Our Skulls Didn’t Evolve to be Punched

Hands evolved to punch faces. Faces evolved to take punches. That’s the hypothesis being bandied about by University of Utah researchers Michael Morgan and David Carrier, the pair proposing that the apparent “protective buttressing” of our skulls and hands is a sign of violent prehistoric fights where fists of fury dictated who would mate and who would exit the gene pool. It’s a great example of a just-so story.

Morgan and Carrier’s new paper, published in Biological Reviews, is a sequel to an initial paper that suggested our hands evolved as cudgels. This was more than a bit of a stretch. “The goal of this study was to test the hypothesis that the proportions of the human hand make it an effective weapon,” Morgan and Carrier wrote in the first study, but they couldn’t provide any evidence that punching was a preferred or even common mode of fighting in the past. The hypothesis rested on a post hoc fallacy of the same sort used by “aquatic ape” devotees – because our hands can be effective weapons, then they must have evolved for that purpose. No surprise that the concept of a spandrel – a trait that wasn’t molded specifically by natural selection, but is an evolutionary byproduct later co-opted for a different use – never appears in Morgan and Carrier’s considerations of pummeling fists.

But the skull paper is even stranger. Although Morgan and Carrier focused on the bludgeoning qualities of modern human hands in their previous paper, their new review suggests that our ancient relatives and forebears – the australopithecines – had faces that were molded into punching bags by natural selection. No sooner did humans come out of the trees, Morgan and Carrier suggest, than they started whaling away on each other. The trouble is that they undercut their own hypothesis, leaving only a crumpled heap of speculation.

Citing crime statistics from western countries, Morgan and Carrier write that fistfights often result in broken noses, jaws, and other facial bones. Therefore, they reason circularly, prehistoric humans that punched each other in the face should have more robust facial bones to cope with such blows. Given that early humans Australopithecus and Paranthropus – the latter often called “robust australopithecines” – had broad faces with wide cheeks and thick brow ridges, they’re obviously perfect candidates for Morgan and Carrier’s favored interpretation.

Morgan and Carrier didn’t study whether or not the hands of the early australopithecines could form a fist. Their previous work was on our species, Homo sapiens. Nor did they look for signs of broken facial bones or blunt-force trauma on prehistoric skulls, or even try to model how early human skulls would have reacted to the stresses of an incoming fist. The entire argument is simply that australopithecine skulls look like they could take a punch.

In Morgan and Carrier’s view, the heavy brows, large jaws, and flaring cheeks of the australopithecines are not signals of the way primates grow or the different plant foods they dined on, as paleoanthropologists have discerned, but were adaptations for reducing damage doled out by males as they competed for mates. There’s no evidence that australopithecines fought like this. The entire conjecture is based on sports like mixed martial arts and modern crime stats. And females don’t even figure into Morgan and Carrier’s hypothesis. Female mate choice, and why sexual dimorphism between the sexes has drastically decreased through time, is either ignored or overshadowed by the belief that we owe our most distinctive features to males walloping each other.  This is bro science – dudes pummeling each other driving human evolution.

The skull of Paranthropus boisei. From Ungar, P., Grine, F., Teaford, MF. 2008. Dental microwear and diet of the Plio-Pleistocene hominin Paranthropus boisei. PLoS ONE 3(4): e2044
The skull of Paranthropus boisei. From Ungar, P., Grine, F., Teaford, MF. 2008. Dental microwear and diet of the Plio-Pleistocene hominin Paranthropus boisei. PLoS ONE 3(4): e2044

Those early humans couldn’t make the tight fists we do, though. Australopithecines – Lucy and her kin – were bipedal walkers that retained some signs of their arboreal ancestry, such as more ape-like arms and fingers. The hands and limbs of archaic hominins don’t match up with the supposedly “buttressed” skulls. More than that, our species doesn’t have the reinforced cheek bones, deep jaws, or prominent brow ridges that Morgan and Carrier cast as defensive structures. If our fists are so well-suited for punching, why have our faces lost their osteological protection? Morgan and Carrier suppose that we’re weaker than our ancestors, and therefore don’t need thick facial bones, but this runs counter to the heart of their hypothesis. If our hands evolved as weapons, then we should see a coevolution between striking hands and stout faces. Our prehistory shows no such pattern.

