The Art of Manliness - #216： How Men Evolved for Fighting

00:00:00.000 brett mckay here and welcome to another edition of the art of manliness podcast so one of the

00:00:18.480 things that makes humans well human is the ability to make a fist other primates can't do this and

00:00:25.140 the commonly accepted theory as to why humans develop this ability to make fists that they

00:00:29.660 needed to do so in order to grasp tools but research connected by my guests today have led

00:00:34.780 them to posit a very different theory they argue that one of the reasons we can make a fist is so

00:00:40.100 that we can give better knuckle sandwiches that's right we have a fist so we can punch their names

00:00:45.260 are dr david carrier and dr michael morgan dr carrier is a professor of evolutionary biology

00:00:49.420 at the university of utah and dr morgan is an emergency room physician when dr morgan was

00:00:54.220 an undergrad at the university of utah he worked with dr carrier on two papers which explored the

00:00:59.280 role of physical aggression what it may have played in the development of the human fist

00:01:04.360 today on the show we discussed that idea and the theory that human bodies especially male human

00:01:09.260 bodies evolved for fighting really great show a lot of fascinating insights from links to resources

00:01:15.420 that we mentioned throughout the show check out the show notes at aom.is slash aggression

00:01:19.940 dr david carrier and dr mike morgan welcome to the show thanks for having us yeah thanks very much

00:01:32.520 uh so you two have uh worked together on research and published a paper that went out i think it was

00:01:37.940 last year that caused some stir um and not only in academic circles but also in the popular press

00:01:45.700 i remember reading this research i forgot where it was it wasn't in an academic journal it was on some

00:01:50.440 website um about how aggression and violence in humans may have shaped the way the human body evolved

00:01:59.440 um so before we get into the specifics of your research i'm curious how did you two get interested

00:02:07.060 in this idea that there might be a connection between um physical you know the physiology of our evolution

00:02:13.800 and the sort of the the emotions of our evolution as well well why don't i kind of start so so i i i was

00:02:20.980 uh an undergrad student um with you know hopes and aspirations uh to go to medical school and um i had

00:02:28.480 been involved with some some research with dr carrier's wife uh using uh life alligators uh and um dave was

00:02:39.220 doing a lot of research on uh human locomotion uh and energy expenditure uh and he and i struck up a

00:02:46.040 conversation one day and and uh you know i think i had mentioned that i had some prior martial arts

00:02:53.480 training i had two black belts and um you know and so it was kind of led to this discussion of dave's

00:02:59.080 interest in uh aggression and violence and uh things kind of spiraled from there and you know i've been

00:03:06.600 lucky enough to kind of happen as a as a a great mentor you know as an inquisitive mind and a great

00:03:12.860 intellect and uh you know asks i think some very important questions questions that that interested

00:03:18.520 me as well with my uh background and experience in in fighting and uh for for me that was kind of

00:03:26.200 uh where my interest in it began yeah and that those conversations uh is really where our our focus on

00:03:33.900 on the hand uh started but going back a step farther early on this question about whether or

00:03:42.200 not humans are specialized for aggressive behavior came out of some work we were doing with domestic

00:03:47.280 dog we've been interested in whether or not there were functional trade-offs in terms of the anatomy

00:03:52.480 that allows an animal to be a very uh efficient runner versus the anatomy that allows an animal to be an

00:03:59.900 effective fighter and we were using two breeds uh of dogs greyhounds and pit bulls greyhound the runner

00:04:06.220 pit bulls the fighter and those two breeds share some anatomical similarities with uh with the bipedal

00:04:13.420 apes the early bipedal apes uh we called the group hominids um were built pretty much like chimpanzees

00:04:20.220 but they were habitual bipeds they were up running around on on the high lakes but they were

00:04:25.760 relatively short and styled animals like pit bulls and then later several million years later you get

00:04:33.540 the evolution of humans this group we call homo and those uh that anatomy is very similar to modern

00:04:40.880 human anatomy in terms of the body anatomy those uh that anatomy is appropriate we think for locomotor

