Eli5:what’s the cause of someone being right or left handed? And why the vast majority is right handed?

Question

Eli5:what’s the cause of someone being right or left handed? And why the vast majority is right handed?

In: Biology

Answer 1

Short answer: We don’t really know.

Longer answer: A lot of smart people have been trying to answer this question for many years. And there’s a lot of ideas and theories, and a lot of supporting evidence for many of those theories (how speech processing tends to be on the same hemisphere of the brain that controls the dominant hand, how having a small percentage of the population being left-handed could lead to evolutionary survival advantages especially in regards to fighting against right-handed people, genetics, etc.). However, nothing has really come out as THE conclusive reason why 90% of people are right-handed and only about 10% are left handed.

This video does a good job of explaining this phenomenon, and what we know and still do not know: https://youtu.be/NPvMUpcxPSA?si=8BzpefrQMfCdsif4