The most important aspect of human evolution was facilitated not by Darwinian-style natural selection but by a crucial technological device invented by early Stone Age women, shows research by a leading British prehistorian.

Timothy Taylor of Bradford University claims that increased brain size was made possible by the invention of the baby sling, a development which enabled slower growing, physically and mentally immature offspring to survive and flourish.

"In effect, kangaroo-style, early female human ancestors became marsupial, carrying their immature youngsters outside their wombs," said Dr Taylor, who has published his research in a book called The Artificial Ape. "The invention of the baby sling, which allowed more babies to successfully mature outside the female body, instantly removed the barrier to increased head and brain size."

Read more here: http://www.independent.co.uk/news/science/archaeology/prehistoric-baby-sling-made-our-brains-bigger-2071291.html