This was a piece of news that my young, single friends received as depressing, and my more seasoned, married friends received along the vein of tell me something I didn't know. What it boils down to, says Cornell professor Cindy Hazan, is that once a couple has produced a child there is no evolutionary imperative for the passion associated with the first flush of love, and the chemical cocktail that produces it dissipates. Monogamy in the animal kingdom Examples of mating, monogamy and the precedence of evolutionary imperatives in the animal kingdom abound in the latest scientific literature. Although mating for life is relatively unusual among mammals, it happens. Wolves and coyotes mate for life, as do spiny mice and swans.
Gerbils mate for life, in pairs or triads.
Don't ask me how that works. King and emperor penguins mate for life, unless the male shows up late at breeding time, in which case the female moves on to another mate. Late in this case means the male needs to be on a particular ice floe within 24 hours of the female's arrival after the couple has been apart for 10 months. Once thought to be models of monogamy, birds are in fact quite frequently involved in extra-pair mating, says Tim R. Birkhaven, a behavioral ecologist of the University of Sheffield, England. In fact, Birkhaven and others have found evidence that the female may retain the sperm from two or more males within her sperm-storage tubules, and then have some physiological control over which male's sperm to use to fertilizes her eggs.