The Purpose of Snake Venom1:302073546779001
Finding Unique Species in São Tomé and Príncipe2073537828001
Adventure in Kenya2:082073541081001
Bob Drewes Slideshow10 Photos
Dr. Robert Drewes has an abiding fascination with the continent of Africa, having conducted field research in 30 different African countries since 1969. His interests include the comparative physiology of frogs and he serves on the board of the Kenya Wildlife Service.
Bob Drewes is living proof that it is possible to have a career doing what you love most since the age of five. Drewes was born and raised about a mile from Steinhart Aquarium in Golden Gate Park. Throughout his childhood, his home was filled with things he had found under rocks or picked up at the beach. “I have always been deeply fascinated by weird stuff,” Drewes says.
He remembers the one Academy exhibit that first fired his imagination as a very small youngster: “Strangely, it was the rotating tray of rocks that would appear normal under incandescent light and then glow brightly as they rotated under fluorescent light,” Drewes says. “As a toddler, I always gravitated to it.” But upon reflection, Drewes says, what really changed his life was African Hall. “I fell in love with Africa in part because of the beauty of that hall and in part because of the influence of my great-uncle, Norman B. Livermore, under whose guidance it was built.” Livermore was the Academy's Chairman of the Board of Trustees during the Depression and war years.
“Like many of my schoolmates from our part of the city, I was raised to be either a doctor, lawyer, or businessman,” Drewes says. It was a prospect that made him deeply unhappy. In pursuing the expected career path, he did very poorly in his early undergraduate period. Finally, he left school and served a tour of duty with the army Special Forces, an experience he found maturing.
Upon his return, Drewes married Gail, his childhood love, and returned to school. “At this point, I was studying psychology, a field I found intuitive and really easy. At the same time, our little apartment on Potrero Hill was full of critters—some reptiles, two monkeys, and a coatimundi. One night as Gail fed our marmoset, she asked me, 'Bob, why on earth are you studying psychology?' From that moment on, I never looked back.”
Drewes completed his undergraduate degree at San Francisco State and his Ph.D. in Biology at UCLA, focusing on the evolutionary relationships of the dominant treefrog family of Africa, Madagascar, and the Seychelles Islands. His graduate career at UCLA also instilled an ongoing fascination with environmental physiology (the study of how individual organisms physically interact with the environment).
Bob's ongoing research on the systematics, natural history, and behavior of African reptiles and amphibians began with a year-long trip to East Africa in 1969, undertaken with his wife Gail and their then nine-month old son, Bart. Gail says, “We got off the plane and I was in Africa. Bob was home.” Drewes has returned to Africa at least once a year since then.
His long association with the Academy has created “a perfect base for someone like me,” says Drewes. “I have the freedom to work in remote, poorly-known wild regions of Africa and at the same time to ask and answer fundamental scientific questions. And we have a collection of nearly 300,000 reptiles and amphibians from all over the world. If I'm doing an anatomical or morphological study, I can just grab specimens of related species off the shelf for comparison.”
He adds, “Imagine getting a job doing what you love more than anything else within the most venerable scientific institution in your own city. How can I describe that? I've had 38 years of adventures in the African bush observing and catching weird critters. And I've also experienced the unbelievable thrill of academic discovery. It's been a hell of a ride.”
Frog populations are vanishing before our eyes. From South America to Egypt, from sites high in the Sierras to pristine rainforests in Eastern Australia, frog populations are in sudden, dramatic decline. “That's a scary proposition,” says Robert Drewes, curator at the Academy's Department of Herpetology. “Frogs serve as a model for environmental health. They lay their eggs in water and their gilled larvae (which we call tadpoles) spend considerable amount of time in the aquatic environment. If there's something wrong with the water, there's probably going to be an impact on the development of frogs. Later after metamorphosis, they become land-dwelling, air-breathing adults that have moist, permeable skins. Thus if there is something wrong with the terrestrial environment, adult frogs will be among the first terrestrial vertebrates affected.”
