Human faces are so variable because we evolved to look unique

Human faces are so variable because we evolved to look unique
The variety of human faces. Credit: UC Berkeley

The amazing variety of human faces – far greater than that of most other animals – is the result of evolutionary pressure to make each of us unique and easily recognizable, according to a new study by University of California, Berkeley, scientists.

Our highly visual social interactions are almost certainly the driver of this evolutionary trend, said behavioral ecologist Michael J. Sheehan, a postdoctoral fellow in UC Berkeley's Museum of Vertebrate Zoology. Many animals use smell or vocalization to identify individuals, making distinctive facial features unimportant, especially for animals that roam after dark, he said. But humans are different.

"Humans are phenomenally good at recognizing faces; there is a part of the brain specialized for that," Sheehan said. "Our study now shows that humans have been selected to be unique and easily recognizable. It is clearly beneficial for me to recognize others, but also beneficial for me to be recognizable. Otherwise, we would all look more similar."

"The idea that social interaction may have facilitated or led to selection for us to be individually recognizable implies that human social structure has driven the evolution of how we look," said coauthor Michael Nachman, a population geneticist, professor of integrative biology and director of the UC Berkeley Museum of Vertebrate Zoology.

The study will appear Sept. 16 in the online journal Nature Communications.

In the study, Sheehan said, "we asked, 'Are traits such as distance between the eyes or width of the nose variable just by chance, or has there been evolutionary selection to be more variable than they would be otherwise; more distinctive and more unique?'"

As predicted, the researchers found that facial traits are much more variable than other bodily traits, such as the length of the hand, and that facial traits are independent of other facial traits, unlike most body measures. People with longer arms, for example, typically have longer legs, while people with wider noses or widely spaced eyes don't have longer noses. Both findings suggest that facial variation has been enhanced through evolution.

Finally, they compared the genomes of people from around the world and found more in the genomic regions that control facial characteristics than in other areas of the genome, a sign that variation is evolutionarily advantageous.

"All three predictions were met: facial traits are more variable and less correlated than other traits, and the genes that underlie them show higher levels of variation," Nachman said. "Lots of regions of the genome contribute to facial features, so you would expect the genetic variation to be subtle, and it is. But it is consistent and statistically significant."

Using Army data

Sheehan was able to assess human facial variability thanks to a U.S. Army database of body measurements compiled from male and female personnel in 1988. The Army Anthropometric Survey (ANSUR) data are used to design and size everything from uniforms and protective clothing to vehicles and workstations.

A statistical comparison of facial traits of European Americans and African Americans – forehead-chin distance, ear height, nose width and distance between pupils, for example – with other body traits – forearm length, height at waist, etc. – showed that facial traits are, on average, more varied than the others. The most variable traits are situated within the triangle of the eyes, mouth and nose.

Sheehan and Nachman also had access to data collected by the 1000 Genome project, which has sequenced more than 1,000 human genomes since 2008 and catalogued nearly 40 million genetic variations among humans worldwide. Looking at regions of the human genome that have been identified as determining the shape of the face, they found a much higher number of variants than for traits, such as height, not involving the face.

Prehistoric origins

"Genetic variation tends to be weeded out by natural selection in the case of traits that are essential to survival," Nachman said. "Here it is the opposite; selection is maintaining variation. All of this is consistent with the idea that there has been selection for variation to facilitate recognition of individuals."

They also compared the human genomes with recently sequenced genomes of Neanderthals and Denisovans and found similar genetic variation, which indicates that the facial variation in modern humans must have originated prior to the split between these different lineages.

"Clearly, we recognize people by many traits – for example their height or their gait – but our findings argue that the face is the predominant way we recognize people," Sheehan said.


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Journal information: Nature Communications

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Sep 16, 2014
verkle at it again, being obtuse & pretending to be stupid not having read earlier posts
These kinds of postulations are BS. There is no scientific basis for claiming that our variableness is due to evolution. It is a scientific observation that our faces are quite variable, but to randomly give credit to evolution is non-scientific. It is the work of atheists.
Variation verkle is part of nature - ALL of nature, it is built into quantum uncertainty ie. Probability.

