Homo sapiens were not always so special. In the ancient past, other human forms lived beside us. The Neanderthals in Eurasia. Small, hobbit-like humans in Indonesia. The mysterious Denisovans in the Ural mountains.
But our time alone may be nearing its end. Through the power of technology, humans are set to take on the role of Intelligent Designer. We can upgrade ourselves and surmount evolution. Ultimately, we can become entirely new beings that set the stage for a posthuman future.
The scenario has played out for decades in science fiction but the prospect is raised more seriously by Yuval Noah Harari, an Israeli historian, in his latest book, Sapiens. In it he sees trouble ahead. The latest human enhancements will be accessible only to the rich, leading to a 21st-century society more unequal than any that came before.
The revolution Harari has in mind is borne of engineering and exploits mechanical, electronic, chemical and genetic progress. In place of treatments that correct biological deficits, like failing hearts, poor hearing and weak eyesight, will be procedures...