Top 10 Indicators of Evolution in Modern Humans

Throughout history, natural selection has played a pivotal role in shaping the evolution of modern humans, rendering many once-essential bodily functions and structures obsolete. What’s particularly intriguing is that many of these remnants still persist, offering us a glimpse into our evolutionary journey. This list highlights the ten most prominent evolutionary adaptations that have left traces behind.

10. Goosebumps - Cutis Anserina

Humans experience goosebumps when they feel cold, frightened, angry, or even in moments of awe. This same reaction is shared by many animals, such as when a cat or dog’s fur bristles, or when a porcupine’s quills rise. In colder environments, the raised hairs trap air between the skin and hair, creating an insulating effect to retain warmth. In response to fear, goosebumps serve to make an animal appear larger, potentially warding off threats. Though humans no longer gain any advantage from goosebumps, this trait is a remnant of our past, from a time when we lacked clothing and needed to intimidate predators. While natural selection eliminated our thick fur, it preserved the mechanism that triggers goosebumps.

9. Jacobson's Organ - Vomeronasal Organ

Jacobson's organ is an intriguing structure in animal anatomy that offers valuable insight into our own evolutionary history. Located in the nose, it serves as a specialized 'smell' organ that detects pheromones—chemicals that influence sexual attraction, alert to danger, or signal food trails. This organ enables certain animals to track others for mating purposes or sense potential threats. While humans are born with Jacobson's organ, it loses much of its functionality during early development, rendering it nearly useless. In ancient times, humans would have relied on this organ to locate mates when other forms of communication were unavailable. Today, modern dating methods like singles events, chat rooms, and bars have replaced its original role in mate-seeking.

8. Junk DNA - L-gulonolactone Oxidase

While many remnants of our 'devolved' past are visible or physical, this is not true for all of them. Humans carry genetic structures that once produced enzymes to process vitamin C, known as L-gulonolactone oxidase. Most animals still have this active gene, but at some point in our evolution, a mutation disabled it, leaving behind what we now refer to as junk DNA. This particular junk DNA serves as evidence of a shared ancestry with other species, making it particularly fascinating.

7. Extra Ear Muscles - Auriculares Muscles

The auriculares muscles, also known as the extrinsic ear muscles, are used by animals to move and rotate their ears independently of their head in order to better focus on specific sounds. Humans still retain these muscles, once essential for the same purpose, but they are now so underdeveloped that they only allow our ears to make small, insignificant movements. The use of these muscles is much more noticeable in cats, who can rotate their ears almost completely backward, especially when they are stalking prey like a bird and need to make minimal movements to avoid scaring their target.

6. Plantaris Muscle

The plantaris muscle is used by animals for gripping and manipulating objects with their feet, much like the way apes use their feet almost as dexterously as their hands. Humans also possess this muscle, but it has become so underdeveloped that it is often removed by doctors when they require tissue for other bodily repairs. The muscle has become so insignificant in humans that about 9% of people are born without it.

5. Wisdom Teeth

Early humans consumed a significant amount of plant-based foods and needed to eat them quickly enough to obtain all the necessary nutrients in a single day. To aid in this, we had an extra set of molars, making our larger mouths more efficient at processing food. This was especially important as our bodies lacked the ability to properly digest cellulose. Over time, as evolution shaped our diets, our jaws became smaller, and third molars became redundant. Today, some human populations no longer grow wisdom teeth, while others have nearly a 100% chance of developing them.

4. Third Eyelid

When you observe a cat blink, you'll notice a white membrane crossing its eye – this is known as the third eyelid. While it's rare in mammals, it's common in birds, reptiles, and fish. Humans still have a vestigial third eyelid, though it's no longer functional. It's small in most people, but in certain populations, it may be more noticeable. The only primate species with a fully functional third eyelid is the Calabar angwantibo, a close relative of lorises found in West Africa.

3. Appendix

The appendix serves no known purpose in modern humans and is often removed when it becomes infected. While its original function is still debated, many scientists support Darwin's theory that it once played a role in digesting cellulose from the plant-heavy diet of our ancestors. As our diet evolved, the appendix became less important. Interestingly, some evolutionary theorists believe that natural selection, despite eliminating the appendix’s functions, favors larger appendices because they are less prone to inflammation and disease. Unlike the small toe, which might eventually disappear despite its lack of function, the appendix is likely to remain with us for the foreseeable future—just lingering without serving a purpose.

2. Coccyx

The coccyx is the vestige of what was once a human tail. Over time, we lost the need for a tail, as swinging from trees gave way to gathering at local waterholes for socializing and sharing neanderthal gossip. However, the coccyx remained, now serving as a support structure for various muscles and providing stability when a person sits or leans back. It also plays a role in supporting the positioning of the anus.

1. Darwin's Point - Plica Semilunaris

Darwin's point is found in most mammals, and humans are no exception. It was likely used to help focus sounds in animals, though it no longer serves a function in humans. Only 10.4% of the human population still has this visible remnant of our evolutionary past, but a much larger number may carry the gene responsible for it, as the ear tubercle doesn't always appear. This point, depicted in the image above, is a small thick nodule located at the junction of the upper and middle sections of the ear.