Behavioral Synchronization In Chacma Baboons

There is a newly published paper by Andrew J. King and Guy Cowlishaw on factors that promote or constrain group synchronization among Chacma baboons (Papio ursinus) in central Namibia. The paper "All together now: behavioural synchrony in baboons" is available online as pdf for free.

 A mother and infant Chacma baboon (Papio ursinus). Flickr photo from Arno & Louise.

Synchronized behavior is defined as behavior performed by individuals in unison. For example, you can say that a group of animals moving through its environment is synchronized in the direction of the movement. Or a group of animals feeding is synchronized in its behavior. Synchronized behavior has its costs and benefits. Group synchronization is costly to achieve, and according to this article, due to age - sex differences, morphological - physiological differences, heterogeneous feeding terrain and visual isolation between group members. The benefit of group synchronization increases foraging benefits and reduces predation risk. A large group who travels together can easily find food or spot predators.

An example of synchronized behavior. A group of baboons traveling in a synchronized direction in Tanzania. Photo from Hole In The Donut Travels.

Interestingly, this research found that the probability of the group to synchronize increases with the number of pregnant females in the group but decreases with the number of sexually swollen females in the group. They think that females that are sexually swollen are not shy about advertising their receptivity to the males in the group. The males, in turn, would zealously guard these sexually swollen females from other males thus disrupting behavioral synchronization. Pregnant females, on the other hand, promotes group synchronization because individuals are not fighting or distracted by mating opportunities.

Read more from the press release, Brazen Baboons: Flighty Females Disrupt Group Harmony.

References:
King, AJ. Cowlishaw, G. 2009. All together now: behavioural synchrony in baboons. Elsevier Retrieved October 31, 2009, from http://static.zsl.org/files/king-cowlishaw-animal-behaviour-2009-910.pdf

PR.com. 2009. Brazen Baboons: Flighty Females Disrupt Group Harmony. Retrieved October 31, 2009, from http://www.pr.com/press-release/188486

Chimps Mourn The Death Of Their Own

A picture is worth a thousand words. So, I'm gonna just let the photo do most of the talking. Ever since this photo was published it has gone viral everywhere. Read about this news story at National Geographic and an in depth explanation of the photo here.

This photo is not surprising because it is well documented that chimpanzees mourn the death of their own. I guess the reason why it went viral is because the sheer volume of individuals mourning the death of this female chimpanzee. It looks almost human-like and behaviors that are human-like tend to evoke empathy in humans.

Effects Of Global Warming On Endangered Primate Species

A study was done by Penn State Graduate students Ruscena Wiederholt and Biology professor Eric Post on how the effects of global warming, such as El Niño and El Niña, on endangered primate species. Focusing on New World Monkeys, Wiederholt and Post studied the trend of abundance and population dynamics in four genera of Atelines: the muriqui (Brachyteles hypoxanthus, formerly B. arachnoides) of Brazil, the woolly monkey (Lagothrix lagotricha) in Colombia, Geoffroy's spider monkey (Ateles geoffroyi) of Barro Colorado Island in Panama, and the red howler monkey (Alouatta seniculus) in Venezuela.

The results of the team's analyses were spectacular. All four monkey species showed drops in abundance relating to large-scale climate fluctuations. Even though the monkey populations were separated by large distances, the three fruit-eating species had synchronous responses to large-scale warming. During El Niño warming events, trees produced more fruit than usual. Then, during the subsequent La Niña cooling events, the trees produced much less fruit, resulting in a local scarcity or even famine.


Some ecologists have speculated that high production of fruit during El Niño events may have been triggered by the increase in solar radiation, despite lower-than-usual rainfall. However, high productivity during an El Niño event might also use up the stored reserves of the trees, which would have difficulty recovering during the subsequent La Niña events, when weather was wet, cloudy, and cool. This mechanism would explain why the fruit-eating monkeys showed a delayed response to the El Niño events after a lag of one or two years.

Howler monkeys also showed declines with warm and dry El Niño events, but their population fall was out of sync with that of the fruit-eating species. The mechanism is not yet clear, but Wiederholt has some ideas. She notes, "Primate researchers have seen elevated adult female mortality and lowered birthrates among red howlers in drought years. Since leaf flush often occurs at the start of the wet season, a prolonged dry season might delay the availability of this resource for the howlers and perhaps cause them nutritional stress."


Warmer temperatures also may cause leaves -- the howlers' primary food -- to mature faster, which would accelerate the leaves' acquisition of toxins and other chemical defenses against monkeys. The factor that the scientists found was most influenced by changes in climate was the monthly maximum number of tree species that were fruiting. Climate changes also were highly correlated with the monthly maximum number of species that were flowering and with annual seed production. The length of the dry season also was highly correlated with annual flower production. Thus, vegetation responses to climatic conditions substantially altered the food resources available to primates, which in turn influenced the decline or rise in monkey abundance.

Read the rest of the article from EurekAlert!

Modern Humans Are Still Evolving But Will Modern Men Get Wimpier?

Two interesting articles that went into my inbox today: Modern man a wimp says anthropologist and Darwin Lives! Modern Humans Are Still Evolving.

A cover illustration from Australian anthropologist Peter McAllister's new book entitled "Manthropology" and sub-titled "The Science of the Inadequate Modern Male." Photo from REUTERS/Hachette Publishing/Handout.

Modern man a wimp says anthropologist  from Reuters, summarizes Peter McAllister's book Manthropology: The Science of the Inadequate Modern Male. Using various data from Neanderthals and ancient aboriginal populations, McAllister concludes that modern men are inferior than their predecessor in running, jumping, and even sheer brute. "Any Neanderthal woman could have beaten former bodybuilder and current California governor Arnold Schwarzenegger in an arm wrestle", McAllister said. John Hawks from John Hawks Weblog has a lot to say about this in his post Is modern man a "wimp"? I think Hawks is spot on with his post.

