As much as I would love to be in the presence of a living Mammoth in all of its woolly Pleistocene glory, “The Mammoth Cometh” (NYT, Feb. 27) had more to say about human hubris than logical priorities for science. Just because we can manipulate genomes to resurrect species does not mean that it should be done, at least not until we have a plan to address the larger issue of extinction.
We are in the midst of a well-documented biodiversity crisis. According to one recent projection, at the current rate of species extinction we will enter official “mass extinction” territory within 300 years. What does that mean? The extinction of 75% or more of all species, something never witnessed in human history. In fact, the last time such a genetic bottleneck took place was 65 million years ago when other members of the charismatic mega-fauna disappeared, the dinosaurs. Putting millions of dollars into the resurrection of a handful of species while we ignore the plight of millions of others is the height of folly.
If we are so guilt ridden by the loss of the passenger pigeon that we are willing to go to heroic lengths to resurrect it, how are we going to feel when we wake up a few decades from now and realize that the biosphere has been decimated? Size matters. I get it. Big, showy animals like mammoths and tree sloths will always attract support but their salvation is a mere parlor trick done as much for our amusement as anything. As David Attenborough once said, humans (or, if I may add, mammoths) could disappear tomorrow and the world would go on taking little notice. But if insects were all suddenly removed, nearly every terrestrial and freshwater ecosystem would collapse overnight. We are tearing at the fabric of life on which we depend for our very survival, yet ignore the first logical step in an informed conservation strategy: learning what species exist on earth to begin with.
Taxonomy, the science of species exploration, has been nearly completely replaced in our universities by molecular phylogenetics, that is, by labs who use DNA to confirm or modify our understanding of evolutionary relationships among the small fraction of species that we already know. In the meanwhile, species are literally going extinct faster than they are being discovered. While the rate of extinction has risen by hundreds of times, the rate of species description has remained steady since the 1940s at about 18,000 species per year.
An increasing number of voices call for replacing what they see as an old-fashioned and inefficient, largely morphology based, taxonomy with high-tech and high-speed molecular alternatives. They call for DNA barcodes in the place of testable theories of species and surveys of DNA diversity in the environment to avoid individuating species. These are faster and cheaper alternatives to traditional “descriptive” taxonomy, but are they acceptable equivalents? Absolutely not. The most interesting and informative details of evolution are written in improbable complexity that is mostly irretrievable from DNA sequences alone.
There are three reasons we should make an inventory and classification of all species an immediate and top priority. Put simply, unless we know what species exist to begin with, how are we to detect or measure their loss? As species go extinct, we lose much more than their contributions to intricate ecosystems. Each species reveals the results of millions of years of trial-and-error experiments carried out by natural selection. Each can tell us something unique about effective and sustainable strategies for survival. For me, however, discovering and describing all species and preserving at least a few specimens and observations about each in our botanical garden herbaria and natural history museums has a much deeper and personal significance.
Every single thing that makes us human was modified from earlier mammal ancestors. In turn, every trait that makes a mammal unique was modified from a previous condition in some ancient quadruped and on and on clear back to the first single-celled organism. As long as humans exist, they will seek to understand what it means to be human. This same innate curiosity drives us to understand both the origin of the Universe and of each and every branch on the tree of life. Every species that goes extinct unknown and unnamed thus diminishes our humanity in a special and irreplaceable way.
An ounce of prevention is truly worth a pound of genetic engineering when it comes to extinction. And avoiding a mass extinction event is vastly more important than populating our zoos with a menagerie of the frisky dead. It would be naïve to think that resurrecting species will not happen; indeed it is underway and inevitable. I will buy my admission ticket along with all the other morbidly curious when the time comes, so I am not suggesting that we never do it. I am, however, asking that we not revive one species at the price of a million others. I am asking that we divert at least a fraction of the science funding lavished on molecular labs to document the species diversity we are in the process of destroying. The return on investment will be huge. We will have an archive of evolutionary creativity to mine in search of sustainable solutions for our own survival. We will enable ecologists and conservationists to have a much finer grained understanding of ecosystems and empower them to do their work better. And we will assure that for as long as humans exist that we can continue the pursuit of understanding who we are and how we got here.