Your statements above are the most dishonest & disingenuous means to muddy the waters suggesting even at a low level there is no evolution.

Yet you HAVE confirmed you accept there is 'micro-evolution' but, you cannot seem to make the leap that all macro-evolution is based on the very SAME organic chemistry as all micro-evolution, so why is that verkle, do u have no speculative imagination to pursue.

The evidence is there but, your prejudice & confirmational bias upon a religious basis gets in the way.

Wake up !

Sep 16, 2014
" It is the work of atheists."

You must not be aware that there are Christian evolutionary biologists and the Catholic Church has long accepted evolution.. But then you probably have a very narrow view of who is truely a Christian.


Sep 16, 2014
For evolution to work then certain individuals with the trait in question have to fail to reproduce and raise young. So how exactly did individuals who lacked facial variation fail to successfully reproduce and raise their young? Were others in the social group less willing to give and receive favours to those in the group who could be easily confused? This social exclusion might sufficiently diminish the mating and childrearing success of the victims. Are identical twins unconsciously discriminated against by others in a social group?

Sep 16, 2014
"The amazing variety of human faces – far greater than that of most other animals – is the result of evolutionary pressure to make each of us unique and easily recognizable"

I would like to see hard evidence of this. There are 7 billion people across many different races adapted to different living conditions. If you took an equal sample from a particular area (same living conditions) and particular lineage (to rule out our ability to travel and cross breed as the reason) e.g. 1000 adult males from Kyoto vs 1000 male Chimpanzees from the Congo, I think that you would find a very similar degree of variation.

The real effect is that we have evolved to distinguish features... so faces look different to us, but chimpanzees probably think the same about themselves.

Sep 16, 2014
Heck, I have heard it said that a pope declared rabbits to be fish!

Sep 17, 2014
Going offered
For evolution to work then certain individuals with the trait in question have to fail to reproduce...
Perhaps but there is bound to be a bell curve aspect to this and how far back any core genetic information is buried - not all 'traits' are singular & thus easily bred in or out - many are combinatorial & vastly complex. This is why it's almost impossible for those like verkle to understand, not entirely their fault - they were indoctrinated into a deterministic view ie "A god did it" whilst being unlucky to miss education

Going asked
Are identical twins unconsciously discriminated against by others in a social group?
Look at details, 'identical' twins have many variations, even when eating the same meals some can express genes differently. Not unusual to find one showing early symptoms of diabetes etc & other issues.

Consider it could be scary to see say triplets all closely identical in a dark alley, might this be socially disadvantaged ie Appear Robotic..

JVK
Sep 17, 2014
Genomes in turmoil: Quantification of genome dynamics in prokaryote supergenomes
http://www.biomed...abstract

"...evolutionary events (hereinafter Genome Dynamics Events or GDE)..."

No evolutionary events = no evolution

A universal trend of amino acid gain and loss in protein evolution
http://www.nature...306.html

"We cannot conceive of a global external factor that could cause, during this time, parallel evolution of amino acid compositions of proteins in 15 diverse taxa that represent all three domains of life and span a wide range of lifestyles and environments. Thus, currently, the most plausible hypothesis is that we are observing a universal, intrinsic trend that emerged before the last universal common ancestor of all extant organisms."

No last universal common ancestor = no evolution

Amino acid substitutions lead to cell type differentiation = no evolution, just theories about it.

Sep 17, 2014
Genomes in turmoil: Quantification of genome dynamics in prokaryote supergenomes
http://www.biomed...abstract

"...evolutionary events (hereinafter Genome Dynamics Events or GDE)..

You post a link describing evolutionary events and then follow up with "No evolution events=no evolution"

A universal trend of amino acid gain and loss in protein evolution
[url]http://www.nature...306.html[/url]

"No last universal common ancestor = no evolution"

You link to two papers supporting evolution and come up with "no evolution"

You have no idea of how arrogantly stupid you are.

[url]http://www.nature...306.html[/url]


Sep 17, 2014
Don't mind the creationist and pheromone anti-science trolls.

"You have no idea of how arrogantly stupid you are" is an apt description though! =D

@Vietvet: "You must not be aware that there are Christian evolutionary biologists".

True.

