from the look-in-the-chinatown-phone-book dept.
There is a brief interview over at NPR with James Pampush, who recently published a paper in the journal Evolutionary Anthropology titled The enduring puzzle of the human chin. This paper is based upon his dissertation work about why homo sapiens have chins at all.
The conclusion of the article is that it appears that the chin perhaps points to some deeper insight into what it means to be human:
Well, if you're looking across all of the hominids, which is the family tree after the split with chimpanzees, there's not really that many traits that we can point to that we can say are exclusively human. Big brains - Neanderthals had larger brains than us. All those animals all walked on two legs. The one thing that really sticks out is the chin.
Paper abstract:
Although modern humans are considered to be morphologically distinct from other living primates because of our large brains, dexterous hands, and bipedal gait, all of these features are found among extinct hominins. The chin, however, appears to be a uniquely modern human trait. Probably because of the chin's exclusivity, many evolutionary scenarios have been proposed to explain its origins. To date, researchers have developed adaptive hypotheses relating chins to speech, mastication, and sexual selection; still others see it as a structural artifact tangentially related to complex processes involving evolutionary retraction of the midfacial skeleton. Consensus has remained elusive, partly because hypotheses purporting to explain how this feature developed uniquely in modern humans are all fraught with theoretical and/or empirical shortcomings. Here we review a century's worth of chin hypotheses and discuss future research avenues that may provide greater insight into this human peculiarity.
(Score: 2) by arslan on Friday February 05 2016, @06:20AM
Doubly human?
(Score: 0) by Anonymous Coward on Friday February 05 2016, @01:12PM
No, just American.
(Score: 3, Funny) by Anonymous Coward on Friday February 05 2016, @02:15PM
I think that was the point.
(Score: 0) by Anonymous Coward on Friday February 05 2016, @06:27AM
Neanderthals were humans, too. There's AFAIK some controversy about whether they were homo sapiens, but there's absolutely no controversy that they were homo.
(Score: 0) by Anonymous Coward on Friday February 05 2016, @06:32AM
technically neanderthals are known as "homo sapiens neanderthalis" and modern humans are known as "homo sapiens sapiens" (this is what my Larousse claims anyway). I think the author meant to say "modern humans", not necessarily "homo sapiens"; I doubt he's confused about neanderthals being "homo". You'll see that the abstract talks about the chin being unique among hominins, the first quote is just regular language used in an interview.
(Score: 0) by Anonymous Coward on Friday February 05 2016, @06:42AM
Nope, neandertals were "homo neanderthalensis", not "homo sapiens neanderthalis". Modern humans are a considered sub-species of the original homo sapiens due to some rather significant mutations occurring over the tens of thousands of years since the species' origin, but our branch of human are the only homo sapiens to have ever existed - there is no other long-lost or extinct branch of homo sapiens, just us and our ancestors.
(Score: 2, Funny) by Anonymous Coward on Friday February 05 2016, @08:06AM
In response to the above, please add "That we know of."
Please don't state things as proven fact like that.
There may well have been distinct species emergent in small batches and we would have no record. It mostly depends on what knocked them out.
In fact pre-history is littered with legends of "humankin".
I have a feeling that, we will one day find that truth is much stranger than reality. I remember how I felt when they found hobbits.
For a better example of what can happen...
We that there was at one time a population bottleneck.
We don't know what caused it and we don't know how long it lasted all we know is that we are survivors of that bottle neck.
But homo sapiens would have been well disbursed, hence there were very likely others that survived that bottleneck, at least for awhile.
They probably evolved independently. We know that egyptians had electricity, romans had steam power and greeks had clockwork computers, this is stuff that survived numerous purgings, truth is we really don't know for certain even what these well documented cultures actually achieved at their pinnacle.
We like to think every culture besides our own was always primitive, but consider how primitive we were 1,000 years ago and consider that with average lifetimes rapidly approaching 100 years because of better diet and excerisze and health care, that 1,000 years is barely over 10 lifetimes ago.
Now consider that the bottle neck was between 70,000 and 100,000 years ago and dropped our direct ancestor's population count down to as low as 2,000.
That's 30,000 years of declining population or population in decline. Meaning many, many diaspora at least for awhile. We haven't had a major evolutionary advance in this time, hence anyone around was at least AS smart as you and I. Nothing about this says that THEY didn't have an evolutionary advance and yes I consider technology to be evolution.
This isn't really a shot in the dark "what if". Our primitive ancestors recorded stories of things that were fanciful but that are rapidly becoming reality.
We're faced with the prospect that they #1 saw actual gods, #2 interacted with someone far more advanced and suffered from an actual break down of the language, i.e. cargo cult. Since I don't believe aliens would give two figs about us, and gods are notorious for not actually showing up as promised, I think the advanced "them" were just other people. People like you and me. They did their thing and then *poof* gone.
God only knows what happened to cause the bottle neck, but humans like to spread. We'll literally try to mate with anything even remotely hominid looking *ever heard of furries?*.
It's entirely possible that ancient stories of gods, devils, demons, angels, devi, asura etc were literally true.
Open your mind and before you laugh, ask yourself this. "Why is there clear evidence of proto-indo-european, strung out through most of the languages of the world?"
Why does ar mean air or high in almost every language. wa is water, ma is mother. These are root cognates and almost no languages are devoid of these common sounds.
I think it's clear evidence that just like english is a universal language right now, there was once another universal language and it was broken and lost during the bottle neck. Do some research, the time tables line up really well.