00:04:48.480 and so it was that comparison with with the two breeds of dogs to the early forms of the bipedal apes that

00:04:58.080 got us thinking about well maybe humans particularly early human or early early ancestors were anatomically

00:05:05.840 specialized for aggression um so second question is um there's you know a long-standing debate

00:05:12.800 and philosophy and sociology biology um about whether or not violence is part of human nature

00:05:23.120 so you know some have argued that humans particular males are socially conditioned to be violent and

00:05:28.400 aggressive while there's another camp that argues that violence and aggression is just a natural part of

00:05:35.200 being human i mean it seems like from the the paper that i read uh you're coming from a school of

00:05:41.200 thought that violence and aggression is part of our might maybe part of our biology if that's the case i'm

00:05:48.400 curious what evolutionary benefit did our early human ancestors get from being violent and aggressive

00:05:58.000 so so i think this is a very very interesting um debate and uh for me it's hard to kind of paint

00:06:05.920 is just the black and white uh nature versus nurture you know i think people oftentimes use the term is

00:06:12.080 is this part of our biology or is this you know quote-unquote instinctual behavior versus as you said

00:06:17.760 kind of kind of social behavior or is this behavior that we're that we're taught and um you know i think

00:06:24.000 those two ideas of uh socialization uh versus instinct when it comes to human behavior are so ingrained that

00:06:32.240 oftentimes it's you know it's impossible to separate the two others and we we always try to do that

00:06:37.680 you know when we're kind of explaining these things um the way i tend to look at it uh brett is uh you know

00:06:45.680 i think our our behaviors ultimately and especially through uh the early development of of uh man

00:06:55.600 we're oftentimes influenced by the environment and the pressures of those environments put on uh the

00:07:01.840 social group right and the social group in turn had to adapt uh and develop different behaviors and

00:07:08.960 different behavior patterns uh to to kind of uh handle the stress the environment was putting on them

00:07:15.680 um and so there there certainly are situations where uh environmental stresses uh would probably

00:07:25.680 lead to promoting or encouraging aggressive and violent behavior within any certain social structure

00:07:32.560 uh at any given time so it's it's it's uh i think it's a it's kind of a a blend of both of those

00:07:38.720 things i think that you know environmental factors affect social behaviors which in turn affect

00:07:44.960 evolutionary behaviors uh which you know ultimately affect the trajectory of our species yes and to add to

00:07:53.200 that those those environmental factors uh influence all species and so there's competition at different

00:08:00.720 levels in basically all species one of the things that's unique to humans which might sort of increase the

00:08:08.160 the the the stakes or increase the pressure is that we have offspring that are incredibly dependent uh

00:08:16.800 we're born in in a very immature state and it takes takes years for parents to raise a young human to

00:08:25.280 the stage where they can take care of themselves and make a contribution to their community and so

00:08:30.320 that investment in offspring uh has been shown to be associated in a variety of different ways of

00:08:36.800 different species associated with uh relatively high levels of aggression high levels of competition

00:08:43.600 and so one of the reasons why humans may be relatively violent when you compare us to other mammals and

00:08:49.840 compare us to other primates may be these very dependent uh we use the word altricial offspring that we have

00:08:56.560 and why is it that males in particular uh of in the human species have a tendency towards violence and aggression

00:09:07.520 well i mean that that's true among mammals in general there's there tends to be relatively high

00:09:12.800 competition among males in all most species of mammals and it's largely because they're competing for access to

00:09:21.280 females and in mammals females make this incredibly high investment in their offspring so there's a long

00:09:28.880 period where instead of just laying eggs like a bird or a lizard uh the female gestates the uh the fetus

00:09:36.080 for a period of time and then after the young are born she nurses it and so for most species of mammal uh

00:09:43.520 fought the dad's not involved at all uh other than just the act of of mating and uh because of that female

00:09:52.240 mammals tend to be picky they tend to be they want to mate with the males that basically have the best genes

00:09:58.400 that puts males in the position of competing and so humans are are similar to other species of mammals in that regard

