For mentors like Duke assistant professor Brian Hare, a visit to graduate students working in a tropical jungle involves more than going over the science.
“It’s sort of a morale booster because field work like theirs is tough," he says. "They’re working in places with no air conditioning in the most hot and humid conditions. And it’s exhausting.”
"I need to remind them to drink lots of clean water, take their malaria prophylaxes and wear a lot of sun screen."
But when they aren't working on their own survival skills, the students gather important data to contrast and compare the thinking style of our two closest ape relatives.
Duke graduate students Evan MacLean and Alexandra Rosati are working this summer with Harvard-based graduate student Victoria Wobber at two reserves in Africa to evaluate tantalizing questions about bonobos and their alter ego lookalike species, chimpanzees.
Wobber previously built evidence that male bonobo toddlers produce the highest levels of sexual hormones in their lives during infancy. She collected hormone samples by enticing the infants to drool saliva as they sucked on a sweet.
This summer, Wobber will administer a battery of mental development tests on 2- to 5-year-old infants of both species. Evaluations will range from tool use and counting ability to social learning skills.
Meanwhile, Rosati will be assessing how each species handles the primate equivalent of “economic decision-making” -- in this case involving food. She and her colleagues have already learned that chimps are gamblers who are willing to risk losing food for the possibility of getting more. But bonobos "prefer the safe option," Hare says. They're more comfortable with a smaller but unchanging ration.
Now Rosati will use Wobber's saliva sampling technique to monitor sex hormones of both species to see if the levels may be tied to their differing food risk strategies.
One of MacLean's summertime projects will evaluate whether young bonobos and chimps learn tasks more quickly – like human children do – when the subject is presented with a happy face. In the process, MacLean will make ape-like vocalizations "equivalent to 'I'm really happy,'" Hare says.