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Where Will Evolution Take Humans Next?

The nature of evolution itself is fast evolving.

Source: ASDF_MEDIA/Shutterstock

As near as paleontologists can tell, evolution has been proceeding apace for 3.5 billion years, give or take. From the emergence of the humble single-cell organism that served as the last universal common ancestor (LUCA) of all life on Earth 3.5 to 3.8 billion years ago, to today, new species have always arisen—sometimes in abundance, as during the Cambrian explosion; and sometimes more sparsely, as in modern times—but evolution itself has proceeded inexorably.

Thus, it is not a matter of speculation, but a matter of fact that homo sapiens will sooner or later go extinct, leaving descendants that are something entirely different—most likely, several somethings different—if past anthropoid evolution is any guide.

Just as the great apes (including chimps, gorillas, bonobos, orangutans) and homo sapiens splintered into different species from common ancestors, humans will likely not evolve into just one new type of ape, but several.

The chief forces that have driven the emergence of diverse new species (speciation), have, in one form or another, caused reproductive isolation of one group a species from others. Emergence of mountain ranges, rising sea levels that create islands, and local changes in food or predators are examples of isolating factors that give rise to new species.

Therefore, to forecast where multiple offshoots of homo sapiens might emerge, the first place to look would be human habitats where strong reproductive isolation is occurring. Extremely remote areas in tropical rain forests in Africa, South America, New Guinea, and Borneo, along with "uncontacted” peoples in the Indian Ocean such as the tribes on the Sentinel Island, would be logical places to start. As late as 2013, there were about 100 remaining “uncontacted” population clusters globally, where, presumably, reproductive isolation from other humans is strongest.

It's ironic, when you think about it: Homo sapiens could evolve fastest into “what’s next” where civilization is most primitive. Put another way, the best way to move forward in time in human evolution may be to go back in time in civilization to study the “uncontacted." However, for ethical reasons, scientists are reluctant to study uncontested or extremely isolated human populations because researchers could bring with them pathogens to which isolated peoples have no immunity, or modern technology that would forever change traditional ways of life.

Does this mean we are unlikely to get a sneak peek at where we are going as a species anytime soon? No.

For better or worse, evolution itself is poised to rapidly evolve inside human populations with extensive interbreeding thanks to the breakthrough genetic technology known as CRISPR.

CRISPR, an acronym for Clustered Regularly Interspaced Short Palindromic Repeats, is a new technology, borrowed from the DNA snipping properties of immune systems of single-cell organisms, that permits geneticists to insert and delete genetic sequences into cells. Initial CRIPSR experiments with human embryo cells show that genetic diseases such as myasthenia gravis might be eliminated.

Although rumors persist that scientists in Asia have actually implanted viable CRIPSR modified embryonic cells in women and brought the human infants to term, there are no documented examples of successful CRISPR gene editing in living humans—yet.

However, successful CRISPR manipulations in other mammals abound, such as in dogs, in which embryos have been allowed to develop into living, breathing creatures. Genetic modifications of canines using CRISPR manipulations in embryos has already occurred, creating animals that look like this one, in whom myostatin genes turn off muscle mass formation much later in embryonic development than in normal dogs.

Canine with myostatin inhibited
Source: CC0 PWOOLF

Given that humans and dogs share 84 percent of their DNA, it is not at all far-fetched—especially considering the success of early CRISPR human experiments—that a human with CRISPR-tweaked myostatin genes might also be engineered.

Would some parents who passionately hoped for an athletic son have a CRISPR myostatin procedure done on a human male embryo? Would other parents who desired tall, blond, blue-eyed offspring do the same? What about high IQ? You get the point.

Parents—somewhere—almost certainly would go to such extremes. Because modified genes in embryos transfer to the germ line (passed on as 23 chromosomes in sperm or egg), they would start to propagate in the general population as CRISPR-modified humans began to have offspring of their own.

Additional CRISPR modifications in successive generations, could, over very few generations, create entirely new species, incapable of interbreeding that produces fertile offspring. In this scenario, human beings themselves, not Mother Nature, would be the major driver of evolution, thereby evolving evolution itself.

My designation for what’s coming after homo sapiens is homo crispr. But there will be as many “flavors” of homo crispr as there are desires for physical appearance, cognitive skills, personality, and any of the other myriad traits that can be modified. Some of these new variants will be able to interbreed, while others will not, such that we might soon see an explosion of different homo species.

What will these new species be like? I’ll answer that question with another question: What do we want new human species to be like? For better or for worse, we will get what we ask for.