Dinosaurs occupy a special place in the mind of every kid who grew up in the 1990s. Jurassic Park brought them back from the dead. Michael Crichton, who wrote the original novel, is often praised for making this process believable. Until recently, most people, including scientists, would have stated that cloning an ancient life form from preserved tissue would be theoretically possible, albeit in the realm of science fiction. We may have even expected it until MortenAllentoft of the University of Cambridge noted that DNA has a half-life of about 500 years; as a result, DNA from 68 million years ago when dinosaurs walked the Earth is long gone. But there is hope for other animals.
An emerging "revivalist" scientific movement has focused its attention toward bringing back newly extinct species. The diverse group of molecular biologists, geneticists and conservation biologists was brought together by National Geographic this past March and reached the conclusion that the necessary tools are available.
One species that is being actively studied with this goal is the North American passenger pigeon. These birds were the cheapest source of protein in the USA at the start of the 20th century. By 1914, overhunting had driven their huge population into extinction. (The buffalo escaped this fate largely because of the shock caused by the disappearance of this once-abundant bird.) Their remains can be seen in museums around the world, and scientists have used them to sequence the genome with the intent of rebuilding it. Once the life code of the organism is reconstructed, it can replace the DNA in another pigeon egg, which will then hatch as a passenger pigeon.
Although the revival of a passenger pigeon is probably a few years away, "de-extinction" has already been performed. In 2000, the Pyrenean Ibex became extinct when the last survivor of the species was crushed by a fallen tree. The species was cloned in 2009, almost a decade after the death of the last specimen. Although the clone did not survive longer than ten minutes, it was a milestone for the field. Further technologies would allow the recreation of species such as the wooly mammoth, the thylacine (Tasmanian wolf), dodos and others. It won't allow us to build a Jurassic Park, but it could be used to prevent the extinction of various rhino species, which still exist but do not have the ability to mate.
Just like most scientific advancements that tinker with life, these ideas have not come without controversy. Proponents claim that the revival of extinct species would preserve the biodiversity of ecosystems. There is supporting evidence for this, since the disappearance of the wooly mammoth resulted in the transformation of the tundra into forests. Furthermore, supporters push the idea that de-extincting one species will allow for the future conservation of others.
These are valid points; however, opponents have pointed out that de-extinction takes an approach that only focuses on superstar animals like the awe-inspiring mammoth while neglecting the smaller, less-exciting plants and animals which co-habited their ecosystems. Since these life forms do not currently exist anywhere on Earth, releasing them would be akin to releasing an invasive species. Ultimately, however, they argue that being able to bring back animals from the dead in the future will put governments on the slippery slope of allowing the destruction of the extant specimens and their habitats today.
In this author's opinion, it would be neat to see the vast majority of extinct species in zoos. Mammoths, giant ostrich-like moa and Steller's sea cows must have been a sight to behold, before our ancestors summarily wiped them out. The ability to right the past's wrongs, however, should not be a carte blanche to destroy today's ecosystems.
Petar Todorov is a senior majoring in chemistry. He can be reached at Petar.Todorov@tufts.edu.