You can say that we would be digging up old laptops and finding abandoned skyscrapers, rusted out cars etc. But maybe we just aren't digging in the right places. If we disappeared tomorrow and came back in 100,000 years I can promise you New York & LA would have been long since reclaimed by nature with nary a trace left.
So assume that something smashed a global society, a great dying of sorts. What is left are independent societies living a post apocalyptic life. They would have evolved in isolation just from environmental factors. But humans are great with inventing crap and that crap rapidly changes who we are, what we eat, how we acquire what we eat etc. Small tribes would gradually coalesce and begin sharing tech, but would be isolated enough to maintain little or no contact with the more primitive tribes that were left. We would have been a curiosity to them, just like we feel about the primitive tribes in the Amazon and etc.
Our ancestors could easily have bumped into dramatically more advanced people and came running in terror back to their tribe to tell all they saw, cargo cult gods in tow.
We might be the next of the primitives to reach this stage of development.
What comes next?
My guess is we explore offworld or run into the "great filter" again so only the isolated tribes are left to tell stories of us to their children and wage war over what Anonymous Coward did and did not sayeth and who were the chosen of the Soylentils vs the damned at Slashdot.
I'm quite certain there may be literal holy wars on vi vs emacs and the people who wage these wars will have absolutely no idea what either actually is.
God forbid they find out about systemd or beta :)
(Score: 1, Insightful) by Anonymous Coward on Friday February 05 2016, @09:46AM
it would be nice if there was an objective definition of species and subspecies. Since there is not, it all comes down to where you draw the line.
For example, if we hold that two populations belong to the species if they can and do (did) produce fertile offspring, recent evidence showed that we were, in fact, the same species.
(Score: 1) by dexcheque on Friday February 05 2016, @02:09PM
An objective definition can be tricky across such a narrow scope of difference, chins notwithstanding.
"For example, if we hold that two populations belong to the species if they can and do (did) produce fertile offspring, recent evidence showed that we were, in fact, the same species."
If this were the Line In The Sand, coyotes, wolves, and dogs are the same species -- they are all canines with many physiological differences, but who can interbreed with relative ease. Horses, donkeys, and mules might, as well (because, rare as they may be, some mules can procreate).
To back up, though, I'm kind of curious about the purpose for chins. Do they serve to offer better support for eating plant matter cultivated on an agricultural scale? Do they better protect throats from rowdy, club-swinging bipedal competitors (chins seem to be more pronounced on men than on women, lending itself to the question)?
(Score: 0) by Anonymous Coward on Friday February 05 2016, @03:32PM
Chins do not have to have a purpose though. As long as they do not decrease our fitness, its all fine.
Anyone read Candide?
(Score: 0) by Anonymous Coward on Friday February 05 2016, @05:03PM
(Score: 1) by dexcheque on Friday February 05 2016, @06:21PM
They don't have to serve a purpose, true. And it's possible, even, that it's simply the result of a harmless anomaly that was never, ever selected out by whatever factors... But, since a pronounced chin is standard for the Modern Man skull, it seems to me the likelihood that it never had any value at all (i.e. was never selected FOR by any factor) is fairly slim. Even considering a population bottleneck of only 2000 folks, that's still a lot of chins all at the same time for them to have not been selected for.
Selection factors are often shifty, shady enterprises -- at least as far as our limited understanding goes. Even environmental factors can be vastly more subtle than simple climate and geography. Just because we don't understand how a thing may have been selected doesn't mean that it wasn't.
(Score: 0) by Anonymous Coward on Saturday February 06 2016, @05:17PM
Good for attaching beards and facial hair. And apparently many women at peak fertility like bearded men: http://witscience.org/study-proves-women-prefer-men-beards/ [witscience.org]
http://beheco.oxfordjournals.org/content/early/2012/12/11/beheco.ars211.full [oxfordjournals.org]
http://www.ehbonline.org/article/S1090-5138%2813%2900022-6/abstract [ehbonline.org]
And beards might be like a lion's mane- for intimidating other males and possibly protection: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2814555/ [nih.gov]
However beards can also be a liability, easy to grab: https://www.biblegateway.com/passage/?search=2+Samuel+20%3A9-10&version=ESV [biblegateway.com]
(Score: 1, Funny) by Anonymous Coward on Friday February 05 2016, @05:05PM
I'm pretty sure it has something to do with cunnilingus. I don't exactly know what, but it's definitely involved somewhere.
(Score: 0) by Anonymous Coward on Friday February 05 2016, @06:15PM
Skill in cunnilingus does not help one procreate. Sure it helps one get laid for fun, but for the purposes of passing on genes... like the joke goes, "One sperm says to the other, 'How far do you think it is to the egg?' and the other responds, 'I'm not sure, we only just passed the tonsils...'".
(Score: 1) by dexcheque on Friday February 05 2016, @06:25PM
It may well provide for more opportunities, however.
(Score: 3, Funny) by JeanCroix on Friday February 05 2016, @07:02PM
(Score: 2) by HiThere on Friday February 05 2016, @07:50PM
Have they considered neutral drift. There's quite a bit of evidence that the human population went through a prolonged period when the population number were quite small, and that's an ideal environment for neutral drift to dominate. (Actually, neutral drift appears to happen as often as adaptive evolution anyway.)
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 1, Interesting) by Anonymous Coward on Saturday February 06 2016, @02:06AM
Chins allow you to hold stuff temporarily if both hands are full. For nomadic people or hunters who had to pack up often, that could be quite handy.
(Score: 1, Insightful) by Anonymous Coward on Saturday February 06 2016, @07:33AM
They also help protect the jugular when you tilt your head down. As warfare became more sophisticated, the jugular needed more protection.