Wednesday, July 29, 2009

A Cross-Species Comparative Study: Grooming Patterns in Captive Populations of Hamadryas Baboons and Geladas

This is the thesis that I've been working on for the past year. Finally got it graded and I am really happy about the thesis. After writing this thesis, I have more follow-up questions pertaining to grooming than I had started with so I guess it's a good thing.

Thanks to Dr. Larissa Swedell for supervising my thesis. Also, thanks to Dr. Sara Stinson and Dr. Ekaterina Pechenkina for reading the thesis and your inputs.

Primates groom themselves (autogrooming) and each other (allogrooming) for a variety of purposes. Allogrooming is arguably an altruistic behavior, and may be explained by kin selection. The purpose of this study is to better understand the grooming patterns of captive hamadryas baboons (Papio hamadryas hamadryas) and geladas (Theropithecus gelada) within the context of kin selection theory, which posits that kin will interact, especially in altruistic ways, more than non-kin.

This study hypothesizes that grooming patterns in hamadryas baboons and geladas can be explained by the patterns of philopatry, dispersal, social system and bonding that are seen in wild populations. The results of this study show that there is a higher frequency of allogrooming than autogrooming in both hamadryas baboons and geladas. It also shows that gelada leader males groomed their females more than hamadryas leader males groomed their females, which does not support the hypothesis of this study. The following results showed a trend but were not statistically significant enough to support the hypotheses: female hamadryas baboons and geladas groomed more than male hamadryas baboons and geladas; hamadryas leader males groomed their females more than females groomed among themselves in the same hamadryas group; gelada females groomed each other more than gelada leader males and their females; male hamadryas baboons groomed more than male geladas; female geladas groomed more than female hamadryas baboons; hamadryas baboons groomed more than geladas.

In addition, this study also hypothesizes that there is a correlation between grooming frequency and temperature. There is a positive correlation between grooming frequency and temperature in hamadryas baboons but a negative correlation in geladas.

A Cross-Species Comparative Study: Grooming Patterns in Captive Populations of Hamadryas Baboons and Geladas

Wednesday, July 15, 2009

New Tamarin Subspecies Found in Brazil

Researchers have discovered a new tamarin subspecies in the Amazon forest of Brazil. A subspecies of the saddleback tamarin, it was named Mura's saddleback tamarin (Saguinus fuscicollis mura) after the Mura Indians, the Amerindian ethnic group that lives in the Purus and Madeira river basins where the tamarins can be found.

Artist Stephen Nash's rendition of the recently discovered Mura's saddleback tamarin. Picture from

This new subspecies has a gray and dark brown pelage and a distinctly mottled "saddle". Its coloration is distinct than the two of its geographically closest relatives, the Wendell's saddleback tamarin (Saguinus fuscicollis weddelli) and Avila Pires' saddleback tamarin (Saguinus fuscicollis avilapiresi). The Mura's saddleback tamarin weighs about 213 grams (less than 3/4 pounds) and is 240 millimeters (9 inches) tall with a 320 millimeter (12.6 inch) tail.

The discovery was published in the June online edition of the International Journal of Primatology: A New Subspecies of Saguinus fuscicollis (Primates, Callitrichidae) by Fabio Röhe, José de Sousa e Silva, Ricardo Sampaio and Anthony B. Rylands.

Monday, July 6, 2009

No Sex Can do The Muriquis Harm

Muriquis feeding and resting. Photo from Primate Info Net.

The muriquis, or woolly spider monkeys live in the rain forest of Brazil. They are considered peaceful individuals but an intra-community lethal attack had left researchers to reconsider how peaceful these monkeys are and why such attack occurred.

The image of peaceful individuals mainly stemmed from the northern population. Leaves are abundant in the northern population, so these muriquis chew on leaves all day and males would patiently queue to mate with females. When food is abundant, animals tend to stay in the same place.

However, in the southern population, fruits tend to be more abundant. Generally, females need more caloric intake compared to males, so females from the southern population disperse from the group to find clumps of fruits unlike the northern population where everyone stays together to eat.

It is in the southern population that a gang of six male muriquis were observed attacking another male from the same group, brutally biting his face, body and genitals. The male died about an hour later.

A change in dietary habit might be the clue to why such assault happened, said lead researcher Mauricio Talebi of the Federal University of São Paulo-Diadema, Brazil. Social bonding also explains why a gang of males attacked another male. Due to lack of readily available mates, males may become frustrated, creating tension and aggression between individuals. Because muriqui males bond for life with male siblings and relatives, this facilitates gang attacks, said Filippo Aureli of Liverpool John Moores University, UK. This assault can be seen as aggression among non-kin males.

For more, read 'Hippy' monkey is a killer when starved of sex on NewScientist and Intra-community coalitionary lethal attack of an adult male southern muriqui (Brachyteles arachnoides) on Wiley Interscience.