In your book Evolving Ourselves, you propose two new drivers of evolution: unnatural selection and nonrandom mutation. Explain unnatural selection.
Charles Darwin and Alfred Russel Wallace discovered that what lived and died on the planet for four billion years depended primarily on two forces: natural selection and random variation (later called random mutation). Natural selection, or “survival of the fittest,” is what one sees in a virgin forest, tundra, or jungle. It is what one partially sees when a town is abandoned or a field lies fallow for a while. But it is not what one sees in a city, suburb, farm, ranch, or garden. In fact, on at least half the Earth’s surface, what lives and dies depends primarily on human choice — on what we find useful, attractive, interesting — rather than on what nature would choose. What lives and dies is increasingly a human choice, not a natural choice; for instance, one would never find a cornfield, with orderly straight rows, one and only one plant, and nothing else living there, absent human intervention.
And what is nonrandom mutation?
For four billion years, genetics tended to mutate slowly and at random — a casino-like system that altered the instructions of all life-forms and allowed a few lucky winners to survive and have progeny. But with the birth of biotechnology, humans began to insert very specific instructions into viruses, bacteria, plants, animals, and now humans. This process was not random tinkering but intelligent design; we want this particular life code to promote this, block that, make this, prevent that. When inserting a specific trait into a plant to make it pesticide resistant or modifying a virus to help us fight AIDS, we are reading and rewriting life code to suit our purposes. This leads to very rapid evolution designed for our goals. (Darwin observed an early iteration of nonrandom mutation based on plant and animal breeding that selected and reinforced certain traits, which he called artificial selection, but it did not involve directly and deliberately inserting or modifying specific gene codes.)
What is life code?
There are ever more ways to modify the set of instructions of any living thing. At a basic level, one can modify the DNA, or one can modify the expression of the DNA (e.g., epigenetic changes), or the way an organism metabolizes, or the environment that alters future DNA. We have bred a series of ever more powerful instruments, including genomics, proteomics, metabolomics, viromics, epigenomics, metagenomics, all of which allow us to redesign life’s instruction set. As we develop more “omics” and better understand how the various sets of instructions interact with one another, we get better and better at developing tailored life code to program organisms for our own purposes.
How does having fewer children affect our evolution?
In theory, it should slow evolution, because there is less random gene recombination. But in practice, we have so modified so many other factors, including our food, diseases, mating choices, stress, and medicines, that we are applying enormous evolutionary pressure for our kids to adapt to an ever-changing environment. Furthermore, we are already altering our kids’ bodies and brains, and those of their progeny, through the use of antibiotics, brain inputs and drugs, chemicals, obesity, and so many other stimuli — positive and negative — that are part of our modernity.
Why do you think it is important for us to plan a way to leave Earth?
We know that life has lived through at least five major extinctions. Betting the entire future of humanity on one planet, one whose fossil record tells us 99 percent of life-forms go extinct, is bad odds. Whether driven by super volcanoes, meteors, warming, freezing, solar flares, dark matter, or a myriad of other threats, there will be other mass extinctions. Even since the last great extinction, and even without a catastrophic driver, all hominids except Homo sapiens went extinct. And we came so close that today a single troop of African chimps carries more genetic diversity than 7 billion humans. If you like and respect humanity, you have to advocate planetary diversification. And this also implies we will have to redesign our bodies to adapt to different environments. Natural selection on Earth is not going to drive these changes.
What changes should we make now to evolve into better human beings?
We don’t have the knowledge, instruments, or nuance to answer this question intelligently on a large scale yet. But in the short term we are modifying things like mitochondria to prevent people and their kids from suffering deadly inherited diseases. We are using gene therapy to cure specific inborn diseases. We are changing the sex of some people’s cells to conquer cancers. We may alter genetic instructions to prevent AIDS contagion or chronic diseases. But these are tiny steps on the way to far more radical changes; our children will have very different options from ours.