How Humans Became (Mostly) Right-Handed 

Some commenters have pointed out that we say "after our lineage split with chimpanzees," "members of our lineage after the split with chimpanzees," and "after our split from chimpanzees" at various points in this episode. Just to clear things up, humans and our extinct relatives share a common ancestor with chimpanzees and their extinct relatives. After our lineage split from this common ancestor, we call our group "hominins." Living chimpanzees also have their own separate evolutionary history since that shared common ancestor.

I was actually born left handed But I had a stroke when I was very young which paralyzed the left side of my body meaning I had to grow up right handed instead. My favorite joke is “ I’m ambidextrous, I just can’t show you right now”

I appreciate that some of our best old evidence of this is from people basically punching themselves in the face on accident.

As a left handed person, I think living in a right handed world forces you to be a lot more ambidextrous than the opposite for right handed people.

You might be interested in how handedness has affected architecture. You will find that in medieval castles and other fortresses that have stairways , those stairways hug the walls such that upon ascending the walls are invariably on the right hand side. This is because it inhibits the movements of right-handed invading swordsmen, giving the (also right handed) defender above an advantage with greater room to swing his sword. Now, a lefty attacking would nullify a lot of that advantage, but the defender would still have the height & weight advantage of striking downwards.

"70% to 95% of us to be exact"... i chuckled

Took a fencing course in college, was one of the best in the class. Finally went up against the other lefty. We engaged and backed off perplexed. Nothing worked the way it was supposed to.

My sister was born a lefty. But when she started writing, she wrote upside and backwards. That is what she put on paper was not only mirror writing, but also inverted vertically. It scared me dad so much, he taught her to write right handed. To this day, she writes mostly right handed, but does most other things left handed. Fortunately it did cause her to stutter like I have heard it can when someone is forced to change.

I used to run a roofing crew. I would purposely hire a lefty because when coordinated with a righty things went quicker and smoother. Things like cutting off extra shingles would be done by the person more comfortable at that particular end of the roof. Sounds weird, but it helped.

one of my teachers used to call me and other lefties a "silver surfer" because whenever we wrote an essay our hand would be covered in graphite

There was a family I knew growing up where a lefty man had married a lefty woman. And they had customized their house to accommodate this: the door hinges, doorknob turns, the refrigerator door, the drawstrings for the blinds etc. Spending time there felt like living in an Escher painting.

About 40 years ago I worked at a company that made woodgrain trim for Jeep station wagons. It was bent by hand . I noticed that if a lefthanded person learned to make a part on one side of the car he could immediately make the same part for the other side. But a right handed person had to learn that side the same way as any other part.

Most of my family members are either lefties or ambidextrous. We have always been very careful of who we sit next to during gatherings like Christmas and birthdays, so that we don't constantly bump into each others when eating. We have a lefties and a righties side of the table. I only very realized that it was an abnormal thing to think of. I went out with a group of friends and asked if we should organize the table according to hand preferences. They were all right handed lol

Footnote: left-handedness had survival value in trench warfare of WWI - soldiers throwing improvised explosives in the dark with their left hand were less likely to be picked off by snipers (who would routinely shoot to the wrong side of the glowing fuse).

Being a Leftie is fine for me until I went to school where their armchairs only have a right arm rest.

As a lefty liiving in a right handed world, things can be frustrating. The doors knobs are on the wrong side and those things at the bank have the pen attached on the right side making them hard to use. Even the gear shifts in cars are installed on the wrong side.

I’m friends with a pair of twins, one right and one left handed. This is called mirroring and occurs when the developing egg splits after a certain time. Identical twins (both right handed)divide before then. I wondered if it’s possible that some lefties could be the remaining twin after an early foetal loss. Often embryos lost very early on are not even noticed as more pregnancies end spontaneously at such an early stage. Just a little pondering of mine.

I used to fence competitively, and found that most fencers have a very difficult time fighting a Leftie. It was a distinct advantage in many bouts.

Being a right handed judo player, grappling with a lefty always feels awkward whereas for the lefty it's business as usual. What's really funny is when you see a really good lefty finally come up against another lefty, because they suddenly look like a beginner again, with neither player knowing how to actually set up their throws because they so rarely encounter one another.

