Genetics can be a fascinating thing. What makes our eyes blue instead of brown? Our hair straight versus curly? Sometimes these answers are determined by the genes our parents pass down; some are determined by mutations in our chromosomes. . . .
More often than not, mutations are random, and so many can be negative. Here is a video showing mutations gone wrong:
It’s no surprise that most people, when they hear the word “mutation”, attribute a negative connotation to it (which is no surprise, given what we just saw in the video above). However, not all mutations are bad.
For example, if you click on this page, there is a description of four beneficial evolutionary mutations humans have developed. You will find out there is a mutation that lessons heart disease, prevents broken bones, makes you a lot more immune to malaria, or, as quoted below, even gives women–yes, apparently only women–the ability to see the world in more colors.
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.
Imagine seeing the world, quite literally, in a different way to most humans on Earth.
Here is another website that lists 10 beneficial mutations (including several of the ones listed above), showing us that humans really do evolve to adapt to our climate (for the most part) or today’s very fast paced world. The webpost even mentions that certain individuals even have rare mutations that don’t necessarily help themselves, but definitely help others:
While most of us are aware of the eight basic blood types (A, AB, B, and O—each of which can be positive or negative), there are currently 35 known blood group systems, with millions of variations in each system. Blood that doesn’t fall into the ABO system is considered rare, and those who have such blood may find it challenging to locate a compatible donor when in need of a transfusion.
Still, there’s rare blood, and then there’s really rare blood. Presently, the most unusual kind of blood is known as “Rh-null.” As its name suggests, it doesn’t contain any antigens in the Rh system. It’s not that uncommon for a person to lack some Rh antigens. For instance, people who don’t have the Rh D antigen have “negative” blood (e.g. A-, B-, or O-). Still, it’s extremely extraordinary for someone to not have a single Rh antigen. It’s so extraordinary, in fact, that researchers have only come across 40 or so individuals on the planet who have Rh-null blood.
What makes this blood even more interesting is that it totally beats O blood in terms of being a universal donor, since even O-negative blood isn’t always compatible with other types of rare negative blood. Rh-null, however, works with nearly any type of blood. This is because, when receiving a transfusion, our bodies will likely reject any blood that contains antigens we don’t possess. And since Rh-null blood has zero Rh, A, or B antigens, it can be given to practically everyone.
Unfortunately, there are only about nine donors of this blood in the world, so it’s only used in extreme situations. Because of its limited supply and enormous value as a potential lifesaver, some doctors have referred to Rh-null as “golden” blood. In some cases, they’ve even tracked down anonymous donors (a big no-no) to request a sample.
Those who have the Rh-null type undoubtedly have a bittersweet existence. They know that their blood is literally a lifesaver for others with rare blood, yet if they themselves need blood, their options are limited to the donations of only nine people.
So what does this tell us? That we’ve not only evolved from apes (so to speak) to become who we are today, but we’re still evolving to become something else in the future! Maybe we won’t develop mental powers like the mutants depicted in the X-Man franchise, but we already have our very own X-men in real life–and that is pretty darn amazing.
Meet humble Australian James Harrison. Because of his blood, and donating over 1100 times in half a century, this one man’s blood has saved over two million human lives–precious new born lives. He quite literally is a hero.