Seeking Theories As To How Human Beings Acquired Individually Unique Faces Over Time

[Safetyhit]

This is something I have pondered for a very long while. Our existences are plausible via both creationism and evolution, in my opinion, however the one thing evolution lacks is an explanation as to how humans not only became self-aware and have individual personalities (although the latter can be categorized to an extent), but also even more strangely acquired unique faces. No other species of living creature is so diverse among it's own population, therefore despite their often many variations (let's say different types of crocodiles or horses) we are still utterly isolated in our rank of individuality.

How did this happen? Many species have been here far longer than us but have not evolved in such a way, some since the dinosaurs existed. I can see how greater intelligence could have somehow spurred individuality, but how could that ever have reflected in our appearances? What biological mechanism could have enabled such an incredibly different yet equally meaningful thing to happen to us?

I know we have some thinkers here so I thought it worth a shot. Obviously no one will know for sure but I'd be interested in hearing sensible opinions.

[Belmont31R]

We don't have the pure DNA from a single species. There were many different hominid species, and with geographical separation certain humans in different parts of the world were exposed to other hominid DNA. For instance, a study just came out to explain Nepalese ability to operate at high altitude with little ill effect while westerners don't. About 50% of the Nepalese tested have an allele from a now extinct hominid sub species that existed 30-40k years ago. This is different from South American people who have adapted to high altitudes. Similar end results but they got there by different means. In South America they have an increase in hemoglobin while Nepalese with the high altitude allele have LESS hemoglobin. Europeans have around 4% Neanderthal DNA while African's have 0%. So modern humans have quite a bit of variation in DNA based on geography and now extinct hominid species they were exposed to in the past.

Im not sure we're so unique in physical appearance being drastically more different from other species. There are theories about stripes on a Zebra being used by Zebras to identify individual members, and things like spots on a Leopard is as unique as a fingerprint. We may not be able to notice those types of unique characteristics but other animals can. There are several species where each member of a group has identity on an individual basis such as whales, lions, wolves, chimps, ect.

[Safetyhit]

We don't have the pure DNA from a single species. There were many different hominid species, and with geographical separation certain humans in different parts of the world were exposed to other hominid DNA. For instance, a study just came out to explain Nepalese ability to operate at high altitude with little ill effect while westerners don't. About 50% of the Nepalese tested have an allele from a now extinct hominid sub species that existed 30-40k years ago. This is different from South American people who have adapted to high altitudes. Similar end results but they got there by different means. In South America they have an increase in hemoglobin while Nepalese with the high altitude allele have LESS hemoglobin. Europeans have around 4% Neanderthal DNA while African's have 0%. So modern humans have quite a bit of variation in DNA based on geography and now extinct hominid species they were exposed to in the past.

Im not sure we're so unique in physical appearance being drastically more different from other species. There are theories about stripes on a Zebra being used by Zebras to identify individual members, and things like spots on a Leopard is as unique as a fingerprint. We may not be able to notice those types of unique characteristics but other animals can. There are several species where each member of a group has identity on an individual basis such as whales, lions, wolves, chimps, ect.

This is an outstanding start, but it may also highlight the initial question. You see I'm not sure we can compare a potential subtle difference in zebra stripe patterns or the ability of one human to adapt to low oxygen better than another to something as pronounced as a different physical configuration. Just within let's say white Europeans from the tenth century for example you have tall, short, fat, thin, long upper torso and short legs, the reverse, etc, etc. Take all of those different body types within one segment of a populace that has been mostly localized and then throw in the unique faces and it is clearly far more distinct that anything known.

Regarding the reference to cross-breeding, if let's say a chimp and an a baboon mated and were compatible to reproduce then their offspring would likely look like a combination of the two sure, but if they did it again would the next offspring be likely much different from the first? And if what you state is the cause then why has this sort of scenario not played out in the vast history of this planet far exceeding human existence before in some way? Why here and now after all the countless eons?

Understand that I would agree what you mention is the most likely explanation, however that said there are still sizable gaps in the theory to fill.

[halmbarte]

image.jpg

Humans use our faces to communicate lots of non-verbal information. We're very good at reading another person's intent from just facial cues*. It's also very important to use to recognize who we are dealing with, with a lot of personal identity being encoded in the face.

