How do we know that Neanderthals were nearly all right-handed?

A while back I wrote about my visit to the Croatia Natural History Museum, where curator Dr. Davorka Radovčić kindly gave three of us a several-hour look at Neanderthal bones from the nearby location of Krapina, one of the most fruitful Neanderthal sites known. At the time I mentioned there was evidence that most Neanderthals were right-handed, but I didn’t really explain why. Now Davorka has sent me two papers (references and links below) that show how we know this. I’m going to write mostly about the Lozano et al. paper (free with the legal UnPaywall app), which tells the tale up to the present. If you can’t get either or both of these papers, email me and I’ll send them.

It is in fact true that about 90% of Neanderthals were right-handed, and that’s the same as present-day H. sapiens sapiens, even though Neanderthals aren’t really the ancestors of modern humans (we do, however, carry some of their genes). That probably means that the common ancestors of our two subspecies—I consider Neanderthals as H. sapiens neanderthalensis, a subspecies of H. sapiens—were also right handed. And indeed, chimpanzees (though not bonobos) are 49% right-handed and 29% left-handed, with 22% of individuals “ambiguous”.

But new data also shows that our ancient ancestors—before the split between modern H. sapiens and Neanderthals, were also right-handed. How did they do this?

It doesn’t come from looking at arm robustness in fossils, for that doesn’t work, nor does it come from looking at brains (as seen in crania), as that doesn’t work, either. It comes from looking at incision marks on the teeth made when a hominin is holding something in its mouth and cutting it—cutting it with the dominant hand. It looks like this (figures from the Lozano et al. paper:

 

Figure 1 [All captions from figures] Demonstration of how marks were likely made on the incisors and canines. A right‐hander pulls down with a stone tool, cutting through the object held between the anterior teeth. Occasionally, when the tool accidentally strikes the tooth’s surface, it leaves a permanent striation on the labial tooth face. Repetitive marking of the labial face allows for the assessment of which hand was used in this bimanual task

Sometimes you’ll hit your teeth with the cutting tool, and the striations (scratches) that this leaves on your teeth—in particular the incisors and canines, but especially the upper incisors—tell you what hand is doing the cutting. Try it!  Imagine you’re holding a piece of meat, or a skin, in your teeth and cutting it with your right hand (if you’re right handed, that’s what you’ll be doing). If you hit your teeth with the cutter (a sharpened stone), it will make a scratch from lower right to upper left, because the tool  will be oriented that way (hold a piece of paper in your mouth and pretend you’re cutting it). If you’re using your left hand, the cuts will be from lower left to upper right. And since you know where in the jaw the teeth are, you can determine handedness if there’s a consistent direction to the scratch marks.

Sometimes the marks will be horizontal or vertical, and sometimes they’ll be made not by humans but by taphonomic (preservation) forces, like sand scratches. You can deal with the latter by using marks only on the front edge, comparing them to those on the rear of the tooth, which should be subject to the same taphonomic modification. Also, you want not he percentage of teeth that show handedness, you want the percentage of individuals that show handedness. To deal with the first and last problem, the authors used these methods:

Thus, striations were separated into four orientation categories: horizontal (H: 0°–22.5°, 157.5°–180°), vertical (V: 67.5°–112.5°), right oblique (RO: >22.5°–<67.5°), and left oblique (LO: >112.5°–<157.5°). This underestimates the number of right or left handers; for example, an oblique mark of 21° would be classified as horizontal, so if the intervals were expanded the tooth being examined would have come from a right‐hander. However, since most studies have not published the raw data and have used the Bermúdez de Castro et al. intervals, we also used them.

Many of the teeth are isolated, especially in the Krapina sample. For this site we used Wolpoff’s reassembled tooth sets, each of which he labeled as a Krapina Dental Person (KDP). His tooth associations were based on similar morphology, occlusal wear, and interlocking interproximal facets, not on the presence of labial scratches. It is unlikely that any of the KDPs in our sample can be grouped together into a smaller number of individuals.

