What’s more fun than a barrel of monkeys? Hanging out in a field of monkeys, especially the gelada monkeys of Ethiopia. Biologist Jacinta Beehner received two grants from National Geographic to study the introduction of new males on gelada females and how geladas assess potential rivals and mates.
What project are you working on now?
This is an exciting time for our long-term project. The infant geladas that were born during the first year of our project (2006) are now reaching maturity and having infants of their own. Perhaps the most valuable resource for long-term projects on natural populations is known birthdates for individual animals, as these allow researchers to accurately calculate ages for important maturational milestones. For example, in our most recent research, we are examining the factors that accelerate or delay maturation in young female geladas. For many female primates, the time to maturation is affected by dominance rank and access to adequate nutrition. However, we have evidence that the arrival of a strange male can actually accelerate maturation in young gelada females—a bizarre phenomenon that we are, at present, calling a Vandenbergh effect. In 1967, John Vandenbergh conducted a remarkable experiment where he demonstrated that juvenile female mice dramatically accelerated their time to maturation when they were housed with an unrelated adult male compared to being housed with just their fathers. This “Vandenbergh effect” has even been implicated in recent controversial accounts that try to explain precocial puberty in young girls growing up in “broken” homes. In our wild geladas, we are trying to understand whether females are accelerating maturation when strange males arrive in the group, or whether they are delaying maturation when they are in units with only their fathers.
What are your favorite and least favorite things about geladas?
Hands down, my favorite thing about geladas is a vocalization I’ve only heard uttered by young adult females that I call the “yep” call. They use it when they sidle up to the dominant male and start grooming him. It’s a variation on a typical monkey grunt, but it sounds more like “yep.” Females will do it three times in a row, “Yep, yep, yep,” almost as if to say “He’s mine!” They have such a self-satisfied look on their face when they use this call. It always gets a laugh out of me.
My least favorite thing is how difficult they are to tell apart. I studied baboons for nearly a decade before I started studying geladas and I never had any difficulty telling one individual baboon from another. I thought I had a talent at distinguishing individual monkeys from one another, but the geladas all looked identical to me until I really studied them for months on end. Also, there are so many of them that we have to tell apart. To look out on a field full of over a thousand grazing monkeys is an enchanting site, until you realize that you actually have to figure out exactly who those furry bodies are.
What is the biggest threat facing geladas today?
The biggest threat to geladas is humans. Ethiopia (a country the size of Texas) has a population of over 80 million people—and much of this population base is not located in the capital city, but in the countryside. The Simien Mountains National Park, at the highest altitudes in all of Africa, illustrates a perfect example of this population explosion. Not long ago, the barren fields above the treeline were considered inhospitable for farming, but now overcrowding in the lowlands has pushed people into the highlands. Farmers now eek out an existence on the sides of mountains (including within the park boundaries). This is prime gelada habitat and it is increasingly being encroached by human farms and livestock. In the long run, preserving this relatively small area for wildlife and subsequent tourism will reap benefits that far outweigh the economic value of the crops and livestock that utilize this area.
Have you ever gotten attached to a certain gelada in particular?
Yes, a male named Djibouti, who was the dominant male over a harem of five females. The females simply loved him and it was easy to see why. He had the confidence that any female would want from a leader male. On many occasions it seemed like his females picked fights with females in other harems just to watch him run to their defense. One of the reasons that I liked him (aside from his dashing looks) was that he was the most habituated gelada in the entire herd. I think he was born habituated to human observers. This is very nice for me, as a researcher, because his demeanor rubs off on all the animals around himthey relax because he is relaxed. This was especially important to me in my early months with the geladas because many of them were unaccustomed to having human observers nearby. The sketch below was drawn from a photo of me with Djibouti.
If you could trade places with one explorer at National Geographic, who would it be and why?
I always find that I’m attracted to environments that are at the polar opposite from the ones I’m currently working in. When I was working in the desert of the Rift Valley, I wanted to work in a tropical lagoon. When I was in the swamps of the Okavango Delta, I wanted to work in an alpine environment. Now that I am on the rooftop of Africa, I’m fascinated by and drawn towards underwater exploration. Assuming I actually knew how to scuba dive, I would trade places with National Geographic Explorer James Cameron, who made a record-breaking solo dive to the Earth’s deepest point!
What do you think National Geographic explorers will be exploring in a hundred years?
Assuming the costs become less prohibitive, I imagine they will be exploring outer space.
If you were to bring back one species of animal that has gone extinct, what would it be?
For purely academic purposes, I’d bring back Theropithecus oswaldi, an extinct relative of the species I currently study. I’d just love to see what a gorilla-size gelada looks like!
Have you ever been lost? How did you get found?
I get lost nearly every day driving around in the U.S. (my iPhone helps me to get “found”), but thankfully I’ve never been lost in the field. I think when you know there is no iPhone to rescue you, you pay more attention to location.
What are you reading?
Right now I’m reading Middlesex, a Pulitzer Prize-winning novel by Jeffrey Eugenides published in 2002. It’s a book about a hermaphrodite man of Greek descent with a condition known as 5-alpha-reductase deficiency, which causes men to be born with female genitalia but at puberty develop fully male features. The book is particularly interesting because I teach an upper level course on hormones and behavior to undergraduates at the University of Michigan, and this puts a romantic and quirky spin on an otherwise very academic problem. Furthermore, most of the story is set in Detroit, Michigan (I live in Ann Arbor), so many of the locations are familiar.
What is your favorite National Geographic photo?
Hands down, it’s the winner of the Photo of the Day for December 8, 2011—an introspective view into the eyes of an adult male gelada taken by our very own Clay Wilton, who worked for our project in 2010.
What is your favorite National Geographic magazine or news article?
Probably in line with my fascination with the exploration of James Cameron, I was just mesmerized by the April 2012 article on the sinking of the Titanic. My son had the fold-out picture of the boat open on our living room floor for days.