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Tue Apr 16, 2019, 10:30 PM

Evolution of the human face points to a non-violent past


Scientists think the human facial structure may have changed because of diet and cooperative social structures

KEITH A. SPENCER
APRIL 15, 2019 11:00PM (UTC)

The human obsession with emoji, and the sheer number of them available on your phone, may have its origins in 6 million years of evolution. A new article in Nature Ecology & Evolution, titled “The evolutionary history of the human face,” suggests that the great array of human facial expressions may make us more unique among species than we’d thought previously. Moreover, the shape and lack of hair on our faces seems to have evolved very specifically so that humans could convey a range of expressions, setting us apart from other hominids and even most other animals on Earth.

That means the minute differences in emoji expressions — and your instant inability to recognize the emotions they represent — are the byproduct of 6 million years of evolution.

The review article, co-written by experts in the field from a number of different institutions and backgrounds including paleobiologists, paleoanthropologists and archaeologists, comments on the origins of the facial muscles and bones that enable such a range of expression. “Modern humans have a short, retracted face beneath a large globular braincase that is distinctively different from that of our closest living relatives,” the researchers write. How this happened relates to both diet and social structure.

Indeed, changes in the human diet changed the way that our teeth look. The use of fire was key: Food that has been cooked or baked in a fire is softer and less sinewy than uncooked meat or plant matter, meaning the human jaw became smaller and our internal teeth smaller. The face become flatter as a result, researchers say.

More:
https://www.salon.com/2019/04/15/evolution-of-the-human-face-points-to-a-non-violent-past/

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Response to Judi Lynn (Original post)

Wed Apr 17, 2019, 01:51 AM

1. Yes.

What a lot of people don't understand is that human evolution is ongoing. And human evolution has probably accelerated in the last 10,000 years.

I've recently read a couple of books on that topic. One is The 10,000 Year Explosion: How Civilization Accelerated Human Evolution by Gregory Cochran and Henry Harpending. It covers such topics as the change in our face and jaw as food, or how we ate, changed. It's totally fascinating.

There's a sense out there that human evolution came to a screeching halt around 10,000 years ago, around the time some of our ancestors became farmers and built cities. That's simply not true, even taking in to account not all of our (collective or individual) ancestors did that.

Another fascinating book on human evolution is Who We Are and How We got Here: Ancient DNA and the new science of the human past by David Reich. For me the most astonishing part of that book, and what has stayed with me since I read it, is that he says if you go back 10,000 years or more in time, you'll find human groups that are as distinctive as ones we know now (think what we refer to as races) and yet they are completely unrelated to modern groups (again, think races). Human evolution is amazing and fascinating, and is, as I said above, an ongoing thing.

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Response to PoindexterOglethorpe (Reply #1)

Wed Apr 17, 2019, 10:12 AM

2. Thank you.

I will look for those books, especially the second one.

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Response to PoindexterOglethorpe (Reply #1)

Wed Apr 17, 2019, 11:55 AM

3. Thanks, added both to my ThriftBooks Wish List. nt

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Response to eppur_se_muova (Reply #3)

Sat Apr 20, 2019, 01:11 PM

14. I just found Thriftbooks about a year ago. Better late than never I guess...:)

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Response to PoindexterOglethorpe (Reply #1)

Thu Apr 18, 2019, 03:55 AM

4. Tremendous reading recommendations. Thank you! n/t

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Response to PoindexterOglethorpe (Reply #1)

Fri Apr 19, 2019, 03:21 PM

7. Poindexter, I'm not sure I agree. We have not evolved in a genetic sense for a very long time.

We now evolve through culture. Remember, evolution only occurs if some genes are removed from the gene pool and new ones become more numerous. Our advances in medicine and tool use mean that most of us will live to reproduce. Evolution works at the population level based on which individuals tend to survive and which ones don't.

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Response to Nitram (Reply #7)

Fri Apr 19, 2019, 03:37 PM

8. Yes, we have evolved in a genetic sense,

and the first book I noted in particular details that evolution.

The sickle cell trait is one example. So is a reduction in our lower jaw.

It's one of those false bits of received wisdom that we stopped evolving around the time we settled down with agriculture, but in fact agriculture helped speed up recent evolution. Certain groups can continue to digest lactose into adulthood. Those are the groups who raise certain animals for their milk and continue to drink milk into adulthood. And it's two separate genes that evolved independently in that case.

Other examples are adaptations to living at high altitude, the "alcohol flush reaction" in many Asians which is actually from a genetic enzyme deficiency. Those deficient in that enzyme are far more likely to develop esophageal cancer if they drink, and that deficiency also causes the flush reaction. Really quite cool in a way.

Light skin and blue eyes are two more examples of recent evolution. Also, the loss of wisdom teeth.

None of those are cultural. They are real examples of genetic evolution.

