Tuesday, January 26, 2010

Sperm vs Sperm

Sperm are no longer just brainless, goal-oriented male reproductive cells!

Well actually, they still are brainless goal-oriented male reproductive cells. It may seem obvious to people everywhere that the only goal programmed into the machinery of a sperm is to get to the egg first. This race for fertilization is nothing new. However, a group of scientists studying the activity of sperm in different species of deer mice have made a new discovery: sperm are capable of altruism.

Altruism is when one individual's actions lessen the fitness of that individual while increasing the fitness of another individual. Too jargony? Lets say Sam and Dean are brothers and need to jump from a burning plane to survive. There is one really old parachute and one really new parachute. Dean lets Sam have the good parachute. This is altruism. Dean may now end up squashed against the earth and never reproduce because he chose the ancient parachute. However, Sam will most likely survive to carry on the family line. Dean and Sam both win, because passing on genes from your gene pool (even if they are not directly your own) still counts.

So back to the deer mice. The deer mice want to pass on their own genes more than anything else. But what if you are a promiscuous species of deer mouse, and the females of your species successively mate with different males only a minute or two apart? How the heck are you going to ensure that your sperm make it to the egg first? Evolution has come up with the answer: cooperation.

The scientists studying the sperm have discovered cooperation among sperm of promiscuous species of deer mice. Rodent sperm have a hooked head so that individual sperm cells can cluster together and swim towards the goal as one. This gives the sperm of that male a competitive advantage and therefore increased chances of sperm from that male getting to the egg first.

I'm quite aware this has little to do with animal behavior, but sperm behavior counts as similar in my book. Anyway, the take home message is- competition is good, but team work is more important. Or you could just stay in a monogamous relationship and that would make things easier evolutionarily. Now, how to pass that message onto the deer mice?

1 comment:

  1. Sperm behavior is animal behavior as far as I am concerned. And I think your Sam and Dean analogy is much geekier than your interest in sperm competition.

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