We moderns tend to think of sexuality as the province of more-or-less monogamous couples, bound together by bonds of love, romantic possessiveness, and jealousy. But according to Sex at Dawn authors Christopher Ryan and Cacilda Jetha, before 10,000 years ago the basic human sexual unit may not have been the couple at all, but rather the small nomadic hunter-gatherer group. Because nature provided for all their needs in abundance, these early humans would have had no modern concept of ownership or property. Everything would have been shared with the group, including sex. Sexual promiscuity would have been the rule rather than the exception.