Why Does Your Body Still Have Ancient Human Parts?

Why Does Your Body Still Have Ancient Human Parts? Hold out your arm, palm up. Touch your thumb to your little finger and bend your wrist. Most people see a cord pop up in the middle of the forearm. Some people have nothing there at all, and they have lost nothing. That muscle is a leftover from life in the trees, and it is only one of the old parts you are still carrying. All research and sources are linked below. RESEARCH & SOURCES: Ear muscles that still try to move - "Electromyographic correlates of effortful listening in the vestigial auriculomotor system" by Andreas Schroeer et al. (2025, Frontiers in Neuroscience) https://doi.org/10.3389/fnins.2024.14... - the superior auricular muscle becomes more active the harder a listening task gets, and the posterior muscle responds to sounds from behind, in a system our ancestors stopped using roughly 25 million years ago. The researchers describe it as a neural fossil, and note that the movement is far too small to help hearing. Goosebumps and hair stem cells - "Cell types promoting goosebumps form a niche to regulate hair follicle stem cells" by Yulia Shwartz et al. (2020, Cell) https://doi.org/10.1016/j.cell.2020.0... - the tiny muscles that raise body hair also anchor and regulate the stem cells that grow new hair, an old part reassigned to a new job. Palmaris longus - A forearm muscle absent in a significant share of people, with reported rates varying widely between populations. Because its loss causes no functional problem, its tendon is commonly harvested for reconstructive grafts. The human embryonic tail - Standard embryology describes a visible tail in the human embryo around the fifth week, containing roughly ten to twelve vertebrae, which is then largely reabsorbed, leaving the fused coccyx. The grasp reflex - The palmar grasp reflex of newborns, and the matching plantar reflex of the feet, fade over the first months of life and are usually interpreted as a remnant of clinging behaviour in primate infants. The recurrent laryngeal nerve - A classic example of an evolutionary constraint. The nerve leaves the brain, descends into the chest, loops under a major vessel and returns to the larynx. In the giraffe the same loop stretches several metres. Richard Dawkins discusses the case in "The Greatest Show on Earth" (2009, Free Press). The appendix is not simply useless - "Biofilms in the large bowel suggest an apparent function of the human vermiform appendix" by Randal Bollinger et al. (2007, Journal of Theoretical Biology) - the appendix contains immune tissue and may serve as a reservoir of beneficial gut bacteria. ______________________ THINGS MENTIONED IN THIS VIDEO: Palmaris longus - The forearm muscle you can see as a cord at your wrist, useful for gripping branches, spare in you, and valuable to surgeons. Arrector pili - The tiny muscles that pull each hair upright. In a furry animal they trap warm air and make a frightened cat look twice its size. In you they just make bumps. Auricular muscles - Three muscles around each ear that once pointed the ear at a sound. They still fire when you listen hard, and move almost nothing. Plica semilunaris - The small pink fold at the inner corner of your eye, the remnant of the third eyelid that birds, reptiles and cats still use. Coccyx - Three to five fused bones at the base of your spine. The remains of a tail you grew and lost before birth. Wisdom teeth - Molars that fitted comfortably in longer ancestral jaws, and often have nowhere to go in a modern mouth. ______________________ Animation by Stick & Stone ⭐ ______________________ #evolution #humanbody #anatomy #vestigial #biology #science #humanevolution #anthropology #facts #explainer #animation #education #ancienthumans #prehistory #anatomyfacts