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Why 90 percent of humans are right-handed

Around 90 percent of people worldwide are right-handed. Scientists have spent decades trying to find out why. Researchers from Oxford University in the UK believe they have a possible answer. Their research suggests that the answer is because of two features of human evolution. The first is walking on two legs, and the other is the large size of the human brain. When humans first started walking on two legs, their hands were free to do things. Our large brain worked out many things to do with our hands like using tools. If most people used the same hand, using tools and working with others became easier. This became useful for things like hunting and cooking.

Scientists thought the key to finding the answer was why only humans are largely right-handed. Primates (monkeys and apes) use both hands equally. The researchers compared human behaviour and brain patterns with 41 species of monkeys and apes. The research findings showed that humans have longer legs compared to their arm length. Another reason is that the left side of the brain controls the right hand. It is also responsible for motor skills and coordination. A researcher said: "By looking across many primate species, we can begin to understand which aspects of handedness are ancient and shared, and which are uniquely human."

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brain scientists / decades / research / evolution / hands / / tools / cooking / hunting / key / monkeys / apes / human behaviour / arm length / motor skills / reason / ancient

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Discussion

1) Do you ever think about being right- or lefthanded?

2) Would you like to be able to use both hands equally well?

3) What do you know about human evolution?

4) Are you good with your hands?

5) What things do you do most with your left hand?

6) How are smartphones changing what we use our hands for?

7) Does being left-handed have any disadvantages?

8) Should we shake hands with right and left hands?