MEN may be capable of subconsciously increasing the quality of their semen when their sperm might have to compete.
Zoologists Leigh Simmons and Sarah Kilgallon of the University of Western Australia in Perth asked 52 heterosexual men aged between 18 and 35 to ejaculate into a container on two occasions, once after viewing images of two men and a woman, and once after viewing images of three women. After looking at male-female images, 52 per cent of the sperm in the samples were motile compared with 49 per cent after women-only images (Biology Letters, DOI: 10.1098/rsbl.2005.0324).
Previous studies have shown that men tend to prefer the kind of 鈥渟perm competition鈥� images used in the study. Men may have evolved to find them more erotic, Simmons speculates.
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