They also tested the “direction” hypothesis by making mouth guards that could be scratched, but also by looking at mouth guards with embedded teeth, as well looking at present day hunter-gatherers and Inuits. These showed directional striations consistent with observed handedness.

Finally, the authors analyzed several samples of hominin teeth: the total sample included five different types of humans (Homo habilis [OH 65, 1.8 million years old], Homo antecessor [from Gran Dolina, 860‐936 kya] the Sima de los Huesos fossils [430,000 years old probably ancestors of Neanderthals], European Neandertals, and modern Homo sapiens).

Here’s the earliest one, the OH-65 Homo habilis, 1.8 million years old. The graph below gives the directions of the scratches, and the predominance of the red bar (right oblique) over the blue bar (left oblique) shows that this individual was probably right handed:

OH‐65 shows a concentration of striations on the labial faces of the anterior teeth. These are visible to the naked eye. Microscopically, they conform to the striations found in much later hominids. The striations are mainly confined to the left and right I1s, the right I2, and right C1. Right oblique scratches predominate, leading to the identification of OH‐65 as a right‐hander. (n = number of striations per category) [Color figure can be viewed at wileyonlinelibrary.com]

The Gran Dolina H. antecessor individual didn’t have enough scratches to be identified but here’s the tooth of a right-hander from about 400,000 years ago (the Sima de los Huesos site):

Here are three Neanderthal teeth with the striations emphasized: the first is a left-hander and the other two right-handers based on the numerical predominance of directionally oblique scratches:

Here’s the final table that tabulates handedness. The earliest hominin was right handed, as were all 15 of the Sima de los Huesos individuals, suggested that by at least half a million years ago, right-handedness predominanted in hominins. The Neanderthals are the ones from Krapina down, and they show a 90% frequency of right-handedness, similar to humans today.

I should add that they also found directional scratches over old directional scratches (the enamel partly heals itself), so the directionality continued throughout the life of an individual, and they find directionality in teeth estimated to be from 10-year-old children as well. Since they didn’t have knives, I suspect much of this involved cutting meat, but also animal skins.

It looks as if since the hominin lineage branched from the lineage leading to chimps and bonobos, we’ve been largely right-handed: about 90%. It would be nice to have earlier fossil data, but this is pretty damn good.  I think the methodology, with its controls and observations of modern humans, is sound. The authors conclude:

We contend that the handedness data reviewed here shows that right‐handedness extends deep into the past of our species. The modern right‐handedness frequencies in earlier European human fossils from Sima de les Huesos and new specimens from the Early Pleistocene of China and Africa suggest that handedness stretches back well before the appearance of Homo sapiens. European Neandertals represent the biggest samples and continue this pattern, showing a right‐to‐left hand ratio identical to that among living Homo sapiens. In our view, the unique 9:1 ratio of right to left handers appears well before the emergence of modern Homo sapiens and is typical of our genus wherever and whenever it is found.

One question remains:

Why does there have to be a dominant hand? Why can’t humans (or those animals that show handedness) be equally dextrous with both hands?

This may be a byproduct of our brain structure (the authors posit that it’s a result of brain lateralization for language or other reasons), or there may be some other reason we don’t understand why one hand must predominate (and it can’t be random because most of us are righties, and there’s a genetic component to that). Who knows? But we do know that most of our ancestors were right-handed—at least according to these data and the data from the Fiore et al. paper.

____________

Lozano, M. et al. 2017. Right-handed fossil humans. Evol. Anthropol. 26: 313-324.

Fiore, I., L. Bondoli, J. Radovčić, and D. W. Frayer. 2015. Handedness in the Krapina Neandertals: A Re-Evaluation. PaleoAnthropology 2015:19-36.