00:10:07.680 but you know i do want to also put out there that it's not just strictly violence and males you know we

00:10:14.640 don't have the we don't have the uh uh what's the word i'm looking for we don't we don't have all the rights

00:10:20.560 and and uh you know the i don't know what i'm trying to say but we don't own violence as the male of the species

00:10:28.880 uh i think you know even though uh predominantly aggressive acts when you look at the male and behavior

00:10:34.880 uh come from males there's plenty of evidence out there uh you know both in in you know our closest

00:10:42.880 relatives chimpanzees uh but you know across the spectrum of females and engaging in violence and

00:10:50.560 aggressive behavior i think on your uh your site before you you reference the book demonic males uh

00:10:56.800 by by rangham i believe um and he has a great accounting of uh you know one of the first witnessed

00:11:03.840 events of of kind of uh chimp uh raiding and you know one of the things that i think was very

00:11:09.920 interesting about that first observed instance of that uh chimpanzee group raiding and essentially

00:11:15.200 attacking another group of chimpanzees was that there were also females involved in the raiding party

00:11:20.800 now they didn't play as big of a role in terms of uh kind of leading this and uh in terms of um

00:11:28.560 i think some of the actual physical aggression that they were definitely part of the of the process as

00:11:33.600 well yeah i mean one thing i've i've read is that uh competition or the violence between or is it

00:11:41.360 conspecific that means like that's like same species right so when males from other species fight or the

00:11:48.640 same species fight other males the same species uh it's all it's very it's almost like a ritualistic

00:11:53.840 dance combat dance there's a lot of posturing and then they'll move to you know if that doesn't

00:12:00.800 work to scare the other guy off and they'll move to shoving and then if that doesn't work then they'll

00:12:04.960 start like the goal of it isn't to kill necessarily it's more to assert dominance and show who's the guy

00:12:12.080 who's in charge yeah i think i think that's uh it's true we we come and refer to these as threat displays

00:12:20.240 uh and and and you see him manifest in different forms in different different uh species you know

00:12:26.480 and you know an animal with with large canine teeth that might be you know gnashing and bearing of the

00:12:32.880 teeth and in uh you know other animals it could be you know certain posturing uh posing their bodies to

00:12:42.240 increase the appearance of their size and their strength um so one of the things that we kind of uh

00:12:50.560 were thinking about that led us into some of our research particularly uh our our paper about uh

00:12:56.960 you know the the human fist was uh you know what what what do humans do what's our natural reaction

00:13:03.520 when we get angry you know even if you if you look at a child on a playground you know at school when

00:13:09.920 they get bullied what's one of the first things you do well a lot of times it's that you clench your hand

00:13:14.880 into a fist and and a lot of times that you know can be our threat displays as human beings you know

00:13:21.120 there's obviously you know vocalization and and taunting and teasing and insults that you know

00:13:27.680 come out but as far as our physical manifestation it's that it's that that presentation of a weapon

00:13:34.400 oftentimes that it is kind of that that threat display that's the first prelude to violence and

00:13:40.400 aggression okay so this is interesting so the fist then the human fist the ability for the humans make

00:13:46.000 a fist um one of its benefits is besides being able to grasp tools right um is making a fist is

00:13:54.240 basically you're making a weapon as a possible threat display i mean so can other primates make

00:14:00.800 a fist or is that uniquely unique to humans as far as we know it it is unique to humans uh

00:14:11.120 well our the human fist requires a specific uh relationship of the proportions of the the palm of

00:14:17.520 the hand the length of the uh the elements of the fingers the length of the thumb and if you look at

00:14:24.960 the other extant great apes the chimps bonobos gorillas they have longer fingers a longer hand and

00:14:33.120 uh a much shorter and weaker thumb than we do and so they they basically don't have the hand proportions

00:14:40.000 that allow them to make up this and and what we've argued is that yes these hand proportions that

00:14:46.560 have always thought to be the human hand forces have always thought to be primarily about manual

00:14:51.600 dexterity uh that's certainly true there's no doubt because humans do so much with our with with their

