Re: What was the adaptative advantage for H. sapiens to lose the large canines?

Marcello,

Thanks for the very interesting question.  It is probably one of those 
questions which will never have a clear-cut definitive answer, while the 
answers you do receive will depend as much on the person's political and 
religious views, as on their knowledge of the facts.  Here's my attempt, 
anyway !

You are right to point out that the large canine teeth of great apes - and 
indeed many monkeys - could be considered anomalous, but only if such 
teeth are seen as evidence of a carnivorous diet.  If you look at the rest 
of the teeth of most apes and monkeys, you will find they are much like 
our own.  The best description of such dentition is "omnivore" or 
generalist.  Our teeth can deal with most kinds of food adequately, if not 
as well as a specialist species, and we can survive with such 
unspecialised teeth because our large brains and relatively greater 
intelligence enable us to seek out the most nutritious food in our 
environment, regardless of habitat or season.

The enlarged canines of most apes and monkeys serve a social rather than 
digestive function.  They are weapons with which to threaten or 
occasionally attack members of their own species, rather than to seize and 
kill prey.  The whole facial region of H. sapiens has undergone a 
continuous reduction in size during our recent evolution, and this has 
included our canines, although you can feel that they still have more 
prominent roots than their neighbours.  As you are no doubt well aware, we 
have developed numerous alternative methods of impressing other members of 
our species than simply baring our teeth.  The most likely selective 
pressure causing the reduction of our facial area was the developement of 
our enormous brain, and consequent dangerously oversized head, which 
required the reduction of other parts of the head, to keep the overall 
size within reasonable limits.

One other point - although there is evidence that we increased our meat 
consumption while reducing the size of our canines, remember that 
carnivorous animals use their canines only to seize their prey - not to 
eat it.  We have other means of seizing prey.