The Penn Stater Magazine

Beth Shapiro: Why Megafauna Went Extinct

April 22, 2011 at 3:15 pm Lori Shontz 2 comments

Let’s get this out of the way first. Woolly mammoths are not going to roam the earth again, said Beth Shapiro, Penn State assistant biology professor and recipient of a 2009 MacArthur Fellowship, despite the fact that researchers have isolated the DNA of the extinct animals.

That’s because even if we could recreate the animals, we couldn’t recreate their environment. Mammoths need the extremely cold temperatures and abundant grasslands of the steppe tundra, she said, “which doesn’t exist today.”

I can hear my husband now: “Bummer.”

But there are still plenty of fascinating ideas in Shapiro’s research into ancient DNA, which she discussed earlier this week in a talk at the always entertaining and informative Research Unplugged program.

Shapiro’s research is centered in Beringia, the land mass between Russia and Alaska. (Or, as she put it: “the part of the world Sarah Palin can see from her backyard.”) By studying the DNA extracted from the bones of herbivores such as musk ox, mammoth, horses, and bison, she is gaining insight into how evolution happens.

In a talk titled “Where Have All the Dodos Gone? The Role of Climate and Humans in Mass Extinctions,” she explained how it’s impossible to pin the blame for the extinction of megafauna on the Ice Age or on the appearance of humans.

The Last Glacial Maximum—the farthest extent of the ice sheets in the Ice Age—has been cited as the cause of some extinctions. But Shapiro said it’s not that simple—some of the animals actually liked the cold, as hard as that may be for those of us lamenting this chilly April weather to believe. “We assume that these guys like it warm,” she said. “They don’t like it when it’s warm. They liked it in the Ice Age.”

But that said, the animals didn’t go extinct when the climate warmed up. Rather, they spread out and adapted—in smaller numbers—to the change. When the climate became more to their liking, their population became less fragmented and larger.

Shapiro showed us graphs that plotted the populations of various megafauna over thousands of years, and it’s clear that there were increases and decreases. But one variable did change with extinction: the arrival of humans. We didn’t cause the extinction, per se, but we made it impossible for the animals to cope in their usual way.

“This time, someone was there,” she said. “All of the sudden, they couldn’t get to the good places that had the grassland. There are people in the way. What we are, really, is the proverbial straw that breaks the camel’s back.”

For more about Shapiro and her research, check out this interesting profile from Research Penn State.

Lori Shontz, senior editor

Entry filed under: Campus events, Eberly College of Science. Tags: Beth Shapiro, MacArthur Fellowship, Research Unplugged, woolly mammoth.