00:14:58.080 hands it's clear that that's quite an important role in the evolution of the shape of our hands but

00:15:04.880 the other thing that may be playing a role is this ability to turn it into a weapon into a form of a club

00:15:11.760 so that the relatively delicate and vulnerable anatomy of the human hand which is so important to uh to

00:15:19.920 our livelihood can also be used as a weapon and so what advantage does making a fist to punch provide

00:15:28.000 humans in fighting is it uh does it provide more power or force what's what's going on there

00:15:34.160 so uh with uh with the first paper that we we publish looking at uh what we call the protective

00:15:42.720 buttressing of the of the hand uh meaning uh the nice kind of compact uh shape that you get when all

00:15:51.280 those proportions that dr carrier mentioned kind of align to form the fist uh we we studied um

00:15:56.960 um the force that could be delivered uh with a formed fist uh versus uh what we could kind of

00:16:06.000 most approximate would be the strike delivered by uh say a gorilla or a chimpanzee or one of our one of

00:16:14.000 our our closest ancestors who can't make a fist so it's kind of an open hand slap or a slap with the palm

00:16:21.600 or the meat of the hand uh and we had uh volunteers come into the lab and we had a couple different

00:16:27.840 contractions set up one of them was a punching bag with an accelerometer we had some force plates that

00:16:33.280 we were looking at um and we kind of looked at uh the amount of force and whether the forces were higher

00:16:40.800 with with kind of this open hand quasi fist uh versus a fully formed fist and we thought for sure that

00:16:48.320 maybe we'd have higher forces delivered with with a fist uh but that wasn't the case there was

00:16:54.160 actually similar forces delivered between a slap and a punch but what we did know was that uh when

00:17:00.720 you when you kind of bring that force down to a smaller pinpoint size you give what's called an

00:17:05.920 increase in the force impulse and and when it comes to doing damage breaking bones damaging soft tissues

00:17:13.920 causing fractures um the force impulse is really what matters that's that that uh element of the

00:17:21.200 of the deliver the force that allows damage to happen and when you have a fully formed fist and

00:17:25.760 you're delivering a strike the force impulse was actually significantly higher than it was

00:17:30.800 uh with uh an open hand secondly having the ability to form a fist protects the anatomy of the hand

00:17:38.160 as dr carrier said um the uh the hand you know has a number of bones that you know are frequently uh

00:17:46.480 injured and fractured uh but forming a fist allows you to make a much more stable stiffer structure uh

00:17:54.400 with which you can deliver that blow decreasing your chance of of injuring hand and this is a common uh

00:18:02.640 a common critique of our of our research is you know people say well well people break their hands all the

00:18:07.360 time and fight you know and i work in an emergency department and i see the results of interpersonal

00:18:12.080 violence all the time there's a common fracture pattern that we see called the boxer's fracture

00:18:16.880 which is a fracture of the usually the the fifth and fourth uh metacarpal bones uh that occurs by

00:18:24.000 someone throwing a punch and and you know landing with the force in a way that kind of transmits force

00:18:28.960 to those bones and breaks those bones but when you actually look at some of the trauma data we have

00:18:34.320 uh you know you you do see these fractures of the hand uh but you see a lot more uh fractures of the

00:18:47.040 face uh compared to how how frequently the the hand is injured when you actually look at the data

00:18:53.600 so so to me that that kind of supports that you know this this ability to form this fist you know not

00:18:58.720 only provides us with with the convenience uh readily usable weapon uh allows us to do more damage

00:19:05.840 when we throw a strike and allows us to protect our weapon when striking and uh besides the critique about

00:19:14.320 the um you know the the hand being damaged during a punch and it's often damaged during a punch with

00:19:20.080 were there any other critiques of your your your paper because yeah i mean do you remember it did

00:19:24.160 cause cause cause a bit of a stir uh in the in the press at least yeah it generated a lot of a lot of

00:19:32.640 uh press about it and and uh it's always kind of an interesting phenomena because uh you know you

