January 5th, 2004


Ligaments and Evolution

The interesting thing about ligaments is that they aren't regenerative. Tendons, muscles, bones, these all will heal themselves when damaged. If you break a bone for example, it will knit itself back together. Ideally you should have it set so that it mends correctly, but the important thing is that the bone will heal itself.

Ligaments on the other hand, do not do this. If you tear a ligament it stays torn. I was thinking about this last night (because I'm an insomniac), and I found myself wondering why this is the case.

Not from a biological perspective: I'm sure there is some cellular reason that doesn't really interest me. But from an evolutionary perspective. Why would a tissue evolve that does not heal itself when damaged? Wouldn't that be counter-productive?

You would think that an organism which heals itself would outlast those which don't. It would live longer and reproduce more, so its characteristics would dominate the species. That's the whole theory of evolution; that's how it works.

The fact that ligaments do not mend themselves must mean that there is some quality they have that is more important than regenerating. In fact it seems to me that this characteristic must go hand-in-hand with not regenerating. Otherwise some form of self-healing should have evolved. There must be something about the ligament's non-regenerative tissue that made it more likely to last. Something that made the species more likely to survive longer. Interesting, isn't it?

Anyway, these are just a computer scientist's muddled thoughts on biology and evolution. Now I'd better get back to Java, where I belong.