90 Comments

  1. Curt Nelson
    Posted October 25, 2018 at 12:09 pm | Permalink

    Occasionally they must have hit their gums with that tool, and empathetic fellow diners would have said, “I hate when that happens.”

    • Dave
      Posted October 25, 2018 at 2:55 pm | Permalink

      More than occasionally, I would have thought. I can imagine their lips would have been a mass of scar tissue too. The obvious way to avoid painful slips of the blade would be to slice off pieces of meat and bring them to the mouth in your fingers. I wonder whether they often had to eat very quickly to avoid losing their food to rivals or animal scavengers, and didn’t have the time for such niceties? Perhaps they just shoved their faces into the exposed meat, grabbed the biggest mouthful they could, sliced it free with the stone blade, and didn’t worry too much about nicking their teeth/lips in the process?

      • Curt Nelson
        Posted October 25, 2018 at 4:36 pm | Permalink

        I’ll bet the process requires three grips — the stone knife and both ends of the meat to pull it taught. So the mouth is necessary, and convenient since that’s where the meat is headed.

      • gravelinspector-Aidan
        Posted October 25, 2018 at 6:49 pm | Permalink

        Or maybe … most of the marks are from processing leather into clothing, sinew into bindings, etc.
        By the time you get to the Neanderthals they were pretty much the dominant carnivore on the landscape. One-one-one, they’d probably have been taken out by a cave bear. But Neanderthals would only very rarely be one-on-one with a bear, but a dozen-on-one.

  2. GBJames
    Posted October 25, 2018 at 12:10 pm | Permalink

    sub

  3. Posted October 25, 2018 at 12:10 pm | Permalink

    I added this information to my Intro Biology for Majors lecture on Evolution of Humans several years ago when it was first published. Great example of hypothesis, predicion, and verification from evidence; or did the do the science backwards?

  4. Cate Plys
    Posted October 25, 2018 at 12:36 pm | Permalink

    I love seeing the real nitty gritty of how something like this is figured out. It’s even better when, as in the case of marks on teeth, I can understand what they’re talking about.

  5. Posted October 25, 2018 at 12:41 pm | Permalink

    Speaking of our cousins, the Neanderthals, I am enjoying PBS’ new show devoted to them. Besides the usual sciencey bits, they have Andy Serkis, the motion capture artist and voice behind Gollum in the Lord of the Rings movies. Over the series, he’s going to gradually morph into a live Neanderthal, or as close as we’re going to get.

    http://www.pbs.org/program/neanderthal/

    • Posted October 25, 2018 at 1:48 pm | Permalink

      I watched it and can agree that it is excellent, and very nicely objective about making various conclusions. For example, there was the bit about a neanderthal rib with a partly healed spear injury. As you saw, their tests led them to not make a conclusion about whether H. sapiens or neanderthal caused the injury, even though the data was hinting at H. sapiens.

    • Diana MacPherson
      Posted October 25, 2018 at 2:50 pm | Permalink

      I forgot all about that. I’ll need to find it & watch what I’ve missed.

    • rickflick
      Posted October 25, 2018 at 4:25 pm | Permalink

      Thanks for the reminder. I’m now watching episode 1. Cool stuff.

    • rickflick
      Posted October 25, 2018 at 4:35 pm | Permalink

      Hmmm…a small disappointment here. The handedness in Neanderthals is said to be known through evidence of thickness of the humerus. No mention of the elegant research on dental striations we just learned about.

      • Posted October 25, 2018 at 4:41 pm | Permalink

        So are you telling us that WEIT is literally on the cutting edge?

