Monday, March 25, 2013

Nazi Cow
On the desktop of my computer there is a picture of a building. It’s an undistinguished piece of architecture – whitewashed walls, a red tiled roof speckled with lichen, and a wooden structure atop the ridgeline that aspires to be a belfry, but falls short. This is Coteford Infant School, in the Northwest London suburb of Eastcote, and I spent three happy years there from 1971 to 1974.

Or rather, this was Coteford Infant School. It’s been gone for more than thirty years now. A new school was built, just up the road, and the old one, surplus to requirements, was torn down. There’s a small cul-de-sac of brick town houses there now, called “Grooms Drive.”

When I look at the picture, with the haze of an early summer day and the lush green of horse chestnut trees forming a backdrop, I can remember the smell of new-mown grass from the playing fields and the excitement of knowing that the summer holidays were almost there. It brings a terrible, but short-lived pang of longing. I’ll never be that young again, and the school building, with all its memories, is gone for good.

Time marches on and the world changes. As a paleontologist, I am intimately aware of this. The collection that I look after, at the Peabody Museum, is a record of past lives in long-gone worlds, albeit a massively incomplete one. I may be intimately familiar with the bones of oreodonts, for example, but I will never see a living one.

Even if, by some miracle of science, I could conjure one up, it would be devoid of meaning in the modern world. Oreodonts are an evolutionary product of the world of the middle Cenozoic, a world without grasslands, where vast herds of oreodonts browsed on low-lying shrubs, in open woodlands that covered much of North America. This biome does not exist anywhere today and so neither do oreodonts.

This idea of a changing planet lies at the core of the work that my colleagues and I are doing on the Peabody’s new fossil halls. All too often, people imagine that the world of past geological eras was much like that of today, only with different animals. It wasn’t. There are no modern equivalents, for example, of the vast forests that existed at high latitudes 55 million years ago– dawn redwoods and cypresses growing in complete darkness for months each winter. The climate was different, the composition of the atmosphere itself was different. That world is gone. We can imagine it - incompletely and from a great distance - through the few fossils that remain, but we can never truly experience what it was like.

All this came to mind when I was reading a report by Carl Zimmer on the ongoing debate regarding “De-extinction” – the (mostly theoretical) process of reviving recently extinct species through modern genetic techniques. Carl’s article is, as ever, an excellent summation of the technical and ethical challenges of doing so and I’m not going to repeat it here – you can go read it in National Geographic. But it did get me thinking about how resistant some people are to the idea of change.

Trying to recreate extinct species is not a recent preoccupation. In the first half of the twentieth century, a pair of German brothers called Heck spent an enormous amount of time and effort trying to recreate the aurochs, the extinct wild ox of Eurasia from which today’s domestic cattle originated. The Heck brothers lacked the sophisticated genetic tools of today’s biologists, but they theorized that if all domestic cattle had the aurochs as a distant ancestor, it might be possible to recreate the species by selective breeding.

We know what the aurochs looked like because our Pleistocene ancestors painted its likeness on cave walls, because its bones can be found in museum collections, and – most persuasively – because it actually survived well into historic times; the last one died in Poland in1627. So armed with this information the Hecks set out to find the most “primitive” living breeds of cattle, pick the most aurochs-like examples of each breed, breed them with each other, and keep back-crossing until they ended up with something that looked like an aurochs.
I say “looked like an aurochs,” because the Heck cattle were not aurochs. They were still domestic cattle. They weren’t even all that aurochs-like; Heck cattle were barely half the weight of their wild ancestors and retained the chunky physique of animals bred for meat, rather than the athletic body of a wild animal that has to live by its wits and avoid predators. In our collections at Peabody, we have the skull of a male aurochs – the real thing, from the Pleistocene. Its horns are wider than the span of my arms. None of the recreated cattle come close to this.

The idea of back-breeding the aurochs, or at least something very like it, from domestic cattle has proved to be a remarkably persistent one – there is a modern program, called TaurOS that is still attempting to do so. One of the main arguments in favor of the effort is that recreating a large, native European ungulate would promote the restoration of the continent’s lost biodiversity. Large ungulates modify the environment through grazing, which impacts vegetation and hence the communities of animals supported by it.

Of course, humans modify the environment as well. We’ve spent the last 10,000 years turning the planet into a place that can support over 7 billion of us, and along the way we’ve eradicated tens, if not hundreds of thousands of species. The charismatic vertebrates that form the focus of the current de-extinction debate are only the tip of a very large iceberg.

So here’s my problem with de-extinction. I can understand throwing resources at the preservation of charismatic megafauna – such as tigers, giant pandas, or elephants - in the wild, because you are also preserving the habitat in which they live and the biodiversity that is associated with it. Whether any of these habitats is actually “natural” after centuries of tinkering around by our species, plus the management protocols that get put in place to preserve them today, is a question for another blog post by someone better informed than me.  But at least they are there and they are real.

