Introduction
If you know a senior citizen who is left-handed, chances are they had to learn to write or eat with their right hand. In many parts of the world, forcing children to use their “proper” hand is still common practice. Even the word for “right” can mean “correct” or “good” in languages other than English. There are, however, many other languages.
But, if being left-handed is so bad, how did it come about in the first place?
Genetic problem
Today, nearly one-tenth of the world’s population is left-handed. Archeological evidence indicates that this has always been the case. For up to 500,000 years, with nearly 10% of human remains displaying the associated differences in arm length and bone density, and some ancient tools and artefacts displaying evidence of left-hand use. And, contrary to popular belief, handedness is not a choice.
It can be predicted even before birth based on the position of the foetus in the womb. So, if handedness is inborn, does it follow that it is genetic? Both yes and no. Identical twins with the same genes can have opposing dominant hands. In fact, this happens just as frequently with any other sibling pair.
However, your chances of being right or left-handed are determined by your parents’ handedness in surprisingly consistent ratios. You have a 17% chance of being born left-handed if your father was left-handed but your mother was right-handed. Only 10% of the time will two right-handed people have a child who is left-handed.
Competitive and cooperative
Handedness appears to be determined by a roll of the dice, but your genes set the odds. All of this implies that there is a reason why evolution produced and maintained this small proportion of lefties over millennia. Several theories have been proposed to explain why handedness exists in the first place. According to a recent mathematical model, the actual ratio reflects a balance of competitive and cooperative pressure on human evolution.
Benefits of being left-handed
The advantages of being left-handed are most obvious in activities involving an opponent, such as combat or competitive sports. For example, nearly half of the top hitters in baseball are left-handed. Why? Consider it a surprise benefit. Due to the fact that lefties are a minority in the first place, both right-handed and left-handed competitors will spend the majority of their time encountering and practising against righties.
As a result, when the two face each other, the left-hander will be better prepared, while the right-hander will be thrown off.
Fighting hypothesis
The fighting hypothesis, in which a population imbalance favours left-handed fighters or athletes, is an example of negative frequency-dependent selection. However, according to evolutionary principles, groups with a relative advantage tend to grow until that advantage disappears.
If people fight and compete throughout human evolution, natural selection will result in more lefties succeeding until they are no longer a rare asset. In a perfect world, 50% of the population would be left-handed. However, both cooperative and competitive behaviour have shaped human evolution. And cooperative pressure shifts the distribution of handedness in the opposite direction.
In golf, where performance is not affected by the opponent, only 4% of top players are left-handed, illustrating the wider phenomenon of tool sharing. Many of the important instruments that have shaped society were designed for the right-handed majority, just as young potential golfers can more easily find a set of right-handed clubs. Lefties would be less successful in a purely cooperative world because they are worse at using these tools and have a higher accident rate, eventually disappearing from the population.
So, by correctly predicting the distribution of left-handed people in the general population and matching data from various sports, the medal indicates that the persistence of lefties as a small but stable minority reflects an equilibrium that results from competitive and cooperative effects that have played out concurrently over time. The most intriguing aspect is what the statistics can tell us about the various populations.
From the skewed distribution of pawedness in cooperative animals to the slightly higher percentage of lefties in competitive hunter-gatherer societies, the answers to some early human evolution puzzles may already be in our hands.
Conclusion
In the end, it appears that genetics play a significant role in left-handedness. We just don’t know how big a role genetics plays. The best explanation we have for this phenomenon is what we’ve stated here: that complex, negotiable factors ultimately determine whether someone is left-handed or right-handed.