Did violence shape our faces?

Jun 09, 2014
University of Utah biologist David Carrier and Michael H. Morgan, a University of Utah physician, contend that human faces -- especially those of our australopith ancestors -- evolved to minimize injury from punches to the face during fights between males. Their research is published in the June 9 issue of Biological Reviews. Credit: University of Utah

What contributed to the evolution of faces in the ape-like ancestors of humans? The prehistoric version of a bar fight —over women, resources and other slug-worthy disagreements, new research from the University of Utah scheduled for publication in the journal Biological Reviews on June 9 suggests.

University of Utah biologist David Carrier and Michael H. Morgan, a University of Utah physician, contend that human faces —especially those of our australopith ancestors—evolved to minimize injury from punches to the face during fights between males. The findings in the paper, titled "Protective buttressing of the hominin face," present an alternative to the previous long-held hypothesis that the of the robust faces of our early ancestors resulted largely from the need to chew hard-to-crush foods such as nuts.

"The australopiths were characterized by a suite of traits that may have improved fighting ability, including hand proportions that allow formation of a fist; effectively turning the delicate musculoskeletal system of the hand into a club effective for striking," said Carrier, lead author of the study. "If indeed the evolution of our hand proportions were associated with selection for fighting behavior you might expect the primary target, the face, to have undergone evolution to better protect it from injury when punched."

The rationale for the research conclusions came from determining a number of different elements, said Carrier.

"When modern humans fight hand-to-hand the face is usually the primary target. What we found was that the bones that suffer the highest rates of fracture in fights are the same parts of the skull that exhibited the greatest increase in robusticity during the evolution of basal hominins. These bones are also the parts of the skull that show the greatest difference between males and females in both australopiths and humans. In other words, male and female faces are different because the parts of the skull that break in fights are bigger in males," said Carrier.

"Importantly, these appear in the fossil record at approximately the same time that our ancestors evolved hand proportions that allow the formation of a fist. Together these observations suggest that many of the facial features that characterize early hominins may have evolved to protect the face from injury during fighting with fists," he said.

The latest study by Carrier and Morgan builds on their previous work, which indicate that violence played a greater role in than is generally accepted by many anthropologists. In recent years, Carrier has investigated the short legs of great apes, the habitual bipedal posture of hominins, and the hand proportions of hominins. He's currently working on a study on foot posture of great apes that also relates to evolution and fighting ability.

Research on the evolution of creatures in the genus Australopithecus - immediate predecessors of the human genus Homo —remains relevant today as scientists continue to look for clues into how and why humans evolved into who they are now from predecessors who inhabited the earth about 4 to 5 million years ago.

Carrier said his newly published research in Biological Reviews both "provides an alternative explanation for the evolution of the hominin face" but also "addresses the debate over whether or not our distant past was violent."

"The debate over whether or not there is a dark side to human nature goes back to the French philosopher Rousseau who argued that before civilization humans were noble savages; that civilization actually corrupted humans and made us more violent. This idea remains strong in the social sciences and in recent decades has been supported by a handful of outspoken evolutionary biologists and anthropologists. Many other evolutionary biologists, however, find evidence that our distant past was not peaceful," said Carrier.

"The hypothesis that our early ancestors were aggressive could be falsified if we found that the anatomical characters that distinguish us from other primates did not improve fighting ability. What our research has been showing is that many of the anatomical characters of great apes and our ancestors, the early hominins (such as bipedal posture, the proportions of our hands and the shape of our faces) do, in fact, improve fighting performance," he said.

Morgan added the new study brings interesting elements to the ongoing conversation about the role of violence in evolution. "I think our science is sound and fills some longstanding gaps in the existing theories of why the musculoskeletal structures of our faces developed the way they did," said Morgan.

"Our research is about peace. We seek to explore, understand, and confront humankind's violent and aggressive tendencies. Peace begins with ourselves and is ultimately achieved through disciplined self-analysis and an understanding of where we've come from as a species. Through our research we hope to look ourselves in the mirror and begin the difficult work of changing ourselves for the better."