Frogs are an indicator species, the world's early warning system. They are considered a “keystone” organism, a central part of an ecosystem, which once removed can lead to the collapse of an entire ecosystem and the food chain that depends on it.
Systematists like Drewes are on the front lines of the research surrounding the worldwide population decline of frogs. “We provide the data,” he says, “that are vital to all other fields of biological endeavor. Our job is to determine what's there, to whom it is related, and how it got there. Armed with these data, the world at large can make informed environmental decisions. The least we can do is let them know what they stand to lose.”
According to Drewes, there are a variety of possible reasons for the decline in frog populations,. They range from increased ultraviolet B radiation due to a decreased ozone layer, acid rain, pH shifts in water, heavy metals that are leaching into the water, as well as widespread habitat degradation. Then there is the onslaught of chytridiomycosis, a fungal infection that has wiped out entire species in a single month. It appears to be one of the dominant influences on the disappearance of frogs in Central America.
When the public asks about the causes behind the frogs' disappearance, Drewes has a ready answer. “Look in the mirror,” he says.
São Tomé and Príncipe, two islands forming a single nation off the western equatorial coast of Africa, may be the last undisturbed paradise on earth. More than 17 and 31 million years old respectively, the sparsely inhabited islands are home to hundreds of species of flora and fauna found nowhere else on earth.
That's exactly why Dr. Robert Drewes, curator of herpetology at the Academy has led two multidisciplinary Academy expeditions there in past years and plans to return in mid-2008. Island biogeography presents a unique opportunity to witness evolutionary processes in microcosm. São Tomé and Príncipe, small and isolated as they are, represent a relatively simple way to uncover evolutionary relationships at work.
The islands are noteworthy for their geological age, and more importantly, for the fact that they've never been attached to the African mainland. Anything that's arrived there—plants, insects, and animals—had to cross significant ocean barriers. Drewes and his team are trying to find out how these colonizations occurred.
Drewes says, “The islands are noteworthy for their high endemicity—that is, the number of species that exist on the islands and nowhere else in the world. Half of all the birds on São Tomé and Príncipe are found nowhere else.” There are some perplexing relationships on the island, as well. “The amphibian fauna we find here is more closely related to East African species on the other side of the continent than to species of the West African coast a few hundred kilometers away.” This is a problem that Drewes and his colleagues are currently exploring.
To investigate further, Drewes and another Academy team will return for a third expedition soon. “I invite scientists and grad students who represent fields that are poorly known on these islands.” He finds the multidisciplinary approach stimulating and productive, “similar to the way field work was accomplished in the old days—like the Galapagos Islands Expedition of 1905-1906. We are all looking at different organisms but asking the same evolutionary questions.”
The next team of scientists will be looking at mushrooms, insects, and various marine groups and will include at least three graduate students. Drewes is particularly thrilled as the expedition has been funded through the generosity of several local Academy members.
The undisturbed biodiversity on the islands is about to change—and change fast—thanks to the discovery of oil offshore. The huge influx of oil money, along with the infrastructure of oil exploration and drilling rigs, will change the islands forever. “That's why,” Drewes believes, “it makes it all the more important to document, describe, and inform the people who live there as quickly as we can. We have to tell them what they've got, and what's unique about their islands so they can make informed decisions.”
Have a Question?
Q: How does snake venom work?
A: Snake venom is purely a food-getting mechanism. It is not a defense. It is a way of immobilizing prey. In the case of vipers and their relatives, the venom pre-digests the usually large-bodied prey from the inside. In the case of cobras, the venom is a paralytic.
More about Dr. Drewes
Current Expedition: Gulf of Guinea Islands: São Tomé and Príncipe
Fascinating Frogs »
Herpetologist Bob Drewes explains how their aquatic youth and terrestrial adulthood give frogs the distinction of being an indicator species.
Frog Sounds »
Knowing frog sounds is the key to identifying the different species of frogs, observes herpetologist Bob Drewes.
Selected Articles and Publications: