Teeth and Your Brain

My daughter is teething.

It's because she's between the ages of 3 months and 12 years.

I find it funny when people ask about whether her recent irritability streak could be caused by teething.

Of course it could be caused by teething!  She's between 3 months and 12 years of age.  Only she knows when one is about to pop through.

Now, my daughter is running a bit behind in comparison to her contemporaries:  shes' just over a year and only just now is getting her top two front teeth.  (I have to say that I may never get used to her mouth full of teeth).  I did notice, however, that the teeth entered in this pattern:

9 months:
Bottom right, Bottom left (within a day or two of each other)

13 months:
Top right, Top left (with a day or two of each other).

Now, it looks like the secondary incisors are coming in and I was wondering as I was trying to keep her gleeful hands out of her diaper change:  which side is going to come in first.   I started to wonder if there was any linkage between the tooth side that comes in and the handedness of a person.

And it turns out THERE IS.

It turns out that the first teeth to erupt have a strong tendency to indicate handedness; so, as you might guess, I have a right-handed daughter.

So, it seems that there is some sort of genetic factor that is controlling, or at least highly suggesting, handedness.  That isn't to say that a person, particularly young enough, can't learn to use other hand.  But I do know from anecdotal examples, that doing this is never a good idea for the person- they seems to suffer all sorts of learn difficulties.

But what is interesting to me that, this genetic factor...well, does it mean that it determines handedness in other toothed animals, as well?  It's kind of weird to think of a shark having a "right fin", but what if they do??    Perhaps this predisposition toward handedness is actually a result of some ancestral cell division (err....let's just simplify that and say that there are different formats (circles, binary, etc) of cell division....you know mitosis, meiosis?  Ok, another topic for another time).

Anyway, it does make one wonder...though I think that most of us with 4-legged companions would all agree that this wouldn't be nearly as surprising as to find out that there are right- and left-handed pigs.