"Certain areas within parts of the brain linked to attachment, nurturing, empathy and the ability to interpret and react appropriately to a baby’s behavior had more gray and white matter between 12 and 16 weeks than they did between two and four weeks." For you father-programmers out there: did you notice any changes in your programming/work abilities around the 12-16 week mark?
I wonder if sleep deprivation is related to raising children pre industrial era. It seems logical but I don't know much on this topic. :)