Questions around raising the dead

De-extinction, an exciting field of science, is still in its infancy

December 31, 2017 12:02 am | Updated 12:02 am IST

There’s a chilling scene in the 2016 Disney masterpiece, “The Jungle Book”, where King Louie, a Gigantopithecus, extends his hand to catch Mowgli before he escapes and the whole temple crumbles in on the ape. Gigantopithecus, literally the “giant ape”, once roamed the plains of Asia, including India, and went extinct due to a lack of food and its giant size. Not much is known about it except that its closest living relatives are orangutans. Can science bring back Gigantopithecus to life? It may sound like science fiction but efforts on “de-extinction” or “bringing animals back from extinction” are well under way.

The science behind it

Intact cells and years of meticulous experiments helped resurrect the first extinct species, namely the Pyrenean ibex or the Spanish mountain goat (bucardo), in 2003. Scientists achieved this by successfully implanting cloned embryos of the Pyrenean ibex into living species of goats. From the many embryos that the scientists implanted, only one approached a near full-term pregnancy. Although the newborn died shortly after birth, an exciting era of bringing animals back from extinction was born. In order to revive extinct animals by somatic cell nuclear transfer (a process where the nucleus from a donor cell is fused with the enucleated egg cell of a recipient cell), scientists need living cells. Although bones and teeth of extinct animals like Gigantopithecus and Tyrannosaurus rex (T-rex) are found, there are no intact cells available from these animals. Even the DNA obtained from the bones and teeth of extinct animals are not intact and are found chopped into smaller pieces due to attrition by microorganisms, enzymes and harmful radiation. In the absence of intact cells, two methods show promise in de-extinction where the genomes of an extinct species and its closest living species are very similar. In the first, gaps in the genome of an extinct species can be filled by their closest living relative’s genome to make a blueprint of a species that closely resembles the extinct species.

In the second technique, portions of the genome of the closest living relative are exchanged with that from the extinct species. For example, if we want to resurrect Gigantopithecus, first its genome needs to be sequenced and compared to the orangutan’s genome to identify the sites where the two genomes differ. Subsequently, using genome-editing technology, the specific sites of the orangutan’s genome are exchanged with that from Gigantopithecus. Although this method is currently being tried to clone a mammoth using Asian elephant DNA, it has not been successful. Assuming that the genomes of Gigantopithecus and orangutan are very similar, making Gigantopithecus chromosomes from its DNA and implanting the viable embryos successful in surrogate orangutan females will take a long time.

The questions

Even if science brings back those magnificent creatures to life, there are many unanswered legal, societal and ethical questions related to de-extinction. Foremost among them are: what is the need to revive an extinct species? Can we create a favourable environment for the extinct animals to survive, and should the animals after their resurrection be released into a captive environment?

None of these challenges is as complicated as the one linked to the hypothetical case of bringing back Neanderthals, the closest of our relatives. Bringing Neanderthals to life will pose additional challenging questions like: should the society of modern humans allow Neanderthals to be captive in the zoos or should they be free in our habitat? As there is evidence that Neanderthals interbred with modern humans in the past, the most important question therefore is, should Neanderthals be allowed to interbreed with modern humans? Whatever the future holds, as Professor George Church of Harvard argues in the 2012 book, “Regenesis”, cloning Neanderthals may provide us with health benefits by understanding whether they are resistant to deadly infectious diseases and their de-extinction “might give us an inkling into another form of human intelligence or different ways of thinking”.

De-extinction is an exciting field of science but is still in its infancy. Let alone ethical and societal concerns, science needs to have advanced quite a bit before de-extinction of many species becomes a reality. As scientists make progress in their labs, it may take a while before you see a Gigantopithecus or a T-rex next time you visit your local zoo. Till then, we will have to watch Hollywood masterpieces to feed our imagination.

Binay Panda is at Ganit Labs, Bengaluru

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