user-pic

Cinema Science: Resurrecting Beasts

In "Jurassic Park," we saw what might happen if some of the world's largest and smartest predators are brought back to life. The movie put the awe in audiences with its strikingly realistic dinosaurs. But how close are we to really being able to bring creatures back from the dead?

Not very. In the movie, geneticists extract dinosaur blood from mosquitoes preserved in fossilized amber, but it is extremely unlikely that DNA would be able to survive for 65 million years, even in the best conditions. If the scientists somehow found a large enough workable sample, they still wouldn't have a complete genome, as it deteriorates over time. They would also need a surrogate mom from a closely related species to provide an egg and carry the embryo. These are just a few of the major advancements which would be necessary to make dinosaur cloning a reality.




This video, from the Howard Hughes Medical Institute, shows the first step in the reproductive cloning process, known as somatic cell nuclear transfer. Cloning existing animals, especially mammals, is challenging enough for scientists. Clones often die soon after birth if they survive at all. And there are always concerns over maintaining a diverse gene pool.

Yet some scientists have already attempted to replicate animals in danger of extinction or which recently went extinct, all of them far less daunting than dinosaurs. Advanced Cell Technology cloned a gaur, a threatened species of Asian ox, in January of 2001. This was the first attempt to clone an endangered species. The gaur was carried to term in a cow, but died of a common infection two days after its birth. In late 2001, scientists in Italy reported the successful cloning of a baby mouflon, an endangered wild sheep, which lived out its adult life at a wildlife center in Sardinia. In 2003, scientists cloned a banteg, an endangered species of wild cattle.

Scientists planned to revive the Australian Tasmanian tiger, or thylacine, hunted to extinction in 1936, but the DNA samples from stuffed museum specimens were too badly degraded to create a viable embryo.

Advanced Cell Technology tried to bring back the bucardo, a recently extinct species of mountain goat, but the newborn died minutes after birth from respiratory failure. The team is currently reattempting the process.

The existing reproductive cloning technology has great limitations for bringing back long dead species. Besides the intact DNA, you also need another species closely related enough to provide the egg and womb for the clone. The surrogate would also need to have roughly the same gestation period as the extinct species. Russian scientists hope to retrieve usable DNA from the well-preserved, frozen mammoths they've found in Siberia, but most experts believe that an Asian elephant, the most likely surrogate, would not succeed in carrying the mammoth to term.

Then there's paleontologist Jack Horner, who dreams of creating a dino-chicken. Instead of cloning dinosaurs, he hopes that by tweaking the genes of birds, the closest living descendants of dinosaurs, we could eventually recreate dinosaurs, or least physically similar creatures. The process would involve pinpointing dinosaur traits, like tails, three-fingered hands, and teeth, in a developing chicken embryo and preventing them from transforming into bird parts by removing certain genes. While a dino-chicken would certainly turn some heads, it wouldn't be a true prehistoric dinosaur.

It looks like we'll have to rely on our imaginations--aided by Spielberg's and Crichton's--to bring back the once-dominant behemoths. For now, we can focus on those species we can actually salvage. There are a few leading endangered candidates: the giant panda, the cheetah, the Sumatran tiger and the gorilla are among them. Scientists are cryogenically preserving tissue samples from many endangered species to clone once the technology has improved. If enough different samples are gathered, the genetic diversity of the species could be maintained through cloning.

Someday, we may experience a prehistoric revival, but dinosaurs would be an unlikely contender because of their age. At least for now, we'll stick with what we know will work: creatures that actually have a chance at survival in our current environment.

Samantha Johnston is currently studying broadcast and print journalism at UCLA Extension. She has traveled through Greece, Ecuador and Peru studying anthropology and archaeology, and earned her BA from the University of California, Santa Barbara, in 2007. On clear, moonless nights, you'll find her stargazing on Southern California's Mount Pinos.

User Comments:

Samantha,

I really enjoyed your article, which does a great job of clarifying what science is and is not capable of doing with cloning of prehistoric and today's animals. Could they clone Neanderthals I wonder?
Mike

blog comments powered by Disqus