DOMINANT male mice have superior sperm, according to a study in Japan.
Sachiko Koyama and Shinji Kamimura at the University of Tokyo raised male
mice in pairs. They established which were dominant or subordinate by their
reactions to intruders.
When the mice reached sexual maturity, the researchers tested their sperm to
assess how many were motile. The more motile a sperm, the more likely it is to
fertilise an egg.
About 48 per cent of the sperm from dominant mice were swimming around, says
Koyama, compared with only 19 per cent of the sperm from subordinates. She
announced the results last week at the International Ethological Conference in
Vienna.
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