6 Ancient Traits Still Found in Modern Humans — Here’s What They Reveal About Your Deep Ancestry

If you look in the mirror, you will see a modern human being, but hidden underneath are clues of traits that have existed for millions of years. Our bodies, up to this day, still carry these pieces of a much older story. Some of these features may have come from our mammal genome, primate lineage, ancient Homo sapiens, and even other human species that no longer exist.

Most of these traits feel and look like they do not have a function anymore, and it will feel strange for us to still have them. However, after learning just how important they were thousands of years ago, possibly longer, we may come to understand their true significance. Additionally, these characteristics in our bodies are a window to our past, and could reveal a lot about our deepest ancestral history. So, let’s look at 6 of these ancient traits.

Arrector Pili (Goosebumps): A Tiny Reminder of Our Furry Past

When you feel cold or even scared, you may notice small, tiny bumps in your skin, pulling your hair upright. This phenomenon is often referred to as goosebumps. Today, when it happens, it often feels like they are just making our skin bumpy and nothing else anymore.

However, for other mammals, this reaction is a lot more significant and beneficial. First off, goosebumps on other animals, especially those with thick fur, will be able to help warm the body when they feel cold. By making the hair stand up, it would be able to trap air and heat more efficiently, and close to the skin, warming the animal.

Additionally, the standing up of the hair allows mammals to look like they are bigger than they actually are. This is useful when facing certain threats. But in the modern world, goosebumps are now just considered a vestigial trait, or an evolutionary leftover of our ancestors that are probably a lot furrier than we are today.

The Palmar Grasp Reflex: Built for Clinging to a Furry Parent

What are vestigial structures? And you have them?

Have you ever seen a baby grab something when they are newborn? Well, if not, you are in for a surprise at just how tight their grips are. This is called the Palmar Grasp Reflex, which is also a vestigial behavior that is automatic and not by choice. Babies often exhibit these traits even before they are born, but after a few months will begin to lose them as they gain more control and precision using their hands.

In apes and monkeys, and possibly our primate ancestors, this reflex is actually vital for survival. The parents in the primate lineages would probably be swinging a lot in trees and jumping through a forest environment. Through it all, baby monkeys must be able to cling to their mothers to survive. They do this by using this tight grip to hold onto the fur of their parents.

However, humans no longer have their thick fur that babies could grab onto. So, this grasp reflex is most likely an evolutionary leftover from a time when our ancestors were much hairier, and in a period when babies must cling tightly to stay safe.

Wisdom Teeth: Extra Molars for a Tougher Diet

In our world today, there are a lot of adults who have had problems with their wisdom teeth and have needed them to be removed. These third set of molars often get stuck because the human jaws have become too small over thousands of years for them to be able to fit all these teeth.

But in earlier humans, at a time when we were mostly hunter-gatherers, not capable of generating our own food, we would often eat tougher materials. This included raw meat and other edible plants. So, those larger jaws and even the wisdom teeth were once necessary to chew these tough, uncooked foods.

However, as humans learn how to use fire and also transitioned to agriculture, their food became softer, and the need to chew on tough, uncooked edibles lessened. Over time, our jawbones shrank faster than our number and size of teeth did. As a result, we have these wisdom teeth that may not be as significant as they once were, creating dental problems.

Read more: Why Do We Have Wisdom Teeth? The Answer Lies in Our Evolutionary Past

The Coccyx (Tailbone): The Ghost of a Tail

At the base of our spines, there is a triangular bone called the coccyx, or tailbone. Nowadays, it just serves as an anchor point for muscles and ligaments in the pelvis. However, scientists suggest that these may have once a part of a real actual tail of the ancestors of humans.

In other mammals, tails are an important body part that provides additional limbs and helps with balance and movement. For tree-dwelling ancestors of humans, having a tail may have been significant for survival. It would’ve allowed them to jump through the trees with a lesser risk of falling down and be able to stay away from the ground where predators may have lived.