      • Diana MacPherson
        Posted October 25, 2018 at 5:28 pm | Permalink

        “thickness of the humerus“. Well that isn’t funny. 😝

        • rickflick
          Posted October 25, 2018 at 7:46 pm | Permalink

          It can be when the ulnar nerve is involved. 😎

          • Diana MacPherson
            Posted October 25, 2018 at 8:53 pm | Permalink

            Touché

            • rickflick
              Posted October 25, 2018 at 9:01 pm | Permalink

              Touché avec not too much pressure. 😎

      • gravelinspector-Aidan
        Posted October 25, 2018 at 6:55 pm | Permalink

        The humerus data has been around for decades. As has been data from reconstructing cores at worksites. Now, that latter might be a teaching effect making some sort of bias on top of an underlying trend … quite hard to tell.
        There was something published not long ago (or mentioned here, I’m not sure) about chimpanzee tool use being right-biased similarly to humans, suggesting an origin of handedness pre-dating our last common ancestor. But that’ll rile up the creationists and raise the presidential blood pressure, so let’s not suggest it.

        • rickflick
          Posted October 25, 2018 at 9:46 pm | Permalink

          Nothing left to say but sounds right to me.

  6. Posted October 25, 2018 at 12:52 pm | Permalink

    Once learned, right or left, a task takes more brain power to learn a different hand.

    I have forced ambidextrousness into everything I do except stringed instruments (right). I am left handed, but I do almost nothing exclusively with my left hand. Teaching tasks to both hands (like eating food) always take a bit of brain power. I think that cost outweighs the benefit.

    Specialization usually wins out over versatility. There are some exceptions. I can shovel more snow than most people off a driveway, because I switch hands all the time. Likewise a football player with two powerful kicking legs, etc..

    • Diana MacPherson
      Posted October 25, 2018 at 2:51 pm | Permalink

      There are a few good, and often used for science, handedness tests online. I am what is called “weakly right-handed” so I use my right hand for a lot of things, but not all of them. There are some tasks I do with my left and when I learn a new task, I sometimes can’t decide on a hand right away.

    • eric
      Posted October 26, 2018 at 6:14 am | Permalink

      Once learned, right or left…

      My albeit limited and anecdotal experience is that it is not learned. As soon as a baby is strong enough to sit up and grab things, they show a handedness preference. Put an object on the left side of their body, and they’ll typically grab at it with the right hand even though that takes extra effort and reaching across the body. And vice versa for lefties. As a parent, you can even experiment on your kid (:)) by seeing just how far to the ‘bad’ side you need to put the object before your kid will finally do the ‘rational’ thing and grab it with the nearest hand instead of the preferred one.

    • Posted October 26, 2018 at 11:46 am | Permalink

      I’ve seen data which suggests that left handers are often more ambi than righties tend to be.

  7. Posted October 25, 2018 at 1:00 pm | Permalink

    The question of why there is handedness is an interesting one. I suspect the reason is that many things we do require only one hand. This forces us to choose one hand or the other.

    Of course, we start life with a strong bias toward one hand or the other. This is likely because being born with completely unbiased handedness would be a disadvantage and, therefore, selected against.

    Perhaps the real question is why is right-handedness set at 90% and not some other fraction?

    Ok, I have my helmet on, ready for all the biologists to tell me my theory is wrong.

    • GBJames
      Posted October 25, 2018 at 1:09 pm | Permalink

      Handedness is common, as I understand it, in other animals of all sorts. Says here that animals without hands show handedness.

      But that’s just a quick Google-informed response.

      • Posted October 25, 2018 at 1:15 pm | Permalink

        Yes, and it is more than handedness in humans. We kick with one foot generally, for example. My proposed mechanism works for all species and parts of bodies. My explanation was a bit too human-centric but that is my species after all.

        • Posted October 25, 2018 at 1:47 pm | Permalink

          Also a dominant eye and a dominant ear. All rooted in brain asymmetry, I assume.

          • Posted October 25, 2018 at 2:25 pm | Permalink

            I am right handed and left eyed. Gave me an advantage playing baseball as my dominant eye was closer to the pitcher and gave be a better view at the ball.
            Same would be true for a right eyed left handed.

