Re: Is it true that we may not all have the same muscles?why?

Erin:  It is true that we all do not have all of the same muscles, but we 
don't all have the same number of bones, the same exact pattern of blood 
vessels, etc. either.  That is what genetic variability is all about!  
Because we all have billions of base pairs in our genomes, the possibility 
of genetic differences among us is very great.  As long as the differences 
are not so large as to endanger our ability to pass on our DNA to the next 
generation, thoses differences, along with environmental influences, will 
dictate what our offsprings are like.  Even if we have the same number of 
muscles, their orientation over the joints can be different among people.  
Couple that with different boney protuberances and we have people that are 
better at jumping or running or leaping due to different angles over which 
the muscles work & better mechanical advantage. Also, the make-up of our 
muscles vary.  Some people have more fast twitch fibers while others have 
more slow twitch ones.  This, with training & practice, allows us to be 
better at some activities & not so hot at others.  Scientists have done 
muscle biopsies from the Quads of atheletes who specialize in swimming, or 
marathons or sprinting.  They have found that the fibertypes vary greatly 
among them & help them to excell in their chosen event.  The difference in 
fiber make up is due to genetic variability, not in training.  People tend 
to gravitate towards activities in which they do well, so we choose sports 
that we can do well at.  Then, once we have "chosen" the sport that we are 
good at, we train & practice and get even better. That is not to say that a 
person with a marathoner's fiber make up couldn't be a sprinter, but that 
person would never be as good, with equal training, as someone with more 
slow twitch fibers.  I hope this answers your question. Keep studying 
anatomy & physiology. They are very interesting & important fields.