We’ll, I’ll be a Monkey’s Uncle. Or an Orangutan’s.

Our Guest blogger today is Dr. Todd Disotell, a professor of anthropology and a molecular primatologist at New York University’s Center for the Study of Human Origins. He will be speaking at HMNS on Feb. 9 at 6:30 p.m. about new molecular analytical techniques and how mapping whole genome sequences has affected what we know about the past. In his blog below, Dr. Disotell debates a recently proposed theory that humans are more closely related to orangutans than chimpanzees – a theory he disagrees with.

Posing for the Camera
Creative Commons License photo credit: jimbowen0306

This past summer upon the publication of a paper by a colleague, I found myself at the intersection of a 25 year old hypothesis, the latest research in genomics and bioinformatics, and popular culture.  Jeffrey Schwartz of the University of Pittsburgh and his coauthor, John Grehan of the Buffalo Museum of Science published an updated version of their hypothesis that orangutans are more closely related to humans than are chimpanzees in the Journal of Biogeography.  This intrigued me because in my final year of graduate school, my advisors and I published one of the earliest papers utilizing DNA sequence data supporting the growing consensus that chimpanzees were our closest relative, followed by gorillas, and much more distantly orangutans.

Perhaps due to my working in New York City, a producer from the Daily Show with Jon Stewart called me at my office and wanted to know if I was willing to be interviewed about Schwartz’s hypothesis.  As a fan I readily agreed and correspondent John Oliver was dispatched to my laboratory to interview me.  During the course of the interview in which I stated that the hypothesis flew in the face of all known genetic evidence, I opined that I would at least get to write a counter paper and perhaps a counter-counter paper if Schwartz responded.  That got me thinking about newly available genomic data that was now available in various databases which had not been fully analyzed.

Confused chimp
Creative Commons License photo credit:
Tambako the Jaguar

I then downloaded the complete genome alignments that included human, chimpanzee, gorilla, orangutan, macaque, marmoset, lemur, and galago.  After writing a series of Python scripts (an open source computer programming language) to parse and reformat the masses of sequence data, I chose the first 1 million bases of each chromosome for which all of the above species were represented.  I then used well characterized statistical and analytical techniques to infer the evolutionary history of each DNA region.  Not surprising to me, the analysis of each region convincingly rejects the hypothesis that orangutans are more closely related to humans than are chimpanzees.  Furthermore, when these 30 million DNA bases are used to estimate the time of divergence between humans, chimpanzees, and orangutans using molecular clock techniques, the orangutan appears to have diverged at over twice the age chimpanzees have from humans.

These results are not at all surprising to the absolute majority of paleoanthropologists and evolutionary primatologists.  However, it is still worthwhile to occasionally revisit theories and hypotheses that we now take for granted when new data are generated and new analytical techniques are developed.  In this genomic age, as the genomes of more and more species and even individuals within species are being sequenced, a whole new class and scale of analyses can be carried out from the keyboard.

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Check out Dr. Disotell’s lecture, “Times Are a-Changin’: New Methods Tell A New Tale of Primate Evolution” at HMNS on Feb. 9 – get tickets here!

Understanding Human Evolution: Fongoli Chimpanzees

Today’s guest blogger is Dr. Jill Pruetz from National Geographic. In addition to being a professor of biological anthropology at Iowa State University, she is currently conducting studies for National Geographic on the evolution of the Fongoli chimpanzees of Senegal. Understanding how the Fongoli chimpanzees survive the harsh conditions of Senegal help us to comprehend how our own ancient relatives might have lived. She will be giving a lecture on the subject at HMNS on Tuesday, March 24. This event is part of the Museum’s ongoing celebration of Darwin2009.

My research focuses on a unique chimpanzee community. The Fongoli chimpanzees live in southeastern Senegal where the climate is very hot, dry and open for this species. Temperatures during the 7 month dry season can reach over 115 degrees Fahrenheit in the shade, and rainfall is less than 35 inches per year. Chimpanzees here live in a habitat that is almost devoid of forest. Over 95% of their extensive home range (from two to nine times larger than the ranges of chimpanzees studied elsewhere!) consists of grassland or woodland, with tiny patches of forest making up the rest.

Grey day over the savannah
Creative Commons License photo credit: Julien Harneis

Other attempts at habituating savanna chimpanzees to the presence of human observers have not succeeded.  I believe that I was successful at Fongoli, in part, because chimpanzees don’t view most humans as predators.  Although they avoid humans – to this day, except for us – they do not react to them as if they are predators. 

People in Senegal do not eat chimpanzees as they do in many countries of Africa but consider them to be close relatives.  They include chimpanzees in their folktales and myths.  Even so, it took us four times longer (four years!) to habituate the Fongoli chimpanzees as researchers studying chimpanzees in more forested areas.

Creative Commons License photo credit: doug88888

The extreme environment at Fongoli is the reason I chose to work here.  This environment is similar, in many ways, to the mosaic of habitats that we associate with the earliest members of our own lineage – the bipedal apes that lived over 5 million years ago.  Hunting with tools, using caves, living with fire, soaking in water pools, and living in a more cohesive community are all behaviors that are fairly unique to the Fongoli chimpanzee community when compared to studies of this species elsewhere.  Each of these behaviors can be tied into the savanna environment in which they live. 

Understanding the behavior of our closest living relatives in this type of environment can help provide insight into how apes respond to the pressures associated with a mosaic habitat, something we knew little about until our study of the Fongoli chimpanzees.

For more information on Jill Pruetz and her work with chimpanzees check out her blog at http://www.savannachimp.blogspot.com and http://www.savannachimp.com

For more information on her lecture here on Tuesday, March 24, click here. This is just one of the many distinguished lectures available at HMNS.