Faces are so important to humans that our brains have a face recognition center that's always working, trying to identify faces. So much so that we see faces in random things, like clouds or burn marks on bread.

H

*Dogs, selected by some 50,000 years of close relationships with humans, are also very good at reading human faces.

[SteyrAUG]

Random variation is huge part of life. There is no master schematic for species as you assume. In fact different species exist because random variation can be so significant as to produce new unique species within a few generations.

And the more environment influences some aspect of a species, the more variation you get. This was driven by both natural and man made selection. In the latter case babies who seemed more expressive were desired as more intelligent.

[Safetyhit]

Random variation is huge part of life.

Sure it is to an extent, but can you provide examples of other species that have individual faces or is that somehow irrelevant? If it is irrelevant, or possibly comparable in some way to another life form can you elaborate?

[MountainRaven]

Having met several dogs - including dogs of the same breed and same litter - I can tell you that dogs don't share a common face.

Humans are geared to using our eyeballs to identify things, including individual humans. I would posit that human beings don't have that many differences in their faces compared to other species - of mammals, at least - but that their brains are wired to identify those differences, creating the illusion of a greater degree of uniqueness than exists in other species. Simply because human brains are not wired to identify individuals of those other species.

[Safetyhit]

Having met several dogs - including dogs of the same breed and same litter - I can tell you that dogs don't share a common face.

Humans are geared to using our eyeballs to identify things, including individual humans. I would posit that human beings don't have that many differences in their faces compared to other species - of mammals, at least - but that their brains are wired to identify those differences, creating the illusion of a greater degree of uniqueness than exists in other species. Simply because human brains are not wired to identify individuals of those other species.

That's a fascinating reply holding some merit, but the physical distinctions we all possess to a strong degree even between immediate family can't simply be attributed to one's viewing context. In other words in my opinion it's not that our perception is so great as much as the differences are rather apparent.

[Belmont31R]

This is an outstanding start, but it may also highlight the initial question. You see I'm not sure we can compare a potential subtle difference in zebra stripe patterns or the ability of one human to adapt to low oxygen better than another to something as pronounced as a different physical configuration. Just within let's say white Europeans from the tenth century for example you have tall, short, fat, thin, long upper torso and short legs, the reverse, etc, etc. Take all of those different body types within one segment of a populace that has been mostly localized and then throw in the unique faces and it is clearly far more distinct that anything known.

Regarding the reference to cross-breeding, if let's say a chimp and an a baboon mated and were compatible to reproduce then their offspring would likely look like a combination of the two sure, but if they did it again would the next offspring be likely much different from the first? And if what you state is the cause then why has this sort of scenario not played out in the vast history of this planet far exceeding human existence before in some way? Why here and now after all the countless eons?

Understand that I would agree what you mention is the most likely explanation, however that said there are still sizable gaps in the theory to fill.

Humans spread out very fast, and adapted to unique locations. Not many other species have the reach we do, and thus there is less reason for variation. If you look at the 3 species of gorillas they have quite different sizes and habits but they all live in unique geographic regions. However, we don't classify humans under sub-species or as completely different species. We're all lumped into one despite radical differences in typical body size, skin color, ect. Neanderthal's were better suited to cold climates in Europe compared to African or Asian hominids. They had stockier bodies and thicker fur. Or if you look at humans an Inuit has a far different body shape than an Ethiopian or Aborigine.

Theres still some remnants like pygmies. Humans are pretty new on the scene. Birds, crocodiles, ect have had a far longer evolutionary history than us.

[montanadave]

Humans spread out very fast, and adapted to unique locations. Not many other species have the reach we do, and thus there is less reason for variation. If you look at the 3 species of gorillas they have quite different sizes and habits but they all live in unique geographic regions. However, we don't classify humans under sub-species or as completely different species. We're all lumped into one despite radical differences in typical body size, skin color, ect. Neanderthal's were better suited to cold climates in Europe compared to African or Asian hominids. They had stockier bodies and thicker fur. Or if you look at humans an Inuit has a far different body shape than an Ethiopian or Aborigine.

Theres still some remnants like pygmies. Humans are pretty new on the scene. Birds, crocodiles, ect have had a far longer evolutionary history than us.

Check out Nicholas Wade's recent book A Troublesome Inheritance: Genes, Race, and Human History. It seems to have ruffled some feathers.