            • Diana MacPherson
              Posted October 25, 2018 at 2:52 pm | Permalink

              I too am left-eyed. It’s my bad eye too which sucks because I use it for looking through a camera.

              • Posted October 25, 2018 at 2:58 pm | Permalink

                So does mine. I can read with it up to about a foot and then it’s all a blur.

            • ThyroidPlanet
              Posted October 25, 2018 at 4:41 pm | Permalink

              I’d think the ear would make a big difference too – phase difference of one head thickness

          • Posted October 25, 2018 at 3:25 pm | Permalink

            As I mentioned, there are tasks that work best if performed with one hand rather than two. I suspect the same is true for our dominant eye and ear. While we have tests that can detect these kinds of dominance, I have not heard any theories on what tasks drive the dominance. As far as I know, we don’t close one eye to perform many task. Besides, the dominance tests don’t involve that anyway.

            The brain is both symmetric in some respects and asymmetric in others. Physically, it is quite symmetric but there doesn’t seem to be much duplication of function between the two sides of the brain. Using the pretty weak computer analogy, perhaps the two sides are virtually identical hardware but they run different software. I do feel the need to mention that the whole left/right brain hypothesis is baloney.

            • Posted October 25, 2018 at 4:39 pm | Permalink

              I think the mystery is not the lateralization of function, which is just specialization, but the fact that the lateralization is the same across most humans.

              • Posted October 25, 2018 at 4:47 pm | Permalink

                That doesn’t surprise me so much. The placement of bones and organs is pretty consistent across humans also. There is a lot more inconsistency if one looks closer at the location of nerves, blood vessels, etc. I believe roughly the same level of inconsistency applies to brain functionality. This is why the first step in many brain surgeries is to map the functionality in the area to be worked on.

              • rickflick
                Posted October 25, 2018 at 8:58 pm | Permalink

                That’s so good to know. I’m overdue for a tune-up.

        • Diane G
          Posted October 29, 2018 at 4:19 am | Permalink

          Handedness is especially weird, though. It seems to me for guitars (and most stringed instruments?) the the left hand does the more intricate job. And IIRC, all those decades ago when first learning the piano, both hands felt equally dumb to start with, and both progressed with pretty much equal nimbleness as the music got more intricate.

          (Hmm…I wonder, if 90% of humans were lefties, would the piano have had the treble end of the keyboard to the left?)

          Another thing that occurs to me is that there are certain things that humans do together in which it helps to have the same handedness. Heck, just sitting at the dinner table; when my lefty mom-in-law or daughter’s sitting next to me, I want to be to their right! Also, we make one-piece school desks and other items designed for one hand or the other; obviously it’s easiest when most can be the same orientation. Wonder if our sociality had something to do with better survival for righties?

          • rickflick
            Posted October 29, 2018 at 6:34 am | Permalink

            Now that you’ve led us into the fairy land of unconstrained speculation, I to have my question. Is the prevalence of right handedness related in any way to chirality in molecules?

            “The term chirality is derived from the Ancient Greek word for hand, χεῖρ (kheir).”

            • Diana MacPherson
              Posted October 29, 2018 at 7:25 am | Permalink

              There are a few interesting studies on brain anatomy and handedneas out there if you google it up. The one I read had a small sample size but they did notice with weak handedness that there were anatomical
              similarities to how things are laid out in the brain that is different from strong handedness.

              • rickflick
                Posted October 29, 2018 at 10:06 pm | Permalink

                Yes, it appears there are very subtle differences. Larger scale studies don’t find big difference.

            • Posted October 29, 2018 at 9:31 am | Permalink

              Except in the manner you mention, I would guess the answer to be “no”.

              • rickflick
                Posted October 29, 2018 at 11:39 am | Permalink

                Imagine there is a gene for handedness which produces a protein containing a component with chirality which allows easier bonding for right than left handedness. See what I mean by unconstrained speculation?