00:19:39.520 find yourself scratching your head wondering if the people writing some of the news articles

00:19:43.440 actually read the paper or actually kind of kind of got what we were after but but it you know it made

00:19:50.080 quite a bit of kind of you know pop science websites uh because i think it's an interesting

00:19:55.040 you know kind of out there study um but you know there there were certainly some some other critiques

00:20:02.080 and i think maybe dave can talk to some of them but yeah i i think one of the most common criticisms

00:20:08.240 that's repeatedly been thrown at us is that uh we're making up an evolutionary story an adaptation

00:20:14.800 story and that a more reasonable explanation is that this is these hand proportions that allow the

00:20:21.360 formation of this are just a coincidence of uh what a coincidence of the consequence of selection for

00:20:30.640 manual dexterity and that's certainly possible but but it's also possible that selection was selection

00:20:40.000 on aggressive behavior was having an influence on the hand proportions and so what we're presenting

00:20:44.800 is really uh an alternative explanation that's not mutually exclusive with the original idea of

00:20:52.480 of of it all being about manual dexterity whereas we're throwing in another possible

00:20:58.640 component that may explain the evolution of our hand proportions and the evolutions of some of the

00:21:04.640 proportions and uh configuration of our face facial skeleton as well yeah we'll get that to the

00:21:10.800 facial skeleton as well that's interesting so i mean i guess the theory i mean i guess if i was

00:21:14.640 listening to you the theory about why our hand is the way it is um i just had the thoughts make sure

00:21:21.120 i'm on the same page like so perhaps it evolved the way it did because of aggression it was like we

00:21:25.680 turned our hand into a weapon basically and that's right and then because because of the proportions it

00:21:32.880 made you know tools or you know weapons or rocks like holding rocks you could use it as a force multiplier

00:21:39.360 and we're yeah because as a consequence we're more dexterous with our hands so it's like aggression

00:21:45.280 led to tool making is that the idea well not necessarily not necessarily because there's there

00:21:51.440 was quick primates in general use their monkeys and the great apes all use their hands uh they all have

00:21:57.360 a capacity for manual dexterity it's important in all groups but we've we've taken it even farther

00:22:03.360 right we have much greater capacity than the other than the other primates so there's it's clear that

00:22:08.160 selection for use of our hands was always there but what we have suggested is that if you start with

00:22:15.040 the hand of something that's sort of intermediate between uh a chimpanzee hand and our hand something

00:22:20.880 that we think was close to the ancestral condition from uh basically our ancestral condition if you start

00:22:28.160 with that hand we think there are a number of ways you could evolve improve you could change the

00:22:33.200 proportions in a number of ways that would improve manual dexterity but we think there's only really

00:22:38.160 one set of uh proportions of the different skeletal elements that allow the formation of of the human fist

00:22:45.440 and so we're arguing that that yes uh certainly manual dexterity is an important part of

00:22:51.200 of the shape of our hand but if you want to actually explain the specific proportions

00:22:58.320 making a fist may do a better job than the use of our hand and using tools and and forming or making

00:23:05.360 tools okay um so the other paper you all put out um which is related to the the the fist making uh

00:23:14.880 paper in a way is that the human face may have been evolved to take a punch um how so and how does our

00:23:22.640 face differ from other primates well that's uh so that the the impetus for that paper was uh actually

00:23:32.560 a critique that we had for our uh paper with regards to the the proportions of the of the hand and the

00:23:38.080 fist where you know someone essentially said if you know if my hand evolved to make a fist then why

00:23:44.480 did my face evolve to take a punch and you said well that's a that's a that's a really good question

00:23:50.400 and uh so we uh started looking back over a lot of the research of uh kind of the the known facial

00:23:58.400 proportions of uh kind of the hominid lineage uh and found that uh that there was uh a increase in

00:24:08.640 in robusticity in terms of certain proportions of the face that also happened to be uh the areas

00:24:15.360 of the face that are most frequently fractured and injured in fights uh we saw this increase in the in

00:24:22.000 the in the strength and robusticity of these components of the face uh for a period of time

