Why there are much more right-handed than left-handed people?

Answer 1

Great question, and the research is not very conclusive in this area.

There is a theory, by Dr. Amar J. Klar (see source), that there is a single gene for right-handedness, and about 80% of the population have it. If you are born without it, then you have a 50:50 chance of being either left- or right-handed. That explains both the current 10:1 ratio of right- to left-handers, and the fact that two left-handers have a higher (but not 100%) chance of producing a right-hander. This also explains the rather interesting fact that more than 95% of right-handers' hair whorls clockwise on the scalp, while the hair of left-handers have a 50:50 chance of whorling either way. I.e. the gene for right-handedness also produces the clockwise whorl on the scalp.

Some of the other theories we can eliminate:

A recessive gene. If left-handedness was simply a recessive gene, then the child of two lefties would necessarily be left-handed. This is not the case.

Re-education of left-handedness. This does explain why there are slightly fewer people over 60 who are lefties (they were educated in an age where schools took active steps to eliminate left-handedness). But this doesn't explain the 10:1 ratio. Plus, even if this was a long-term thing in history, a leftie forced to be a rightie would not pass his false right-handedness on to children (that's called Lamarckism) ... so this would not affect the current population.

Killing of lefties. This would have to be occurring for tens of thousands of years, at a horrific pace, to account for the current 10:1 ratio. And yes, lefties fighting using weapons designed for righties would have a disadvantage (and a disproportionate mortality rate), but the short time that humans have been carrying weapons and killing each other (relatively short in evolutionary terms) would not account for the current ratio.

Answer 2

left handedness is a genetic mutation of the chromosones. It can be passed on in the sense that it is more likely in a parent that possessed it, but can also develop spontaneously. It is quite a minor one and doesn't really affect evolution much, but as it is unnatural it is in the minority. On top of that the life expectancy of left handed people are less than right handed. Imagine back in earlier history where not only would we have difficulty using tools made for right handers but we wouldn't have long to learn and with a history of earlier death we might be unnatractive to females for potential mates, keeping our numbers low.

There's lots of potential reasons we can't really prove, the simplest is it's a minority condition that doesn't always pass on.

Answer 3

2 Million years ago 60-70% of Australopithecines were right handed. 1.6 Million years ago, 70-80% of Homo habilis was right handed; and it was only 100,000 years ago that 80-90% of archaic humans became right handed.
The left hemisphere became organized for language, gesturing and fine motor control for the right hand over the course of evolution. Why? It was a selective advantage to have different areas of the brain "specialized" in different functions. The left frontal/parietal somatomotor areas and the left pyramidal tract mature earlier in the fetal brain, this structures are the ones that determine right-handeness.

Answer 4

The Latin word for left is sinestra, which is the root word for sinister, possibly because being left-handed gives one an advantage over one who is trained to fight right-handed. Fighting someone with that kind of advantage could get you killed, and that is evil from your point of view. Ergo sinister = evil.

Mothers as recently as my generation have so feared the label sinister that they have punished their children for using their left hands. The superstition is certainly older than Christianity, and probably even older than the Romans, who coined the negative word. Egyptian hieroglyphs which come to mind show people using their right hands, not their left.

Answer 5

It has to do with genetics.The right-handed gene is the dominant gene. To be left handed you have to have two left handed genes (one from each parent). If you have any combination with a right handed gene, you will be right handed. This works out to about 20% of the population being left handed.

Answer 6

because back in the day, people were forced to learn it the right handed way. And their kids follow them, and then so on and so on. Now there isnt a rule. My grandmother can right right and left at the same time!

Answer 7

Human brains are wired to be right handed.
some times one slips out left handed. But not to
worry a lot of famous people were/ are left handed.

Answer 8

because there's been periods in history where left-handed pple have been put to death before they were allowed to have kids. during these periods, usually in christian societies, left-handedness was though to be of the devil

Answer 9

The best are always in the smaller percentages.

Answer 10

left handers are more intelligent