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Michael Beechert’s Guide to the Stars: Biology Professor Kevin Peterson

Dartmouth has a wealth of experienced professors who lead their respective research fields, while also working closely with students — inspiring them in the classroom and leading them in laboratory environments. And while at Dartblog we talk frequently about problems that need to be fixed at the College, there are still many bright spots. Our professors deserve more recognition for their achievements. As such, this is one of a series of posts that shines a spotlight on the best professors in Hanover:

Kevin Peterson1.jpegKevin Peterson is a Professor of Biological Sciences as well as an Adjunct Professor of Earth Sciences. Trained as a paleontologist, he focuses his energies at the intersection of geology and genetics in order to explore comprehensive explanations of the origins and development of animal life on Earth. By looking at the entire picture painted by both the fossil record and genomes, Peterson has been able to provide the scientific community with important insights as to how and why organisms got to where they are today.

Born and raised in rural western Montana, Peterson started a fossil collection at the age of four. His path towards paleontology was not a straight one, however, as his undergraduate studies at Carroll College (Helena, MT), from which he graduated maxima cum laude in 1989, were on the pre-med track. After realizing that medical school wasn’t for him, Peterson did some soul-searching and decided to pursue the subject that had so fascinated him as a young child. He went to UCLA, where he completed his Ph.D. in Geology in 1996, and he became interested in how paleontological questions could be addressed on a molecular level. After a post-doctoral stint at the California Institute of Technology, a job advertisement brought Peterson to Dartmouth for the first time in 2000, where he fell in love with the Upper Valley, and where he has made his home ever since.

The work performed in Peterson’s laboratory revolves around an event known as the “Cambrian explosion,” which began around 540 million years ago. At that point in time, most animal phyla — the taxonomic rank directly below kingdom — began to be indicated in the fossil record. Prior to the Cambrian explosion, animal fossils are very rare and restricted to rocks just slightly older than the Cambrian, but within a few million years after the start of the Cambrian, animal fossils become widespread and diverse across the globe. In other words, fossils from virtually every group of skeletonized animals are commonly found in Cambrian-aged rocks.

This sudden appearance of animals, however, has long posed a challenge to the model of natural selection as first proposed by Charles Darwin: Iif evolution really took place when competing animals slowly scrapped it out for superiority, eliminating rivals in the process, why would animal life as we know it show up more or less all at once at the base of the Cambrian?

In order to shine light on these mysteries, Peterson has dived into the genomes of various organisms and mapped out how they are related on a molecular level. His voluminous research (h-index of 51 and 9922 citations) is in large part based on the idea that the key to unpacking what happened during Cambrian explosion lies in understanding both records of the history of life: the geologic and the genetic. Using “molecular clocks,” a technique that estimates when evolutionary lineages like animal phyla diverged from one another using differences in genetic sequences, Peterson’s group showed that animals do, in fact, have a deep but unrecorded Precambrian history — all of the major animal lineages were in fact present in the Precambrian, just as Darwin predicted. For reasons that are not well understood, however, they do not make their appearances in the rock record for tens, and in some cases hundreds, of millions of years later.

Peterson currently dedicates much of his time to the role that microRNAs may have in differentiating, say, humans from sponges. As Peterson’s research has shown, a surprisingly high proportion of the genetic material of complex animals is shared with simpler organisms. But microRNAs, a type of RNA molecule classified as non-coding (it doesn’t direct protein production), are to be found in the genetic code of people where they’re missing in that of sponges. Peterson has hypothesized that, because microRNAs accumulate over time in complex organisms, they can be used to peer through some of the dust unleashed by the chaos of the Cambrian explosion, when life as we know it began to assume wildly different forms.

Peterson has had plenty to do in the classroom this year as well. In the fall, he was responsible for a section of the Biology Department’s introductory course, “The Science of Life,” that was titled “Major Events in the History of Life and the Human Genome.” Currently, he is teaching a class called “Macroevolution,” and in the spring he will be offering a course called “RNA: The Real Secret of Life.”

Addendum: Here, you can listen to Professor Peterson discuss, among other things, the usefulness of microRNA in determining to whom turtles are related:

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