April 21, 2007

The coolness of evolution

Cool story on NPR the other day about toxoplasma gondii.

According to the tale, the simple toxoplasma gondii protozoa can only reproduce within the bodies of cats. The problem is that the oocysts are shed from the cat in feces where they infect other animals (mice, people, rats, whatever) where the protozoa cannot reproduce.

So, toxo has a bit of a challenge. How to get from the mouse back into a new cat?

Research suggests that the toxo infection causes the mice to be less fearful of cats - and in fact to be attracted to the smell of cat urine. Something about causing changes in the brain (listen to the NPR story for more details, folks). This makes the mouse more likely to be caught, giving toxo a better chance to get into the cat's system.

Genius, I tell you, genius!

I love evolution. The truly freakish ways in which organisms solve their problems of needing an unoccupied nitch and filling that nitch are wonderful to learn about.

How can you not love evolution?


calencoriel said...

You realize, however, that evolution is not something that the organisms "solve" for themselves. There's a mutation that occurs by happenstance and then IF it's something that helps the organism, it increases their chance to survive, reproduce and then pass that gene to the next generation. It's not that the organism solves the problem by adapting - the adaptations are happening all the time in the form of mutation. Sometimes they're helpful, sometimes they're harmful, and most times we never even know they occur.

But IF they occur AND it's something that will aid the organism in its survival and subsequent breeding opportunities then there's evolution...but the organism isn't solving anything...it's just lucky.

But yeah...you gotta dig evolution b/c there are some crazy things going on out there that help organisms win the game of life...

which you win by reproducing, btw... just ask any kid in IB Bio...

PHSChemGuy said...

Yeah, I understand that evolution doesn't actually aim for a nitch. The nitch exists, and organisms randomly change bit by bit, and the ones whose random changes best fit that nitch (or any nitch, honestly) happen to reproduce fractionally more frequently, and over time the whole species or group nudges that way.

But to me the cooler thing is that there are two ways to win by reproducing...

Way #1 - reproduce like a bandit, making offspring left and right all the time - just flood the world with your spawn. let lots of them die off, who cares? There are a hundred million more of them out there to carry on your genes.

Way #2 - reproduce once, put all your resources into that one basket, protect the basket like mad so that you make sure that the one offspring keeps your line going...

It's always good to know that there's a choice. And it's got a lot of social implications in terms of the differences between how the upper and lower socio-economic levels reproduce, eh?