Most of the comments here are implying that there is some environmental change which has caused breastfeeding to become harder or less efficient. The article doesn't seem to say that, though. I didn't see any implication that breastfeeding was better back in prehistory. It's possible that it's always been hard. Being in a social group large enough that there are other mothers would solve the issue, largely.
It's against the rules to imply this but most of the comments here are written by people who don't read the articles.
Note, snark like the above is explicitly forbidden.