"Jan Philips"  wrote in message
>
> The "Mystery Hunters" program (a great program) on the Discover Kids
> channel says that just 10,000 years ago our eye teeth were fangs.  How
> does natural selection cause us to lose something so quickly?  It
> doesn't seem to me that a few thousand years ago someone with small
> fangs would have a survival edge over someone with larger fangs.
> (This could be applied to other things we lost too.)
>
There are very few mutations which build a structure up, but many mutations
which tear a structure down (if you throw a bomb into a building almost
always you will make it lower, just occasionally you will blow a piece of
debris onto the roof and make it higher). This means that there are probably
lots of mutations available for losing something, like fangs.

A very small selective pressure can have a big effect in quite a short time.
The classic example is a tiny pressure on mice to get bigger, which results
in them being the size of elephants in 60,000 years. The example is in
Dawkin's book The Blind Watchmaker, unfortunately I haven't checked the
maths.

With both these factors working together, it is indeed possible that we
could lose something in quite a short time, by evolutionary standards.
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 7/22/03 12:08:46 AM