Summary Scientists may finally have cracked the strange phenomenon by studying 2,000 humans and chimps – and extrapolating the results.
Web Desk) - Two ancient clues may finally solve the mystery of what makes us left or right-handed.
Over 90 per cent of people are right-handed – but we have never understood why.
Scientists may finally have cracked the strange phenomenon by studying 2,000 humans and chimps – and extrapolating the results.
As the brains of our ancestors swelled to ever bigger sizes, their preference for right-handedness grew too.
Neanderthals were mostly right-handed.
But the farther back you go on our family tree, and the smaller our ancestors brains become, the weaker the preference gets.
Left- or right-handedness is mostly determined by genetics.
Fetuses have a favoured hand as early as eight weeks in the womb.
Now, scientists analysed hand preferences in over 2,000 individuals from 41 species of monkeys and apes, including humans.
Most species used both hands equally – but humans stood out as an anomaly.
Only the orange East Javan langur were more right-handed than humans – and orangutans and snub-nosed monkeys showed a slight preference for their left hands.
Brain size and relative length of arms and legs were the two biggest factors in determining hand preference.
Scientists believe there is a strong evolutionary trend for right-handedness.
Our older ancestors from 3 million years ago only showed a slight preference for right handedness.
But Homo ergaster and Homo erectus from about 2 million years ago show a stronger bias for right hands.
The preference grew stronger and stronger the closer the primates came to present day humans – Homo Sapiens.
Picking one side over the other makes animals more likely to survive.
And when our ancestors started walking on two legs instead of all fours their hands were freed up to use tools and perform complex motor skills.
But then why did humans ‘choose’ our right hands?
It comes down to our brains – which are split into two hemispheres.
Each side performs different tasks and so right-handedness may have become baked in.
Scientists added that: “culture may have acted concurrently with or amplified the effects of this emerging trajectory of hominin right-handedness”.
But some mysteries still remain such as: why are there any left-handed people at all?
