Mutants and Metahumans

Inheritance and Evolution

Our scientific observations of mutation, evolution, adaptation, sensation, perception, and ability can greatly inform our understanding of fictional universes.

Over a decade ago, I worked at a summer camp for gifted kids. A group of them, lovers of the X-Men comics, adopted me as their “Professor X” (Graduate Student B) and tended to think of camp as their equivalent of Xavier’s School for the Gifted. These teens felt themselves to be as different from their school peers as the ones who found their own safe haven at Professor Xavier’s school; they hoped they could be as special, that they might have the power to change or save the world.

X-Men casts the existence of Mutants (capitalized here to distinguish the race of Mutants from the Marvel series from the discussion of other mutants and mutations) as a step forward in evolution. Indeed, one of the several animated X-Men series was subtitled “Evolution” [ 1 ]. However, the association of mutation with evolution understates the prevalence of mutation; the great diversity extant in human sensation, perception, and ability; and the role of adaptation in evolution.

In this installment of It’s Not Brain Surgery, I’ll talk regarding the things you probably didn’t learn about sensation and perception in school, how these traits are passed on from one generation to the next, and how prevalence of a trait in a population will change over time due to evolution. Along the way we’ll see how these scientific observations can inform our understanding of fictional universes, from the Mutants of X-Men to Muggleborn wizards in the Harry Potter novels.

Sensation and Perception: The Not-So-Basics

My elementary school science textbooks talked about five senses: sight, hearing, touch, taste, and smell. Even my college courses persisted in this canon. It was a surprise, then, to learn early in graduate school that the story of the five human senses is such a simplification that it is almost a polite fiction. The human senses can better be described as dozens, and people whose senses work differently have a vastly divergent experience of the world than those who are neurotypical.

A small change encoded in a recessive gene can enhance an individual’s sensory experience; a sudden brain injury can alter it permanently. The bizarre experiences associated with schizophrenia, hallucinations, and delusions have some basis in altered sensory perceptions.

Touch is only one of the somatic, or bodily, senses. We also have senses of proprioception, the sense of the body’s position, temperature, pain, and itch. Vision, hearing, taste, and smell are not far from their descriptions your elementary school science book, but the sense of balance is almost never mentioned. All of these senses are composites of different stimulus properties encoded by nerve endings encountering the environment and are put together by the brain [ 2 ].

For example, information about color is received by cells in the eye called cones; information about motion is received by cells called rods. These two types of information are sent along separate pathways in the brain to the visual cortex, where they are integrated into a single conscious perception of a scene [ 3 ].

Mutations in the genes governing color sensation — a change in a single amino acid on a single chromosome — can give rise to red-green color blindness. Similar changes affect how different two colors need to be for an individual to tell them apart [ 4 ]. Most changes result in a diminishment of color sensation; however, it is rarely the case that individuals exhibit psychophysical behavior that indicates an enhancement of color sensation due to this type of mutation [ 5 ]. The rare person who has this enhanced color sensation is, in a way, an X-Men-type mutant with a superpower, albeit a superpower that is not likely to be useful in fighting crime.

Humble beginnings have led to great heights.

While sensations depend on discrete physical properties of the body and the environment, perceptions are put together in the brain. This makes them much more individual, subject to influences not in the physical stimulus, and changeable to some degree through learning.

One of the more interesting experiments in both cultural and perceptual psychology involved asking individuals from different cultures to name colors presented to them. It was at first believed that categorization of colors was related to changes in the cone cells mentioned above, based on the direction of light received by the eye, resulting in members of cultures closer to the equator perceiving fewer colors than those at higher latitudes [ 6 ].

However, later researchers asked members of different backgrounds to sort colors into groups of similar shades rather than naming them. This showed that these equatorial cultures’ members could perceive the same number of colors as those from northern cultures.

Furthermore, color categorization schemes could be learned in the laboratory [ 7 ], [ 8 ]. This example not only demonstrates the importance of research methodology on findings, but also shows that our learning influences our perception.

Genetic Transmission

In much of our speculative literature (a term I am using to include film, television, video games, and comics in addition to novels, short stories, and poetry), special abilities originate in a person’s genetic code. In X-Men, this is mutation. In the Avatar: The Last Airbender [ 9 ] universe, bending abilities (except for those of the Avatar) are passed down from parent to child; the child of two waterbenders will always be a waterbender, but the child of a firebender and an earthbender may be either.

