Spring 2001 -- Vol. 18, No. 1

FACES OF PENN STATE

Andy Clark
Professor of Biology

Andy Clark studies population genetics, looking for patterns of variation among fruit flies. Thanks to technological advances and Internet access, the productivity of such research has grown immensely.

Some people hear the words "biological evolution" and think only about bones and the study of things that are no longer living.

For professor Andy Clark, the field positively surges with activity and electricity. He focuses on population genetics, looking at patterns of genetic variation among Drosophila, the common fruit fly, and humans to try to understand how the process of evolution works.

"It's easily the most exciting time of my career," Clark says. "It's a time when you almost have to put the brakes on to keep focused. Really, the only limit is the number of hours in a day. Everywhere you turn new problems can be addressed with greater power than ever before."

Years ago, the study of biological evolution was driven by mathematical theory. Ideas and relationships were proposed long before they could be demonstrated in a laboratory setting. With the ability to obtain protein data and the development of DNA sequencing, the field became much more data driven. Technological advances in recent years have provided even more tools--and Clark has made the most of those changes. A combination of laboratory and theoretical strengths make him somewhat of a rarity in the field.

"Both approaches provide productive ways to address questions," Clark says. "There's a lot of opportunity to come up with interesting questions to take into the lab by doing the theory first. It is also often that we observe something in a lab and only understand what it means after weeks of mathematical analysis."

Thanks to improved technology, progress sometimes comes quickly. For example, a postdoctoral student in Clark's laboratory, Bernardo Carvalho, used information about the genome of the fruit fly Drosophila melanogaster to identify several genes on the species' Y chromosome.

It turned out that much of the sequence was in the "trash bin" of the recently published genome sequence, but it was not recognized as a gene because it was in pieces. Carvalho and Clark learned the genes on the Y chromosome had grown huge by insertion of junk DNA, and the genes got big with a sequence that escaped previous analysis.

"In a couple of months, using just the tools that are available now, we solved a puzzle that had withstood 40 years of very, very hard work," Clark says. "It felt like cheating."

With ongoing excitement created by the Human Genome Project, the experience of Clark and others has become even more valuable to geneticists trying to understand the causes and risk factors for diseases like cancer and heart disease. While Clark cautions that the use of DNA to predict health might be "chancy," the potential of such efforts stirs his enthusiasm. "The challenge to understand how differences in genes produce variability in the performance of flies and people is a big one," Clark says. "But, the fusion of mathematics, computer science, and genetics as an attack on this problem will get me up in the mornings for a long time to come."

-- By Steve Sampsell

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