Mammoth skeleton : Wiki Commons
Although humans and woolly mammoths co-existed for millennia, the shaggy giants disappeared from the globe between 4,000 and 10,000 years ago, and scientists couldn’t explain until recently exactly how the Flintstonian behemoths went extinct.
“We were interested to know what happened to this species during the climate warming at the end of the last ice age because we were looking for insights into what might happen today due to human-induced climate change,” said Glen MacDonald, director of UCLA’s Institute of the Environment and Sustainability (IoES). “The answer to why woolly mammoths died off sounds a lot like what we expect with future climate warming.”
“It’s not just the climate change that killed them off,” MacDonald said. “It’s the habitat change and human pressure. Hunting expanded at the same time that the habitat became less amenable.”
She and Wayne, a UCLA molecular geneticist and professor of ecology and evolutionary biology who studies ancient DNA, used different methods of examining the mammoth fossils to reconstruct the ancient population size.
“It’s a dramatic advance in the amount of data,” said Wayne, who reconstructed mitochondrial DNA from radiocarbon-dated woolly mammoth remains. “Essentially, larger populations should have greater genetic diversity. However, in this case, the extent of fossil remains provided a more high-resolution picture of how the population size changed through time than genetic diversity.”
Mapping the size and location of both mammoth and human populations alongside temperature changes and plant locations through time gave the researches a uniquely complete view of what happened, MacDonald said.
“We are, in a sense, time-traveling with our maps to look at the mammoths,” he said.
It’s something MacDonald has dreamed of for a long time, he said. He was working in Siberia several years ago when a colleague found a woolly mammoth tooth.
“We looked at it and held it, and just the thought that those immense creatures had been there not that long ago in geologic time and yet completely disappeared was really amazing,” MacDonald said. “How warming in the past has been involved in extinction might help us prevent extinctions in the future.”