Hormones

There is an old and very crass joke that goes "How do you make a hormone?" "Kick her in the crotch!".  I did say it was crass.  But seriously what is the deal with hormones.  Ok you expect a bit of a change when you are pregnant, after all it is making some pretty big changes to your body.  But really what is with the emotional stuff.  What evolutionary niche did the tendency to cry at the slightest provocation fill?  Last night, ok the house was a mess, what else is new, I was seeing all the new furniture I had dreamed of disappearing, it was the start of my working week, but why oh why did I burst into tears when I started putting the kids toys away.  Feeling overwhelmed yes, tired yes, but weepy WHY?  When we were still hunter gatherers and that Sabre toothed tiger was stalking the slow one in the mob, (ie the one with the big pregnant belly waddling along behind everyone else) was bursting into tears really going to make the tiger stop and decide to eat the slightly faster grandmother over there?  Hmm I don't think so.  The extra blood, the fat deposits even the water retention I can all understand as being beneficial for mother and bub but I just don't get the over emotional hormonal state.  Oh Well only 30 weeks and 3 days to go, but who is counting ;-)