I've sometimes thought that handedness developed as an expediency. We need to grab stuff with a hand so often that it's best to have a default idea of which hand to use, rather than having to decide in each situation. Imagine if each time you wanted to grab something you had to take a few milliseconds to think, "right or left?" If you were fighting with someone who had already decided, he'd beat you every time. Why it's right i have no explanation for.

Funny story: i worked with a guy who applied for a grant from an organization that supports and recognizes left-handed people...he wrote out this multi-page essay about how he wasn't even left-handed and essentially just wrote this essay out of sheer boredome... they ended up giving him the grant because....he literally was the only person to submit an essay for this grant!

Left handed advantage in fencing is actually insane. It's not about surprise, it's about having to invert all your well trained motions when fighting a left-handed person.

If somebody doesn’t say “oh hey your left-handed, didn’t know that” are you even left-handed ?

This was very interesting to watch! I often ask myself if I'm right or left handed, while I can use both with ease and often favour my left than my right and vice versa in certain things. There some things that I do that using my left hand comes so naturally, then there's things I do naturally with my right hand. I naturally use my phone with my left hand and when I'm on a call to my left ear as well, I use a knife in my left hand and the fork in my right (funny enough I can't seem to do it the other way around 😅 (it feels extremely awkward and unnatural). I was often told as a child to use my right hand as I would often swap my hands when learning to write or to draw, and even to use scissors (which I used and still use my left hand for - again feels natural).

I am a left handed person and it shows in the way I write and use my mouse on my left hand during gaming. Sadly, I was forced to use a right handed guitar because my guitar teacher told me it's better off for me to learn right-handed than left-handed. So far, it kinda helped me because I have a stronger grip on my left and it was easier for me to do bar chords.

Leftie advantages: You always know what to say when the teacher asks a fact about yourself, so you get to sit down quicker.

I was the only left handed kid in my 1st grade class. The other kids wondered why I always had lead pencil stains on my hand. Right handers don’t know our struggle.

I had also learned about handedness and distribution of language function having a correlative relationship. Interesting topic!

Im whats called Cross-dominant. I can use both hands, but for different tasks. I cant write with my right hand, but I play golf right handed. Some things I can do equally well with either hand. Some things I suck at with both hands. Playing things like tennis or rounders when I was a kid always confused me. I never knew which handedness I should be.

Knew a girl in High School who could write cursive with either hand neatly. She could also write cursive with either hand as a mirror image neatly. It was fascinating.

”Kangaroos are mostly lefthanded”, that's why they drive on the left side of the road.

This was fascinating. Really makes me wonder what other everyday things like this may be evolutionally influenced/shaped

I use this reference during the Ice Age segment of my novel. Its a good thing this video was uploaded mere weeks before I sent it off otherwise I would have missed out!

Right-handed people will never know the pain of having to write left-to-right with a number 2 pencil all throughout school and constantly having to scrub the graphite off your hand because of how it smudges as it moves over what you just wrote.

Horses are “handed”, going more easily one direction than the other. We spend a lot of time training them to be ambidextrous.

Some of us reached perfection earlier than others and remained left-handed.

@1:43 suboptimal knife grip, chef's grip is better (and imo safer) for most cutting, also the grip on on the carrot like asking for an injury

Eons: "Turns out Neanderthals have been using their teeth as a 3rd hand for quite a while." Me, using my teeth to hold something while opening a door: "Oh, you don't say."

A friend broke her arm when we were in second grade. I started practicing writing my name with my left in case I ever needed to sign a paycheck left handed. It was for naught 'cause I broke my left arm in my 40s

The boxing example is so true. When I taught southpaws, or ESPECIALLY switch fighters (capable of switching stances well) I would often feel like I was standing wrong for a bit. Takes some getting used to.

I’ve never watched a video that repeated itself so much, yet said so little. Halfway through I said to myself “I bet they’ve done this just to hit the 10 min mark”, I was spot on. Not even 1 second longer. So a 4 minute video essay was extended by repeating the exact same thing over and over in different ways.