"and the Catholic Church has long accepted evolution."

False.

These arrogantly stupid sects are as creationist as the troll. They are not accepting the biological mechanisms but putting up false mechanisms (magic agency) and constraints (1 breeder pair bottleneck for humans).

And then these organizations, who makes a living out of unwarranted belief without evidence or as here with massive evidence against, try to lie to people about what they are, accepting only a few bits more than the usual "young Earth" creationists. It's like if a rapist said that they liked the clothes of their victim and put some aside instead of ripping it all off in the act. Is that any less contemptible? They should be as ashamed as the troll should be.

Sep 17, 2014
@Going: Sexual selection is powerful, especially in humans. If people are easier to recognize, they could be seen as better mate choices.

Interesting idea on twins. AFAIK likelihood of twins are suppressed in humans as opposed to other primates. But don't quote me on that, I would have to find the reference first!

@t_d_lowe: The evidence is in the article. I dunno if it is sufficient to swing a consensus, but it looks good to this layman!

JVK
Sep 17, 2014
You link to two papers supporting evolution and come up with "no evolution"


Genome Dynamics Events are RNA-mediated events that link the epigenetic landscape to the physical landscape of DNA in the organized genomes of species from microbes to man.

The current SCIENTIFIC "Perspective" on evolutionary events is that none have been described.

Combating Evolution to Fight Disease http://comments.s....1247472

RNA and dynamic nuclear organization http://comments.s....1252966

Until someone shows how an evolutionary event could lead from an RNA-mediated event to the evolution of biodiversity, serious scientists will continue to view Darwin's 'conditions of life' in the light of the biological fact that they have always been nutrient-dependent and always been pheromone-controlled.

Nutrient-dependent/pheromone-controlled adaptive evolution: a model. http://www.ncbi.n...24693353


Sep 17, 2014
This comment has been removed by a moderator.

JVK
Sep 17, 2014
Human pheromones: integrating neuroendocrinology and ethology
http://www.nel.ed...view.htm

"We have addressed several aspects of what is consciously perceived to be visual attraction both from an ethological and neuroendocrinological approach. In other mammals, the olfactory link among hormones, pheromones, and a conspecific's hormones and behavior would readily establish that visually perceived facial attractiveness, bodily symmetry, attractive WHRs, and genetically determined HLA attractiveness, are due to the neuroendocrinological conditioning of visual responsivity to olfactory stimuli. Yet, we have merely scratched the surface with regard to the pheromonal basis of human mate choice. As we can "see", the model of humans being primarily visual creatures may require some reconsideration. Human life and interactions are influenced by pheromones whether or not affect or effect are part of our consciousness. The affective hormonal reactions caused by olfaction..."

JVK
Sep 17, 2014
Sexual selection is powerful, especially in humans.


http://www.amazon...99737673

p. 210 This model is attractive in that it solves the "binding problem" of sexual attraction. By that I mean the problem of why all the different features of men or women (visual appearance and feel of face, body, and genitals; voice quality, smell; personality and behavior, etc.) attract people as a more or less coherent package representing one sex, rather than as an arbitrary collage of male and female characteristics. If all these characteristics come to be attractive because they were experienced in association with a male- or female-specific pheromone, then they will naturally go together even in the absence of complex genetically coded instructions."

Torbjorn_Larsson_OM is one of the most uninformed vocal antagonists I have encoutered. He thinks sex differences 'evolved.'

JVK
Sep 17, 2014
From Fertilization to Adult Sexual Behavior
http://www.hawaii...ion.html

"Similarly, therefore, if specific genes or genomic regions are found to be primary determinants of sexual orientations, upstream and downstream genes are likely also to play crucial roles. And these multigene interrelationships will have profound impact upon phenotypes and judgments derived therefrom. Parenthetically it is interesting to note even the yeast Saccharomyces cerevisiae has a gene-based equivalent of sexual orientation (i.e., a-factor and alpha-factor physiologies). These differences arise from different epigenetic modifications of an otherwise identical MAT locus (Runge and Zakian, 1996; Wu and Haber, 1995)."

Sex differences in cell types are nutrient-dependent. They are also pheromone-controlled, and they arise -- as do all other differences in cell types -- from RNA-mediated events.

