Indications of spermatic firepower are evident in the differences between a man's first spurts and his last. A human ejaculation typically consists of anywhere from three to nine spurts. Researchers who somehow managed to capture "split ejaculates" for analysis found that the first spurts contain chemicals that protect against various kinds of chemical attack. What sort of chemical attack? Aside from leucocytes and antigens present in a woman's reproductive tract {more on that later}, they protect the sperm from the chemicals in the latter spurts of other men's ejaculate. These final spurts contain a spermicidal substance that slows the advance of any latecomers. In other words, competing sperm from other men seems to be anticipated in the chemistry of men's semen, both in the early spurts {protective} and in the later spurts {attacking}.
( Christopher Ryan )
[ Sex at Dawn: The Prehistoric ]
www.QuoteSweet.com