"He makes a persuasive case that complex life must have the traits we see today. And he argues that it would almost certainly develop the same way everywhere. W

"He makes a persuasive case that complex life must have the traits we see today. And he argues that it would almost certainly develop the same way everywhere. Which means that, if we find complex life on other planets, it will quite likely share the same traits." "is so compelling that it’s hard to imagine any other way" The explanation is just a hypothesis about the cellular structural evolution of the living organisms we're having all around us. From what I understand that was only one successful combination of cell structures working under a given set of conditions. In another conditions another combination could have formed the basis of later evolved complex life. Sure, the E.T. life would most likely have similar composition of chemical elements (because of their abundance in the universe, if nothing else), but I can't expect it to necessarily have the same base structural cell model at their core. I think Mr. Gates' fascination with related problems affected his disposition for healthy criticism here.