Recreating a species that inhabited a world that’s long gone has none of these “added value” advantages. The vast broadleaved forests of the Eastern USA that were the home of the passenger pigeon are mostly gone. So are the Mascarene forests that were the home of the dodo, and the high latitude steppes that supported mammoths.

Could we recreate the world as it was before we became agricultural and started clearing the forests? The story of the Heck cattle provides a cautionary tale and, at the risk of providing a proof of Godwin’sLaw, it’s worth looking at. You see, the Heck brothers’ work attracted the attention of a rather sinister patron, in the form of Hermann Göring. He’s better known as the former head of the Luftwaffe and a relentless thief of artwork from all over Occupied Europe, but Göring was also Reich Master of the Hunt (yes, they really had a state position for a Master of the Hunt),  Master of the German Forests, and an advocate for the protection of endangered species.

Göring saw the recreation of the aurochs as the centerpiece of the Nazi’s plans to create a primal forest reserve that would cover vast swaths of Eastern Europe and be the home not just to the aurochs, but also bison, wolves, bears, wild boar and other large mammals. The human population of the area wouldn’t be a problem, because the Nazis would murder or deport them all.

This is an extreme example, but the question of where you put your newly “de-extinct” species is a real one. Even with the full resources of a genocidal state behind him, Göring’s forest preserve would not actually have been primary forest, any more than the Heck cattle were aurochs. It would have been an artificial environment, created by humans to fit a particular need – in this case, a hunting preserve for a small group of the Nazi elite. And when de-extinction advocates talk about recreating the “mammoth steppe” of Northern Eurasia, for example, they’re not actually restoring a natural environment. They’re just doing what our species has been doing for thousands of years – modifying the environment to suit our own needs.

To be fair, some “de-extincters” are quite open about this. The TaurOS project, for example, doesn’t claim that it’s re-creating the aurochs. Instead, it’s creating cattle that could fill the role formerly occupied by the aurochs and thus generate environments that are more biologically diverse through grazing. What I like about TaurOS is that it recognizes and acknowledges that farmland grazing also promotes greater biodiversity – the creation of the new cattle is intended to tackle the problem of farm abandonment rather than recreate some mythical “wildwood.” It recognizes that human landscapes have intrinsic biodiversity value as well. From my perspective, this is a much more honest position than trying to claim that you’ve resurrected something that was lost.

So maybe this is a problem of semantics. Would I feel differently if, rather than claiming that they were breeding wooly mammoths, the various groups of researchers working on this problem were to say “we believe there are important benefits for humanity in the creation of a diverse grassland ecosystem in Northern Asia. A key element required for the project, but missing from the modern fauna of the region, is a mega-herbivore, a role previously filled by the wooly mammoth. We propose to use genetic engineering to combine genetic material from mammoths and elephants to create a cold-tolerant proboscidian”? OK, it’s less sexy than saying “we’re going to de-extinct mammoths,” but it’s a more accurate description of what’s actually being done.

The problem is that I’m still not convinced that it’s worth doing. Suppose, for argument’s sake, that it was possible to recreate the passenger pigeon, as has been proposed, through a mixture of DNA sequencing and selective breeding. As Carl Zimmer asks, would the inhabitants of suburban America really want vast flocks of pigeons roosting in the cities and crapping on their cars? But you could fix this. You could, perhaps, create a modified passenger pigeon that lived in small flocks. Or that pooped less. Or that had poop that smelled of roses. In principal, you could genetically engineer a passenger pigeon for the 21st Century. But why would you? We already have lots of pigeons. The ones that are adapted for living in our highly modified, urbanized world are the ones that are still with us.

I’m a custodian of extinct species – that’s my job. Over the years I’ve had the privilege of preserving the mortal remains of dodos, moas, aurochs, passenger pigeons, Labrador ducks, wooly mammoths, thylacines, Christmas Island rats, giant ground sloths, great auks and a host of other creatures that are no longer with us. Perhaps that makes me a little jaundiced. But it seems to me that the de-extinction debate is a distraction from thinking about the challenges that we face in the world today.

I could, if I had a large amount of money, buy all the houses in Grooms Drive and pull them down; dig up the post-modern brick roadway and lay black tarmac, carefully source roofing tiles, window frames, and a battered wooden belfry; and plant horse chestnut trees. I could scour London looking for original 1960s vintage classroom furniture and hire a crack team of chefs to recreate the truly abysmal cuisine of school lunches from 40 years ago. I could recreate Coteford Infants School in every conceivable detail. But I would still be 47, not 7, and my pastiche would not be Coteford Infants ca. 1974. Time changes and I have to get over it and move on. As scientists, and as a species, we need to do the same.

[yes, I'm aware it's nearly a year since I last did a post, but this one got me going. With thanks to Carl, who persuaded me to write it down rather than just going for a cold shower and forgetting about it]