Here’s a question for you: What do you get when you put a mammoth genome into an elephant egg? Is it a mammoth or an elephant or something else? And why would you do it?
When news about the half-life of DNA preserved in ice came out, it was a bit of good news and bad news: DNA degrades at such a speed that while we can reconstruct a Neanderthal genome and a Mammoth genome, any dinosaur genomes have been lost to the sands of time. Probably the closest we can get is an ostrich. But resurrecting Homo neanderthalensis, or the Wooly Mammoth, seems all of a sudden tantalizingly within reach, in this era of synthetic biology, cloning, and genome sequencing.
There have been better discussions than I can start talking about why we would or wouldn’t want to resurrect certain species. The general consensus was that passenger pigeons are best left to museum displays, and ground sloths are awesome. I wanted to instead take a different tack: if we were to bring back something that had the genome of a neanderthal or a mammoth, or even a passenger pigeon, would it be a revivified species or a new one?
Smallest Meaningful Units: The Passenger Pigeon
Passenger Pigeons are probably the simplest of the above listed species because they were so plentiful and they went extinct so recently. As a result, we have numerous samples, records of behavior and just generally we know the most about them. There are numerous closely related species which could incubate an egg, perhaps. It seems like an easy fix: bring passenger pigeons back to our zoos, at least!
But here’s the thing about passenger pigeons: they’re gregarious. By which I mean, they like big flocks, and by that I don’t mean a couple hundred birds. We’re talking the swarms that filled the sky for days. At their peak, passenger pigeons probably accounted for at least a quarter of the land birds in North America: 3 to 5 billion birds. The nesting sites were called “cities” for a reason.
But a breeding program, bringing passenger pigeons back from extinction, would (1) start slowly, with a few birds, and (2) probably not dedicate hundreds of acres to their breeding grounds.
Which would mean that we would keep having to fertilize pigeon eggs with passenger pigeon DNA for as long as we wanted “passenger pigeons” — because passenger pigeons simply don’t breed in captivity. They need their cities, with hundreds of thousands or more birds pressed closely together, to breed. So even if we could get a few passenger pigeons, that’s far from having a sustainable population.
Which brings up another question: would a passenger pigeon which grew up in a lab, isolated, rather than a city full of other birds, really be a passenger pigeon?
Language, Culture, and Humanity: Homo Neanderthalensis
The problem of culture becomes even more of an issue with another popular candidate for resurrection: the Neanderthal man. Genetic evidence suggests that neanderthals and early humans interbred — implying that if someone was willing to bear and rear the genetically-neanderthal offspring it would perhaps be possible.
But so much of human development occurs after birth, and requires social cues from other humans; that’s obvious from the studies we’ve done on long-term effects of neglect: a human cannot grow in isolation. It’s fairly natural to expect that certain cultural elements would be different between a neanderthal and a human, and we don’t know exactly what those look like — we certainly wouldn’t be able to recreate a neanderthal setting and culture for our nascent species. Would Homo neanderthalensis raised as Homo sapiens be one, or the other, or neither?
We’ve done some similar studies on chimpanzees, actually, to see if they could develop language. And the results are mixed. Some researchers insist that chimpanzees raised in human families learn sign language and can interact with humans as conversational partners, and some insist instead that the chimpanzees in these studies are instead incredibly skilled at mimicking their human trainers. But in whether or not they can develop a symbolic language with something we would recognize as grammar, chimps raised by humans do seem to classify photos of themselves more closely with human photos than chimpanzee photos; and when they are returned to live among chimpanzees instead of humans they show symptoms of isolation and loneliness. On the other hand, these chimps are still chimps — they don’t respond to humans the way human children would, either.
If anything, an individual with a neanderthal genome raised as a human would have an even more complicated identity, because the likelihood that he or she could speak and converse would be significantly higher.
All Animals Have Cultures: Wooly Mammoth
So what about the mammoth? The problem is, many of the same problems involved with humans or passenger pigeons come right back to haunt us. Elephants can breed in captivity, yes, and they probably don’t have language, but they are highly intelligent organisms with what most people would recognize as culture and they seem to have some kind of theory of mind. So many of the neanderthal/human questions would be raised by the idea of a mammoth being bred from and raised by elephants.
But on top of this, while culture and development may be the most obvious difference here, it’s hardly the only one. Who knows what differences in mitochondrial DNA may do to change the identity of an individual? How about diet and gut microflora (something which, like mitochondria, is often inherited from the mother exclusively).
So for a myriad of reasons, it seems like the closest we could actually get to a mammoth — or a passenger pigeon, or a neanderthal, or a ground sloth — is a chimera, halfway in between its genome donor and the animals that gave it everything else.
And with that, I leave you with the video that inspired this post, from DNews, in which all of the complexity, culture, and maternal contribution of mammalian development is simplified into “Wouldn’t it be cool to have mammoths?!”
Featured image is by Charles R. Knight [Public domain], via Wikimedia Commons