We see a similar pattern in Barbara Hambly’s Darwath [ 10 ] novels, in which mage abilities are inborn and passed down from parent to child; a plot of these stories revolves around the predatory Dark Ones targeting mage-born children before their powers can be expressed, drastically reducing the number of potential mages in the world.

Likewise, in the Harry Potter [ 11 ] series, Muggles usually have a Muggle child; witches and wizards usually have magical offspring. However, a witch or wizard can be born to two Muggles, and a non-magical child, or Squib, may be born to magical parents. All these patterns are explainable through genetics, and through the interactions of genes and environment in an individual or over generations (called “epigenetics”).

You may be familiar with the concepts of dominant and recessive genes. If a child receives half of its genetic information from its father and half from its mother, and if a characteristic is encoded by two genes, then whether the father’s or the mother’s gene is expressed depends on which genes are dominant and which are recessive.

I’m going to give the canonical and not-terribly-accurate example of eye color, for simplicity’s sake. My father and mother both have brown eyes, and my eyes are blue. The gene for brown eyes is dominant, while the gene for blue eyes is recessive.

Let’s draw a Punnett square:


The top row and right-hand column each represent one of my parents. For me to have blue eyes, each of my parents must carry the recessive blue-eye gene, even though they both have brown eyes. When my parents’ genes combine to create offspring, there are four possibilities. The offspring can inherit two brown-eye genes, two blue-eye genes, a brown-eye gene from my father and a blue-eye gene from my mother, or a blue-eye gene from my father and a brown-eye gene from my mother.

If both genes are for brown eyes, then obviously the offspring’s eyes are brown, and likewise for blue. But if one gene is for brown eyes, and one gene is for blue, then the offspring’s eyes are also brown, as the brown gene is dominant, and expresses itself over the blue-eye gene [ 12 ].

I call this example “canonical” because it is often used in classrooms to introduce the concept of dominant and recessive genes. It is not entirely accurate, however, because eye color is encoded over multiple genes, and minor mutations can easily occur.

Let us imagine, therefore, that the gene for waterbending is recessive, and the gene for non-bending is dominant. We know that the character Katara [ 13 ] is a waterbender, and that her mother and father are not. Both of Katara’s parents must carry the recessive waterbending gene:


Each child has a 25 percent chance of being a waterbender, and 75 percent chance of being a non-bender. This is why we see Katara, a waterbender, and her brother Sokka, who is not a bender.

The Benders of the world of Avatar pass on their gifts genetically.

In the case of Mako and Bolin from the sequel series Legend of Korra, one parent was a firebender and the other, an earthbender.


Because the genotypes of all possible offspring are the same, and because this union produced Bolin, an earthbender, and Mako, a firebender, it appears that whether the offspring is a firebender or an earthbender is a random process, with each offspring having an equal chance of being either type of bender. The children of characters Katara and Aang show additional complexity, in that one child is a waterbender, one an airbender, and one not a bender at all. This suggests that bending is not inherited in the simple fashion described above  —  it must be encoded on multiple genes  —  and that there may be dominant/recessive interactions among different types of bending.

While no one is manifesting optic blasts in nature, genetic mutation is a fact of our ecosystem.

There are also cases where more than genetics determines the expression of a trait. In the Darwath series, character Rudy Solis is an artist from California. When Rudy is brought magically to Darwath (which is in a sort of parallel universe), he discovers that he possesses the ability to be a mage. It transpires that as a child, he magically made a dead branch flower. However, when he told his mother about this, she spanked him and told him not to imagine things. Rudy’s mage-powers then remained dormant until he became aware that these powers were possible in Darwath.

We therefore see that expression of a trait sometimes requires an environmental stimulus, even though the trait itself is encoded in a person’s genes. This may be like the mutant phenomenon in the X-Men, where powers are often dormant until triggered by an extreme emotional state. Magneto’s powers were first expressed in the X-Men [ 14 ] film, when he was forcibly separated from his mother during the Holocaust. As a further example taken from the same film, Rogue’s abilities were first expressed during a romantic encounter.


