At the time, researchers were learning how to reconstruct the genomes of extinct species based on fragments of DNA retrieved from fossils. It became possible to pinpoint the genetic differences that set ancient species apart from their modern cousins, and to begin to figure out how those differences in DNA produced differences in their bodies.
Dr. Church, who is best known for inventing ways of reading and editing DNA, wondered if he could effectively revive an extinct species by rewriting the genes of a living relative. Because Asian elephants and mammoths share a common ancestor that lived about six million years ago, Dr. Church thought it might be possible to modify the genome of an elephant to produce something that would look and act like a mammoth.
Beyond scientific curiosity, he argued, revived woolly mammoths could help the environment. Today, the tundra of Siberia and North America where the animals once grazed is rapidly warming and releasing carbon dioxide. “Mammoths are hypothetically a solution to this,” Dr. Church argued in his talk.
Today the tundra is dominated by moss. But when woolly mammoths were around, it was largely grassland. Some researchers have argued that woolly mammoths were ecosystem engineers, maintaining the grasslands by breaking up moss, knocking down trees and providing fertilizer with their droppings.
Russian ecologists have imported bison and other living species to a preserve in Siberia they’ve dubbed Pleistocene Park, in the hopes of turning the tundra back to grassland. Dr. Church argued that resurrected woolly mammoths would be able to do this more efficiently. The restored grassland would keep the soil from melting and eroding, he argued, and might even lock away heat-trapping carbon dioxide.
Dr. Church’s proposal attracted a lot of attention from the press but little funding beyond $100,000 from PayPal co-founder Peter Thiel. Dr. Church’s lab piggybacked mammoth research on to other, better-funded experiments. “This set of tools can be used for many purposes, whether it’s de-extinction or recoding the human genome,” Dr. Hysolli said.
Analyzing the genomes of woolly mammoths collected from fossils, Dr. Hysolli and her colleagues drew up a list of the most important differences between the animals and elephants. They zeroed in on 60 genes that their experiments suggest are important to the distinctive traits of mammoths, such as hair, fat and the woolly mammoth’s distinctively high-domed skull.