National Geographic : 2017 Apr
Beyond Human 55 fairly aggressive way.” The optimal Earthling turned Martian, he says, would be long and slender, because gravity on the red planet has about one-third the force of Earth’s. Over generations, eyelashes and body hair might fade away in an environment where people never come directly into contact with dust. Impey predicts—assuming that the Martian humans did not interbreed with terrestrial ones—significant biochemical changes in “tens of generations, physical changes in hundreds of generations.” one Human trait witH a strong genetic component continues to increase in value, even more so as technology grows more dominant. The universal ambition of humanity remains greater intelligence. No other attribute is so desirable; no other so useful, so varied in its applications, here and on any world we can imagine. It was indispensable to our forebears in Africa and will come in handy for our descendants on the planet orbiting the star Proxima Centauri, should we ever get there. Over hundreds of thousands of years, our genes have evolved to devote more and more resources to our brains, but the truth is, we can never be smart enough. Unlike our forebears, we may soon not need to wait for evolution to fix the problem. In 2013 Nick Bostrom and Carl Shulman, two researchers at the Future of Humanity Institute, at Oxford University, set out to inves- tigate the social impact of enhancing intelligence, in a paper for Global Policy. They focused on embryo selection via in vitro fertilization. With IVF, parents can choose which embryo to implant. By their calculations, choosing the “most intelligent embryo” out of any given 10 would increase a baby’s IQ roughly 11.5 points above chance. If a woman were willing to undergo more intensive hormone treatments to produce eggs faster—“ex- pensive and burdensome,” as the study notes with understatement—the value could grow. The real benefit, though, would be in the compound gain to the re- cipient’s descendants: After 10 generations, according to Shulman, a descendant might enjoy an IQ as much as 115 points higher than his or her great-great-great-great-great-great-great-great-grandmother’s. As he pointed out to me, such a benefit is built on extremely optimistic assumptions, but at the least the average recipient of this genetic massag- ing would have the intelligence equal to a genius today. Using embryonic stem cells, which could be converted into sperm or ova in just six months, the paper notes, might yield far faster results. Who wants to wait two cen- turies to be the scion of a race of geniuses? Shulman also mentioned that the paper omitted one obvious fact: “In 10 generations there will likely be computer programs that outperform even the most enhanced human across the board.” There’s a more immediate objection to this scenario, though: We don’t yet know enough about the genetic basis for intelligence to select for it. One embryo doesn’t do advanced calculus while another is stuck on whole numbers. Acknowledging the problem, the authors claim that the ability to select for “modest cognitive enhancement” may be only five to 10 years off. Starch metabolism Humans with high-starch diets, such as those heavy on rice, have evolved specific genes that help them digest these foods. Salt retention Some tropical popu- lations have genes that prevent them from losing too much salt in sweat when exposed to high temperatures. Short stature Small bodies in pygmy peoples may result from early reproduction, a response, in turn, to tropical diseases and early death.