Essentially, evolution is the result of a lot of mating. Above, we saw how the combination of parents’ genes leads to characteristics in their offspring. Over time, decisions about mating result in more or fewer members of a group expressing a particular trait.

Going back to the Avatar: The Last Airbender universe, Katara is quite possibly the last waterbender in the Southern Water Tribe. The long war with the Fire Nation has resulted in the death or imprisonment of every other waterbender. Because bending is a recessive trait, the offspring of non-benders are less likely (only 25 percent) to be benders themselves. Without the eventual infusion of Northern Water Tribe genetic information, and the offspring of Katara herself, the ability to waterbend would have evolved out of the Southern Water Tribe. Likewise, in the Darwath universe, the targeted predations of the Dark Ones result in those carrying the genes for mage-powers to be wiped out in childhood, before producing children of their own. By the end of the series, the only known child with mage abilities is Rudy’s daughter, Gisa.

The practice of eugenics is the attempt to evolve more desirable characteristics in generations of human offspring. Often accompanied by forced sterilization of those with “undesirable” characteristics, eugenics also involves the selective mating of individuals with desirable traits [ 15 ]. This practice is embedded in the Death Eater agenda in the Harry Potter universe. The Death Eaters under Voldemort wish to expel all Muggleborn wizards and witches from their world, and to force “pureblood” wizards and witches to produce offspring together. They harshly punish purebloods who marry Muggles or Muggleborns, aka “blood traitors.”

Even when eugenics is not a factor, evolution is still subject to sexual selection. Males and females of a species seek out desirable traits in one another. This leads to the propagation of those traits that more males and more females prefer, over traits are not as preferred [ 16 ].

If more women prefer men with beards, over time more men will be hirsute, because more hirsute men will pass on their genes. It is important to realize, however, that only traits that influence an organism’s ability to pass on its genes will be subject to this kind of evolution. Take, for example, the human appendix. It is a more-or-less unused organ that persists in the human body despite its relative uselessness. Despite this, humans will not evolve to not have an appendix, because the existence of an appendix is unrelated to whether a person survives long enough to produce offspring.

Improved medicine over the 20th century and into the 21st may likewise have led to an increase in the number of people with genetic traits that might not be strictly “preferred.” The population may now consist of an increased number of people with severe allergies or childhood diseases like diabetes, because such individuals now live long enough to have children of their own instead of dying during their own childhood.

In the Darwath universe, mage abilities are generally rare because magic is disapproved of by a powerful church; mages are not generally attractive husbands or wives outside of the city where the more powerful mages live. Likewise, in Katherine Kurtz’s Deryni [ 17 ] series, Deryni magic is rare because of religious oppression.

All these cases are examples of evolution that happens slowly, over generations. X-Men postulates a faster evolution in which a mutation on a single gene increasingly gives rise to radically different abilities and appearances: telepathy, telekinesis, shapeshifting, healing ability, speed, etc.

This, of course, is exceedingly unlikely, even under the punctuated equilibrium hypothesis of evolution, which suggests that occasionally a mutation may be so valuable to species survival that individuals possessing it very quickly come to be the majority of the species [ 18 ]. In this case, despite the trappings of science, the X-Men universe is the least realistic of any fiction postulating the existence of special traits.


  1. Humble beginnings have led to great heights.” Anton Gvozdikov. Shutterstock. Moscow, Russia – November 20, 2016: Cosplayer posing at the Gamefilmexpo festival.
  2. The Benders of the world of Avatar pass on their gifts genetically.” Net Sama. Flickr.
  3. While no one is manifesting optic blasts in nature, genetic mutation is a fact of our ecosystem.” Anusorn Nakdee. Shutterstock. DNA helix break or Replace for concept of Genetic engineering and gene manipulation, molecule or atom, Abstract structure.

Dr. Robare has served as a panelist and sometime track head for PhilCon, the United States’ oldest continuously running science-fiction conference. She’s raising a new generation of nerds with her family outside of Philadelphia. Becky received a PhD in Cognitive Neuroscience in 2010 and now works as a research analyst and medical writer for a medical research non-profit. We’re ecstatic to unveil her series, “It’s Not Brain Surgery”, and her participation on several of our roundtables!


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  13. Katara. In Avatar wiki. Retrieved November 30, 2014, from
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  15. Editors. “Eugenics.” HISTORY, 13 Jan. 2021,
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