But, as our ancestors shifted to a different lifestyle that allowed them to live in both the trees, but also in the ground, these tails may have been less needed. Then, after millions of years, after transitioning to bipedalism, tails became even less useful, or even a hindrance in being able to stand completely upright. This could be the reason why it was reduced to a small bone at the spine’s end.

Read more: Why Did the Ancestors of Humans Lose Their Tails Around 20 to 25 Million Years Ago? — Here’s What Researchers Discovered

The Appendix: From Plant-Digester to Bacteria Safe House

Proof of evolution that you can find on your body

The appendix is an organ attached to the beginning of the large intestine. However, some people have it removed for a variety of reasons and still manage to live normally. So, for a long time, experts thought it could be useless now in the modern human body. But recent research showcases that they may have been serving as a house for beneficial bacteria that help our bodies repopulate the helpful microbes in the gut after an illness.

But, a long time ago, this structure in our body may have been an evolutionary remnant that is a part of a different and larger organ, called the cecum. Back then, even before being capable of consuming meat, our ancestors may have once just eaten tough plant materials that were harder to digest. But, as we learn how to diversify our diet, and be able to eat softer and easier to digest food, the need for it is reduced, and is possibly transformed to function differently.

Read more: Scientists Explain: Why Humans Have an Appendix — And What Evolution Says About This Puzzling Organ

Neanderthal and Denisovan DNA: Ancient Cousins in Our Genes

Some of the most surprising traits may not have been as visible in the human eye but instead hidden in our DNA. Neanderthals went extinct about 40,000 years ago, and Denisovans did about 50,000 to 30,000 years ago. However, both of these different human species have left a mark on our bodies that could still be observed today.

Studies show that most people with ancestry outside of Africa have about 1 to 2% DNA coming from Neanderthals, and some groups from Asia and Oceania also have a high likelihood of having Denisovan DNA. These were the results of our species interbreeding with those now extinct human relatives.

But their genes aren’t only a remnant of the past, but still actively affecting some individuals’ bodies. For example, Neanderthal genes could influence hair and skin color, sleeping habits, and even the immune system. While Denisovan DNA could help people utilize oxygen better in high-altitude environments with thin air.

Read more: 7 Clues Hidden in Your Body That Could Mean You Have Neanderthal DNA

Author's Final Thoughts

Even though we, the modern humans, are often considered advanced evolutionary creatures, we still hold traits and characteristics that were developed in the past. Some of those features may have come across as useless, but they may be hiding a benefit that we just haven’t discovered yet.

But, most importantly, these ancient traits most probably helped our ancestors survive during their time. So, we should learn about them and see ourselves as a part of a long chain of life, that is actively changing, and being influenced, even by the distant echoes of our deepest ancestral past.

Read next: Why Do We Feel the Need to Collect So Many Things? — Here’s How the Urge to Accumulate May Have Helped Our Ancestors Survive

References & Further Reading

Dhawan, S. S., Yedavalli, V., & Massoud, T. F. (2023). Atavistic and vestigial anatomical structures in the head, neck, and spine: an overview. Anatomical Science International. https://doi.org/10.1007/s12565-022-00701-7

Smith, H. F., Fisher, R. E., Everett, M. L., Thomas, A. D., Randal Bollinger, R., & Parker, W. (2009). Comparative anatomy and phylogenetic distribution of the mammalian cecal appendix. Journal of Evolutionary Biology. https://doi.org/10.1111/j.1420-9101.2009.01809.x

Ohta, Y., & Nishikimi, M. (1999). Random nucleotide substitutions in primate nonfunctional gene for L-gulono-gamma-lactone oxidase, the missing enzyme in L-ascorbic acid biosynthesis. Biochimica et Biophysica Acta. https://doi.org/10.1016/S0304-4165(99)00123-3

Simonti, C. N., Vernot, B., Bastarache, L., et al. (2016). The phenotypic legacy of admixture between modern humans and Neandertals. Science. https://doi.org/10.1126/science.aad2149

Reilly, P. F., Tjahjadi, A., Miller, S. L., Akey, J. M., & Tucci, S. (2022). The contribution of Neanderthal introgression to modern human traits. Current Biology. https://doi.org/10.1016/j.cub.2022.08.027