In the lead-up to what we’d find out is the return of Jonathan Hickman to Marvel Comics, as he overhauls the X-Men franchise, the publisher released this vague teaser which hints at an interesting conflict. Presumably, it’s between the mutants and the humans, implying that the world is not big enough for both, war is inevitable, and there can only be one winner.
The “conflict is inevitable” premise is based on a real biological phenomenon known as the competitive exclusion principle (because one of the hallmarks of science is inventing fancy jargon for relatively simple concepts). This states that two distinct species cannot occupy the same biological niche.
A niche is more than just a habitat; it includes all the important details of how a species interacts with their environment. The most important component of a niche is food. Two species can live pretty much on top of each other, as long as they pursue different food.
But if two species try to eat the same food source in the same place, a conflict will result. Even the tiniest advantage for one of the competing species will eventually lead to total extinction of the other, unless it can adapt its way out of the head-to-head competition.
Species can avoid competitive exclusion through something called niche partitioning, when competing species divide up the resources to avoid direct competition. A fascinating recent example was discovered in South Florida, where a native species of green anole (small lizards similar to geckos) adapted to live higher in the trees. An invasive competitor, the brown anole from Cuba, had begun to occupy the same niche as the natives, forcing them to move in order to survive.
Keep in mind this was a genetic adaptation to the different niche, not just a change in behavior. The freshly adapted green anoles have heritable anatomical changes to their body plan, such as longer and thinner digits, that better suit them in their new niche. When facing elimination, the green anoles found a way.
The invasive species of modern humans have a long history of forcing competitive exclusion upon others. A glance at the “family tree” of our closest relatives reveals a whole bunch of species that no longer walk the Earth. As we migrated out of Africa, the mastodons and other huge mammals (megafauna) suffered habitat loss and were possibly hunted to extinction, but the hominins that modern humans encountered (Neanderthals, Denisovans, Homo floresiensis, and Homo naledi, etc.) probably met their demise due to competitive exclusion.
In the X-Men teaser, the implication is that, in the Marvel Universe, humans and mutants are attempting to occupy the same niche and are thus locked in a struggle with only two possible results: competitive exclusion or niche partitioning. One group must adapt or or go extinct.
There’s just one problem with this. Competitive exclusion is the outcome when two different species attempt to occupy the same niche. If the two populations are the same species, or are otherwise capable of interbreeding, the more likely outcome is that the two groups will simply merge into one interbreeding population.
As my colleague Rob DeSalle has already explained for us, mutants are not a distinct species. They are humans, fully and completely, albeit with some enhancements due to the mysterious X-Gene. At best they are a subspecies, Homo sapiens superior, but they don’t really meet the ecological criteria for that either, since they live in the same area, have the same lifestyle, and pursue the same resources.
The unity of mutants and baseline humans within one species is evidenced by the many examples of successful interbreeding. Occasional hybrid reproduction between mostly separated populations leads to something called gene flow, through which two closely related species can contribute to each other’s gene pool.
The X-Men live among the human population, and so, over future generations, there is nothing to keep them distinct from one another. Their genetic destiny is to simply contribute their wonderful traits to the human gene pool.