@Valryan14 15 October 2020 edited

Why does left-handed people exist? In our society, mostly in the different fields are right-handed people and only few are left-handed. And there are lots of rumors about them that more left-handed people excel in some different fields like sports. Boxing, softball, tennis, and other sports with a use of handedness is where left-handed people excel. So let's discuss what is the cause of its existence why does left-handed people exist.

https://unsplash.com/photos/PxxAXP1hVh8 If you know an older left-handed person, chances are they had to learn to write or eat with their right hand. And in many parts of the world it's still a common practice to force children to use their "**proper**" hand. Even the word for "**right**" also means "*correct*" or "*good*" not just in english but many other languages too. If being left-handed is so wrong, then why does it happen in the first place? Today, about 1/10 of the world's population are left-handed. Archeological evidence shows that it's been that way for as long as 500,000 years. With about 10% of human remains, showing the associated differences in arm link and bone density. And some ancient tools and artifacts showing evidence of left-hand use.

https://unsplash.com/photos/Hl3LUdyKRic And despite what many may think, handedness is not a choice. It can even predicted even before birth base on fetus' position in the womb. So if handedness is inborn, does that mean it's genetic? Well, yes and no. Identical twins who have the same genes can have different dominant hands. In fact, this happen as often as it does with any other sibling pair. But the chances of being left or right-handed are determined by the handedness of the parents. In a surprisingly consistent ratios, if your father is left-handed and your mother is right-handed, you have a 17% chance of being born left-handed. While 2 right-handed couple will have a left-handed child but only 10% of the time. Handedness seems to be determined by a roll of the dice but the odds are set by your genes. All of these implies that there's a reason that evolution has produced the small proportion of left-handed people and maintained it over generations.

https://www.google.com/search?q=competitive&client=ms-android-xiaomi-rev1&prmd=inbv&sxsrf=ALeKk02mSyd-YppyT_MnUIWFmqhTMU1yOw:1602815511564&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjnzNOJibjsAhWFLqYKHfx7AFIQ_AUoAXoECCAQAQ#imgrc=mUkktlwkMpXSTM A recent mathematical model suggest that the actual ratio reflects a balance between these 2 pressures on human evolution: **Competitive** **Cooperative** The benefits of being left-handed are in an advantage in involving an opponent in combat or competitive sports. According to principles of evolution, groups that have a relative advantage tend to grow untill that advantage disappears. If people were only competing and fighting throughout human evolution, natural selection would lead to more left-handed people being the ones made it until that so many of them is no longer a rare asset. So in a fairly competitive world, 50% of the population would be left-handed. But human evolution has been shaped by cooperation as well as competition. And cooperative pressure pushes handedness distribution in the opposite direction. By correctly predicting the distribution of left-handed people in the general population, as well as magic data from various sports, the model indicates that the persistence of left-handed people as small but stable minority reflects an equilibrium that comes from competitive and cooperative effects playing out simultaneously over time.

https://www.google.com/search?q=puzzle+evolution&client=ms-android-xiaomi-rev1&prmd=isvn&sxsrf=ALeKk00sttbevbTLJaGCvusfmmvOSqHI8Q:1602815689339&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjUo7beibjsAhUJxIsBHdTrCKIQ_AUoAXoECA8QAQ#imgrc=4imVcFWa4t7BHM And the most intriguing thing, is that the numbers can tell us about various populations. From the distribution of pawnees in cooperative animals to a larger percentage of left-handed creature in a competitive hunter gathered society, we may even find that the answers to some puzzles of early human evolution is already in our hands. Image sources: ***Lead Image*** https://unsplash.com/photos/PxxAXP1hVh8 ***First Image*** https://unsplash.com/photos/PxxAXP1hVh8 ***Second Image*** https://unsplash.com/photos/Hl3LUdyKRic ***Third Image*** https://www.google.com/search?q=competitive&client=ms-android-xiaomi-rev1&prmd=inbv&sxsrf=ALeKk02mSyd-YppyT_MnUIWFmqhTMU1yOw:1602815511564&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjnzNOJibjsAhWFLqYKHfx7AFIQ_AUoAXoECCAQAQ#imgrc=mUkktlwkMpXSTM ***Fourth and last Image*** https://www.google.com/search?q=puzzle+evolution&client=ms-android-xiaomi-rev1&prmd=isvn&sxsrf=ALeKk00sttbevbTLJaGCvusfmmvOSqHI8Q:1602815689339&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjUo7beibjsAhUJxIsBHdTrCKIQ_AUoAXoECA8QAQ#imgrc=4imVcFWa4t7BHM