I would add that with women in the workforce as much as they are, men have also become primary caregivers, or at least share the burden of child-rearing to some capacity. The stay at home hubby is more widespread now than ever.
However, the automatic assumption that it is women is still reflected in our courts and in our divorce laws. The reasoning behind it, which I believe
was well founded-- The younger the child, the more important that the primary caregiver maintain physical custody should joint custody be impossible, simply because the bond is stronger there and the child more comfortable and trusting. Women could, in earlier years, claim a monopoly on this traditional role, but no longer.
These reasons, to a large extent, have been demolished by our culture first, and economic necessity second. Many women now hold full time jobs and work as many if not more hours than men. This leaves either the male to bond with the kids or some daycare worker.
Whatever the situation, the divorce laws have hardly kept up with the changing times. They still reflect the assumption that women are the primary caregiver and therefore the child is best off in her care.
here is a story for you men -- My cousin's wife walked out on him and their three children (and one was an infant). Harry, my cousin, raised the kids -- you know the bathing, soothing, helping, disciplining, etc. for many years. Then the ex-wife takes Harry to court suing for legal custody (and child support). She claimed she could be a better mom since she did not work. She wanted to be there for her children. The judge listened to the case and made a decision. He decided to give the kids to the mom but since they lived close, he told the mom that she would have to give Harry the kids when he got off work and pick them up before he went to work and Harry would get the kids on the weekends. AND NO CHILD SUPPORT. This way both parents would win - she would take of the kids during the day and get to know them and Harry would not have to pay for a babysitter. She refused the deal. Harry got the kids (which is what he wanted) and never saw or heard from her again.
The judge was a woman.