Sep 17, 2014

"We cannot conceive of a global external factor that could cause, during this time, parallel evolution of amino acid compositions of proteins in 15 diverse taxa that represent all three domains of life and span a wide range of lifestyles and environments. Thus, currently, the most plausible hypothesis is that we are observing a universal, intrinsic trend that emerged before the last universal common ancestor of all extant organisms."

No last universal common ancestor = no evolution


Big surprise- Kohl completely misinterprets what the authors are saying. They're saying that the changes seen are not externally affected due to the vast differences in environments between the 15 studied taxa, so the changes are intrinsic and came from their last shared ancestor.

How on Earth did you get "no LUCA" out of that?

JVK
Sep 17, 2014
...emerged before the last universal common ancestor of all extant organisms.


The "intrinsic trend" links the epigenetic landscape to the physical landscape of DNA in organized genomes via pre-existing variation and the de novo Creation of chemical receptors that allow nutrients to enter cells and alter the RNA-mediated events that lead to amino acid substitutions that differentiate cell types in all individuals of all species.

How do you get mutations, natural selection and the evolution of biodiversity out of anything known about biophysically-constrained nutrient-dependent 'conditions of life' and RNA-mediated events that link ecological variation to ecological adaptations via conserved molecular mechanisms in species from microbes to man?

JVK
Sep 17, 2014
Counting fish teeth reveals DNA changes behind rapid evolution
http://newscenter...olution/

The changes in teeth are RNA-mediated via amino acid substitutions that differentiate all cell types in all tissues of all organs of all organ systems via conserved molecular mechanisms in all vertebrates.

http://perfumingt...mit.y=21

Sep 17, 2014
biophysically-constrained nutrient-dependent 'conditions of life'


We've been over this many times before, but you still don't understand. The conditions of life refers the the environment. Tell us how topology and weather are nutrient-dependent, biophysically-constrained, and pheromone-controlled.

The changes in teeth are RNA-mediated via amino acid substitutions


This tells me you either didn't read the fish paper or failed to understand it. The teeth changes were due to an altered cis-regulatory sequence (not an amino acid substitution). The regulatory sequence is non-coding, so there are no amino acid changes. Why were you under the impression there was a substitution?


JVK
Sep 17, 2014
Why were you under the impression there was a substitution?


Thanks for asking. Ecological adaptations are manifested in teeth in a predatory nematode compared to a grazing nematode and the physiology of reproduction in both P. pacificus and C. elegans is nutrient-dependent and pheromone-controlled via RNA-mediated events and amino acid substitutions that differentiate cell types in individuals of all species.

Why do you think the researchers were under the impression that differences in teeth evolve in the sticklebacks? Is there a model for that?

Sep 17, 2014
That didn't answer my question. You could have read the paper and saw that it was a regulatory change rather than a substitution, but you didn't. I called you out on it and you just brushed it off, as you did with Sean Pitman reapeatedly correcting your incredible ignorance here:

http://www.educat...nicorns/

JVK
Sep 17, 2014
Pittman wrote: "There was no change in the citrate receptor or transport protein, or any other protein."

"...competition for two carbon sources caused initially isogenic populations of the bacterium Escherichia coli to diversify into two coexisting ecotypes representing different physiological adaptations in the central carbohydrate metabolism." http://dx.doi.org....1001490

Pittmans says no change, and serious scientists note the change in ecotypes.

Until you learn how cell type differentiation occurs in species from microbes to man, you can only continue to display your ignorance, which is compounded when you add the ignorance of others whose comments support the pseudoscientific nonsense of your ridiculous opinions. I'm not going to detail the relationship between altered cis-regulatory sequences and amino acid substitutions, because it is already clear you understand nothing about conserved molecular mechanisms and believe in ridiculous theories.

Sep 18, 2014
Pittmans says no change, and serious scientists note the change in ecotypes.


Really gotta work on that reading comprehension, James. Pitman was telling you there was no change in any receptor genes and that the new phenotype was due to the translocation of the promoter that allowed expression of the transporter under oxic conditions. The oxic expression was the distinguishing factor between the two ecotypes.