              • Posted October 29, 2018 at 11:45 am | Permalink

                From the existence of prion diseases, I assume that any variations in chirality in our molecules is probably a bad thing. Probably just more unconstrained speculation.

            • Torbjörn Larsson
              Posted October 29, 2018 at 1:27 pm | Permalink

              The prevalence of left handed – vital heart – inside is related to chirality in the sense that cellar cilia has a rotation direction same as prokaryote flagella. AFAIK the fetus body cavity liquid rotation is set up by those cilia when tilted, and from that the inside polarity can be set up.

              But the outcome is random AFAIK, the heart et cetera could as easily ended up on the other side.

              • rickflick
                Posted October 29, 2018 at 3:55 pm | Permalink

                See! I knew it. Thanks Torbjörn.

              • Diane G
                Posted October 29, 2018 at 10:10 pm | Permalink

                Indeed, thanks Torbjörn! Nice speculating, rick!

          • Posted October 29, 2018 at 9:26 am | Permalink

            Yes, that is interesting about the guitar. I play guitar and I’m right-handed. I imagine it to be possible, but difficult, to learn to play the other way. Basketball players work very hard to learn to dribble and shoot with their opposite hand. I made some progress in that direction when I was young. It’s an ability that improves fairly quickly with practice.

            • rickflick
              Posted October 29, 2018 at 11:31 am | Permalink

              Baseball players, I heard, develop switch hitting since it has advantages against some pitchers. I’d agree that if you start young it wouldn’t be that difficult to do.

              • Posted October 29, 2018 at 11:46 am | Permalink

                I’m guessing that hitting against a particular pitcher is aided by an ability to mentally model that pitcher’s movements so as to predict each pitch’s trajectory faster and better. This modeling is done more efficiently in a batter’s brain with the same handedness as the pitcher.

            • Diana MacPherson
              Posted October 29, 2018 at 2:07 pm | Permalink

              How easy it is to learn with the other hand probably has a lot to do with whether you’re strong or weak handed. I’m weakly right handed so I do a lot of tasks with both hands or switch between them. I am right handed for most things but I wear my watch on my left hand, I knit (badly) with my left hand, play golf with my left hand, etc.

              • rickflick
                Posted October 29, 2018 at 4:02 pm | Permalink

                So you’re telling us you’re ambidextrous? I’ve always wanted to know…do you have trouble sometimes with tasks when you have to “decide” which hand should go first or dominate? Do you, for example, reach for a glass of wine with both hands causing an awkward spillage? There is an hypothesis one hears of that the adaptive source that causes handedness has to do with this kind of “deciding”.

              • Diana MacPherson
                Posted October 29, 2018 at 5:01 pm | Permalink

                No not ambidextrous but weakly right handed. Handedness is described as strongly left or right so you don’t use your non dominant hand for much, weakly left or right handed so you vary your hands and use you dominant for things like writing but you may vary your hands for other tasks and ambidextrous when’re you use either hand for whatever task.

              • Diane G
                Posted October 29, 2018 at 10:14 pm | Permalink

                Interesting stuff, Diana. Sadly, I think this is the first I’ve heard of strong vs. weak handedness. Makes immediate sense, of course…

              • Diana MacPherson
                Posted October 29, 2018 at 10:37 pm | Permalink

                I may have heard about it earlier but I serendipitously started reading about it out of curiosity. I’d always considered myself a wussy right handed person as I use my left for a lot of things.

            • Diane G
              Posted October 29, 2018 at 10:23 pm | Permalink

              I wonder if soccer players try to develop their opposite foot?

              • Diana MacPherson
                Posted October 29, 2018 at 10:38 pm | Permalink

                I think they do. To be flexible with your foot work is a big advantage.

              • Posted October 29, 2018 at 11:46 pm | Permalink

                Oh yes. Absolutely.