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Squirrel
not rated yet Jun 09, 2014
The hands of austropiths and homo are physically less "tough" than that of other apes--one of the advantages of bipedality is that hands freed for rough locomotion duties can be structurally fine-tuned to be better able to do fine finger movements. That is why boxers wear "gloves"--punching the hand into teeth can do real harm to delicate but dexterous able finger bones. I suppose David Carrier and Michael Morgan would counter-argue that better hand (and upper body) control allowed violence against the face with improvised weapons such as nearby branches and stones.
Squirrel
not rated yet Jun 09, 2014
Not yet up on Wiley's "Biological Review" Early View section or elsewhere--University of Utah Health Sciences press release department should check whether papers due to appear have in fact appeared before sending them off--they may get better coverage as the work they describe can be read and so commented upon.
Rustybolts
1 / 5 (3) Jun 09, 2014
We are ready know DNA adapts and makes changes. Seems like a silly question to me. The tough question would be could the female species after watching males get there head beat in, could they some how alter there DNA for the new male species just buy watching them? Don't jump to say no to quickly that is a trick question.
krundoloss
1 / 5 (2) Jun 09, 2014
It would be interesting to define if repeated injury to a body part, or the breaking of it, would lead to offspring with a tougher version of that body part. It would be logical for evolution to work that quickly and directly.
ectogamit
5 / 5 (3) Jun 09, 2014
DNA does not react to physical trauma. There would need to be a reason that a flatter face increased survival and that trait was passed down as a result. Something like a gene mutation in a line that caused increased intelligence that also happened to carry a mutation for a flatter face which increased survival by chance. Or simply, a flatter face was more sexy so a flatter faces resulted in more offspring etc. Who knows, there are to many variables.
GTime
1 / 5 (3) Jun 09, 2014
If this is the case, why did we lose our animal jaws, sharp teeth, and claws?

If our faces evolved in response to continued fighting (and there is no doubt our faces are MUCH different from ape-like creatures), why did we lose strong jaws, sharp teeth, and claws since, if we evolved in response to fighting, we would continue to fight and sharp claws and teeth with strong jaws would have continued to be useful, very useful, and simply further evolved into better fighting tools.

Indeed, if anything our jaws, teeth, and claws would have gotten BIGGER, more sharp, not dull, and smaller, as are our teeth and our flimsy fingernails today.

No evidence for evolution here; none that I can see.
JVK
1 / 5 (4) Jun 09, 2014
No theory is too crazy for evolutionary theorists to propose. Their lack of restraint is due to the fact that no experimental evidence of biologically based cause and effect at the level of conserved molecular mechanisms has ever been required. So long as evolution "just happens" it can happen in any theory, no matter how ridiculous the theory seems to those who have an understanding of the basic principles of biology and levels of biological organization required to link the epigenetic landscape to the physical landscape of DNA in the organized genomes of species from microbes to man.

See also: "Isbell calls these findings "the first neuroscientific support" for her snake-centric evolutionary theory." excerpted from http://news.scien...te-brain
JVK
1 / 5 (3) Jun 09, 2014
http://www.huffin...211.html

"[W]hat Haldane, Fisher, Sewell Wright, Hardy, Weinberg et al. did was invent.... The anglophone tradition was taught. I was taught, and so were my contemporaries, and so were the younger scientists. Evolution was defined as "changes in gene frequencies in natural populations." The accumulation of genetic mutations was touted to be enough to change one species to another.... No, it wasn't dishonesty. I think it was wish fulfillment and social momentum. Assumptions, made but not verified, were taught as fact."
krundoloss
1 / 5 (2) Jun 10, 2014
It just seems to me, that regardless of scientific proof, that evolution would work in a similar way that our bodies do. If you punch bricks, eventually you will build up calcifications in your knuckles, deaden the nerves, and make your fist much tougher. It would make sense, that your offspring would have tougher fists, or at least a greater tendency to develop tougher fists. No one really understands evolution anyway, people claim to, but there is a lot more going on that just random mutation and natural selection!
RealScience
5 / 5 (4) Jun 10, 2014
@JVK - are you still trying to pretend that mutations are never selected for as a part of evolution through natural selection?

If so, the Huff Post link you cite disagrees with you. In it Noble goes on to say:
By "replacement" I don't mean to say that the mechanism of random change followed by selection does not exist as a possible mechanism. But it becomes one mechanism amongst many others...
anonymous_9001
5 / 5 (4) Jun 10, 2014
It would make sense, that your offspring would have tougher fists


If you know nothing about heredity, sure. There isn't a means by which the body would be able to rewrite germ cell code to result in tougher hands in the next generation in response to punching something. Propose a mechanism and we can go from there.
JVK
1 / 5 (4) Jun 10, 2014
If experimental evidence is found that supports a link from mutations and natural selection to the evolution of biodiversity, Noble and many other serious scientists will be among the first to examine the evidence. Until then, evolutionary theorists should probably start examining the evidence that links sensory input to receptor-mediated behaviors in species from microbes to man via conserved molecular mechanisms. That way, some evolutionary theorists will recognize the difference between pseudoscientific nonsense and established scientific facts before they have the scientific facts forced down their throats by the laypersons who have suffered from diseases and disorders that might already have been eliminated if only the evolutionary theorists had learned about the basic principles of biology and levels of biological organization that link sensory cause to behavioral affects.

http://www.the-sc...st102124
RealScience
5 / 5 (5) Jun 10, 2014
@JVK - if experimental evidence had been found to support your hypothesis that mutations are never selected for, serious scientists might take your claim seriously. Oh, that's right - you have admitted that there is no such experimental evidence to support your hypothesis.

