Real-life Jurassic Park

If a group of researchers has its way, this ice-age mascot 8212; and a host of other bygone mega-fauna 8212; may walk again. Last month, writing in the journal Science, zoologist Alexei Tikhonov of the Russian Academy of Sciences and Ross MacPhee of the American Museum of Natural History announced they had decoded 13 million base pairs of DNA extracted from the jawbone of a frozen mammoth that died 28,000 years ago on the Siberian steppe. They, in other words, had assembled half the genome, and claim they could finish the job in three years.

That would put scientists within striking distance of an even greater feat: repopulating earth with creatures that vanished ages ago. Genetic wizards have already cloned sheep, monkeys, pigs and cats. But resurrecting millennial beasts like the mammoth or giant armadillo is far trickier. Although many experts scoff at 8220;restarting evolution8221; through cloning extinct animals, it has sparked excitement in biotech labs.

8220;This is the greatest symbol of the Pleistocene era,8221; says Larry Agenbroad, a woolly mammoth expert at the University of Northern Arizona. The mammoth is part of a grand new strategy to restore long-gone megafauna. Scientists call it rewilding.

Some scientists estimate that the early hunters of the Pleistocene killed mammoths and scores of other giant mammals in the Americas in roughly 20 generations 8212; a tick on the evolutionary clock. 8220;When our species goes into a Garden of Eden, things change,8221; says veteran paleoecologist Paul S Martin, who pioneered the idea of hunter 8220;overkill8221; four decades ago. The strategy calls for repopulating earth with bygone or endangered species as the best way to repair an environment that is out of kilter, and to prevent even more animals from dying out. Proponents hope genetic engineering could allow their dream to come true. One team is trying to bring back the bucardo, a Spanish goat that disappeared five years ago; an Australian team is studying a way to clone the extinct Tasmanian tiger.

In Ireland, where some 9,000 bird species have been lost, scientists are considering reintroducing flightless rails, which are heading for extinction. Perhaps the most ambitious effort is on in Siberia, where scientists led by Sergey Zimov are trying to transform a vast swath 16,000 sq km of chilly marshlands in Yukutia region into the grasslands and dry forests that flourished during the last ice age. They plan to let loose long-absent musk oxen, aurochs, elk, wolves and one day maybe even the mammoth. Zimov calls this the Pleistocene Park.

Bringing back ghosts of the Pleistocene would be rewilding8217;s biggest prize but also its biggest challenge. Since DNA falls apart over time, even in the deep freeze of Russia8217;s permafrost, some scientists despair of ever finding enough unbroken mammoth cells to produce a clone. Sperm cells are hardier, and if mammoth semen could be retrieved from the tundra, it could be used to impregnate elephants the offspring would be half-breeds.

With the mammoth genome at hand, geneticists now speak of creating a transgenic mammoth by removing the nucleus of an egg from, say, an elephant and replacing it with mammoth DNA. Herds of skeptics abound. Would resurrected species trample the suburbs? Rewilding experts say animals would be contained in national parks. Would they bring new viruses? The risk is small but can8217;t be discounted.

In the end, there may be little choice. By failing to intervene, scientists say, we could be unwittingly giving a hand to evolution8217;s hardiest predators: weeds and pests. 8220;Nowhere is pristine anymore,8221; says Cornell University ecologist Joshua Donlan, one of rewilding8217;s leading architects. 8220;In future, almost every ecosystem is going to be managed. Either we do it by design or default.8221;

Newsweek