Saying that our hands are adapted to strike or that our skulls evolved to withstand those anatomical truncheons is fine as a hypothesis. But a hypothesis is just the initial fuel for the scientific engine. Morgan and Carrier haven’t let that experimental machinery run, instead looking to isolated tidbits of modern culture and projecting those behaviors onto our past. That’s not science. That’s storytelling.


Morgan, M., Carrier, D. 2013. Protective buttressing of the human fist and the evolution of hominin hands. The Journal of Experimental Biology. 216: 236-244

Carrier, D., Morgan, M. 2014. Protective buttressing of the hominin face. Biological Reviews. DOI: 10/1111/brv.12112

38 thoughts on “Our Skulls Didn’t Evolve to be Punched

  1. Human skulls became lighter as diet changed from plant to meat based. No protruding jaw, giant muscle attachment needed. Our big brain was made possible by the same change. An overall lighter skeleton is the result of neoteny / domestication. Better tools and weapons reduced the need for heavy musculature-skeleton system. Don’t use it, you loose it.

  2. Modern doctors know that human hands are not adapted for punching–guys who get mad and punch things (windows, walls, pickup trucks, and skulls) often break bones in the punching hand–they may knock out the other guy, but then they’re moaning and holding their own smashed hand. I worked in EMS for six years, and saw a lot of guys who’d gotten mad and punched something/someone. It is possible to increase bone size and strength by stressing it below the breaking point, but even so–human hands are not ideal “tools” for hitting hard things with. They’re too flimsy. Much better suited for holding the branch, rock, rolling pin, hammer, blackjack that actually contacts the human skull.

  3. What evolved was tool use in humans which would include sticks and rocks. If I’m living in a doctor/police-less world then there is no way I’m fighting by the Marquess of Queensberry rules. I’m grabbing the nearest rock/stick and I’m whaling away, I’m not going to use my fists unless I absolutely have to.

  4. Interesting topic, but your critique is poor. If you took the time to read the previous paper (Morgan and Carrier, 2013), you would find the following sentence:

    “[T]he earliest undisputed hominins, the australopiths, had manual proportions very similar to those of modern humans.”

    You should do your homework before writing. Also, invoking adaptationist rhetoric is a poor substitute for providing legitimate evidence against a hypothesis.

  5. Interesting hypothesis and it does beg the question why the radical difference between male and female faces? I had hoped the author would have speculated on an alternate hypothesis to add to the discourse, rather than call the study ‘story telling’. As I see none, I will. I’ll try to provide another possibility. Something in the environment has driven the dichotomy of male/female facial structure. That may be social interaction or physical interaction in the environment. I would put forward, it was not being pummeled by fist alone, but fighting in general. Look to other mammals and the head ‘gear’ they have for both display and protection. Watch two male rams in mating season…In part, anyway, these researchers are on to something although the weapon could be fist, club, rock, stick. Primitive cultures still demonstrate some of these battles to demonstrate fitness for mating.

  6. First: I do not think there is good support for their hypothesis about skulls having evolved by blows to the head. k

    “Citing crime statistics from western countries, Morgan and Carrier write that fistfights often result in broken noses, jaws, and other facial bones. Therefore, they reason circularly, prehistoric humans that punched each other in the face should have more robust facial bones to cope with such blows.”

    Why is this circular reasoning? Populations where blows to the face are common would indeed evolve stronger faces. I don’t understand why the idea is being demolished, rather than the support for it.

  7. Fisticuffs appear to be a fairly recent development in human interaction. Most ethnic groups develop othe strategies for conflict resolution – read sticks and rocks through spears and other sophisticated weaponry. Those groups who have most recently been affected by creeping Western culture are not seen standing upright whacking each other with closed fists. They’re smarter than that. Hands that are smashed and broken cannot carry out the work of survival.