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Response to PoindexterOglethorpe (Reply #8)

Fri Apr 19, 2019, 03:57 PM

9. What selective pressure is it that would lead to a complete loss of wisdom teeth?

Mine were removed by a dentist. Wisdom teeth would only disappear if people with wisdom teeth died in far greater numbers than those without. The same is true of alcohol flush syndrome. Most people would be able to reproduce well before they died of esophageal cancer from drinking alcohol. Have you read that there is any evidence that the proportion of people with fair skin and blue eyes is increasing? Yes, this is a relatively recent evolutionary development that occurred in some populations at high latitudes, but are there any adaptive pressures that are working to increase the proportion of those genes in the world population? If the ozone layer failed, more people with fair skin would die of cancer. But would that happen before they had a chance to reproduce?

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Response to Nitram (Reply #9)

Sat Apr 20, 2019, 12:34 AM

10. I don't know. But the reality is that

modern people have fewer wisdom teeth than in generations past. And blue eyes and fair skin really are a relatively recent occurrence.

The fact is that the Asian Flush is a real genetic thing. It doesn't matter that all humans aren't subject to it. Just that it really has affected those with it in that population.

At some point in the past there were no humans with fair skin and blue eyes. Now there are lots of them. So, yes, they've been increasing.

It doesn't matter that those who live at low altitudes aren't affected by the genetics of those at high altitudes. You are entirely missing the point if you think that all humans must be subject to these genetic influences for them to matter. The reality is that these genetic influences are actually happening, are influencing the population.

Do a bit of research. Don't just dismiss evolution.

Humans are evolving. Are continuing to evolve. Just because every single one of us aren't subject to the exact same evolutionary pressures doesn't mean they don't exist.

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Response to PoindexterOglethorpe (Reply #10)

Sat Apr 20, 2019, 10:22 AM

12. Yes, wisdom teeth changed over time when there were selective pressures that helped eliminate them

from the gene pool. There can be no such evolution taking place now because wisdom teeth don't kill people before they can reproduce. You seem to ascribe to a sort of Lamarckian evolution. I don't dismiss evolution. I'm a biologist and understand that evolution does not bring about major changes unless there are selective pressures pushing a population in certain directions. And please, Poinmdexter, enough with the patronizing "do a little research." I've been researching evolution my entire life. If you cannot name a mechanism for an evolutionary change you claim to see taking pace in the present, then you are in error.

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Response to Nitram (Reply #12)

Sat Apr 20, 2019, 11:40 AM

13. So if there are no selective pressures to eliminate wisdom teeth,

why is one in four people missing at least one wisdom tooth?

While Lamarck was wrong in thinking that acquired traits could be passed on, you must be aware of the research that shows that environmental conditions can turn some genes on or off, or that prenatal conditions can matter, and can affect descendants several generations on.

Selective pressure isn't simply people with a trait dying before they can reproduce. It can be selective if there's simply a small but real advantage and so that those with the trait have more children. If you are defining selective evolution as one that massively transforms an entire population, well that definition overlooks the very real changes that happen in smaller segments of the population. Just because I can't name the mechanism, doesn't mean it doesn't exist. The example of the gene that causes the "asian flush" response to alcohol turns out to be connected to the enzyme that is a factor in developing esophageal cancer from drinking alcohol is one such. I'm sure it took some interesting research to figure that one out.

Here's a link to just one recent article about human evolution. https://phys.org/news/2018-11-human-evolution-possibly-faster.html

If people like that say human evolution is happening and even speeding up, I'm going to trust their judgement. Oh, and you might want to click on the link at the bottom of that article, the one that says Natural selection is not the only process that drives evolution.

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Response to Judi Lynn (Original post)

Fri Apr 19, 2019, 03:14 PM

5. A Ted talk awhile back analyzed how we are smarter than our great grandparents

Though he didn't necessarily attribute it to evolution, it was a consideration. Maybe why the older RW's are always trashing millennials. They know they are smarter.

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Response to Farmer-Rick (Reply #5)

Sat Apr 20, 2019, 12:36 AM

11. In all honesty, I'm not that certain that we, collectively, are

very much smarter than our great grandparents.

Most of us have been the beneficiaries of education, but in all honesty, if you put us into some sort of level playing field, I'm not convinced we'd do that much better.

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Response to Judi Lynn (Original post)

Fri Apr 19, 2019, 03:16 PM

6. We learned to kill without using our teeth to rip out an enemy's throat.

I'm not so sure that suggests a non-violent past. And smile while we did it.

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Response to Nitram (Reply #6)

Sun Apr 21, 2019, 02:29 PM

16. I'm missing the "non-violent past" part as well.

I swear when I first saw this post/article it mentioned losing our prominent brow .. it sounded like it was because we didn't have to be fearsome???.. and I wondered about the DNA connection to how THAT would work....

Anyway, I'm going to throw in 'Sexual Selection' for fun. Ladies choice (when we became 'less violent instead of taking and raping') of who to pass along genetic material with.

Just sayin... (with a wink and a nod).

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Response to Judi Lynn (Original post)

Sun Apr 21, 2019, 12:17 PM

15. Cooked food too, me thinks

Made the whole flatter face possible.

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