              • Diane G
                Posted October 30, 2018 at 2:58 am | Permalink

                Thanks Diana & Paul. In retrospect that was a very stupid question! 🙄

              • Diana MacPherson
                Posted October 30, 2018 at 8:59 am | Permalink

                No it wasn’t!

  8. ThyroidPlanet
    Posted October 25, 2018 at 1:46 pm | Permalink

    Sub

  9. Posted October 25, 2018 at 1:50 pm | Permalink

    What an interesting technique. But don’t we have written evidence, like with the Big Bang? What does the Koran say?

    • gravelinspector-Aidan
      Posted October 25, 2018 at 7:00 pm | Permalink

      What does the Koran say?“I was written in a culture dominated by left-handers (when the writing system was devised)”. (Which was pre-Koran, so probably didn’t exist. But “Meh”.)

      • rickflick
        Posted October 25, 2018 at 9:48 pm | Permalink

        Weren’t there some kind of restriction on which hand to wipe your ass with using 3, not 1, not 2, but 3 rocks?

  10. Posted October 25, 2018 at 2:12 pm | Permalink

    Where did you get that statistic on handedness in Homo sapiens? I have been looking for that data for years and have gotten values all over the map.

  11. Posted October 25, 2018 at 2:32 pm | Permalink

    So what IS the handedness ratio in bonobos?

  12. Posted October 25, 2018 at 2:53 pm | Permalink

    The post reminds me of how far we have come in time, space, and technology.

    When so many “things” are geared to right handedness you never get to practice and become reasonably proficient at using the left hand as an option.
    Playing the drums if right handed you have no choice but to practice getting the lazy hand (mine being the left) to get even controlled strokes, weight, speed to match the right hand.
    What would be interesting would be to see if use of the left hand for easy tasks like, picking up keys, pointing directions, stirring a pot while cooking as opposed to someone who has not practiced say, using the opposite, left for many, for learning an instrument, golf? or similar.
    I hold my phone with my right and scroll with my left, didn’t think about it until i was told.
    Probably there is no difference and individuals may just have a little more confidence in using the left (or right) hand when needed… perhaps using a knife or/and teeth would NOT be a good way to start.

    • Diana MacPherson
      Posted October 25, 2018 at 2:59 pm | Permalink

      How hard using your non-dominant hand is probably has to do with how strongly or weakly handed you are. There are a few tests you can take yourself online. One is the Edinburgh Handedness Inventory.

      • Posted October 25, 2018 at 3:14 pm | Permalink

        Thanks, I’ll give it a try, i practice latin rhythms for excise and fun and that tends to make my weak hand “wake up”.

      • Posted October 25, 2018 at 3:26 pm | Permalink

        The EHI was comprehensive and eh…handy, thanks for that.

        • Diana MacPherson
          Posted October 25, 2018 at 3:37 pm | Permalink

          Yeah it was a bit of serendipity that I was looking into handedness for no reason other than I read something else (which I forgot about) that made me go look into it. Then poof! this article talks about it.

    • Eric Grobler
      Posted October 25, 2018 at 3:01 pm | Permalink

      At least the British change gears with their left hand!

      • Posted October 25, 2018 at 3:11 pm | Permalink

        NZ also, but auto transmission has put paid to that for most. Disturbingly right hand road drivers (tourist mainly) have caused a few head on collisions.

        • Diana MacPherson
          Posted October 25, 2018 at 3:12 pm | Permalink

          It always surprises me that they let tourists from right side driving countries just get in a car and drive away in NZ. Most when I’ve rented are stick (which is fine that’s what I’ve driven for years) but it is an adjustment.

          • Posted October 25, 2018 at 3:17 pm | Permalink

            When it got really bad they started installing audio (some vehicles) and visual reminders on board rentals, camper vans, etc.

          • infiniteimprobabilit
            Posted October 26, 2018 at 8:50 am | Permalink

            ?

            Well, right-hand countries let tourists from left-hand countries (NZ, Oz, UK, Japan) just get in a car and drive away. It cuts both ways.