  8. As co-author of the paper I will say that I will have no problem with the critiques of our research. I am thrilled to see people’s reactions and opinions. One of the purposes of our research is to generate debate, discussion, understanding of the more fundamental and problematic issues of human violence and aggression. I realize that this is a blog post and not true journalism, nor peer review, but I have to say that Mr. Switek’s piece shows such a gross misunderstanding and misrepresentation of our research that I truly have to question if he has read our papers.

    I urge people to read the papers themselves and I would expect better from National Geographic.

    M. Morgan, MD

  9. I suppose human fist as a weapon should focus on technique, such as how to give a most powerful punch with the best speed and angle. Anyway, evolution should be analyzed from a more diversified point of view, not just concentrating on the bone for evidence.

  10. Mike Morgan, I found and read your paper. Thanks for making the pdf open access, I sincerely appreciate not running into a paywall. I think “bro science” is a perfectly apt description, however. I thought that perhaps the paper might contain some substance that wasn’t reflected in the press reporting, but alas no. Not all published papers represent research. Sometimes the searching is just perfunctory; merely a poorly founded frame for a foregone conclusion.

  11. @Mike

    “I realize that this is a blog post and not true journalism, nor peer review”

    And yet it does a much better job in discussing your work and not just regurgitating what I assume was a press release, than anything I read yesterday from “proper” science journalists. There are several obvious questions (even for a layman like me) that were not asked by those “proper” science journalists or I have to assume even by the reviewers.

    It would be interesting if you could address some of the issues raised in the blogpost instead of just dismissing them in such a general fashion (e.g. use of weapons, co-evolution fists-jaws, methodological issues…). If you want to “generate debate and understanding” one would hope that you are also willing to engage in such a discussion. Especially as a non-specialist I would love to hear your side to form my opinion.

  12. “True journalism”? Being a scientist myself, I have to say I’m almost uniformly appalled by science journalism. Science journalists are expected to write about all of science, not just the one narrow field they might have any (however limited) understanding of – it’s not surprising that they routinely misrepresent research, mention everything except the important point while confusing much older news for the great new breakthrough, get basic concepts and even names wrong, and so on and so forth. I’ll take a blog post written by a scientist over science journalism any day of the week, and twice on Sunday.

    Oh – since you’re apparently into titles, Dr. Morgan, I should probably mention I’m a doctor of natural sciences (they’re not considered part of philosophy anymore where I come from).

  13. The literature on the relationship between the structure and function of the hominin masticatory system is vast. I’m afraid the paper does pretty much nothing to negate any of that. But what really bothers me about the paper is the complete and utter failure (so far as I could see) to provide any sort of phylogenetic context for the hypothesis. There were a rather large number of early hominin species, and several of them were contemporaneous. Some lineages, such as the paranthropines, were not ancestral to anything modern and could have had no influence on the genus Homo. If the authors wish to provide the evolutionary history for some sort of modern trait, they should start with the evolutionary history of the lineage–that is, phylogeny. Modern humans are a twig on a branchy bush. Perhaps the authors are unfamiliar with that bush….

  14. M. Morgan MD,

    Well, your speculations garnered you lots of publicity, so the fact that there’s no scientific substance to them is by the way, isn’t it?

  15. Brian, your commentary misrepresents our arguments, misrepresents what we present in our two papers, and misrepresents the scientific literature we cite.

    You state that we “didn’t study whether or not the hands of the early australopithecines could form a fist”. As we explain in our 2013 paper, the people who do study hominin hands have shown that the lengths of the hand bones in australopiths have human-like proportions. Given similar hand proportions, we think it is a safe to suggest that they could probably form a fist.

