Scientists Reveal Humans Are Evolving to Lose Some Body Parts — Here’s What We May Not Have in the Future

Humans are still evolving, although the changes in our species’ bodies are not inherently noticeable to the average person. Scientists even think that we are slowly losing some body parts. Features that were once useful for our ancestors to survive in the environment they are in, but have now lost their functionality.

There are many evolutionary reasons why humans have several parts of their bodies that are no longer needed. In science, those are usually called vestigial organs. So today, let’s explore what these parts are and if humans would really evolve to lose them over time.

What Are Vestigial Body Parts?

A vestigial body part is something that was once useful to ancient humans, but today, does very little or nothing at all. They existed because, for thousands of years or more, they were needed, but since human civilization has rapidly developed over the past few thousand years, we have not evolved to lose them yet.

However, it is important to know that evolution does not have a predetermined goal or a mechanism to remove traits and body parts that are not useful, but also harmless. So, in other words, vestigial organs could persist in a population until it becomes disadvantageous to the humans who still have them.

This is because evolution is more complex than simply losing a body part that is not needed anymore. These organs were naturally selected just like the other traits in the past, and unless they have become harmful to the point that they trigger a high enough selective pressure, evolution will not work quickly to “remove” them.

Read more: Live Science

Why Are These Body Parts Disappearing?

Every 'Useless' Body Part Explained From Head to Toe | WIRED

So, evolution will not quickly remove a body part unless there is a significant selective pressure; however, over a long enough period of time, it could still make these vestigial body parts slowly disappear and fade away. This phenomenon could be explained or caused by a combination of subtle selective pressure and the chances of genetic drift in a population.

Yes, some organs might not be as useful anymore, but it still takes precious energy away from our bodies to grow and maintain them. Evolution often favors efficiency because in the natural world, those who can adapt to the environment win, and if an individual gains a marginal disadvantage from having these vestigial organs, over time, they could fade away in a population.

Another is genetic drift, which pertains to random fluctuations in the gene pool. If an organ is very significant to the individuals, the less chances it will disappear, but in the cases of vestigial parts, their prevalence in a population is subject to randomization. Over enough time and generations, this randomness could cause the gene to eventually disappear completely.

Now, let’s explore several key examples of these vestigial organs that may or may not live on our population in the future.

What Might We Lose in the Future?

Keep in mind that these vestigial parts could still persist at the individual level even into the future, but we are referring to the body parts that may not persist or be as prevalent in our total gene pool and population.

First, there are our body hairs. In the past, humans who shared a common ancestor with apes, millions of years ago, needed their body hair to keep them warm. However, as we venture out to different environments, evolution favored less and less body hair.

This is part of the open savanna hypothesis, which suggests that we have gained and lost several traits and characteristics as our environments have transitioned from forested areas to grasslands. In these fields where humans needed to run for hours to hunt for their food, under the scorching heat of the sun, losing their body hair was important for thermoregulation, reduction of parasites, and, eventually, survival.

Hominins with less body hair were able to cool down better by sweating, which is a process that is more efficient on bare skin. Later on, when the Ice Age came, humans learned how to make clothing to keep themselves warm; one of the reasons the body hair, just like that of chimpanzees, did not come back to our population.

In today’s world, the same reasoning applies, as our body hair is no longer as needed before for warmth, and our population often removes it by choice. Just like explained above before with other vestigial organs, this process may take countless years due to not having significant disadvantages or selective pressures.

Second is our wisdom teeth. Some people are already born without these specific teeth. It could be because they can pose some dental problems, in other words, a significant disadvantage to the population who mainly have it.

Humans before agriculture and the development of our cooking abilities often relied on hard-to-chew food to survive. However, as we transition to a softer diet, our jaws began to shrink, and the wisdom teeth have been impacted a lot. It caused pain, and sometimes, serious life-threatening problems like infections and limited eating.

However, due to our improved technology and medical expertise, they can often be removed easily and safely now. Although this only happened relatively recently in the history of humans, it may still effectively neutralize the strong selective pressure that wisdom teeth once caused. This may result in the gradual disappearance of the wisdom teeth, but possibly not in every single human being.

The last one we will talk about in this article is the appendix. Before, humans were thought to possess a much larger digestive system called the cecum. Charles Darwin argued that it was because of our need to break down tough plant materials as our main diet for millions of years before softer food was the norm.

After thousands of years, the cecum shrank, but the appendix remained. This is one of the reasons scientists have been studying it more closely, as it may not be as fully useless as we once thought.

However, the fact remains that humans could survive without them, so over time, a genetic drift or subtle selective pressure that we can’t directly observe or notice right now might affect their prevalence in the future of humans.

Read more: The Sun

Why Some Vestigial Parts Stick Around Longer

Our Body Parts That Will Be Unrecognizable in 100 Years

There are some body parts that stick around longer than necessary compared to others. However, the main reason why we have them still applies. Evolution may only remove the vestigial organs or parts, even if they are useless, if they become harmful or consume too much energy.

Some more reasons include repurposing, where useless organs may acquire new functionalities, even if it is minor, to help our bodies do their job more efficiently. Just like the appendix, where modern studies are now suggesting could host beneficial backup bacteria, acting as a “safe house”.

Another could be developmental constraints, because our bodies are very complex, and our organs are often intertwined. So, the genes and developmental pathways for some vestigial structures are still attached to a significant organ or parts. In this case, the risk of removal of these parts is not justifiable enough, and so if they are not harmful, they will often remain.

Examples include the wisdom teeth, as a simple genetic change could affect and risk unintended side effects to the development of other teeth or the jaw, because of how intertwined they are.

Author's Final Thoughts

So, yes, we may lose some body parts while we are continuing to evolve. However, this process is not as simple as one part being gone quickly in a population. There are countless factors at play that we could not see unless we look at our evolutionary history and overall trajectory as a species.

However, one thing is for sure: evolution is an ongoing process and will continue happening indefinitely, for as long as our environments change, and we continue to adapt and have the desire to survive and reproduce.

Read next: Archaeologists Found Early Humans Mastered Spears 300,000 Years Ago — But Here’s Why No Other Species Developed Tools the Same Way

References & Further Reading

Sarkar, A., Saha, A., Roy, S., Pathak, S., & Mandal, S. (2015). A glimpse towards the vestigiality and fate of human vermiform appendix — a histomorphometric study. Journal of Clinical and Diagnostic Research. https://pmc.ncbi.nlm.nih.gov/articles/PMC4378721/

Scheiwiller, M., et al. (2020). Third molar agenesis in modern humans with and without other tooth agenesis. PeerJ. https://doi.org/10.7717/peerj.10367

Xia, B., et al. (2024). On the genetic basis of tail-loss evolution in humans and hominoids. Nature. https://doi.org/10.1038/s41586-024-07095-8

Hawks, J. (2011). Selection for smaller brains in Holocene human evolution. arXiv preprint. https://arxiv.org/abs/1102.5604

Gruss, L. T., & Schmitt, D. (2015). The evolution of the human pelvis: changing adaptations to locomotion and birth constraints. International Journal of Primatology. (via PMC) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4305164/