Brother Sperm Help Each Other Out
Science used to believe that sperms mindlessly raced towards a singular destination, with the sole mantra of "PENETRATE EGG" guiding their swim. However, we've found that they can battle against one another, take a breather, and now - even help each other out. Related sperm can identify each other and "draft," setting up a semen train a la Lance Armstrong, getting in line in order to reduce the overall drag.
"It's really amazing that this single cell can do this," states Heidi Fisher, evolutionary geneticist at Harvard University. "We used to think of sperm as packs of DNA with really fast tails. But [now we know] they're able to make these complex organizations."
The discovery was made by Fisher and colleague, Hopi Hoekstra, who took sperm from mice, put it in a dish, and watched what happened. The sperm were identified by a special dye which glowed under UV light. The sperm of one mouse glowed green, the other red.
Two experiments were performed: one using sperm from unrelated mice and one using sperm from related males. In both tests, the sperm grouped up. When both sets of sperm were unrelated, they grouped up randomly. But when the sperm was from a related male, they tended to cluster more often with their genetically-related sperm than a stranger's sperm. Even odder: once the sperm reached the egg, the competition was back on and brother sperm became rivals once again.
Source: National Geographic