Did (or do?) humans ever breed at certain times of the year to produce offspring in a timely manner to survive harsher elements? Or, rather, is there any way to prove that our ancestors had a mating season?
The more I think about this question the more dumb it sounds to me. And it may just be a product of my northern climate where everything has its time and place. The birds, deer and fish all mate in the early spring to have babies tough enough for winter. Is it our adaption through technology that has allowed us to produce offspring willy nilly?
There have been studies done on the seasonality of estrus in primates. tl, dr; more food = more sexytime.
http://www.ncbi.nlm.nih.gov/pubmed/16151605
Since primates, and eventually the genus Homo, evolved in a tropical climate, where there is only wet season and dry season, it stands to reason that primates wouldn't need to evolve a temperate-zone strategy to ensure that babies would be born when the ground wasn't frozen solid. In the tropics, there generally isn't a temperate-zone-type "winter" season when there is no food at all available. Food during a tropical dry season can vary in its palatability, desireability, and nutrition, but it's still there.