Primatology.net

Earlier this year, I blogged about long-tailed macaques (Macaca fascularis) in Thailand using human hair as dental floss to clean their teeth. This behavior gives us an insight to culture transfer as mothers were observed teaching their infants how to floss repeatedly.

In Kyoto, Japan, a Japanese macaque (Macaca fuscata) name Chonpe was observed flossing her teeth using her own hair. She perfected not one, but three flossing techniques.

Lead author Jean-Baptiste Leca told Discovery News that dental flossing could have been a fortuitous yet “accidental byproduct of grooming.” Leca, a post-doctoral fellow at Kyoto University’s Primate Research Institute, explained that “Japanese macaques sometimes bite into hair or pull it through their mouths to remove external parasites.” The hair might have become stuck in Chonpe’s teeth, and as she drew the hairs out, “she may have noticed the presence of food remains attached to them”. “The immediate reward of licking the food remains off the hair may have encouraged her to repeat the behavior for the same effect in the future,” he added.

Chonpe is a middle ranking female with no children. Her only close kin is her mother and her sibling, therefore diffusion of knowledge is somewhat limited to her only sibling. She was observed flossing her teeth about four years ago and had only recently seen this behavior spread among Chonpe’s troop. Chonpe was also observed her rolling small stones in her hand while attempting to remove a spine stuck in her palm, so she might be particular an innovative individual, the researchers added.

Read about the article from Discovery News, Tidy Monkey Flosses Teeth and The first case of dental flossing by a Japanese macaque (Macaca fuscata): implications for the determinants of behavioral innovation and the constraints on social transmission on the journal Primates.

Originally posted on The Prancing Papio.

Another interesting paper on teeth, specifically the eruption of the first molar (M1), by Jay Kelley and Gary Schwartz from The Institute of Human Origins, Arizona State University (ASU) Since the emergence of M1 correlates with many life history attributes in extant primates, data from this paper can be used to compare the life history among extant primates and also extinct apes and hominins.

“Knowing the age when the first molar appears in the mouths of most primates allows researchers to predict a host of life history attributes, such as gestation length, age at sexual maturity, birth spacing and overall lifespan,” said Schwartz. “Humans are unique among primates because our life histories are so slow and thus our molars emerge relatively late. Given that apes are our closest living relatives, understanding the broader context of when the characteristic slower development of humans evolved is of great interest.”

“Like annual growth rings inside trees, the cells that produce teeth (both the enamel and underlying dentine) leave behind a trace of their presence, not as annual markers, but as growth lines that appear every day,” said Kelley. By slicing the teeth in half, he and Schwartz were able to examine these incremental growth lines in ape individuals that died as their first molars were just erupting into their mouths. “Because teeth preserve this phenomenal internal chronometer, we were able to count up how many days it took the first molars to form,” said Schwartz. “In apes and monkeys, first molars start forming very close to the time of birth. As the first molars were still erupting in our specimens, development was incomplete and the final growth line was laid down on the day those animals died. Therefore, by counting backwards from the final growth line to the day of birth, we determined their age at death and thus the age at which that molar was erupting.” Using this novel approach, the two scientists were able to mark the age of the gorilla’s first molar emergence at 3.8 years, nearly identical to that of a wild chimpanzee’s. The orangutan’s age at first molar emergence was surprisingly much later, at 4.6 years, which falls closer to the age of approximately 6 years in modern humans.

Read the article, Molars provide insight into evolution of apes, humans by ASU and Dental development and life history in living African and Asian apes from PNAS.

Originally posted on The Prancing Papio.

Great apes (orangutan, gorilla and chimpanzee) depend on their teeth to get them through tough times when food is scarce. Natural selection favor individuals with teeth that can process fallback foods, foods that are harder than the great apes normal diet of fruits. The evolution of the thickness of enamel in great apes reflects the mechanical demand of their diet.

“It makes sense if you think about it,” says GWU’s Paul Constantino. “When resources are scarce, that’s when natural selection is highly active in weeding out the less fit, so animals without the necessary equipment to get through those tough times won’t pass on their genes to the next generation.”

Read the Science Daily article, Among Apes, Teeth Are Made for the Toughest Times and The Influence of Fallback Foods on Great Ape Tooth Enamel by Constantino et al. (2009).

Originally posted on The Prancing Papio.

From BBC News, chimps from the Nimba Mountains of Guinea, Africa were observed using tools to chop up and reduce food into smaller bite-sized pieces.

Kathelijne Koops and William McGrew of the Leverhulme Centre for Human Evolutionary Studies, University of Cambridge (UK) with Tetsuro Matsuzawa from Kyoto University, Inundate (Japan) observed this behavior and published it on Primates. They found that these chimps use tools to process Treculia fruits, a large volley ball-shaped fruit that is hard and fibrous.

Do chimpanzees (Pan troglodytes) use cleavers and anvils to fracture Treculia africana fruits? Preliminary data on a new form of percussive technology (free abstract).

Originally posted on The Prancing Papio.