            What is mildly disconcerting is that most car rental agencies are located in the centre of cities, or at airports, so the visiting tourist’s first moments of driving on the ‘wrong’ side are in heavy traffic.

            cr

            • infiniteimprobabilit
              Posted October 26, 2018 at 8:54 am | Permalink

              Oh and by the way Diana, it’s depressingly hard to rent a manual in NZ now. Most rentals are automatics. Unlike in Europe where manuals seem to be the default, specially in the cheaper price brackets.

              cr

              • Posted October 26, 2018 at 10:48 am | Permalink

                That was also the case in the UK two years ago: mostly automatics. I think it makes sense for rentals. I was happy to not have to get used to shifting with my left hand. Driving on the “wrong” side on narrow country roads in the Lake District was challenge enough for me. I imagined the rental people were surprised when I brought the car back without incident but perhaps it was just my relief.

              • Diana MacPherson
                Posted October 26, 2018 at 12:30 pm | Permalink

                The signal and windshield wiper controls are also on opposite sides.

              • Posted October 26, 2018 at 12:45 pm | Permalink

                Yes, but they are fairly easy to get used to as they need very little manual dexterity and it is not so much a problem if you make a mistake.

              • Diana MacPherson
                Posted October 26, 2018 at 12:19 pm | Permalink

                The same as in Canada then. Just took longer to get there I suppose.

      • gravelinspector-Aidan
        Posted October 25, 2018 at 7:04 pm | Permalink

        Only if we’re driving a right-hand car. Or we’ve got a broken left hand. (Been there, got both tee shirts, though not simultaneously. Hell, I’ve even driven an automatic on a couple of occasions and that was weird!)

  13. Joe Dickinson
    Posted October 25, 2018 at 3:24 pm | Permalink

    Interesting. I was guessing that one could deduce handedness from flaking patterns on stone tools. With either pressure or percussion flaking one would expect the piece being worked to be held in the non-dominant and the relevant tool in the dominant hand.

    • Diana MacPherson
      Posted October 25, 2018 at 3:36 pm | Permalink

      I was expecting the same.

    • Posted November 3, 2018 at 2:28 pm | Permalink

      So was I. But I am not disappointed by the post, not at all!

  14. CAS
    Posted October 25, 2018 at 3:35 pm | Permalink

    This discussion has to be from the point of view of an outside observer, not the person doing the cutting. Otherwise you seem to have this backwards.
    “If you hit your teeth with the cutter (a sharpened stone), it will make a scratch from lower right to upper left, because the tool will be oriented that way (hold a piece of paper in your mouth and pretend you’re cutting it). If you’re using your left hand, the cuts will be from lower left to upper right.”

    • Charles
      Posted October 25, 2018 at 4:16 pm | Permalink

      Yes. And then there is the problem of overhand or underhand cutting motion.

  15. Posted October 26, 2018 at 11:47 am | Permalink

    What a fascinating use of “indicators”!

  16. Torbjörn Larsson
    Posted October 29, 2018 at 1:22 pm | Permalink

    Thanks for an interesting article in an interesting work!

    we don’t understand why one hand must predominate (and it can’t be random because most of us are righties, and there’s a genetic component to that).

    The null hypothesis for alleles is drift, so it could be random outcome in that sense. Presumably it would not be very difficult to evolve since our insides have long had such a polar destiny.

    But FWIW the last suggest a just so adaptation hypothesis: the distance from the hearth may make for a better precision grip.

  17. ThyroidPlanet
    Posted October 29, 2018 at 5:14 pm | Permalink

    There’s a self-experiment you can do, something like rubbing your head in a clock wise direction while rotating your foot in a counter clockwise direction, and Vice versa. Also could add in rubbing your tummy.

    Jeff Bridges had a blurb on it. It’s how I learned about it.

    Not that it tell someone you much about the topic here.


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