Primatologists in Boston adopt the latest high-tech tools to answer age-old questions about evolution.
Constanza Villalba
Tickets to Jane Goodall’s talk at Harvard this weekend sold out almost as soon as they went on sale. More than a thousand people will pack Sanders Theater to hear the famed wildlife conservation champion speak about her 35 years studying chimpanzee behavior in the jungles of Tanzania.
A look at what Boston primatologists are doing today reveals just how much their field has changed since Goodall’s heyday. Researchers don’t just observe their subjects with the naked eye, as Goodall so often did. They rely on a wide range of technologies, from video cameras suspended high in the air to the latest tools of molecular biology, to learn more about animal locomotion, reproductive ecology, and sexual selection.
“What I’ve tried to do is look at the physiology [of wild orangutans] and get more-detailed data by bringing more-advanced techniques into the field,” says Harvard anthropologist Cheryl Knott. One way Knott delves into the physiology of these Indonesian apes is by analyzing urine samples. Orangutans are highly endangered and bear young only every eight or nine years–the longest interval between births of any mammal. Knott has found that females become reproductive only when they are gaining weight.
An orangutan in Indonesia (Credit: Tim Laman)
To identify which females are ovulating or pregnant, Knott uses human home pregnancy and ovulation tests on urine samples. To gauge the metabolic status of the animals, she uses kits originally developed for diabetics; these kits tell her whether an orangutan is metabolizing fat by measuring urinary ketones, by-products of fat metabolism.
Other modern technologies are contributing to Knott’s research. Over the years, she and her colleagues have plotted the ranges of orangutan populations on almost 5,000 maps. Knott has digitized that information and imported it into a geographic information system (GIS) database that essentially allows her to assign satellite-based Global Positioning System (GPS) coordinates to orangutan movements.
Knott suspects that this new approach may reveal social interactions between orangutans that have thus far gone unnoticed. Orangutans are generally thought of as solitary primates. But researchers typically track them from the ground and may thus be unaware of other orangutans in nearby trees. Knott has a hunch that the animals sometimes shadow one another or maintain contact in other ways.
Climbing with monkeys
Halfway around the globe, in Ecuador, Boston University doctoral student Denise Guillot is using another type of imaging to study monkey locomotion. With a tree-climbing course under her belt, Guillot sets up video cameras on mobile platforms that she and her colleagues construct 65 feet off the ground in the rainforest canopy. She films spider, howler, and woolly monkeys and analyzes the footage to compare how the different species move through the forest.
The woolly monkey of Ecuador (Credit: Denise Guillot, BU)
Spider monkeys spend a lot of their time hanging from tree branches and swinging from limb to limb. Howler monkeys, on the other hand, spend more of their time on the tops of tree branches, on all fours. Woolly monkeys display both types of behavior.
The range of behaviors exhibited by three so closely related species allows Guillot to correlate the animals’ skeletal structures with their locomotor tendencies. She’s ultimately interested in how upright postures and arm-swinging evolved in apes, including humans.
Long-legged lemurs
Another Bostonian interested in primate movement is BU anthropologist Richard Lawler. Lawler spends a month each year in Madagascar, studying a species of lemur known as Verreaux’s sifaka. These lemurs have leg adaptations that allow them to leap from tree to tree. During mating season, males often chase after females, which raises the question, Are fleet-footed male lemurs more successful at mating than the slowpokes?
A Verreaux’s sifaka, a species of lemur in Madagascar (Credit: Richard Lawler, BU)
Indeed, using the same kind of DNA analysis used in paternity tests, Lawler has shown that the males with the strongest legs have the most offspring.
Such direct measures of evolutionary “fitness” became possible only around the mid-1990s, when polymerase chain reaction (PCR) machines, required for DNA analysis, became common. Lawler collects DNA from ear snippets gathered when lemurs are trapped and released, but other primatologists are analyzing DNA extracted from feces and hair left in abandoned nests.
Even with high-tech tools like GPS and PCR on hand, however, today’s primatologists say they still carry on Goodall’s legacy, observing animals in the wild and using the kind of data gathered only by the watchful eye.