00:24:26.960 and so we it's not really what we expected to to find but uh we we started looking at some of the current

00:24:33.440 uh uh philosophies on why the faces were so robust and a lot of those center around uh our diets and

00:24:41.440 and having large jaws and you know to attach large uh muscles of mastication to for us to adapt to a

00:24:49.440 new uh a new diet as a species but uh we we didn't feel that that's fully explained uh the increase of

00:24:56.640 these proportions i think maybe Dave can kind of talk to a little bit more about the anatomic detail of

00:25:01.040 it but but yeah that kind of critique of why didn't my face evolve to take a punch led led to the second

00:25:06.160 paper that you're talking about yeah and one of the things that's interesting is that um there's a

00:25:12.160 coincidence in terms of the timing of the evolution of these characters so around five to six million

00:25:19.440 years ago we start in the fossil record we start to see evidence of early bipedal uh what we call the

00:25:27.120 group hominins and this is the group that eventually gave rise to humans so they appear in the fossil

00:25:32.560 record four to four five six million years ago they had body proportions very similar to chimpanzees but

00:25:38.880 they were standing up on two legs but at the same time that our ancestors evolved to stand on two legs

00:25:46.000 eventually and walk and run on two legs um the hand proportions that would allow the formation of

00:25:53.120 fist appear in the fossil record as well and then at the same time that that those two things show up

00:26:00.560 again this is four to six million years ago we have these this trend towards increase in robusticity

00:26:07.920 of the facial skeleton specific specifically of the components of the facial skeleton

00:26:13.200 that break when modern humans uh fight today so all these things seem to be linked uh temporarily

00:26:20.320 okay so but our so i guess if i understand you so there was a period in our uh evolutionary history

00:26:26.640 history when our face got stronger basically but that has gone away we it the human face today is

00:26:32.800 pretty fragile yes yeah yeah and specifically those are so when when we see you know trauma coming in

00:26:42.240 you know from uh interpersonal violence uh the most commonly fractured bones of the face are usually the

00:26:50.080 the mandible um in fact i had a patient last night that had bilateral mandibular fractures as a result

00:26:56.400 of getting beat up uh by two guys in the park um so we see the mandible breaks we see the the nasal

00:27:03.200 complex so nasal fractures break we see uh the zygoma break and then we see uh the orbit so the the kind

00:27:10.400 of bony protective cage around the eye are most frequently broken um and that's kind of where we also saw an

00:27:16.960 increase in terms of robusticity in the in the kind of the fossil record of of the hominin facial proportions

00:27:23.440 and so what's the why is it that it got weaker so it's a good question and uh we don't have a clear

00:27:32.800 answer but but there is um a correlation in terms of upper body strength so these early uh these early

00:27:41.600 bipedal apes the what we call the australopis had great upper body strength and that was true of uh

00:27:49.360 the early species of homo the first early humans about two million years ago but what you see with

00:27:55.760 the evolution of homo through time is a reduction in upper body strength and that again coincides with

00:28:04.160 that reduction in upper body strength which would be a reduction ability to strike with a fist

00:28:09.040 uh is coincident with a reduction in the strength of the facial skeleton so the other thing is that

00:28:16.320 with with uh you know somewhere around three million years ago we our ancestors started to use tools as

00:28:24.880 weapons or at least there's more evidence of that and so the targets would have changed as well the the

00:28:30.400 target if if there was uh homicidal intent would have switched possibly uh from maybe the face to

00:28:39.040 striking the cranium with the weapon and so both both the fact that we think the targets changed at

00:28:45.600 least to some extent and also there was a reduction through time of upper body strength that may help

00:28:52.240 explain why the facial skeleton during the past two million years has become less robust so um earlier on

00:28:59.440 we were talking about why men in particular might be more violent and aggressive than females the idea that

00:29:06.880 men have to compete you know it's sexual repro sexual reproduction is what's driving or sexual

00:29:12.320 selection is what's driving that that tricks men have to compete um with that in mind are there

00:29:18.320 differences between the physiology of men and women that make men better adapted for fighting

