Like many people, I once trusted in the wisdom of Nature. I imagined that there were real boundaries between the natural and the artificial, between one species and another, and thought that, with the advent of genetic engineering, we would be tinkering with life at our peril. I now believe that this romantic view of Nature is a stultifying and dangerous mythology.

Every 100 million years or so, an asteroid or comet the size of a mountain smashes into the earth, killing nearly everything that lives. If ever we needed proof of Nature's indifference to the welfare of complex organisms such as ourselves, there it is. The history of life on this planet has been one of merciless destruction and blind, lurching renewal.

The fossil record suggests that individual species survive, on average, between one and ten million years. The concept of a "species" is misleading, however, and it tempts us to think that we, as homo sapiens, have arrived at some well-defined position in the natural order. The term "species" merely designates a population of organisms that can interbreed and produce fertile offspring; it cannot be aptly applied to the boundaries between species (to what are often called "intermediate" or "transitional" forms). There was, for instance, no first member of the human species, and there are no canonical members now. Life is a continuous flux. Our nonhuman ancestors bred, generation after generation, and incrementally begat what we now deem to be the species homo sapiens — ourselves. There is nothing about our ancestral line or about our current biology that dictates how we will evolve in the future. Nothing in the natural order demands that our descendants resemble us in any particular way. Very likely, they will not resemble us. We will almost certainly transform ourselves, likely beyond recognition, in the generations to come.

Will this be a good thing? The question presupposes that we have a viable alternative. But what is the alternative to our taking charge of our biological destiny? Might we be better off just leaving things to the wisdom of Nature? I once believed this. But we know that Nature has no concern for individuals or for species. Those that survive do so despite Her indifference. While the process of natural selection has sculpted our genome to its present state, it has not acted to maximize human happiness; nor has it necessarily conferred any advantage upon us beyond the capacity raise the next generation to child-bearing age. In fact, there may be nothing about human life after the age of forty (the average lifespan until the 20th century) that has been selected by evolution at all. And with a few exceptions (e.g. the gene for lactose tolerance), we probably haven't adapted to our environment much since the Pleistocene.

But our environment and our needs — to say nothing of our desires — have changed radically in the meantime. We are in many respects ill-suited to the task of building a global civilization. This is not a surprise. From the point of view of evolution, much of human culture, along with its cognitive and emotional underpinnings, must be epiphenomenal. Nature cannot "see" most of what we are doing, or hope to do, and has done nothing to prepare us for many of the challenges we now face.

These concerns cannot be waved aside with adages like, "if it ain't broke, don't fix it." There are innumerable perspectives from which our current state of functioning can be aptly described as "broke." Speaking personally, it seems to me that everything I do picks out some point on a spectrum of disability: I was always decent at math, for instance, but this is simply to say that I am like a great mathematician who has been gored in the head by a bull; my musical ability resembles that of a Mozart or a Bach, it is true, though after a near fatal incident on skis; if Tiger Woods awoke from surgery to find that he now possessed (or was possessed by) my golf-swing, rest assured that a crushing lawsuit for medical malpractice would be in the offing.

Considering humanity as a whole, there is nothing about natural selection that suggests our optimal design. We are probably not even optimized for the Paleolithic, much less for life in the 21st century. And yet, we are now acquiring the tools that will enable us to attempt our own optimization. Many people think this project is fraught with risk. But is it riskier than doing nothing? There may be current threats to civilization that we cannot even perceive, much less resolve, at our current level of intelligence. Could any rational strategy be more dangerous than following the whims of Nature? This is not to say that our growing capacity to meddle with the human genome couldn't present some moments of Faustian over-reach. But our fears on this front must be tempered by a sober understanding of how we got here. Mother Nature is not now, nor has she ever been, looking out for us.