4 beneficial evolutionary mutations that humans are undergoing right now

The genetic mutation that drives evolution is random. But here's a list of some beneficial mutations that are known to exist in human beings

4 beneficial evolutionary mutations that humans are undergoing right now

Most random genetic changes caused by evolution are neutral, and some are harmful, but a few turn out to be positive improvements. These beneficial mutations are the raw material that may, in time, be taken up by natural selection and spread through the population. In this post, I'll list some examples of beneficial mutations that are known to exist in human beings.


Beneficial mutation #1: Apolipoprotein AI-Milano

Heart disease is one of the scourges of industrialized countries. It's the legacy of an evolutionary past which programmed us to crave energy-dense fats, once a rare and valuable source of calories, now a source of clogged arteries. But there's evidence that evolution has the potential to deal with it.

All humans have a gene for a protein called Apolipoprotein AI, which is part of the system that transports cholesterol through the bloodstream. Apo-AI is one of the HDLs, already known to be beneficial because they remove cholesterol from artery walls. But a small community in Italy is known to have a mutant version of this protein, named Apolipoprotein AI-Milano, or Apo-AIM for short. Apo-AIM is even more effective than Apo-AI at removing cholesterol from cells and dissolving arterial plaques, and additionally functions as an antioxidant, preventing some of the damage from inflammation that normally occurs in arteriosclerosis. People with the Apo-AIM gene have significantly lower levels of risk than the general population for heart attack and stroke, and pharmaceutical companies are looking into marketing an artificial version of the protein as a cardioprotective drug.

There are also drugs in the pipeline based on a different mutation, in a gene called PCSK9, which has a similar effect. People with this mutation have as much as an 88% lower risk of heart disease.

Beneficial mutation #2: Increased bone density

One of the genes that governs bone density in human beings is called low-density lipoprotein receptor-related protein 5, or LRP5 for short. Mutations which impair the function of LRP5 are known to cause osteoporosis. But a different kind of mutation can amplify its function, causing one of the most unusual human mutations known.

This mutation was first discovered fortuitously, when a young person from a Midwest family was in a serious car crash from which they walked away with no broken bones. X-rays found that they, as well as other members of the same family, had bones significantly stronger and denser than average. (One doctor who's studied the condition said, "None of those people, ranging in age from 3 to 93, had ever had a broken bone.") In fact, they seem resistant not just to injury, but to normal age-related skeletal degeneration. Some of them have benign bony growths on the roof of their mouths, but other than that, the condition has no side effects - although, as the article notes dryly, it does make it more difficult to float. As with Apo-AIM, some drug companies are researching how to use this as the basis for a therapy that could help people with osteoporosis and other skeletal diseases.

Beneficial mutation #3: Malaria resistance

The classic example of evolutionary change in humans is the hemoglobin mutation named HbS that makes red blood cells take on a curved, sickle-like shape. With one copy, it confers resistance to malaria, but with two copies, it causes the illness of sickle-cell anemia. This is not about that mutation.

As reported in 2001 (see also), Italian researchers studying the population of the African country of Burkina Faso found a protective effect associated with a different variant of hemoglobin, named HbC. People with just one copy of this gene are 29% less likely to get malaria, while people with two copies enjoy a 93% reduction in risk. And this gene variant causes, at worst, a mild anemia, nowhere near as debilitating as sickle-cell disease.

Beneficial mutation #4: Tetrachromatic vision

Most mammals have poor color vision because they have only two kinds of cones, the retinal cells that discriminate different colors of light. Humans, like other primates, have three kinds, the legacy of a past where good color vision for finding ripe, brightly colored fruit was a survival advantage.

The gene for one kind of cone, which responds most strongly to blue, is found on chromosome 7. The two other kinds, which are sensitive to red and green, are both on the X chromosome. Since men have only one X, a mutation which disables either the red or the green gene will produce red-green colorblindness, while women have a backup copy. This explains why this is almost exclusively a male condition.

But here's a question: What happens if a mutation to the red or the green gene, rather than disabling it, shifts the range of colors to which it responds? (The red and green genes arose in just this way, from duplication and divergence of a single ancestral cone gene.)

To a man, this would make no real difference. He'd still have three color receptors, just a different set than the rest of us. But if this happened to one of a woman's cone genes, she'd have the blue, the red and the green on one X chromosome, and a mutated fourth one on the other... which means she'd have four different color receptors. She would be, like birds and turtles, a natural "tetrachromat", theoretically capable of discriminating shades of color the rest of us can't tell apart. (Does this mean she'd see brand-new colors the rest of us could never experience? That's an open question.)

And we have evidence that just this has happened on rare occasions. In one study of color discrimination, at least one woman showed exactly the results we would expect from a true tetrachromat.

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Image courtesy of iStock

This is what aliens would 'hear' if they flew by Earth

A Mercury-bound spacecraft's noisy flyby of our home planet.

Image source: sdecoret on Shutterstock/ESA/Big Think
Surprising Science
  • There is no sound in space, but if there was, this is what it might sound like passing by Earth.
  • A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
  • Yes, in space no one can hear you scream, but this is still some chill stuff.

First off, let's be clear what we mean by "hear" here. (Here, here!)

Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.

All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.

BepiColombo

Image source: European Space Agency

The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.

Into and out of Earth's shadow

In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.

The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."

In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."

When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.

Magentosphere melody

The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.

BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.

MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.

Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.

Photo by Martin Adams on Unsplash
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NASA finds water on sunlit moon surface for first time

Water may be far more abundant on the lunar surface than previously thought.

Lunar surface

Credit: Helen_f via AdobeStock
Surprising Science
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  • A study published Monday used NASA's Stratospheric Observatory for Infrared Astronomy to confirm the presence of molecular water..
  • A second study suggests that shadowy regions on the lunar surface may also contain more ice than previously thought.
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