Ever wonder why humans outlive apes? The answer might be because we eat a lot of meat. Genes evolved in humans to adjust to a meat-rich diet helps fight diseases associated with aging such as cancer, heart disease and dementia. Not to mention, the expansion of brain size in the genus Homo is also attributed to an increase in meat diet. Check out the MSNBC article “Meat may be the reason humans outlive apes” and the paper “Evolution of the human lifespan and diseases of aging: Roles of infection, inflammation, and nutrition” by Caleb Finch on PNAS.

Originally posted on The Prancing Papio.

Black and white colobus monkey, one of the folivory species threaten by global warming.

A paper by Korstjens et al. (2009) suggests that even an annual temperature rise of 2°C would threaten folivory primates because these species would be forced to spend more time resting than foraging for food. This paper, Resting time as an ecological constraint on primate biogeography, was published online on Animal Behaviour. Here’s the abstract:

Time constraints can limit an animal’s potential to survive in a given habitat and the maximum size of its group. Many studies have, therefore, investigated the ecological correlates of time allocated to travelling, foraging and vigilance. However, animals spend more time inactive than active, and understanding the determinants of this resting time may provide new insights into the habitat-specific time-budgeting problems that animals face. We analysed the environmental constraints that determine the minimum amount of daytime an average primate has to spend resting, using data from a wide range of ecologically different species. However, total resting time consists of two components: enforced resting time (imposed on the animal by ecological constraints) and free resting time (the time available for allocation to ecologically functional activities). We show that the ecologically important enforced resting time is determined by diet and annual temperature as well as by temperature variation. Our tests of the biological significance of this relationship show that enforced resting time distinguishes between locations that are suitable or unsuitable for particular genera. We show that an annual temperature increase of 2–4 °C would greatly increase enforced resting time, leading to serious time-budgeting problems for many species. The effect of changes to enforced resting time on the biogeographical distribution of species is especially strong for folivorous primates. This study shows that resting time is an important component of animal behaviour that can help us understand extinction risk and geographical distribution of taxa.

Read more about this paper on PhysOrg.com, African leaf-eating monkeys are ‘likely to be wiped out’ by climate change.

Originally posted on The Prancing Papio.

A group of researchers from University of St. Andrews, Scotland argues that Campbell’s monkeys (Cercopithecus campbelli campbelli) have a primitive form of syntax after spending months of recording their calls as they response to both natural and artificial stimuli. Lead by Dr. Klaus Zuberbühle, the team found that male’s alarm calls are made up of an acoustically variable stem, followed by an acoustically invariable suffix. These calls translate to either a specific alarm call or a non-specific alarm call, depending on the syntax.

I’m not an expert in language and linguistics but these findings are interesting in the development of language and speech in primates. Is there a reason why these monkeys are capable of understanding syntax while apes (such as gorillas and chimpanzees) don’t?

Read the New York Times article here.

Campbell’s Monkeys Use Affixation to Alter Call Meaning by Ouattara et al., (2009)

Originally posted on The Prancing Papio.

While I was away at the AAA meeting in Philadelphia, my inbox was flooded with articles on primates from behavioral to molecular level. Here’s whats happening this week in primatology:

Primate study halted by US university: Administrators at Oklahoma State University (OSU) in Stillwater have abruptly cancelled an anthrax vaccine study that would have killed dozens of baboons. Can I tell you how happy I am about this? No animals should suffer for science, not even to find a vaccine for humans.

Did Social Climbing Give Us Bigger Brain? by Urban Ethology. It takes a big brain to scheme and plan, so maybe we can thank Machiavellian Intelligence and our complex social system for that big brain of ours.

Monkeys Recognize Their Pals In Photos.Tufted capuchin monkeys (Cebus apella) were tested to see if they have facial recognition using photographs. Pokorny and de Waal (2009) published their findings in the online early edition of Proceedings of the National Academy of Sciences (PNAS). Monkeys recognize the faces of group mates in photographs (free abstract).

Social Conformity Not Unique To Humans. Another study on capuchin monkeys (talk about conforming, LOL). Dr. Marietta Dindo and Professor Andrew Whiten of the University of St Andrews show that capuchin monkeys would copy behaviors of other individuals. Not only do they copy other individual’s behavior, they would copy behaviors that are the most popular in the group.

Why Some Monkeys Don’t Get AIDS. Yea, why? It’s not fair! Two studies reveal why some monkeys don’t get AIDS and possibly identifying genes that are related to the progression or resistance to AIDS. Nonpathogenic SIV infection of African green monkeys induces a strong but rapidly controlled type I IFN response (Jacquelin et al., 2009) and Global genomic analysis reveals rapid control of a robust innate response in SIV-infected sooty mangabeys (Bosinger et al., 2009). Both are free access articles in pdf.

And finally, Scent Signals Stop Incest In Lemurs. Chemical identifiers secreted from genital glands by both males and females ring-tailed lemurs (Lemur catta) allow them to avoid incest and engage in nepotism. Decoding an olfactory mechanism of kin recognition and inbreeding avoidance in a primate (Boulet et al., 2009).

Originally posted on The Prancing Papio.