A study released this week by biologists at the University of Colorado has found that over the course of millions of years, humans steadily evolved to form monogamous pair bonds and also have a fun little fling or two here and there. Approximately 3.5 million years ago, our early hominid ancestors first began to develop long-term, exclusive pairings with their mates while getting themselves a little something extra on the side, too, said lead researcher James Garvey, who added that by the Pleistocene Epoch, our ancestors had been hardwired to enjoy the occasional purely physical, no-strings-attached dalliance if the opportunity happened to present itself amid their otherwise monogamous lifestyles. The tendency of human beings to provide for their young resulted in both male and female parents cohabiting but every now and then slipping off elsewhere to get some outside action, whether it was just a one-time thing or fairly regular hookups with someone they had an understanding with about this kind of thing. In this way, forming stable, monogamous pairs while every so often indulging ones innate, red-blooded urges with a different partner has become a fundamental biological trait of our species. The researchers, who emphasized that such flings are totally natural, went on to note that there was no evolutionary reason why anyone needed to know about them. 