Humans are a diverse bunch, and with diversity comes a lot of genetic mutations. While many may hear the term “mutation” and automatically think of harmful diseases such as cancer, there are plenty of examples of common human mutations that are actually beneficial, or at least not detrimental. Here are a handful of common mutations that you might well be harboring yourself, or at least know someone else who does.
Even though around 8 percent of the world’s population has blue eyes, the mutation that gave rise to it is an incredibly recent one in the history of our species. While every single human used to have brown eyes, researchers have managed to pinpoint the mutation that led to blue ones. While changes in a gene called OCA2 causes a change in the amount of pigment produced in the iris, thus creating different shades of brown, it is a mutation in a nearby gene called HERC2 that acts as a switch that turns OCA2 off, resulting in no brown pigment and blue eyes as a result.
What is more amazing still is that researchers have been able to trace this gene variant back to when it likely first occurred, some 6,000 to 10,000 years ago. The first blue-eyed person likely lived in Europe as a 7,000-year-old Spanish skeleton is thought to belong to the oldest person found with the mutation.
This is one of the most satisfying examples of human evolution currently knocking about. While many of us in the West take drinking milk for granted, we stand pretty much alone in our ability to do so. Like all other mammals, most people around the world stop drinking milk when they reach adulthood as they lose the ability to digest it.
But around 10,000 years ago, as Europeans started to domesticate animals like cows, a mutation in the MCM6 gene meant that some people kept producing the enzyme lactase, allowing them to drink milk. What is even more amazing is that Europeans are not alone. Other farming communities that domesticated cattle, such as one in India, separately evolved the ability to digest milk, too.
Along with blue eyes and lactose intolerance, this is one of the most well-known genetic mutations that people have. While we probably all know someone who has been kissed by fire, the hair color is actually still pretty rare as only 4 to 5 percent of people have it, which to some makes the coloration all the more beautiful.
People in northern Europe are more likely to have red hair, and while some people have argued that it evolved under positive selection as a response to shorter days and longer nights, others suggest that it was, in fact, the absence of negative selection that allowed it to prevail in the higher latitudes. It is more common in people from Scotland and Wales not due to any particular reason apart from genetic drift, and the fact that these nations were probably quite isolated in the recent past.
Around 36 percent of Northeast Asians have this genetic mutation that means that when they drink alcohol their skin flushes a deep red. This facial flushing is not – as most people assume – because they are drunk, but rather as part of an immune response. The response is not due to the alcohol itself, but rather a substance that it is broken down to in the liver.
At some point in the not too distant past, there was a single point mutation in the gene that codes for the enzyme ALDH2, which prevents alcohol from being fully digested, meaning that some of the toxic intermediate substances accumulate and cause an immune response.
Missing wisdom teeth
Late erupting wisdom teeth can cause man all sorts of problems. But some people, roughly 40 percent of Asians, 10 to 25 percent of Americans of European descent, and 11 percent of African Americans, are lacking at least one third molar, as wisdom teeth are technically known. Amazingly, it is thought that around 45 percent of Inuits are also in this select group.
It is believed that like all mammals, human ancestors had three sets of four molars at the back of the mouth to help grind up the tough vegetation they ate. But as our ancestors managed to tame fire, the food they ate became softer and their jaws became narrower, eliminating the space needed for the final set that we call wisdom teeth. The oldest fossil known to have missing third molars is from China and is around 350,000 years old. It is thought that this is where the mutation originally arose.
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