Around the world, only 5 to 20 percent of the population is left-handed. But why?
A 2012 study suggested that societies that had more shared tools have people with the same hand dominance. It makes sense, right? If you only have right-handed tools to work with, you’d better learn to be right-handed or risk injury.
Another study thought handedness came into play for better combat. Those who were left-handed, it was determined, had a better chance of winning a fight. Although perhaps that is because most people are expecting an attack from the right.
And then there is the theory of genes. Some scientists thought genes were definitively the way that we get our hand dominance. However, some identical twins favor different hands.
Huh. So, why are some people left handed?
Well, it looks like it’s a combination of environmental factors and genetics. And a new study has begun to find some of the genes that are most responsible for it.
A gene called PCSK6 is known to provide the information as to where internal organs should be in the body. People with mutations to this gene can have conditions where their organs are reversed in their body (situs inversus), or basically have two left sides to their body and multiple spleens (left-handed isomerism).
But it was also found that this gene can affect how the brain works, specifically when it comes to hand dominance.
There’s still more research to do, but it gives scientists a good place to start.
Pretty cool, huh? Here are some other interesting stories that came about this week…
1. Babies know animals should have guts. In this study, it was found that infants expect things that move to have organs inside. When objects were made to appear to be alive and then were broken apart, babies showed surprise that the objects were hollow.
2. A mom posted on her blog about how teenage girls should cover up. This created a slew of responses, from pats on the back to comments about “slut shaming”. I read many of the responses and I liked this one because while the author disagrees, she keeps it civil.
3. A study found that kids can’t properly assess risks. No wonder they don’t listen when you tell them to “stop doing that or you’ll get hurt”! :)
4. Some airlines are making kid-free quiet zones in their planes. Good idea or insulting? Let me know in the comments!
5. More than one fifth of parents think it’s okay to skip the kid’s seatbelt. Interestingly, the wealthier the parent, the more likely they are to say that kids not wearing a seatbelt sometimes is okay.
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Photo courtesy of Heather Katsoulis on flickr.com.