An Evolutionary Debate on the Risks of Childbirth Scientists are revisiting an influential theory that the evolution of big brains made human childbirth risky. Author: CARL ZIMMER Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to email a link to a friend (Opens in new window)Click to print (Opens in new window)MoreClick to share on LinkedIn (Opens in new window)Click to share on Reddit (Opens in new window)Click to share on Tumblr (Opens in new window)