It had taken me 18 years to realise that everything around me was designed for right handed people. I always wondered why I sucked at pc gaming. It wasn’t until I was 18 and during my first ever exam that I saw someone asking for a left handed chair( there was a table attached to the chairs) then I asked for one and I was blown away by how much since it made compared to the right handed one. I took it for granted that my hand movements sucked but now I know why.

lefty: *uses left hand in the middle ages* everyone: "iS tHiS wiTchCraFt?"

One important group is left out of this conversation-- musicians. Most instruments incorporate equal dexterity in their mastering. Born right handed, playing drums made me reasonably ambidextrous. They even have a name for it--"matched grip"

A thing that has always been noteworthy for me: when I was really young (4 or so) my left handed aunt taught me to knit and crotchet using my left hand. I am otherwise right handed, but on both sides left handed-ness is very common. She grew up in a time that forced her to learn to write with her right hand and later remarked that she didn’t even realize she was teaching me on one hand vs the other. I still can’t make my brain knit or crochet using my right hand as a dominant hand. I think it’s because I was taught so young that the muscle memory is just engrained that for these two crafts it’s a left handed as dominant hand task.

the worst are the scissors that are designed to be so painful to use if you arent right handed 😭

"Although we're the only species on Earth that's so strongly handed" My man's never seen a fiddler crab, I guess?

In cricket, the left-hand bowlers are considered to have an X-factor as they have a different angle, and they cause problems for most batters. As a result, any good left-handed bowler is picked earlier than the others making the aforementioned interaction more favorable for them because you don't usually find left-handed bowlers in domestic circuits. For anyone wondering Shaheen and Starc are prime examples of this today

There could also be another point added that i just thought of: Wernicke's and Broca's regions (language centers) are mostly located in the left hemisphere. Our lingual abilities could also be linked to hemispheral dominance in humans. Evolution may have favoured left hemisphere for some reason. Specialized areas for tasks like tool making, language comprehension and communication seem to be located in left side more..

Being left handed and living in a right handed tool world, has given me almost ambidextrous nature. I can pitch a softball, bowl, and anything else done underhanded with either hand. I play drums open handed on a right hand set, which is 100 times easier than crossing your right hand to play the hi hat. I play guitar equally bad left or right handed. Overall I would rather be left handed than right handed, except when a fountain pen is involved.

have we considered that the less-lateralized brains in lefties could be a result of lefties being forced to do more tasks with their right hands, since the world as we know it and the majority of the tools we make are very biased to right-handedness these days? like having to navigate keyboards, guitars, door handles, etc. (all put the important things on the right side), forcing these people to adapt more significantly than a right-handed person would. not to mention cultures where your left hand is the one you don't eat or touch with.

I remember hearing that you could figure out which skeletons were archers based off on the arm bones ...i was in a discussion of medieval battlefields (and the battles). O could be misremembering or was misinformed. Still, it's interesting to consider how our daily lives are shaped by and help shape our bodies.

My granny was left-handed and as a kid she was forced to write with her right hand at school. As a result, her handwriting always sucked later in her life. Even at old age, she complained about these experiences when she was young.

PBS host: Being a leftie can have advantages Me, a leftie: oh really? How many decades/centuries did it take you to make scissors that work for both hands?

My daughter is left handed and self taught herself to play the guitar. When we finally took her to get professional lessons her teacher was shocked that not only did she play left handed but she also perfectly played her chords upside down. He said he, as a professional should correct (not playing left handed) the upside down playing but it intrigued and fascinated him so much that he allowed her to continue and it actually was her greatest strength

Another leftie living in a right handed world. My older brother taught me to swing a basball bat - right handed of course, so I'm a bit a switch hitter, though I actually prefer to hit (and golf) right handed. Still swing tennis and pingpong rackets with my left hand. Being a leftie also helped me when learning the piano... my left hand didn't struggle with bass lines, and my right hand dexerity was already well developed so the instrument just really brought the skill level up on both sides.

Growing up, my dad and two of my three sibs - as well as me - were lefties. I had no idea that right-handers were dominant until I was in school (and began the long search for those weird lefty desks from middle school all the way through all my college years.)