It is you who should look at the experimental evidence that selection for some mutations is part of the process. Oh, that's right, you have admitted that you "throw out results that appear to attest to mutations as the cause of adaptive evolution". That makes your ingorance willful.

Captain Stumpy
5 / 5 (3) Jun 10, 2014
If experimental evidence is found that supports a link from mutations and natural selection to the evolution of biodiversity
@jk
this is why you are considered a crackpot. not ONLY is there evidence (SEE LENSKI)
but YOUR OWN MODEL PROVES THAT EVOLUTION IS SELECTION VIA MUTATION FOR BIODIVERSITY etc...

or did you forget our conversation? I asked
DOES your model make any changes to the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element?
This is a yes or no answer
(this is the definition of mutation) to which you answered
YES!
--Thanks for asking
so, drawing from your own words AGAIN...
IF mutations are BAD AND you say yourself that your model causes mutations
YES!
--Thanks for asking
THEN one can only conclude, per your own words and conclusions, that YOU are an IDIOT! and that you don't understand you own model let alone your field!
this is your own logic and in your own words, jk.
JVK
1 / 5 (4) Jun 10, 2014
http://www.scienc...14000197 offers the first evidence from serious scientists that John A. Davison, who died in 2012, and I have accurately represented how biodiversity arises.

It does not arise from mutations, natural selection, and evolution. The chromosomal rearrangements are nutrient-dependent and pheromone-controlled and they link ecological variation to ecological adaptations.

PZ Myers continues to tout the pseudoscientific nonsense that is typical of an atheist blogger whose idiot minions are also encouraged to attack when Myers leads the way. Anyone who does not know the difference between his ignorance and experimental evidence of cause and effect in the context of cell type differentiation will find other idiots to discuss their ridiculous theories with on Myers blog site: http://freethough...s-place/
Captain Stumpy
5 / 5 (3) Jun 10, 2014
I have accurately represented how biodiversity arises
@jvk
yes, we know. with your model, it arises via MUTATIONS
It does not arise from mutations
are you being stupid again? your model for diversity is completely out the window, because you say
It does not arise from mutations
but at the same time promote mutations with this
Nutrient-dependent/pheromone-controlled adaptive evolution
you just dont know what you are saying!
I asked
DOES your model make any changes to the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element?
This is a yes or no answer
(this is the definition of mutation) to which you answered
YES!
--Thanks for asking
so, drawing from your own words AGAIN...
IF mutations are BAD
mutations are bad
AND you say yourself that your model causes mutations
YES!
--Thanks for asking
THEN one can only conclude, per your own words and conclusions, that YOU are an IDIOT! and that you don't understand your own model let alone your field!

this is your own logic and in your own words, jk
silversphere
not rated yet Jun 10, 2014
well no need to worry. i mean who has written this obviously never fought.
What about eyebrows, cheeckbones, lips, teeth and noses?
You're gonna need another explanation sir.
RealScience
5 / 5 (3) Jun 10, 2014
@JVK, regarding the Wang and Davis link you just posted, do you understand the difference between germline and somatic genomes?
Captain Stumpy
5 / 5 (4) Jun 10, 2014
Anyone who does not know the difference between his ignorance and experimental evidence of cause and effect in the context of cell type differentiation
is NOT going to learn ANYTHING from jvk, especially by reading your post, jk! mostly because you don't know WHAT YOU ARE TALKING ABOUT!
I can link so many conversations where not only do you get confused about MUTATIONS, which is just your inability to comprehend the lexicon of your field, but you cannot answer other biologists talking to you here! I leave you with RealScience's words, to which I have watched you flounder, mis-comprehend studies to and BLATANTLY LIE
It is you who should look at the experimental evidence that selection for some mutations is part of the process. Oh, that's right, you have admitted that you "throw out results that appear to attest to mutations as the cause of adaptive evolution". That makes your ignorance willful.


This makes you stupid, jk, NOT IGNORANT. you've been taught, you ignore it!
OdinsAcolyte
not rated yet Jun 16, 2014
You imagine you know better than millions of years of evolution. Hmmm.
I smell arrogance. I can see the reasons for the evolution. I cannot see why one thinks they know better than nature. Glory in your humanity. There are sound reasons for the way we are.
Those reasons have not vanished. I like the research. I don't agree about the peace thing. It is desirable and every man's wish. We do not always get to have what we wish for.
Jantoo
1 / 5 (1) Jun 16, 2014
Looks good, but the most rude and aggressive people should have the flattest faces according to this theory.