Fisher, HE (1994)
The Journal of NIH Research 6#4:59-64. Reprinted in Annual Editions: Physical Anthropology, Spring 1995
Romantic love (characterized by at least two emotional stages, attraction and attachment) is a cultural universal. I propose that the human neurophysiology for these emotions evolved in our first hominid forebears some 4 million years ago as chemical mechanisms designed to initiate affiliation and sustain ancestral pair bonds through the infancy of a single altricial (helpless) child, a period of about four years. Serial monogamy during reproductive years has had adaptive advantages throughout human evolution, and natural selection has resulted in primary human mating behaviors that are still visible in worldwide patterns of marriage, divorce, and remarriage, as well as in the characteristic ebb and flow of human romantic love.