    You point out that we did not “look for signs of broken facial bones or blunt-force trauma on prehistoric skulls, or even try to model how early human skulls would have reacted to the stresses of an incoming fist”. Given the very few fossils of the australopith face, I am not optimistic that evidence of healed facial fractures exists. Modeling of strain in the facial skeleton as a result of an incoming fist is going to be interesting and I hope we can help make it happen. Nevertheless, without modeling we can be confident of the direction of the effect on bone strain and susceptibility to fracture that increased facial robusticity must have. Modeling will help with the finer points of the strain patterns and amplitudes, but it is not necessary to know what the basic effect is.

    Modeling of bone strain in the face of australopiths during feeding has only been accomplished by one research group during the past few years. Nevertheless, the feeding hypothesis to explain the evolution of the australopith face is almost universally accepted by the anthropology community. At what point during the past 60 years did the feeding hypothesis transition from being an adaptationist story to a respected hypothesis?

    You state that there’s no evidence that australopithecines engaged in fist-fights. True, there is no direct evidence, but we didn’t suggest that there is. What we suggest is that australopiths were the first apes that had anatomy that would allow them to throw punches at each other. Similarly, there is no evidence that australopiths ate foods that contained hard objects, yet most anthropologists think that biting hard objects played an important role in the evolution the australopith face.

    Anthropologists think that biting hard objects may have been important to the evolution of the hominin face because the biomechanics and comparative biology are largely consistent with this explanation. The biomechanic argument is compelling. However, recent studies of microwear patterns on the teeth and of carbon isotopes suggest that australopiths rarely, if ever, ate foods that contained hard objects, with the exception of Paranthorpus robustus. Your commentary did not mention this growing body of literature.

    You state that “females don’t even figure into Morgan and Carrier’s hypothesis” and “This is bro science – dudes pummeling each other driving human evolution.” In fact, a large part of the support for our hypothesis is based on the observed differences between males and females in both australopiths and Homo. The observed sexual dimorphism is pronounced and must mean something. This sexual dimorphism can’t be explained by the 60-year old feeding hypothesis but is consistent with the buttressing hypothesis. We emphasize these points, but they are not mentioned in your commentary.

    You state, “why sexual dimorphism between the sexes has drastically decreased through time, is either ignored or overshadowed by the belief that we owe are (sic) most distinctive features to males walloping each other.” On the contrary, sexual dimorphism is an important part of our thesis and is discussed at great length. Additionally, we reviewed the literature to specifically make the point that sexual dimorphism has NOT “drastically decreased through time”. These are points that cause me to doubt you carefully read the paper.

    You state “Those early humans couldn’t make the tight fists we do, though”. What exactly is your evidence for that statement? Obviously you disagree with the literature, but you owe us an explanation for why you disagree with the observations in the literature that indicate australopiths had human-like hand and finger proportions.

    You state “If our hands evolved as weapons, then we should see a coevolution between striking hands and stout faces. Our prehistory shows no such pattern.” The main point of our paper is that there is very good evidence of such a pattern. We have reviewed the literature to make this argument and we think it is clearly described and referenced in our paper. It is irresponsible for you, as a journalist, to state that the fundamental basis of our argument is wrong without providing justification for your offhand dismissal of our work.

    Finally, suggesting that a new idea is nothing more than a just-so story does not move the field forward. To me it appears to be an attempt to stop people from thinking. All hypotheses start out as stories. Some of these hypotheses turn out to be good hypotheses. And some good hypotheses turn out to impact our understanding.

  16. Brian, thanks for turning a critical eye on this hypothesis. The whole thing strikes me as rather silly. Faces are most likely to respond to uses/functions of the FACE.

  17. If our skulls evolved greater thickness due to getting punched, they should have gotten even thicker after we discovered rocks, sticks, and swords. Gun are probably a bit too recent on the evolutionary scale, but a few more thousand years and let’s see what we get!

