Might have to do with matter dominating over anti-matter. Edit: apparently it has more to do with the Weak Nuclear Force, which is the only law of nature that is not symmetric with respect to swapping left vs right (chirality). In other words, there may be a parallel universe identical to ours, except that left and right are swapped. In this case, most people are left handed. But the Weak Force must be different in this universe.
Right handed dominance is more prevalent across nearly all populations (I want to say all, but I don’t know that for sure), and there is good evidence that it is prevalent in primates as well (both from observational studies as well as neuro anatomy). There might be more recent research that can pinpoint a reason, but last I heard we don’t really know why. There is some evidence that the same structures in the brain associated with both tool usage and language development are associated with hemisphere dominance, but I don’t think there is anything conclusive. If that were the case, then hemisphere dominance is sort of an “accident” of evolution, where a selected for trait (tool use, language) is closely linked to structures in a particular half of the brain which is associated with right hand dominance.
There is a new theory emerging that this may be influenced by or stem from the same root as the asymmetry of the respiratory diaphragm, but it’s pretty early days on that one.
Pure conjecture here, but the fact that it’s consistent across cultures points to it being based in biology.
The two most likely reasons I can think of are:
Injury – the left side contains the heart, and there may be a slightly larger chance that you will be injured on your dominant side. As humans have industrialized, this has actually gotten worse because there is a subconscious bias when designing equipment and safety mechanisms that favors a consistent dominant hand.
Pathology – many cultures have some history of evil being associated with using the left hand, the best explanation I’ve heard for this is that in many cultures with poor sanitation, the dominant hand is used for eating and interacting, and the non dominant hand is used for less sanitary endeavors, such as cleaning yourself after pooping. This would mean that a left handed person would be much more likely to spread disease, and that societies that cast them out would perform better over time.
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Might have to do with matter dominating over anti-matter. Edit: apparently it has more to do with the Weak Nuclear Force, which is the only law of nature that is not symmetric with respect to swapping left vs right (chirality). In other words, there may be a parallel universe identical to ours, except that left and right are swapped. In this case, most people are left handed. But the Weak Force must be different in this universe.
Right handed dominance is more prevalent across nearly all populations (I want to say all, but I don’t know that for sure), and there is good evidence that it is prevalent in primates as well (both from observational studies as well as neuro anatomy). There might be more recent research that can pinpoint a reason, but last I heard we don’t really know why. There is some evidence that the same structures in the brain associated with both tool usage and language development are associated with hemisphere dominance, but I don’t think there is anything conclusive. If that were the case, then hemisphere dominance is sort of an “accident” of evolution, where a selected for trait (tool use, language) is closely linked to structures in a particular half of the brain which is associated with right hand dominance.
There is a new theory emerging that this may be influenced by or stem from the same root as the asymmetry of the respiratory diaphragm, but it’s pretty early days on that one.
Pure conjecture here, but the fact that it’s consistent across cultures points to it being based in biology.
The two most likely reasons I can think of are:
Injury – the left side contains the heart, and there may be a slightly larger chance that you will be injured on your dominant side. As humans have industrialized, this has actually gotten worse because there is a subconscious bias when designing equipment and safety mechanisms that favors a consistent dominant hand.
Pathology – many cultures have some history of evil being associated with using the left hand, the best explanation I’ve heard for this is that in many cultures with poor sanitation, the dominant hand is used for eating and interacting, and the non dominant hand is used for less sanitary endeavors, such as cleaning yourself after pooping. This would mean that a left handed person would be much more likely to spread disease, and that societies that cast them out would perform better over time.