This week’s question was asked by Kendalyn Gregar, fifth grade, La Grange Elementary School, Tomah.
Teacher: Chelsey Juliot.
QUESTION: Why do we all look different?
ANSWER: It’s a good thing we don’t all look the same. It would be a real problem to identify people if we all looked alike. There would be no difference between your doctor, your teacher, your store clerk or your mother. Distinguishing between individuals is an important task for human interactions. Imagine all the cases of mistaken identity: awkwardly waving at a stranger you thought was a friend! Being wrongly accused of committing a murder!
It is quite remarkable that there is massive variation among human faces compared to animals that pretty much all look the same. Did you ever try to tell the difference between two worms, or two raccoons or even two Holsteins? I should say that farmers appear to be able to tell their cows apart only because they see them two or three times a day.
Since ancient times, humans were relatively defenseless, and a man alone in the wild found it tough to survive. He needed others around him, a tribe if you will. Some animals, such as bears, are powerful. They can take care of themselves. Not so with humans.
Humans, in a tribal environment, were driven to do certain things to survive. Humans had to learn to communicate with each other. They had to know what was said and know which person said it. They had to find a way to tell people apart, recognize individuals and remember things about each one. That created a mental filing system with a file for each person they knew. A special part of the brain evolved to help us humans do that. The job of that part of the brain is to evaluate the face. All incoming visual face data is sent there.
The capacity of the human brain is huge. It is programmed to recognize faces because individual recognition is important to make our way in the world. An infant must learn to recognize its own caretaker and bond with her. Humans also have prolonged childhoods, and it would be extremely difficult to stay as a family if people cannot recognize the faces of their own family members. Our brains can recognize different faces even though differences can be small in many cases.
There’s more variation in human facial traits than there is for other body traits. For example, there are greater variations in the distance between the eyes or the length of a nose compared to arm length. In addition, facial traits aren’t connected to each other the way other body traits are, such as someone with long legs tends to have long arms. But you can have close-set eyes and either a wide nose or a small nose. Faces are unpredictable like that.
Researchers found that the relationship between our genes and certain traits, like height, is quite reliable. But they found the genes that influence facial features to be less straightforward. They have tested genetic sequences from Neanderthals to the present time.
Another reason we look differently is due to our development over many centuries. Scientists can tell quite a bit about a person’s racial identity by measuring the skull. Different populations tend to have skulls that are different in shape due to genetic drift and adaptation to the local environment.
The nose can look different because of adaptation. Populations that have lived tens of thousands of years in cold regions may develop narrower nasal passages to limit heat loss. Some populations developed larger skulls with flatter faces to increase brain capacity. The mixing of populations can result in further variation. India, for example, has experienced waves of migration from different parts of the Earth, and there has been a lot of mixing among people with European, African and Asian features.
When people migrated away from the tropical areas with loss of production of vitamin D (lower sun levels), they developed lighter skin and blue eyes. Red hair is a mutation in the north of Europe that is known to prevent rickets in darker climates. Whenever a population occupies a different natural environment, changes take place in that environment.
Some interesting observations. Eskimos aren’t blond, yet they live in the far north where production of vitamin D from the sun is certainly lacking. Eskimos developed a hunting technology that provided them with a diet high in vitamin D, a diet of whale, seal and walrus.
Facial recognition is fascinating. I admire people who can recognize another person quickly, even though they have met only once or twice or a long time has passed between meetings. It is something I have struggled with.
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