Image: Carlo Giambarresi
The goal of reanimation research is not to make perfect living copies of extinct organisms, nor is it meant to be a one-off stunt in a laboratory or zoo. Reanimation is about leveraging the best of ancient and synthetic DNA. The goal is to adapt existing ecosystems to radical modern environmental changes, such as global warming, and possibly reverse those changes.
Ecosystems that depend on “keystone species” have lost the species diversity they once had because some species no longer fit. As environmental change occurs, ancient diversity may be needed again. For instance, 4,000 years ago the tundras of Russia and Canada consisted of a richer grass- and ice-based ecosystem. Today they are melting, and if that process continues, they could release more greenhouse gas than all the world's forests would if they burned to the ground. A few dozen changes to the genome of a modern elephant—to give it subcutaneous fat, woolly hair and sebaceous glands—might suffice to create a variation that is functionally similar to the mammoth. Returning this keystone species to the tundras could stave off some effects of warming.
Mammoths could keep the region colder by: (a) eating dead grass, thus enabling the sun to reach spring grass, whose deep roots prevent erosion; (b) increasing reflected light by felling trees, which absorb sunlight; and (c) punching through insulating snow so that freezing air penetrates the soil. Poachers seem far less likely to target Arctic mammoths than African elephants.
“De-extinction” is not a novel idea. Medical researchers have resurrected the full genomes of the human endogenous retrovirus HERV-K and the 1918 influenza virus. Insight into these reanimated species could save millions of lives. Several other extinct genes, including for mammoth hemoglobin, have been reconstructed and tested for novel properties. Moving from these few genes to most of the 20,000 or so in a bird or mammalian genome may not be necessary, and even if it is, it may not be hard to do. The costs for a variety of relevant technologies are low—and dropping.
Breeding animals and raising them until there are sufficient numbers to release into the wild is an ambitious undertaking, but the expense should be comparable to breeding livestock or preserving other endangered wildlife. These costs could be reduced if we used genetic means to improve the species we revive—boosting their immunity and fertility and their ability to draw nutrition from available food and to cope with environmental stress.
Aside from bringing back extinct species, reanimation could help living ones by restoring lost genetic diversity. The Tasmanian devil (aka Sarcophilus harrisii) is so inbred at this point that most species members can exchange tumor cells without rejection. A rare transmissible cancer spread via facial wounds is driving the species toward extinction. Reanimating ancestral, diverse Sarcophilus histocompatibility genes, which govern tissue rejection, could save it. Similar arguments could be made for amphibians, cheetahs, corals and other groups. Ancient genes could make them more tolerant of chemicals, heat, infection and drought.
Reanimation is not a panacea for ecosystems at risk. Preventing ongoing extinction of elephants, rhinoceroses and other threatened species is critically important. By all means, we must set priorities for allocating finite conservation resources. But it is a mistake to look at this issue as a zero-sum game. Just as a new vaccine can free up medical resources that would otherwise be spent on sick patients, reanimation may be able to help conservationists by giving them powerful new tools. That this is even a possibility is reason enough to explore it seriously.
http://www.scientificamerican.com/article.cfm?id=george-church-de-extinction-is-a-good-idea&WT.mc_id=SA_Facebook
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