeys and great apes is not as large as we thought it was in terms of tool use and modification,” he told BBC Nature. Dr Pansini captured the footage while studying stress-related behaviour in the zoo’s mandrills. His research during that time helped inform the design of a specially landscaped enclosure, which contained shrubs to give the animals hiding places. The design won an animal welfare award in 2007. In the footage that Dr Pansini captured, a large male mandrill strips down a twig, apparently to make it narrower. The animal then uses the modified stick to scrape dirt from underneath its toenails. Though the scientist was excited to witness this deliberate tool modification, he said it was not entirely surprising. “Mandrills have been seen to clean their ears with modified tools in the wild,” he told BBC Nature. “This was thought to help prevent ear infections and therefore might be an important behaviour in terms of hygiene.” He thinks the captive setting may have helped bring out this behaviour. “Animals have more time in captivity to carry out tasks that are not focused on looking for food or mating,” he said. “So in zoos, you can occasionally pick up behaviours that are a little bit strange. “In the wild this ‘pedicuring’ would be considered trivial,” he explained. “But cleaning their ears with the same modified tool probably gave the animals some relief from the pain in their ears. “So we’re witnessing the same behaviour that’s used in quite important tasks being adapted for a less important task,” Dr Pansini said. Dr Amanda Seed, an expert in primate tool-use from the University of St Andrews, UK, praised the researchers for capturing such interesting footage. She added, though, that it was not entirely clear that the mandrill was deliberately modifying the stick for the specific goal of producing a “sharpened toenail-cleaning tool”. She told BBC Nature: “For me, the behaviour is closer to what we already know from other species, using a stick for self-cleaning purposes, than the tool modification of say chimpanzees - which rake their stick tools through their teeth to produce a brush for gathering termites. “But these definitions are always tricky. You could say that as soon as an animal pulls a branch from a tree, they’re modifying that branch.” Dr Sonya Hill a research officer at Chester Zoo, added that research findings from zoos could have a “direct impact on evidence-based conservation and husbandry practices”. “They can also contribute to a wider body of scientific knowledge, as this mandrill study has shown.” From BBC Nature Follow the link to watch the video. — Primate Win x

The Santa Ana Zoo in Prentice Park is pleased to announce the birth of a Silvery Langur (Trachypithecus cristatus) on the 31st of January, 2012. The proud parents are Oliver and Daria. The yet to be named baby is the second offspring of this pair. Mom, dad and baby can be found at home in the primate area at the zoo.

Bright orange at birth with pale skin, over the first three to five months of life Silvery Langurs change to a grayish coat with a darker face and hands, and eventually weighing up to fifteen pounds.  Silvery Langurs are at home in the dense tropical forests of Indonesia and Malaysia where they are considered near threatened with a decreasing population mostly due to land clearance, often for palm oil plantations. Silvery Langurs are specialist leaf eaters with a digestive system adapted to ferment the tough cellulose material in leaves.  With a diet high in vegetation, Langurs will sit quietly for many hours digesting their food.   

From ZooBorns

The Philippine tarsier, a small nocturnal animal, has the world’s highest pitched primate vocalization ever documented.

The distinctive tiny tarsier possesses large eyes relative to its body as well as the world’s highest frequency primate call. Hear that call here.

“Tarsiers are among only a handful of mammals that are known to communicate in the pure ultrasound,” lead author of a paper in the Royal Society’s Biology Letters, Marissa Ramsier, told Discovery News. “No other primate is known to produce and detect signals as high as the tarsier.”

