Resurrecting the Woolly Mammoth
As an ecologist of ice age giants, I long ago came to terms with the fact that I will never look my study organisms in the eye. I will never observe black- bear-sized beavers through binoculars in their natural habitats, build experimental exclosures to test the effects of mastodons on plants, or even observe a giant ground sloth in a zoo.
De-extinction could change that. On Friday, a group of geneticists, conservationists, journalists, and others convened in Washington, D.C. to discuss resurrecting extinct species, including the woolly mammoth. De- extinction sounds like science fiction, but it’s rooted in very real conservation concerns. With the sequencing of the woolly mammoth genome complete and recent advancements in biotechnology, the question of whether to clone extinct species like mastodons, dodos, or the Shasta ground sloth is rapidly becoming more of a question of should, rather than how. The latter isn’t straightforward, and involves the integration of a number of cutting edge disciplines, but I’d like to focus on the former: should we clone woolly mammoths? What Should We Consider???
A growing problem I’ve had (and one which Brian Switek raises in a recent post at National Geographic) is that the de-extinction proposals are Big Ideas, but they they’re often shallow when it comes to ecology. Even the concept of “de-extinction” itself is misleading. Successfully cloning an animal is one thing; rescuing it from the black hole-like pull of extinction is another. Decades of conservation biology research has tried to determine the careful calculus of how many individuals and how much land are needed for a species to survive without major intervention, accounting for its needs for food, habitat, and other resources.
The woolly mammoth is the ice age species with the best-preserved specimens, and it was the first to have its genome sequenced (though the Neanderthals followed in 2010). As far as de-extinction efforts go, it’s likely to be one of the first successful cloning efforts.
However, not all mammoths were woolly tundra-dwellers; in North America, mammoth remains have been found at elevations ranging from sea level to the mountains of the Colorado Plateau, and from Canada to central Mexico. The largest of these, the Columbian mammoth, dwelled in savannas and grasslands like African elephants today, and the smallest— Pygmy Mammoths—lived on the isolated Channel Islands off the California coast.
While knowing their habitat alone is useful in terms of identifying potential cloned mammoth reserves, we do in fact know quite a lot about what mammoths ate. Based on plant materials found in fossilized dung, the contents of permafrost-preserved stomachs, and isotopes in teeth enamel, we know that most mammoths were grazers, preferring grasses and herbs to woody trees and shrubs.
In this way, mammoths were similar to modern African elephants, though evolutionarily they’re more closely related to the forest-dwelling Asian elephants. Unlike horses and camels, which evolved in North America, mammoths were relatively recent comers, arriving around 1.7 million years ago via the same land bridge that the first humans would later take during the last ice age.
Mammoths likely had elaborate social systems similar to modern elephants, and are thought to have lived in groups of up to twenty individuals. Woolly mammoths males had musth glands, which are important in modern elephant reproduction today. Groupings of mammoth bones at sites where multiple individuals died together show extended family structures. Preserved mammoth tracks show extended families walking side-by-side, as well as a decline in juveniles that indicate populations were in decline due to human hunting. Modern elephants have elaborate communication systems involving touch, sight, chemistry, and sound (including infrasonic and seismic communication across long distances). While fossils cannot recapture the sound of a mammoth’s trumpet call, but we do know from modifications in their hyoid bones, tongue, and voice box that they would have been capable of low frequency communication, too.
The mammoth steppe is just as extinct as its namesake, due to a combination of climate change and the loss of those mega herbivores that were likely “keystones,” ecological engineers of their own habitats. Assuming that parts of modern Siberia or boreal Canada would do, how much land would a woolly mammoth need? The science on this is much less clear. By matching the isotopes in tooth enamel with the isotopes in soils, we know that some species of mammoths and mastodons roamed as much as 500 km a year, perhaps migrating to track their habitats.
Calculating the carrying capacity of a mammoth herd is not trivial (trust me—I’m working on it!), and involves a careful consideration of how much forage mammoths would need to consume (modern elephants eat as much as 440 pounds a day), proximity to water (modern elephants drink around 60 gallons daily), and the complex interaction between animals, plants, and the changing climates they experienced as their populations dwindled. Once we know how much land a mammoth herd needs, it’s another matter entirely to determine how many of those herds are necessary to maintain viable populations of woolly mammoths in the wild. Whatever that number may ultimately be, it’s worth pointing out that 14,000 years ago, it only took small bands of spear-wielding humans and a backdrop of changing climates to push mammoths and other ice age mega fauna over the brink.
When we think of cloning woolly mammoths, it’s easy to picture a rolling tundra landscape, the charismatic hulking beasts grazing lazily amongst arctic wildflowers. But what does cloning a woolly mammoth actually mean? What is a woolly mammoth, really?
Is one lonely calf, raised in captivity and without the context of its herd and environment, really a mammoth? Does it matter that there are no mammoth matriarchs to nurse that calf, to inoculate it with necessary gut bacteria, to teach it how to care for itself, how to speak with other mammoths, where the ancestral migration paths are, and how to avoid sinkholes and find water? Does it matter that the permafrost is melting, and that the mammoth steppe is gone? As much as I love mammoths, the ecologist in me can’t help but answer: yes—it does matter.
I understand the impetus to resurrect the woolly mammoth—it comes from that same sense of wonder and drive for discovery that led me to be a scientist in the first place. When I watched 10,000 BC, I admit that I wept openly at the sight of CGI mammoths on the big screen. I would be the first person on a plane to Siberia if mammoths showed up in Pleistocene Park. Science needs icons—rallying points that capture the public interest. Cloning a woolly mammoth could be the equivalent of the moonwalk for biology, resurrecting not just an extinct species, but also rekindling a child- like sense of excitement for the natural world (though admittedly, cloning’s public opinion record has tended to be more one of fear and admonition that scientists are “playing God”). And yet, as Hannah Waters rightfully points out, cloning extinct species may actually be more about us humans than the wildlife we care about.
Ultimately, cloning woolly mammoths doesn’t end in the lab. If the goal really is de-extinction and not merely the scientific equivalent of achievement unlocked! then bringing back the mammoth means sustained effort, intensive management, and a massive commitment of conservation resources. Our track record on this is not reassuring.
In the meantime, the least we can do is be guided by what we do know about woolly mammoths in their ecological context. Before we talk seriously about de-extinction, let’s apply the lessons of the woolly mammoth to help save species in the face of pre-extinction.