In the years since the 1859 publication of "On the Origin of Species," Charles Darwin's ideas about evolution have become foundational to the field of biology. Yet though his ideas were revolutionary, Darwin was not all-seeing — and recent scientific work has revealed a missing element in his theories. That missing piece has to do with sperm.
Indeed, beginning in 1970 and continuing full throttle with new research published earlier this year, biology experiments highlighting "sperm competition" among males are filling in some of the blanks left by the great 19th-century evolutionary scientist. As it turns out, there are evolutionary battles raging in microscopic, behavioral, and physical fields. These skirmishes are about the rights and abilities of rival males to impregnate females.