  18. Whilst not my field I was led to believe that the skull evolved more in response to its ever expanding contents and the problematic exit known as the birth canal. Similarly a social creature that evolves chiefly to defend itself against it’s own social kin is not really fulfilling the definition of social.. I’m surprised that if wedid indeed evolve as rutting rams that we’ve stuck together this long. That said any hypothesis that claims a single factor for the evolution of anything.. is usually wrong and more oft guilty of using science to support a political agenda. The same was true of a 2012 publication in the NS that claimed banobo’s were caring on account of being matriachal …it followed the similar premise that males are violent and females are not. My response to that was just as if not more scathing than yours. http://conceptual-reflections.w43w.com/895/new-scientist-bad-scientist/

  19. Face it fellas, your hypothesis amounts to a Dragonball Z fantasy. The fact that hands make fists does not in any way I can see, correlate with bone structure in the face. I can see how you might want it to, but some of us are a tad older than 9. Given the circumstances, I thought our host here was fairly generous in his account.

    @ David Carrier, your 1st paragraph (after the claim of misrepresentation.) Ok, they could maybe make a fist.

    2nd paragraph, so…you got nuttin.

    3rd paragraph, if your hypothesis gains any ground in 60 years I am sure the scientific community will get back to you.

    4th paragraph, we have concluded that perhaps they were able to make fists, this by no means assumes they fought like John Wayne and Ali. Making the argument that “well it worked for them” is as childish as your assumptions.

    5th paragraph, that is a stretch. Also see paragraph 4.

    The rest of your argument is equally lacking in any substance that I can see.

    Your arguments seem to be as vacuous as your paper.

  20. @shelidigger
    not withstanding that this has proved to be one of the most entertaining comment threads I’ve read in years I think your point.
    4th paragraph, we have concluded that perhaps they were able to make fists, this by no means assumes they fought like John Wayne and Ali”.. is worth exploring further…

    Boxing is an art. It’s a skill akin to any martial art that is learned and practised over many years..whilst violent it is still a nurtured skill on a par with ballet or dancing ( i.e. Capoeira which draws its origins from African fighting traditions). There are rules and many forms of attack are forbidden. In boxing one is permitted to use only two weapons: the fists. The use of the head, the teeth or the feet is forbidden as is grappling (holding).

    Now this is significant. In boxing, an organised sport with rules, one is bound by those rules to spar (to use only the fists). Compare this to ‘Cage fighting’ and you will note that the feet are as likely to be used as weapons whilst the hands are used more for grappling and wresting whereas the glove in boxing is designed to handicap the wearer. One cannot hold anything whilst wearing a glove thus it prevent the hand being used for grappling.

    Remove the gloves and allow any part of the body to be used as a weapon and the fists are not the first choice.. the head, feet and teeth are more likely to be used as the weapon whilst the hands do what nature designed them for.. to hold the opponent whilst one butts and bites him!

    it’s not gracious nor entertaining but it is how one wins a brawl, a no rules battle..

  21. I believe that you have misrepresented Morgan & Carrier here
    They are specifically NOT arguing that modern human faces are adapted to being punched. Indeed–they very kindly acknowledged my commentary on their paper about fists last year
    Where I argued that human hands were more adapted to holding than hitting (various arguments but the most obvious is that we need to wear protection or we break our hands). They have incorporated this into their current paper.
    This is how science works–we make hypotheses–in this case by reverse engineering and then we test them. Rebuttals, corrections, alternatives are incorporated–hopefully in a mutually beneficial and collegiate manner. How else do you suggest we do it?
    From what I can see of their argument they are suggesting that we have become more gracile (less resistant to damage) but that previous australopithecine skulls do show adaptation to combat rather than to diet. They usefully compare sexual dimporphism in this respect. This is a perfectly good “just-so story”. The previous “just so” story was that ancestors had big jaws to munch big leaves.
    Morgan & Carriers response–why do the females also not have big jaws then? What were the large orbits for in males but not females? And so on. Now–they might be wrong–and there are other hypotheses to consider (sexual selection for example). But all of the them will also be “just so” stories. And none the worse for that.
    I know that Steve Gould has taught us that its very clever to go around throwing the “just so” taunt at things we don’t like. What, exactly, is the alternative? Just-so stories are fine. They guide research. They generate hypotheses to test. Actually–I know what the alternative is. “Just growed” stories.
    (Sorry for all the self-citations here–but given that Nat Geo asked my opinion on this paper and then ignored it–I felt I ought to say something)

  22. This article somehow misses the notion that our ancestors used sticks and rocks to hit each other. If the early hand could not make a tight fist, it still could hold sticks and rocks. Combat is still a very plausible explanation for bone thickness in skull and face.

