Thursday, January 05, 2006

Olivia Johnson, " Why I'm Happy I Evolved"

This was published as an op-ed piece in the NY Times. It was copied here. It's a great column, with lots of examples of strangely evolved creatures.
[T]he sea slug Elysia chlorotica … not only looks like a leaf, but it also acts like one, making energy from the sun. Its secret? When it eats algae, it extracts the chloroplasts, the tiny entities that plants and algae use to manufacture energy from sunlight, and shunts them into special cells beneath its skin. The chloroplasts continue to function; the slug thus becomes able to live on a diet composed only of sunbeams. …

[T]he wasp Cotesia congregata … injects her eggs into the bodies of caterpillars. As she does so, she also injects a virus that disables the caterpillar's immune system and prevents it from attacking the eggs. When the eggs hatch, the larvae eat the caterpillar alive. …

Suppose you find that a particular bacterium lives exclusively in the gullets of leeches and helps them digest blood. Then I can tell you how that bacterium's genome is likely to differ from those of its free-living cousins; among other changes, the genome will be smaller, and it will have lost sets of genes that are helpful for living free but useless for living inside another being. …

When I was in school, I learned none of this. Biology was a subject that seemed as exciting as a clump of cotton wool. It was a dreary exercise in the memorization and regurgitation of apparently unconnected facts. Only later did I learn about evolution and how it transforms biology from that mass of cotton wool into a magnificent tapestry, a tapestry we can contemplate and begin to understand.

Some people want to think of humans as the product of a special creation, separate from other living things. I am not among them; I am glad it is not so. I am proud to be part of the riot of nature, to know that the same forces that produced me also produced bees, giant ferns and microbes that live at the bottom of the sea.

For me, the knowledge that we evolved is a source of solace and hope. I find it a relief that plagues and cancers and wasp larvae that eat caterpillars alive are the result of the impartial - and comprehensible - forces of evolution rather than the caprices of a deity.

More than that, I find that in viewing ourselves as one species out of hundreds of millions, we become more remarkable, not less so. No other animal that I have heard of can live so peaceably in such close quarters with so many individuals that are unrelated. No other animal routinely bothers to help the sick and the dying, or tries to save those hurt in an earthquake or flood.

Which is not to say that we are all we might wish to be. But in putting ourselves into our place in nature, in comparing ourselves with other species, we have a real hope of reaching a better understanding, and appreciation, of ourselves.

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