Handedness

I have two questions,

1) Is this a good explanation (below) of why most of us are either righthanded or lefthanded?

2) Is this explanation new?

Concerning 2), I have of course searched but have not been able to find this explanation, otherwise I would not have posted it here. What I did find was “Researchers are still trying to understand what makes people prefer one hand over the other and why righties dominate.”

Source Megan Gannon, 2019, www.livescience.com/what-causes-left-handedness.html

I have also found other websites and basically all are saying something similar: “we don’t know”.

My explanation is about the first part of the quote above (what makes people prefer one hand over the other) and not about the second part (why righties dominate).

Here is my explanation:

I start by looking at our two hands as one tool, one pair of hands, and not as two separate tools. The brain has evolved to its maximum economical size while maximising the versatility of our pair of hands. Any further increase will cost more than what it will deliver. There are two possibilities, either a) it is better to have two hands with exactly the same skills, or b) it is better to have one hand with slightly better capabilities, and one hand with slightly worse capabilities. In b) it is like taking a little bit of the capability from one hand and giving it to the other, thereby creating handedness. This breaks a symmetry, and whereas as a physicist I like symmetries, there are sometimes good reasons for such ‘symmetry breaking’. For many of the great things that hands can do they actually have to work together, as one tool. It is not too difficult therefore to think of situations where b) is preferred. You need one hand to firmly hold something (lower level skills) and the other hand to do something with it (higher level skills). Both of them need not be equally good, and if they are that is overkill, and therefore a waste of resources. If you can write with your right hand then it is a waste if you can write equally well with your left hand. If some of the versatility of one hand is removed and added to the versatility of the other hand, or if the two have complementary skills, this can make the pair of hands a better tool. Most people will use their left hand to hold a needle and their right hand to put a thread through the eye of the needle. They will be unable, or will need more time, to do it the other way around, and there is no need anyway to be able to do it the other way around. ‘Handedness’ therefore follows logically from the premise that evolution always works to optimise the use of resources.