  23. “No sooner did humans come out of the trees, Morgan and Carrier suggest, than they started whaling away on each other.”

    If that were the case, you’d think our skulls would have evolved to survive harpoons.

  24. @malcom.mcewen Good points, and it might aslo be worth mentioning that there are actual instances of primates who were never taught the socially acceptable ‘human’ way of fighting, (chimpanzees), who literally tore the faces off, and gouged the eyes out of humans they attacked, and to my knowledge never struck them with a clenched fist, (which in fact, could just as easily injure the attacker, as has already been pointed out.) I would think it more likely that australopith-on-australopith combat would more akin to the biting, clawing, gounging, and ripping of chimpanzee combat rather than the sparring with clenched fists of modern human boxers.

  25. Really interesting critique–it has certainly generated a lot of discussion! I tend to agree with you. This seems like a just-so story right now, but hopefully it will inspire some really cool studies in the future. A whole suite of characters associated with the shoulder, arm, and hand had to have changed in order to allow our ancestors to throw a punch. When did each feature evolve? In what order and what was the social and ecological context in which they arose? I feel like, at the very least, we need to know more about the evolution of punching before we can even begin to think about looking at how the human form may or may not have been evolving to cope with combat.

  26. Ah, huzzah! Regardless of just how worthy or disappointing the study is, it’s good to hear someone calling for the brakes to be put on! It’s simply too easy to make up a story, “just so” or not, point to some facts which are consistent with it, and call it “science.” At least in some areas. I mean, as if applying the human intelligent practice of using spandrels to the vagaries of evolution isn’t itself something of a “just so story”? In this whole field, how much opportunity is there for letting the “experimental machinery run” as it does — and often is required to do — in most areas of science? The responses by the authors show that it is always possible to find support for such stories or think up new variations. How many other ideas have been accepted largely because nobody was motivated to think up hard-hitting criticisms?

  27. Wait, wait, they’re from the University of Utah. I can go one better.

    Our eyes evolved to find evidence of cold fusion.

    (Takes bow and sits down.)

  28. Brian, what you’re saying is that, if this is true, why haven’t we seen an evolutionary arms race, of skulls with even thicker brow ridges, heavier upper jaws, etc., vs bigger fists, thicker fingers, etc. Good point. Very good point on the issue of spandrels. Robust australopiths may have “just become” that way, at least in part.

  29. Also, those thick, beetle-browed ridges would “explain” stereotypical violent black criminality, would they not? A very snarky blog post is in the works.

  30. Even if it had made sense, how would this be more plausible then the prevailing theories? I could say human hands evolved to grasp other human hands, as an act of love, which helps get mates (And fits the sexual selection theme of this “theory”.), but to say this is more likely then something supported by every line of evidence and that has not been anywhere near disproven for decades would be stupid, if you fet my metaphor.

  31. Brian – 5: David + Mike – 0. Full marks to those two buffons for wading in below the line and making themselves even more ridiculous.

  32. If new information hasn’t come along while I wasn’t looking, Neanderthals, separated from us by about 500,000 years, seem not to have used throwing implements while hunting. Their injuries have been analyzed and come closest to those of modern rodeo cowboys. In other words, they attacked their prey close-up to bring it down. Nothing was mentioned of hand or facial injuries. That suggests that they did not engage in fisticuffs. Alternatives are knives or clubs; and they are much closer to us than P. boisei.

    The reduction in sexual dimorphism over time suggests that our evolution has proceeded in the direction of more female choice and less male intimidation.

    The fisticuffs hypothesis does not hold a lot of water and is not suggested by the evidence.

Leave a Reply

Your email address will not be published. Required fields are marked *