Re: human body

Hi Danny,

Thanks for your question about the size of peoples' legs and feet. 
It occurs to me that you have displayed one of the characteristics 
of a scientist by asking this question. You have observed 
something that anyone can observe, and yet you have been able 
to notice something interesting.

I have no doubt that you have classmates with one leg longer 
than the other, or one foot larger than the other. In fact, if you 
were able to find someone without these subtle 'imperfections' I 
would be quite amazed.

How can it be possible that two seemingly identical body parts can 
be different? There could be many reasons on a biological basis. 
There could be medical reasons as well. Let's think about biological 
possibilities that you might relate to everyday life.

Almost everyone favors one hand over the other, whether they are 
right-handed or left-handed. Let's take me for an example. I use my 
right hand a lot more than my left. The muscles on my right arm are 
therefore larger and stronger than the corresponding muscles on my 
left arm. These stronger muscles put an increased tension on the 
bones in my right arm (muscles insert into bones). The bone 
responds by trying to grow stronger to compensate for the added 
stress, and maybe ends up being thicker than the matching bone 
in my left arm. It also might end up being a little bit shorter. In the 
case of legs, people can also favor one leg over the other (which 
relates more directly to your question).