Ramsier, co-director of the Biological Anthropology Research Lab at Humboldt State University, and her colleagues, made the determination after studying six tarsiers that were captured in the vicinity of Motorpool, Surigao del Norte, Mindanao, Philippines. To estimate auditory sensitivities, the researchers first used a minimally invasive brainstem response test. This showed that the primates can hear in the ultrasound range, up to 91 kHz. For comparison, humans have a high-frequency detection limit of only about 20 kHz. Next, the scientists recorded vocalizations made by the tarsiers. In some cases, the tarsiers were opening and closing their mouths, looking like they were communicating, but no sound was heard. Sensitive high tech recording equipment revealed that the primates were indeed communicating, but in ultrasound frequencies. Philippine tarsiers join a select group of mammals that have this ability. The group includes certain bats, rodents, cetaceans and even domestic cats. Ramsier explained that “kittens produce a pure ultrasonic call from about 2-6 weeks of life when they are first exploring their environment, and a mother cat produces its own purely ultrasonic call in response to the kitten.” Cats at these times of life can therefore communicate in ways not detected by their owners, “unless they follow them around with a bat detector.” All of these ultrasound-producing animals can then communicate within their own private “channel,” which could prevent detection by predators, prey and competitors. It could also enhance energetic efficiency and improve detection against low-frequency background noise. Humans, on the other hand, may have no evolutionary advantage to producing and detecting ultrasound. “Humans are big and noisy,” Ramsier said. “If a predator is nearby, it will likely see and hear us.” Conversely, tarsiers are small and active during the night, so it is relatively easy for them to use masked vocalizations as a covert strategy. Ramsier thinks they do this by constriction of their larynx and rapid opening and closing of their vocal chords. They probably have special auditory features that enable hearing of ultrasound. Chris Kirk, an associate professor in the department of anthropology at the University of Texas at Austin, told Discovery News that this “study is important because it expands the number of primate species that concentrate a large part of the acoustic energy in their vocal communications within the ultrasonic range.”

Kirk continued that one of the documented tarsier calls look to be a classic “ventriloquial” call, meaning a vocalization that conceals the location of the sender.

“In fact, it looks an awful lot like the ‘seet’ alarm calls or (those of) passerine birds, but scaled up to a higher frequency range,” he said.

Ramsier and her team also suspect that the tarsier ultrasound calls are alarms, especially since the little primates only emitted the vocalizations when they were near humans during the study.

From discovery.com

Gorillas bare their teeth in a playful “grin” to reassure one another during play, scientists have discovered.

This “flash of teeth” seems to let their playmate know that they do not intend to harm them.

The researchers, from the University of Portsmouth, study the facial expressions of primates to uncover the evolutionary origins of human smiling and laughter.

They published their findings in the American Journal of Primatology.

Lead researcher Dr Bridget Waller explained that non-human primates have two expressions “that shed light on our smiling”.

Their “playface”, she explained, appears to be a foundation of human laughter.

Dr Waller told BBC Nature: “[During play, gorillas] open their mouths and cover their teeth as if to say, ‘I could bite you but I’m not going to’.”

Another expression the primates use, where they reveal both rows of “sparkly white teeth” is believed to show one of the origins of human smiling.

This is not a playful expression, Dr Waller said. “It’s a greeting; a subordinate display.”

The different contexts in which gorillas use these facial expressions reveals that smiling and laughing are probably rooted in very different “ancestral displays”, as Dr Waller explained.

“People think we smile when we’re happy, but that’s not true,” she told BBC Nature. “You smile when its appropriate in a situation. You smile at someone in the corridor - you don’t laugh at them.” Dr Waller and her colleagues wanted to find out more about the contexts in which these two expressions combined; when gorillas flashed their upper teeth as they played. Watching the animals revealed that they would do this during particularly “rough” and intense play and they would play for longer when they bared their teeth. “It’s possibly because, when play gets rough, you need an extra signal to show each other that [you’re] just playing,” Dr Waller said. The findings, she said, showed the foundation of people’s social laughter; when humans laugh along in conversation to put one another at ease. “I always think of facial signals as about reducing uncertainty,” said Dr Waller. “We use [these] non-verbal signals all the time.” Prof Richard Byrne, an expert on primate communication and behaviour from the University of St Andrews said it was interesting to study the facial expressions of non-human primates because most of our our own expressions “seem to be ‘primitive’, in the main”. “Superficially [their] expressions may look a bit different because the ape or monkey faces are so different to our own,” he said. “But when examined properly, most human expressions have proved to be shared with quite distantly related primate species - and therefore must derive from an ancient shared ancestor.” From BBC Nature

I went home for a few days and forgot to tell you :)