In last week’s Right Turn, we talked about how stem cells are responsible for the colours and patterns of bird feathers—and birds, as the graphic on the right demonstrates, are basically just tiny dinosaurs. Given that there is much promise in stem cell research (and also a great deal of hype), it makes one wonder: What, if anything, can stem cells do for the big reptilian dinosaurs that lived tens of millions of years ago?
The April 2013 issue of National Geographic’s cover story featured the headline, “Reviving extinct species,” and explored in detail the so-called de-extinction movement that’s becoming more and more realistic as research in stem cells and genetics moves forward. The article was followed up by a TEDx talk on de-extinction.
But unfortunately, this research might not be of much help to the forebears of today’s bird species; the idea of cloning dinosaurs (or any creature that went extinct significantly long ago) remains out of the realm of possibility due to the deterioration of any remaining DNA.
For more recently-extinct species, though—ones like the woolly mammoth, passenger pigeon, Tasmanian tiger and the dodo, to name a few—it might just be possible. Researchers, most notably Spanish biologists who’ve worked with the now-extinct Pyrenean ibex, have been trying to manipulate the preserved DNA of one species in order to splice it into the genome of a similar relative through somatic-cell nuclear transfer (SCNT). With the Pyrenean ibex, a regular goat was used as the surrogate, and although their attempts haven’t been entirely successful (of 57 implanted embryos, only one highly disfigured clone was born, and it died within minutes), the technique is still seen as one that should work. For the passenger pigeon, the common rock pigeon could be a surrogate; for a mammoth, it is possible the African elephant would be used.
As Dr. Hendrik Poinar of McMaster University told National Geographic, the technique is there and researchers have ample mammoth genetic material to work from, so “[i]t’s just a matter of finances now.”
Setting aside the fact that it’s theoretically possible, one more question remains to be asked—one that was quite prominent on the cover of the April issue of National Geographic: Should we? As is usually the case with such questions, there’s a diversity of opinions about that.
On one hand, many of these animals are thought to have gone extinct due to anthropogenic causes, so some have argued that we have a moral obligation to restore these species if we can. That’s the argument put forward by Dr. Michael Archer of the University of New South Wales, who has been working for over a decade to bring the Tasmanian tiger back to life. Others simply want to test the boundaries of modern science to discern whether or not it’s possible, and what we can learn in the process.
On the other side, however, is a question of what end we seek by bringing back these species. Constraints will limit the populations, at least initially, so it will be generations before they can be re-introduced to the wild (if that is even possible). A point brought up by American author Jackson Landers in a recent panel discussion is whether or not these species will actually resemble their now-extinct forebears, or simply be simulations of them. Learned behaviours will certainly be lost on any cloned specimens.
More to the point, given the fact that habitat destruction and poaching are the biggest reasons species continue to be pushed to (or past) the brink of extinction, and they haven’t come close to being resolved, then it’s unclear where the de-extinction movement moves forward. As conservation paleoecologist Jacquelyn Gill said on the Scientific American blog, “[p]erhaps the best course of action is to first demonstrate that we can effectively manage living rhinos and elephants before resurrecting their woolly counterparts in a warming, fragmented, overpopulated world.” Given that Endangered Species Day is this Friday, it’s a good time to talk about what we might do for some of the world’s critically endangered animals right now.
Gill’s idea is in the works, though. And extinct animals aren’t the only ones benefiting from stem cell research, even if they are the most heavily covered thanks to the cachet of bringing them back from the dead. A research team from The Scripps Research Institute in California is working to generate iPSCs from highly endangered species (including the drill and the northern white rhino) to preserve genetic material. (The group also tried for crowdfund a Regenerative Zoo project, which would have generated iPSCs of the Javan Banteng, Somali Wild Ass and the Black-footed Cat.) Artificial insemination has already boosted captive breeding programs for some species, including the panda and the koala, and including iPSC techniques in the arsenal of conservationists may enable greater genetic diversity and simplify the process of retrieving reproductive material and developing embryos for implantation.
It remains to be seen whether or not the woolly mammoth will once again roam the planet, but stem cell research will surely play a role in the return of any now-extinct species. Either way, stem cells are already being used to help protect critically endangered species, so there’s another feather in the cap of the incredible stem cell.
Friedrich Ben-Nun I., Montague S.C., Houck M.L., Tran H.T., Garitaonandia I., Leonardo T.R., Wang Y.C., Charter S.J., Laurent L.C. & Ryder O.A. & (2011). Induced pluripotent stem cells from highly endangered species, Nature Methods, 8 (10) 829-831. DOI: 10.1038/nmeth.1706
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