00:29:26.160 definitely and then the faces is sort of a classic example of that as well so one of the most sexually we use the

00:29:33.440 phrase sexual dimorphism uh to talk about anatomical physiological physiological differences between

00:29:39.840 males and females and one of the parts of our body that is most different most dimorphic between males and

00:29:46.160 females is in fact the facial skeleton and again the biggest differences between males and females are the

00:29:52.400 parts of the facial skeleton that tend to break the most when when my humans fight so uh males the

00:30:00.000 the things that the the features of the face the features of the skull that distinguish a male skull

00:30:06.240 from a female skull is greater robusticity in the characters that tend to break when we fight greater

00:30:12.400 robusticity that is in males and that's not the only the you know face is certainly not the only place

00:30:19.280 where you see the dimorphism as well i mean you see it uh in in the the upper extremities you see it uh in

00:30:26.800 in terms of uh the skeletal structures and their ability to support a much greater uh muscle mass than than

00:30:34.480 than on females um so you see you see dimorphism represented throughout the entire body uh between

00:30:40.960 men and women and another good example that's consistent with this aggression hypothesis is that that

00:30:49.040 dimorphism in body strength is most pronounced in the arms or the upper body than in than in the legs

00:30:56.480 so males and females humans are uh males are at greater strength in their legs and females but

00:31:03.280 the extent to which there's a greater strength is more much more pronounced in the upper body so yeah

00:31:10.480 the idea is that men would be using their arms to throw throw punches that's why there's that that's

00:31:16.160 right yeah that's right basically fighting with with the arms right i think i i one i heard one guy

00:31:22.400 describe the shoulders of human males as sort of like they're our version of antlers right it's sort

00:31:29.200 of um you know how male um stags they grow big antlers because they use that to in these like

00:31:36.640 ritualistic battles between other males to find out who's the top guy or you know a guy with a larger

00:31:43.760 upper body torso and bigger arms is sort of displaying like hey i can punch really well so don't mess with me

00:31:50.160 i think that's right i think we do tend to pay attention to uh the shoulders the the uh the

00:31:57.760 strength in the upper arms and and possibly the strength of the neck in terms of evaluating

00:32:04.240 an individual's ability to basically evaluate evaluating their formative ability so uh both males and

00:32:11.760 females look and can distinguish uh from looking at that part of the body can distinguish a male's

00:32:17.520 ability to fight but on top of that there's a number of studies out there that show that we can

00:32:23.840 look simply at a male's face and have a pretty good be pretty we have a pretty accurate assessment of

00:32:31.360 their fighting ability just from looking at the face but i tend to agree with with uh your uh the

00:32:38.640 observation of your friend um so i'm curious i mean why i'm sure people are listening to this like why

00:32:45.200 why is it important that we know or study where why uh violence and aggression may have uh influenced

00:32:54.320 our physiological evolution i mean what what what what do you what what can we do with this information

00:32:59.360 that you all are uncovering or putting out there i think i think that's that's a uh really the meat of

00:33:06.880 of our interest in this particular field is um you know coming to a deeper understanding of of

00:33:16.080 you know let's call it human nature for for lack of a a better term and you know for a long long time

00:33:22.720 in the science community people people you know really wanted to hang on to this idea of the noble

00:33:28.080 savage and these humans were you know superior in a certain way because we were masters of our domain

00:33:33.920 we weren't uh we had the ability to be selective of whether or not we were violent or aggressive but

00:33:41.040 i think when you kind of look at the evidence you know we're we're arguably one of the most violent

00:33:47.680 species you know and you know if you look further at some of the data we you can kind of trend

00:33:53.040 historically that i think we're becoming less violent as a species but but those tendencies are are

00:34:00.080 still there and my argument and i don't know if uh dave would agree with me but my argument is that um

00:34:08.080 it's it's a lot of that is this kind of displaced uh behavior you know there was a one point in

00:34:15.280 time in our development as a species where uh violence was absolutely critical to our survival you

