Wednesday, January 16, 2013
One thing you can say about natural selection is that it just doesn't care. It doesn't care about beauty, elegance, or simplicity of design – those are all things that we humans see in nature. As far as biology is concerned, if something works, it works. Never mind how it looks.
Take aquatic birds, for example. When you see a bird preening its feathers, it's not trying to make itself pretty – again, that's just our interpretation. What it's really doing is spreading oil over its feathers, keeping them clean and water-resistant. All birds have oil glands, and the more time a bird spends around water, the more oil it needs.
As you might expect, species that spend most of their lives on or under water – grebes and loons, for example – have evolved super-sized oil glands to keep them from getting waterlogged.
And then there are the cormorants.
When some distant ancestor of modern cormorants first ventured into the water in search of food, it must have been soaked when it climbed back onto land. So it spread its wings out to dry in the sun. That bird survived and passed its behavior along to its descendants, who never evolved the extra-large oil glands of other aquatic birds. Cormorants – which eat fish and nothing else – can only stay in the water for short periods of time. Then they have to get out and dry off before getting wet again.
Does this make sense? Would you buy a boat that wasn't waterproof, that had to be hauled out to dry every hour or so? Have cormorants really evolved the most beautiful or elegant solution to the problem of wet feathers?
Natural selection doesn't care.