I'm not going to detail the relationship between altered cis-regulatory sequences and amino acid substitutions, because...


No, you're not going to detail it because there is no relationship. One involves changing the expression of a protein and the other involves changing the amino acid sequence of the protein. They are not the same process. Altering expression does nothing to the gene sequence itself.

Sep 18, 2014
@JVK
It's a shame you put so much effort into being so stupid.

Sep 18, 2014
Uh huh. So, why do the Chinese all look alike?

Sep 18, 2014
antigoracle again with a redneck blurt
Uh huh. So, why do the Chinese all look alike?
They don't look alike to me, in respect of Asians, I've worked in the jungles of Malaysia, visited Singapore, Hong Kong & the Chinese "New Territories", met a large number of people over many years across the world, easy to distinguish & of course there are common features.

antigoracle every time you post you seem to want to show us you have narrow uneducated & inexperienced views, you seem to be on a mission to make yourself as erratic & as unimpressive as possible, why do you go to so much trouble; type without thinking like some reactionary droid devoid of empathy, don't proof read & blurt comments, often with an angry bent.

My earnest advice is get an education & above all travel (far) more :-)

JVK
Sep 18, 2014
Differences in the appearance of Chinese were detailed in the context of the same model that explains all cell type differences in all individuals of all species.

http://www.ncbi.n...3960065/
"Two additional recent reports link substitution of the amino acid alanine for the amino acid valine (Grossman et al., 2013) to nutrient-dependent pheromone-controlled adaptive evolution."

"These two reports (Grossman et al., 2013; Kamberov et al., 2013) tell a new short story of adaptive evolution. The story begins with what was probably a nutrient-dependent variant allele that arose in central China approximately 30,000 years ago. The effect of the allele is adaptive and it is manifested in the context of an effect on sweat, skin, hair, and teeth. In other mammals, like the mouse, the effect on sweat, skin, hair, and teeth is due..."

Sep 20, 2014
If you are thinking that jk's posts don't make sense you are correct.

JVK
Sep 20, 2014
There is no way to make sense when someone has been taught to believe in pseudoscientific nonsense.

First you must learn the difference between theory and biological facts. Then you can learn the facts about RNA-mediated cell type differentiation that make ridiculous claims about mutations, natural selection, and evolutions incomprehensible to serious scientists.

After you learn something about biological facts, you can see how they are linked from the Laws of Physics via chemistry to molecular biology and dispense with the pseudoscientific nonsense of evolutionary events that have not been described.

I dispensed with that nonsense 30 years ago, so you may have some catching up to do. But that's not my fault, is it? If my posts don't make sense to you, blame your physics, chemistry, and biology teachers. Tell them to start making sense out of their nonsense about evolutionary events.

http://perfumingt...-futile/

Sep 21, 2014
jk, you manufacture and sell cologne with pig pheromones in it that you say will make the user irresistible to women, that is pseudoscientific nonsense. Unfortunately that colors everything you say so don't talk to me about pseudoscientific nonsense because you are the king of pseudoscientific nonsense.

JVK
Sep 21, 2014
I do not temper my accurate representations of RNA-mediated events that determine cell types via amino acid substitutions. For those who want to proceed with caution, see:

"Regulatory RNA exchange between different organisms could be an important component in the hologenome's genetics, since RNA is a 'universal language' which affects other epigenetic processes, and in certain cases can become heritable."

http://jp.physoc....abstract

For those who wish to keep their head in the sand or up their (somewhere else) let "I Have Questions" be your guide to all answers. Do not follow any logical course that requires you to learn about physics, chemistry, or the conserved molecular mechanisms of biologically-based cause and effect. Simply insult anyone who tries to teach you.

Or see any of the 1100 blog posts at http://perfumingthemind.com/

Sep 21, 2014
@I Have Qestions, thank you for explaining the reason one feels the need to hold ones's nose while reading JVK's comments.

JVK
Sep 21, 2014
Thanks to all for proving that "Ignorance is bliss." If it weren't, you might learn something about the difference between pseudoscientific nonsense and biologically-based facts.

Interplay of microRNA and epigenetic regulation in the human regulatory network
http://www.fronti...14.00345

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