Written by: Jenn Xu
Image from broughtonsoftware.com
Evolution is something that has been going on since life began on planet Earth, many millennia ago. It is a never-ending cycle of growth, adaptation, and creation. All species evolve to better suit their environments and to successfully reproduce and pass down their genes to the next generation. Eventually, even humans will evolve—and we already are. Homo sapiens have only been around for a very short amount of time since our planet first came into existence. We are evolved from our ancestors, and them from their ancestors too. This never-ending cycle begs the question: how will we humans evolve in the future?
The evolutionary concepts we study today are credited to Charles Darwin, as a result of his study of finches in the Galapagos Islands. He noted that all the finches on separate parts of the islands shared many similar features, save for their beak sizes due to the differences in food sources. He concluded that they had all originally evolved from a common ancestor. Natural selection had run its course by choosing physical traits that would be more beneficial than others based on the finches’ environments over others that were less helpful. This weeded out the finches with less beneficial traits and gradually created the new species. Evolution by natural selection, or Darwinism, is the idea that all life on Earth was evolved from the same, common ancestor. The species we all know today are those evolved from nature selecting individuals with traits that were superior to others and therefore allowed them to survive and/or reproduce more.
With natural selection in mind, how will that affect humans’ evolution? Right now, it is difficult to come up with ideas as to what new species may come of humans, seeing as macroevolution takes thousands of years, and future changes in the environment are hard to tell in the present day. Humans are spread all over the globe, making it a tedious task to take every factor into account. Therefore, this analysis into human evolution will only take into consideration the possible traits that microevolution will bring about to our species.
Microevolution is a change in trait frequencies between generations within a population. Relative to macroevolution, the changes occur in a short amount of time. Microevolution does not create new species but rather brings changes to a population of an already existing species. This means that an individual with this new or more prominent beneficial trait would still be able to mate and reproduce with an individual of the same species without this trait. They would also be able to have fertile offspring, solidifying the idea that they are still the same species, only with slightly different traits.
Major causes of microevolution aside from natural selection include gene flow, sexual selection, artificial selection, and genetic drift. To begin, gene flow is the exchanging of genes between two populations of the same species. This would create a shared gene pool between the populations. Back in the old days, our continents were separated by oceans and long distances to travel without efficient transportation. Due to this, traits from different peoples around the world were not mixed and matched and they stayed relatively consistent. In our world today though, due to globalization and immigration, the world will likely eventually have one big shared gene pool instead of many separate smaller ones. At some point, physical traits would homogenize. Dominant traits—such as brown skin, hair, and eyes—would stabilize to be displayed at a higher percentage. Recessive traits would become much rarer.
Next, sexual selection (the selection of mates rather than random mating) combined with artificial selection (selective breeding of a species by humans) may occur in the future as some people look for partners with rare traits. Individuals with rare, recessive traits would become far and few between due to the homogenization of traits. For example, one may seek out a partner who also has the recessive allele for blue eyes in order to try for a child that has blue eyes.
Finally, genetic drift may take place as humans move to colonize other planets in our solar system (and potentially beyond!). This cause of microevolution involves a change in the gene pool of a population by chance, although colonizing another planet is more of a conscious choice than an accident. Despite that fact, we’ll be focusing on something known as the “founder effect”, wherein a small group of a population leaves to begin a new population, changing the gene frequency in both populations. This new population—in our case, the group of planet colonizers—becomes limited in terms of the gene pool. There would be a change in the trait frequencies among these colonizers, but the change wouldn’t be too great. The colonizers would probably rely on mutations (a factor in natural selection) in terms of microevolution in these new, extraterrestrial environments.
Microevolution also heavily relies on changes in the environment in terms of natural selection, forcing populations to adapt. It’s the epitome of “survival of the fittest”. Think about a situation where a rabbit population moves to a colder climate where snowfall is more prominent. Against the white layer of snow, rabbits with darker coats would stand out and be preyed upon more often than those with lighter coats that would blend in better with the white landscape. As a result, those with lighter coats would survive better, reproduce more, and change the trait frequency of coat colours within the population.
But what about humans? What changes in our environment could bring about microevolution? Well, the biggest factor that would affect human microevolution would be the solar system colonization efforts, as mentioned before. Those environments are so far removed from Earth that there are bound to be changes to the human body. We already are aware of a few, due to the physical changes in astronauts that return from missions in outer space. A few new changes that we could potentially see in the future of colonization are evolved eye functions, differences in skin tone, and thicker eyelids. Eyes are likely to become larger in order to take in more light as humans adjust to dimmer environments further from the Sun. Bouncing off of this idea, humans may develop low-light vision too for the same purpose. Finally for eye changes, in order to protect our vision from cosmic rays, we may make use of the humans’ third eyelid too. This feature is something that has now become a vestigial structure in our bodies. In other animals, the third eyelid runs horizontally across the eyes as a sort of windshield function that spreads tears over the eye’s surface to keep it moist—though it heavily restricts the free eye movement we humans enjoy now. Relating to those cosmic rays, the thicker eyelids we are likely to develop in outer space would be a result of them too. In terms of skin tone, it will probably become more pigmented than before to serve as protection against UV rays that are stronger in space, where we don’t have the ozone layer to help us out.
There are a few features that we humans may encounter in the future too, that are completely related to advancements in technology and science rather than the introduction of new environments. The first would be the integration of cyborg-like features. As all novel technology does, cyborg features will probably become popular for some time among the general public as they become more accessible. However, it is speculated that they would also go out of style as people begin to strive to attain a more “natural” human look (a luxury in times where any physical feature can be chosen or modified). Along with the insane technological advancements, the human brain will most likely grow too as our minds become more complex. As a result, this would mean we would have larger foreheads too. Finally, genome editing—something scientists are already doing much research into—will be refined in the coming decades and centuries. Even today, the methods for this topic are becoming more and more capable. Thanks to this, most future human features could be based on preference. This would drastically change the gene pool of the human population on the planet.
In conclusion, there is a lot to absorb when it comes to human evolution. There are far too many factors that it is nearly impossible to account for every single one of them to create an accurate picture as to what future humans will look like. I mean really—seeing as us humans are more often than not the very species that causes the most changes to the Earth in the first place, I believe that the human condition is the most interesting yet unpredictable factor of all.
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