As a righthanded person who plays guitar, I'm often amazed at the intricate fretwork I can accomplish with my left hand. Yet, if I try playing lefthanded, the same left hand becomes utterly spastic when I use it to strum.

Since childhood I've had a Quaker Parrot that is decidedly left handed (footed? clawed?). If you hand her anything like a Cheerio to eat, she will always grab it with her left foot. Likewise she will always step onto your finger left leg first, and step off of it in the same manner. When she was about 20 years old, she fell from a perch and broke her left leg in 3 places. The vet said they didn't have much hope for her surviving the injury, but we gave her constant care and made sure her leg was always well bandaged and dry. She made a full recovery and regained full use of her left leg which she still uses almost exclusively for any task. I've never had another animal with a distinct preference for one side over the other but she was determined, even with a serious injury to continue using her dominant leg and the vet believes that it was her constant use of the leg after the bandages came off that allowed it to regain all of its strength.

It's all about hips for me. I'm right-handed and play many sports but I always main whichever hand is needed for my left foot to be forward such that power generation is a counter-clockwise hip rotation. E.g. baseball: right-handed, disc golf: left handed. (Same full lower-body and core motion, just different hand). I think the eyes are also extremely important. If you have far better sight in one eye than the other, you're a lot more likely to use whatever main hand that goes along with that eye (e.g. shooting a rifle).

Any thought on the development of teaching skills and it's effect on handedness? Maybe it was developed by chance when our ancestors had to choose a hand to teach others. Standing side by side, they would eventually standardize the teaching of skills and favor one hand over the other. The kangaroos choosing a hand lines up with this theory because the kin are taught in this same, first-person (or first-kangaroo, if you prefer) manner.

I’m a left handed boxer (southpaw) and I used to go into the ring with my opponent in a right hand stance until my opponent was tired or if I was losing the fight. As soon as one of those two things happened, I would wait until the next round and get into my Southpaw stance and when my opponent saw the switch, you could see the dreaded look in his eyes. Priceless 😂😂😂

I'm a piano player and it is usually pretty easy to see what kind of handedness the composer has just from looking at the music, most people are right handed and tend to write more difficult parts higher on the staff. As a right-handed person, imagine my shock any time my left hand has to work more than my right

Wow, I just noticed that the toilet flush lever is on the left side! And the garage light switch is also on the left! And the front foor knob is also on the left!

I found this video too late. Oh well. But it doesn't seem to explain an art class of mine back in 1976. One day, the professor asked for a show of hands of how many were left handed. So many students in the class held up their hand including me. He was very surprised, and so was everyone! But since then I've watched closely in films. It seems that there are quite a few left-handed actors, too.

Charles Xavier: "Welcome to the X-Men. What's your mutant power?" Me: "I'm left handed."

I had an lovely aunt (now deceased) who was a University Math Professor, and who was also ambidextrous. I was told that the 1st day of each class she would enter the room, quietly face the blackboard or whiteboard, then put up TWO complex mathematical equations - _SIMULTANEOUSLY!_ From that moment on she had *every* student's attention. 😉👍 (I miss you, Aunt Jean!)

Im left-handed, only troubles i had was in army since the weapons were made for righthands , bullet ejection was facing in so i kept burning my righthand with bullet casings

I used to do Muay Thai in highschool and one of my mates was left-handed but had to learn how to fight as right-handed. It sure made matches interesting when he'd suddenly change his stance from right to left, it always threw his opponents off for a hot second, since our whole defense is weakened if the other person's dominant side is different than ours.

I feel like a significantly higher ratio of left handed people clicked on this video than right handed people.

As a lefties, I just figured out how to use a can opener this year, I have to say I'm proud

I always assumed that our heart is more to left so left hand tended to be in more protective stance

I use my left hand mostly for sensitive detailed work like drawing, writing etc. and my right hand for mostly things that need strenght like throwing a ball, punching or cutting things. That has exceptions tho. Like i crochet with my right hand. I use my right hand for cutting and my left for spreading things while using a knife. I had and still have a big trouble when i start to do something new because i can’t choose which hand to use. I thought i was a leftie because of writing but i might be cross-dominant.

