Why do we as Homo sapiens have a huge variety of facial features, and is this exclusive to the Homo sapiens?!
We put Ghayath's question to population geneticist Sir Walter Bodner from Oxford University...
Walter - You've hardly ever, I imagine - unless youíre a pair of identical twins, seen anyone who looks just like you do. We are enormously variable in facial features, and we donít definitely know why that is, but it obviously has strong evolutionary basis; there must be something thatís selected for that. I think itís part of the way humans have evolved socially that it's been very important to be able to recognise people who are part of your own group, even your own family. There are very special regions of the brain for identifying faces and there are complex processes by which we analyse and discern what it is in a face that we recognise.
Felicity - How much of that variability is down to genetics?
Walter - Well nearly all of it. If youíve ever seen identical twins, theyíve got exactly the same genetic makeup and when you see them the first time, if youíre not their parents or anything, theyíre almost impossible to distinguish from each other and that tells us that the face is very largely genetically determined. You can vary it; you can have blue hair if you want; you can do things to your face if you go to the right sort of surgeon but, by and large, most of the features that we recognise in a face are very much genetically determined.
Felicity - When we look at other animals, we donít pick up on as much variability perhaps in their facial features. Is this something which is unique to humans?
Walter - No I donít think it is, but remember if you go to another country; if you go to Africa or you go to China, you probably donít find it as easy to recognise the facial differences there as you do in your own group. So thatís one thing, we donít necessarily know how to recognise that chimps may look very different to each other, so thereís undoubtedly a lot of variation there. Of course, if you take domesticated animals like dogs, a lot of variation has been selected for, so I think there is quite a lot of variation out there; most of it we donít quite know how to recognise.
"Why" is because humans take a long time to reach survivable maturity, so we have evolved to recognise our parents and tribe at an early age. We are therefore extremely good at facial recognition, to the extent that Heathrow Airport is going to replace its e-passport machines with more humans because we are far quicker at detecting a match (or a mismatch) despite variants due to makeup, spectacles, facial hair, etc., than any machine.
The two sides of the brain process data differently. We use both sides of the brain at the same time. However, we are only conscious of one side of the brain at a time. The other side will be unconscious but complementary. The left brain is more differential and allows us to see differences. The right brain is more integral and allows us to see what things have in common.
"However, we are only conscious of one side of the brain at a time." Show me that study! Whales all look the same to me but whales know one another. Your basis has no facts so your conclusion is spurious. mrsmith2211, Sat, 23rd Jan 2016
Please define consciousness. alancalverd, Mon, 25th Jan 2016
To answer the original question, many factors must be considered.
An extrapolated question to why humans have such a variety of appearances, is why are the insides of humans, more uniform than the outsides? Why is the heart more uniform looking than the face? One would be hard pressed to tell a pretty person from an ugly person, by looking at the stomach or heart. Maybe a doctor can see these differences, but it will take a more trained eye than it takes to differentiate a face. A child can do that.
One question that was asked is what is consciousness?