The two rules for what lived and died, over the long term, were pretty clear: natural selection and random mutation. But over the last century or two, and especially over the last decade, humans fundamentally altered these rules. Life as we know it will undergo rapid and accelerating change; it will be redesigned and will diverge, especially post May 2014.
Already, we largely determine what lives and dies on half the surface of the planet, anywhere we have built cities, suburbs, parks, farms, ranches. That makes both cornfields and beautiful gardens some of the most unnatural places ever designed. Nothing lives and dies there except what we want, where and when we want—orderly rows of plants that please us. All else is culled. (But leave this fallow and untended for a couple of years and you will begin to see what is driven by the other evolutionary system, natural selection.)
In redesigning our own environment, we create and nurture completely unnatural creatures. These range from miniature pigs the size of Chihuahuas and corn that cannot self-replicate to the big tom turkeys that breed our Thanksgiving meals, animals so grossly exaggerated that they are unable to copulate naturally and require artificial insemination. No humans, no big Thanksgiving turkey breasts; today’s beasts are, on average, 225% larger than they were in the 1930s.
Without human intervention most of the creatures that live around you would simply have been selected out. (Let a Lhasa Apso loose on the African plain and watch what happens.) Same is true of humans; in an all-natural environment, most of humanity would not be alive. Just unnaturally selecting out microbes and viruses like smallpox, polio, bubonic plagues, and most infections, means billions more get to live.
As we practice extreme human intervention and alter the course of natural selection we create a parallel evolutionary track, one whose rules and outcomes depend on what we want. Life begins to diverge from what nature would design and reward, absent our conscious and unconscious choices. A once unusual observation, that during the Industrial Revolution black moths in London survived better than white moths because they were better camouflaged in a polluted environment, has now become the norm. Life around us is now primarily black-moth-like-adaptations to our environments: cute dogs, cats, flowers, foods. We have so altered plants, animals, and bacteria that to survive they have to reward us, or at least be ignored by us.
These two parallel evolutionary systems, one driven by nature, the other by humans, both breed, expand, and evolve life, driving parallel and diverging evolutionary trees. The divergence between what nature would choose and what we choose gets ever larger. Many of the life forms we are so accustomed to, and dependent on, would disappear or radically modify in our absence.
But the true breakpoint began over the past few decades, when we began not just choosing how to breed but how to rewrite the code of life itself. In the 1970s and 1980s, biotechnology gave us the ability to insert all kinds of gene instructions. Random mutation is gradually being displaced by intelligent design. By 2000 we were decoding entire genomes and applying this knowledge to alter all kinds of life forms. Today’s high schoolers can spend $500 and alter life code using methods like CRISPR; these types of technologies can alter all subsequent generations, including humans.
In May 2014, a team of molecular biologists led by Floyd Romesberg created a new genetic code, a self-replicating system that codes life forms using chemically modified DNA. This is a BFD; insofar as we know, for 4 billion years all life on this planet replicated using the four known base pairs of DNA (ATCG). Now we can swap in other chemicals. This third evolutionary logic-tree of life would initially be completely human designed-driven and could rapidly diverge from all known life. In theory scientists could begin to breed plants and animals with a very different genetic makeup from that of any other creature on the planet. And these new life forms may be immune to all known viruses and bacteria.
Finally, if we discover life on other planets, something that seems increasingly likely, the biochemistry of these other life forms is likely to further increase the variety and options that life on Earth can take, providing life-designers with entirely new instruments and ideas to program-redesign existing life forms so they adapt to different environments.
So the biggest story of the next few centuries will be how we begin to redesign life forms, spread new ones, develop approaches and knowledge to further push the boundaries of what lives where. And as we deploy all this technology we will see an explosion of new life forms—something that could make the Cambrian explosion look tame.
Life is expanding and diverging. Humans will not be immune to this trend. We already coexisted and interbred with other versions of hominins; it is normal and natural for there to be different versions of ourselves walking around. Soon we could return to this historically normal state but with far more, and perhaps radically different, versions of ourselves. All of which may lead to just a few ethical, moral, and governance challenges.