I only realised I was ambidextrous when I was about 10, and found out that right-handed ppl don't "just choose to use their right hands most of the times bc of social reasons". I was shook.

this comment section would have you believe that 80% of humans are left handed lol

I am generally left sided (writing, eating, playing football) but in many other situations I use my right arm, for example in playing volleyball, basketball, while throwing a ball or in boxing.

I was ambidextrous until I started school and noticed that writing with your left is a pain in the neck. Since then I split duties so I do any heavy lifting with my left and anything that needs a fair amount of dexterity with my right.

I do my eye makeup like eyeliner and eyeshadow with each hand corresponding to my eye. I can also use a knife, thread a needle, sew, and do almost any other non-writing task ambidextrously. Unfortunately when I was a kid my teacher saw me regularly write with both hands and told me to stop and only use my right hand. So I can't write well with my left hand anymore.

I once had an encounter with the greeter at the grocery store that I frequented, an older man who only had one arm (it was his left, and I got the idea that he had lost his right arm at a very young age.) I visited the store shortly after badly breaking my left humerus and was in a full left-arm cast from my shoulder to my hand at the time, and he stopped me to ask about the injury. He asked if I was having trouble doing things with a broken arm, because he had "heard that people prefer one hand over the other". It was so bizarre to hear from someone who had no personal experience with handedness.

When I learned Gregg Shorthand, I was taught to write on the right side of the page, then move to the left, so as to not smear the ink from the pen. Also, I put the notebook upside down so the page coil would not interfere with the speed. I shoot right handed tough because of eye dominance.

Left-handed, grey-eyed, ginger woman here (apparently a rare critter, according to some, lol). Since dominant forelimbs in mammals and other vertebrates was mentioned, here are observations regarding avians: they, too, appear to have a dominant foot. And, there's an indication that it impacts how they prefer to interact with humans (avians living in captivity). I began observing this in avians kept as companion animals over the course of many years, and because they were the object of my interest, and I am left-handed, I wondered about them, too. Nine species of parrot and one domesticated breed of duck later, I did notice patterns. What I qualified as left/right dominant for each avian consisted of 2 distinct categories: 1) The preferred foot first extended for most activities, including stepping onto a human hand or arm, or holding and manipulating objects, like food. 2) The preferred human hand for interaction with each avian. Because all the birds, with exception of the Pekin ducks (2 individuals) and 1 individual Cockatiel, American Budgerigar, and Scarlet macaw, respectively, lived with other humans prior to residing with me, and my right-handed spouse, this provided interesting results. Most of the parrots exhibited a consistent and overwhelming use of dominant foot with stepping, holding, and defense (pushing another bird away, for example). The next observation was interesting, because some of the birds had first lived with my right-handed spouse, and came to know me later, or vice versa. The birds showed an absolute preference in terms of which hand we as humans offered food, a step up, or grooming and petting of their heads. If we offered the "other" hand, the macaws, Senegal, 2 Budgerigars, and both ducks either hesitated, waited, or pushed our hand away (with ther bills), refusing our approach. Switching our hand to match their dominant-sided foot proved notable, and I found out my right-handed spouse had noticed this before I'd discussed my own observations of the birds with him. He found himself naturally switching hands to approach each bird to avoid "misinterpretation" by individual birds. I myself had noted the same thing, and in discussing it, realized that the pstticines residing with us appeared to be largely Left-dominant in their own use of limbs. We noted that both ducks, which were acquired at 3 days of age and imprinted on me, but also interacted with my spouse a great deal, showed the same preferences when we picked them up, petted them, swam with them, or gave treats. While dominant foot in avians didn't seem surprising to us, the added element of requiring us as humans to use the "correct hand" to approach them added an additional layer of insight for us, since they were requiring us to adapt to their preference, regardless of our own hand-side dominance. Below are my observations from journals and notes. * = did not reside with other humans during lifetime Pekin duck 1 - Left Pekin duck 2 - Right Cockatiel 1 - Left Cockatiel 2 - Right Budgerigar 1 - Left Budgerigar 2 - Left* Budgerigar 3 - Right Budgerigar 4 - Left Budgerigar 5 - Left (disfigured legs and feet due to neglect and abuse) Budgerigar 6 - Right Budgerigar 7 - Left Scarlet macaw - Left* Blue & Gold macaw - Left Senegal parrot - Left Golden-capped conure - Right Blue-crowned conure - Right Nanday Conure - Right Indian Ringneck parrot 1 - Right Indian Rigneck parrot 2 - Left

