Re: isn't 6 fingers better than 5 fingers?

Hi Kai

your question is very good and insightful. The answer is very pragmatic.

Higher organisms are very complex machines; a finger, for example, needs 
skin, bone, blood and lymph supply, nerve supply, but also needs the 
correct bony support and positioning so that it functions effectively.

The trouble is that most mutations are random; if you can imagine a very 
complex piece of machinery, and making a random change, it is no surprise 
that most mutations lead to damage and non-functional machinery. 

In the case of the fingers, an extra finger would need all the things I 
mentioned above, but would also need to confer an advantage over and above 
5 fingers. It is not clear that 6 fingers would be an advantage over 5. 

It is only the rare or occasional mutant that actually eventually leads to 
an advantage for the host organism.

hope this helps
david