I've heard of this, but haven't read it - it sounds an interesting book.

For anyone who's interested in the connections between evolution and babies' needs, Meredith Small's 'Our Babies Ourselves' is a good (and easy) read - well researched, and she bases her observations on a range of anthropological studies of hunter-gatherer, pre-industrial and western industrialised cultures. I couldn't find it in bookshops here, but got it from Amazon recently. None of the conclusions are incredibly surprising but they are backed up by research (which you can then quote to people who tell you to put your child in a cot and stop breastfeeding them all night!).