I am a RN and I worked on a neurological unit for several years. Part of my patient population was stroke victims. One thing neurologists and neurosurgeons always note is the patients dominant hand which identified the patients dominant brain hemisphere. This is because if a person had a stroke that effects the non-dominant side of the brain, they have a higher percentage of recovery because the dominant side of the brain can take over for the damaged side. Now this is very simplified and there are many other factors, but it was always something that was noted in their records.

My mother was a leftie and got forced, as most were at the time, to learn to write and do other things right handed. So she became semi ambidextrous as a result - she could even hit me with either hand, though I think she preferred her right hand for that, and for throwing shit at me.

I grew up right handed, but in my twenties I had a huge spiritual awakening. After that I was able to use both hands where before I could only use the right. I still write right handed, but I’m legible left handed now too. I also gained the ability to use both hands for complex tasks simultaneously.

I am left hamded but I noticed that im more dominant with my right eye. I also noticed that i like to walk on the right side of someone and when I put shoes on I always put on left shoe on 1st, There is more to this then what we think because at my work place im in charge of 200 employees i move things around for them as in how I would do it and they have to work backwards

I am surprised that eye dominance wasn't mentioned because there is usually a correlation between the two. When aiming and throwing and other handed activities, having your dominant eye towards the front is a huge advantage.

It's amazing how smooth the host rocked his outfit of the day

Brodmann area 44 is also part of Broca's area, the brain region responsible for production of speech, which is further evidence that handedness was somehow evolutionarily linked to use of language by ancestral humans

My husband was left handed as a kid until he brike his left hand and started using his right. He can write, use a utensil, and do most sports with both hands now. This is very helpful for me as I'm left handed and there's no sitting on the wrong side of the table with one another

I taught my son to read and write pre-school. I'm left handed, he just naturally copied me. However, it seems he's more naturally right handed. Now, as a dentist his ability to swap sides or hands appears to help him a little.

My late Dad was right handed except for eating. The first thing he would do when he sat down to eat he would swap his knife and fork. As kids we would prank him by setting his place for left handed so that he would have to do a double swap. Miss you dad ❤️

I’ve always been left-handed when it comes to physical activity: running, stretching, gymnastics, boxing…. But I learned to write with my right hand. But I draw and paint with both.

I’m left handed and in school we didn’t have lefty scissors so I had to teach my self to use my right hand. Now as an adult I can’t use scissors with my left hand. I also had to use a righty mitt when we played baseball so I throw with my right most of the time .

In Europe, passage in tunnels underneath the castles and stairways were turning right. For it was difficult for right-handed attackers during siege to strike "behind the corner". Thus, left-handed squads were formed and highly used for their striking from left to right with ease - somewhat of today s.w.a.t. reminiscence.

Literally was just thinking to myself I was itching for an eons video. I'm clearly well conditioned by their upload schedule

I used to be left handed but when I was 8 yr old my parents forced me to be right handed as some relatives told my parents that being left handed bring bad luck/ omen so I had great difficulty in shifting from left to right handedness. My Right hand writing is really bad and lost how to write by left-hand completely but still my left hand had more force than right hand. In any fight, I mostly throw left punch as it is stronger one for me even though I am right handed

I showed up late to a Calc class in college one day. My instructor was one of those that erased all the notes when they got the bottom of the one section of the board they used. I sat down reached in my bag for a pencil and pad and started writing. I had my eyes on the board and never looked at my paper (a trick I learned in jr high). When I finished I looked down and I was writing left handed. I’m predominantly right handed. All my notes were mirror image (written right to left).

“70-90% to be exact” lmao

Im disappointed there's no poll for you to see what percentages your viewers are for left/right handedness

I'm not ambidextrous but I write and cut and do technical things with my left hand, but I throw and punch and generally have more power in my right arm than my left.