Primatology.net

(Photo courtesy of Bristol Zoo Gardens)

With a little help from clomifene (a drug that women have been using to aid in ovulation), Salome, a western lowland gorilla, carried a baby to term and gave birth on December 15th. The 30-year-old gorilla from the Bristol Zoo was mating, just not successfully conceiving. Veterinarians reported that she had a diminished ovarian reserve and after gynecological consults, Salome was given a drug to stimulate ovulation. Three months later she became pregnant.

Bristol Zoo deputy director, Dr. Bryan Carroll reported that,

“Female gorillas, like their human counterparts, find conceiving more difficult as they get older, so zoos may now be able to give some of their important breeders a helping hand. Being able to treat female gorillas with human fertility drugs is potentially a very important breakthrough.”

It will be interesting to see where this goes and what debates, if any, it sparks in zoo science over the next few years.

Six out of 21 monkeys in the Shirakami Mountains tested positive for B virus according to the Daily Yomiuri. In a statement issued by Kazutaka Osawa of Nagasaki University, the infected monkeys (between 3 and 13 years old) were captured near residential areas between July and November. The transfer of the disease to humans usually occurs through bites and scratches by monkeys.

Bad news for humans as 80% of those who have contracted the B virus and go untreated die from complications. Since 1932, approximately 40 human deaths have been reported in relation to monkey bites.

Today’s interesting press release from the University of St Andrews calls attention to a paper on the singing behavior of gibbons as a mechanism to ward off predators in addition to mating practices. Esther Clarke, Klaus Zuberbuhler, both of the University of St Andrews and Ulrich Reichard, of the Max Planck Institute observed the singing behavior of white-handed gibbons in Khao Yai National Park, Thailand. The experimenters said:

“We are interested in gibbon songs because, apart from human speech, these vocalizations provide a remarkable case of acoustic sophistication and versatility in primate communication. Our study has demonstrated that gibbons not only use unique songs as a response to predators, but that fellow gibbons understand them.

This work is a really good indicator that non-human primates are able to use combinations of calls given in other contexts to relay new, and in this case, potentially life-saving information to one another. This type of referential communication is commonplace in human language, but has yet to be widely demonstrated in some of our closest living relatives – the apes.

Not unlike humans, gibbons assemble a finite number of call units into more complex structures to convey different messages, and our data show that distant individuals are able to distinguish between different song types and understand what they mean. This study offers the first evidence of a functionally referential communication system in a free-ranging ape species.

Finding this ability among ape species, especially gibbons who in a sense bridge the evolutionary gap between great apes and monkeys, could shed light on when this ability developed in the primate lineage.”

Here’s the paper.

Fifty years is all it would take to destroy two-thirds of the forests in the Congo River Basin. Currently, about 3.7 million acres of forest each year is lost to logging, agriculture, and road development (among other things). In a World Wildlife Fund (WWF) report, Laurent Somé, WWF’s Central African Regional Office Director, briefly touches on some of the problems associated with deforestation:

“Tropical forest is vanishing at a rate of 5 percent a decade, wrecking habitats and releasing 3 billion tons of carbon dioxide a year, which is a fifth of global greenhouse emissions.”

The WWF report further elaborates:

“The region is blanketed by a patchwork quilt of logging concessions. While the logging itself is usually selective and does little damage, the associated roads, infrastructure and migration degrade surrounding landscape and result in massive wildlife depletion.”

Recent posts have raised the important issue that deforestation and habitat destruction are contributing to the spread of Ebola — in which the importance of forests could not be clearer. The WWF and other organizations (like the Wildlife Conservation Society) are working to promote awareness of this severe situation in hopes of saving the land and its inhabitants. Reuters UK reports that the WWF, which in the past two decades has protected millions of acres, is in the process of gaining 300,000 more protected acres in the next few months.

Soon the Baktikop forest will have few more inhabitants. According to Willie Smith, founder of BOS (Borneo Orangutan Survival) Foundation (as reported in ANTARA News), the Forestry Ministry will allow for about 200 orangutans to be released to the protected Baktikop forest in early 2007.

The Nyaru Menteng Rehabilitation and Reconstruction Center in Central Kalimantan has been caring for these orangutans since they were seized in Semarang, Yogyakarta, Bandung, and Sukabumi, where many were exploited for entertainment. The success of nursing the orangutans back from poor health and releasing them will open up much needed space at Nyaru Menteng for those in need.

In a recent Current Biology article, “Male Chimpanzees Prefer Mating with Old Females,” Muller, Thompson, and Wrangham report on the sexual attraction of males to females in the Kanyawara chimpanzee community in Kibale National Park, Uganda. The authors indicate that female chimpanzee mothers become more sexually attractive with age. A concept that is contrary to human norms.

“Cross-cultural studies indicate that women’s sexual attractiveness generally peaks before motherhood and declines with age. Cues of female youth are thought to be attractive because humans maintain long-term pair bonds, making reproductive value (i.e. future reproductive potential) particularly important to males. Menopause is believed to exaggerate this preference for youth by limiting women’s future fertility. This theory predicts that in species lacking long-term pair bonds and menopause, males should not exhibit a preference for young mates. We tested this prediction by studying male preferences in our closest living relative, the chimpanzee (Pan troglodytes). We show that despite their promiscuous mating system, chimpanzee males, like humans, prefer some females over others. However, in contrast to humans, chimpanzee males prefer older, not younger, females. These data robustly discriminate patterns of male mate choice between humans and chimpanzees. Given that the human lineage evolved from a chimpanzee-like ancestor, they indicate that male preference for youth is a derived human feature, likely adapted from a tendency to form unusually long term mating bonds.”

The authors note that the functional explanation for this attractiveness is not necessarily clear and long-term data is currently undergoing analysis to better explain some possibilities: older females tend to be high ranking which translates into increased fitness (and chimps do not go through menopause), more experience as a mother could lead to increased infant survival, and the genes of those who live longer are desirable.

In the meantime, the authors conclude that natural selection has shaped the values for female mates quite differently for chimps and humans.

“Chimpanzee males may not find the wrinkled skin, ragged ears, irregular bald patches, and elongated nipple of their aged females as alluring as human men find the full lips and smooth complexions of young women, but they are clearly not reacting negatively to such cues.”