00:34:22.000 know it meant that you were going to eat it meant that you were going to survive it meant that you were

00:34:27.840 going to be able to mate and to carry on your your genetic uh information um to the next generation

00:34:36.160 and your ability to defend yourself to defend your food resources to defend your mating rights

00:34:41.440 uh determine that determine your survival and i think that that's been such a huge part of our

00:34:48.240 uh of our evolution you know getting back to that discussion of these are the environmental

00:34:52.960 pressures that affect our socialization and affect our behaviors and groups uh but i think nowadays we

00:35:00.880 have a very very different society very very different social structures uh that in the long long history

00:35:07.920 of human existence you know accounts for just a small small fraction of time and and we have uh these

00:35:16.240 behaviors and these tendencies uh that are that are kind of displaced we no longer have the evolutionary

00:35:21.440 pressures you know you don't have to fight for your food anymore um you don't have to fight for your

00:35:27.920 mate anymore you don't have to defend your territory anymore uh but but we still have uh i think something

00:35:35.760 about us and something inside of us uh that that makes aggression uh part of our makeup and part of who we are

00:35:43.920 and i feel the better we can understand that uh the better steps we can take towards towards uh managing

00:35:52.160 that and using it responsibly and and um you know using that energy uh towards toward better endeavors

00:35:59.680 rather than in the harm of one another yes yes and to add to that

00:36:04.880 the if if if in fact we are our musculoskeletal system is specialized for aggressive behavior

00:36:14.880 if that turns out to be true then this uh debate about human nature we think basically just goes away

00:36:23.120 and what you what you end up with is the acknowledgement that uh a tendency towards aggressive behavior is in

00:36:30.160 fact part of who we are it's not all who we are um i mean we are we have just as great as capacity for

00:36:37.600 cooperation empathy uh wanting to have a secure peaceful environment in which to live in right those

00:36:44.080 are both aspects of who we are but i think there's value in in at least asking the questions we're asking

00:36:51.520 because it has potential to uh resolve this this argument that's been going on for for hundreds of years

00:37:00.000 about human nature and if we can get past that argument we can focus our attention on specifically

00:37:07.520 on what we need to do to secure a more peaceful future um so dave and mike where can people learn

00:37:16.720 more about uh your work and perhaps read these papers you've put out uh all right i believe our fist

00:37:25.440 paper uh is is on plus one plos one's open access so uh anybody can can find it online and read read it um

00:37:37.040 the uh the paper that we did looking at the proportions of the human face was published in uh journal biological

00:37:44.640 reviews um and that one yeah you can usually access through through uh various uh academic libraries um but

00:37:53.760 there's there's plenty of writing and criticism and critiques out there to to kind of get through

00:37:59.040 online with regards to this stuff um uh dr carrier has another another paper that uh i think is in

00:38:06.800 publication right now that that you worked on um looking at the screen on the hand yeah that's been

00:38:12.720 published as well yeah and uh that was published in a journal called experimental biology journal of

00:38:19.200 experimental biology great well dr dave carrier dr mike morgan thank you so much for your time it's

00:38:24.560 been a pleasure our pleasure thank you so much for having this breath thank you my guests today were

00:38:29.040 dr david carrier and dr michael morgan uh you can find more information about their work just google

00:38:34.640 uh punching fist evolution you're going to find the a lot of papers that they've put in and just

00:38:39.040 news articles about their research um and also make sure to check out the show notes at aom.is

00:38:44.240 slash aggression for links to resources that we mentioned throughout the show so you can delve deeper into this topic

00:38:48.640 well that wraps up another edition of the art of manliness podcast for more manly tips and advice

00:39:04.480 make sure to check out the art of manliness website at artofmanliness.com and if you enjoy

00:39:08.240 this show and have gotten something out of it i'd appreciate it if you give us a review in itunes or

00:39:11.680 stitcher that helps spread the word about the show as always i appreciate your continued support and until

00:39:15.920 next time this is brett mckay telling you to stay manly

The Art of Manliness - July 31, 2025

#216： How Men Evolved for Fighting

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