The Time article, Darwin Lives! Modern Humans Are Still Evolving, is about a study in a contemporary Massachusetts population led by Stephen Stearns and his team of scientists from Yale University. Using correlations between women's physical characteristics such as height, weight, blood pressure, and cholesterol levels with the numbers of offspring produced, they found that "stout, slightly plump, but not obese" women tend to have more offspring as oppose to women with very low body fat count, as well as women with lower blood pressure and lower cholesterol levels.

Stearns explains that women with very low body fat count, low blood pressure and low cholesterol levels do not ovulate. Ovulation is, of course, when the matured ovarian follicle ruptures and discharge an ovum (or the egg). While human females ovulate about once a month, female chickens ovulate once a day. Of course, we refer to chicken ovum as chicken eggs.

Stearns and his team thinks that the characteristics for producing maximum offspring (stout, slightly plump, higher blood pressure and cholesterol levels) were passed down from mothers to daughters. Separating social and cultural factors using statistical analysis, Stearns and his team were able to conclude that these characteristics were passed down genetically. "Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection" Stearns says. So women who have more children are more likely to pass down these traits to their offspring.

It explains the notion that modern humans are still evolving because variation in reproductive success means that there are selective pressure that favor certain traits. Interesting to note that while fertility is being shaped by natural selection (as per Stearn and his team's study), artificial selection is also shaping the width of female pelvis and the average brain size of infants being born. Mothers with a narrow birth canal (smaller pelvis size) puts both her and her infant in jeopardy during childbirth. The infant will be stuck in the birth canal due to restricted space. An infant with a larger than average brain size will also get stuck in the birth canal. Both scenarios will likely kill the infant and mother. However the advent of Caesarean section negates the restriction of a narrow birth canal and allows infant with larger brain size to be born.

So, we can see that modern humans are evolving through variation in reproductive success, female pelvis size and average infant brain size is also evolving through artificial selection though it is too early to say which direction the selection is favoring.

When It Comes To Being The "Missing Link", Ida -- You Are NOT The Candidate

Main slab of Darwinius masillae (specimen PMO 214.214), new genus and species, from Messel in Germany. Photo from Wikipedia.

Ida or "Aunt Ida" as many might recall from this summer of craziness sent shock waves around the nation as it was herald the missing link between prosimians and anthropoids (primates and human). Deserving of its own genus, Ida was given the name Darwinius masillae by Franzen et al. (2009) as they describe this specimen in their paper. Darwinius to celebrate the bicentennial celebration of Darwin's claim to fame "Origin of Species" and masillae for the location where Ida was discovered (Messel Pit, Germany).


Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology was published this summer. Soon thereafter, the general public expressed sheer amazement and curiosity, especially the press who were all too excited to report such breaking news. Hence, "Aunt Ida" became synonymous with "Ida" due to the general public's warm family reception. Others, such as the religious nuts were quick to point out that Ida was just another god(s) creation and the notion of a "missing link" is preposterous. Even Google participated in this frenzy, much to the chagrin of religious right-wing, featuring Ida in Google's logo on May 20th, 2009.

Ida as Google icon. Illustration from Google.

American Museum of Natural History soon announced that you can see Darwinius masillae in their Extreme Mammal exhibit (which I later find out that it is just a cast). The Discovery Center at Times Square also got into the game by exhibiting Darwinius masillae. All these publicity and attention makes one wonder. Is this just a publicity stunt on a premature discovery and discussion? Not to mention all the money they made from this discovery "that changes everything".

I, for one, was on the fence. While I was amazed and interested with the discovery, all these publicity stunt just does not bode well with me. I chose not to write about Ida's discovery in this blog, not because I was too lazy to add my one cent but rather I'd prefer to sit back and listen to all the discussions. One, I'm not a paleontologist nor am I an expert on skeletal morphology. I'd love to know if  Darwinius masillae actually groomed each other though.

So what made me wrote this blog entry? My inbox is filled with new articles about Darwinius masillae but this time disproving its role as the missing link. A new paper, published by Seiffert et al. (2009), concludes that Darwinius masillae is closely related to the genus Afradapis (an adapiform or adapoid). They also conclude that Darwinius masillae sits on the dead end of the evolutionary branch, without leaving any descendants let alone being the missing link for humans. Thus the title "missing link" is not befitting of this 47 million year old Eocene primate.

Phylogenetic position of the adapiforms Afradapis and Darwinius within primates. Photo from Wired.

So now that you have both sides of the story, what's your opinion on  Darwinius masillae? I'm betting my bananas that Darwinius masillae is just another product of a highly publicized discovery. Not to undermine the important discovery of this new genus but quoting my undergraduate professor, Dr. Sara Stinson, "There is no such thing as a missing link. We know where everything goes". She's right ... in fact the idea of a "missing link" is just an agent used by those who do not believe in evolution. You know, like the idea of Crocoduck (Hint: Kirk Cameron).

Further readings:
Bone Crunching Debunks ‘First Monkey’ Ida Fossil Hype from Wired.
So Ida's not the "missing link": questions and answers with Erik Seiffert from Times Online.
'Eighth wonder' Ida is not related to humans, claim scientists from Guardian.co.uk.
Darwinius on Wikipedia.

References:
Franzen, JL. Gingerich PD. Habersetzer, J. Hurum, JH. von Koenigswald, W. Smith, BH. 2009. Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLos ONE 4(5): doi:10.1371/journal.pone.0005723.

Seiffert, ER. Perry, JMG. Simons, EL. Boyer, DM. 2009. Convergent evolution of anthropoid-like adaptations in Eocene adapiform primates. Nature 461, 1118-1121 doi:10.1038/nature08429.