Scientific discoveries about the animal kingdom fuel ideological battles on many fronts, especially battles about sex and gender. We now know that male marmosets help take care of their offspring. Is this heartening news for today's stay-at-home dads? Recent studies show that many female birds once thought to be monogamous actually have chicks that are fathered outside the primary breeding pair. Does this information spell doom for traditional marriages? And bonobo apes take part in...
