Once a week.
Subscribe to our weekly newsletter.
Your body’s full of stuff you no longer need. Here's a list.
Evolution doesn't clean up after itself very well.
- An evolutionary biologist got people swapping ideas about our lingering vestigia.
- Basically, this is the stuff that served some evolutionary purpose at some point, but now is kind of, well, extra.
- Here are the six traits that inaugurated the fun.
Evolutionary anthropologist and Boston College post-doc, Dorsa Amir, started the whole thing with a series of eight tweets, and boy did she start something fun. Amir laid out a list of weird, once-useful details of the human anatomy that we continue to carry around within — and on — us. Basically, this is the stuff that served some evolutionary purpose at some point, but now is kind of, well, extra.
Natural selection, after all, has no reason to clear away unnecessary traits if they pose no evolutionary disadvantage. And when we say "started the whole thing," what we mean is that, this being Twitter, some arguing was inevitable. Some people took issue with Amir's use of the word "vestigial." One issue with the word is that early traits may still be beneficial in ways we don't yet know — the microbiome-managing appendix and the immune system's tonsils were both considered among these for some time. A trait's stated assumed value is also always just our best guess, so a certain amount of uncertainty is understood to be baked-in. It's important to remember, too, that if a mutation just happened to happen and persisted because it was useful, it's not the same thing as saying it has a reason to exist. The reason was randomness, unless one doesn't believe in evolution.
The plica semilunaris
The human eye in alarming detail. Image source: Henry Gray / Wikimedia commons
At the inner corner of our eyes, closest to the nasal ridge, is that little pink thing, which is probably what most of us call it, called the caruncula. Next to it is the plica semilunairs, and it's what's left of a third eyelid that used to — ready for this? — blink horizontally. It's supposed to have offered protection for our eyes, and some birds, reptiles, and fish have such a thing.
Palmaris longus muscle. Image source: Wikimedia commons
We don't have much need these days, at least most of us, to navigate from tree branch to tree branch. Still, about 86 percent of us still have the wrist muscle that used to help us do it. To see if you have it, place the back of you hand on a flat surface and touch your thumb to your pinkie. If you have a muscle that becomes visible in your wrist, that's the palmaris longus. If you don't, consider yourself more evolved (just joking).
Darwin's tubercle. Image source: Wikimedia commons
Yes, maybe the shell of you ear does feel like a dried apricot. Maybe not. But there's a ridge in that swirly structure that's a muscle which allowed us, at one point, to move our ears in the direction of interesting sounds. These days, we just turn our heads, but there it is.
Goosebumps. Photo credit: Tyler Olson via Shutterstock
It's not entirely clear what purpose made goosebumps worth retaining evolutionarily, but there are two circumstances in which they appear: fear and cold. For fear, they may have been a way of making body hair stand up so we'd appear larger to predators, much the way a cat's tail puffs up — numerous creatures exaggerate their size when threatened. In the cold, they may have trapped additional heat for warmth.
Image source: Decade3d-anatomy online via Shutterstock
Way back, we had tails that probably helped us balance upright, and was useful moving through trees. We still have the stump of one when we're embryos, from 4–6 weeks, and then the body mostly dissolves it during Weeks 6–8. What's left is the coccyx.
The palmar grasp reflex
Palmar reflex activated! Photo credit: Raul Luna on Flickr
You've probably seen how non-human primate babies grab onto their parents' hands to be carried around. We used to do this, too. So still, if you touch your finger to a baby's palm, or if you touch the sole of their foot, the palmar grasp reflex will cause the hand or foot to try and close around your finger.
Other people's suggestions
Amir's followers dove right in, offering both cool and questionable additions to her list.
Lower mouth plate behind your teeth. Some have protruding bone under the skin which is a throw back to large fangs. Almost like an upsidedown Sabre Tooth.— neil crud (@neilcrud66) January 16, 2019
Hypnic jerk as you fall asleep
What about when you “jump” just as you’re drifting off to sleep, I heard that was a reflex to prevent falling from heights.— Bann face (@thebanns) January 16, 2019
This thing, often called the "alpha jerk" as you drop into alpha sleep, is properly called the hypnic jerk,. It may actually be a carryover from our arboreal days. The hypothesis is that you suddenly jerk awake to avoid falling out of your tree.
Nails screeching on a blackboard response?
Everyone hate the sound of fingernails on a blackboard. It's _speculated_ that this is a vestigial wiring in our head, because the sound is similar to the shrill warning call of a chimp. https://t.co/ReyZBy6XNN— Pet Rock (@eclogiter) January 16, 2019
Ok what is Hair in the ears for? I think cuz as we get older it filters out the BS.— Sarah21 (@mimix3) January 16, 2019
You may be onto something. Tooth-bearing with the jaw clenched is generally recognized as a signal of submission or non-threatening in primates. Involuntary smiling or laughing in tense situations might have signaled that you weren’t a threat.— Jager Tusk (@JagerTusk) January 15, 2019
Sometimes it feels like my big toe should be on the side of my foot, was that ever a thing?— B033? K@($ (@whimbrel17) January 16, 2019
Twitter should always be so much fun.
The team caught a glimpse of a process that takes 18,000,000,000,000,000,000,000 years.
- In Italy, a team of scientists is using a highly sophisticated detector to hunt for dark matter.
- The team observed an ultra-rare particle interaction that reveals the half-life of a xenon-124 atom to be 18 sextillion years.
- The half-life of a process is how long it takes for half of the radioactive nuclei present in a sample to decay.
Humans are particularly prone to shiver when a group does or thinks the same thing at the same time.
A few years ago, I proposed that the feeling of cold in one's spine, while for example watching a film or listening to music, corresponds to an event when our vital need for cognition is satisfied.
Certain colors are globally linked to certain feelings, the study reveals.
- Color psychology is often used in marketing to alter your perception of products and services.
- Various studies and experiments across multiple years have given us more insight into the link between personality and color.
- The results of a new study spanning 6 continents (30 nations) shows universal correlations between colors and emotions around the globe.
The root of color psychology<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="9e40cf62fa8922fcca6c57e2fcb215b6"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/OM4fXB23pCQ?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>There is a very likely chance you've even been "fooled" by color marketing in the past, or you've chosen one product over another subconsciously due to colors that were designed to influence your emotions.<br></p><p>Companies that want to be known for being dependable often use blue in their logos, for example (Dell, HP, IBM). Companies that want to be perceived as fun and exciting go for a splash of orange (Fanta, Nickelodeon, even Amazon). Green is associated with natural, peaceful emotions and is often used by companies like Whole Foods and Tropicana. </p><p><strong>Your favorite color says a lot about your personality. </strong></p><p>Various studies and experiments across multiple years (<a href="https://www.researchgate.net/publication/49595886_Personality_Traits_and_Colour_Preferences" target="_blank">2010</a>, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/jopy.12087" target="_blank" rel="noopener noreferrer">2014</a>, <a href="http://oaji.net/articles/2015/1170-1448038739.pdf" target="_blank" rel="noopener noreferrer">2015</a>, and more recently in <a href="https://www.verywellmind.com/color-psychology-2795824#modern-research-on-color-psychology" target="_blank" rel="noopener noreferrer">2019</a>) have given us more insight into the link between your personality and your favorite color.</p><p>Red, for example, is considered a bold color and is associated with feelings such as excitement, passion, anger, danger, energy, and love. The personality traits of this color might be someone who is bold, a little impulsive, and who loves adventure. </p><p>Orange, on the other hand, is considered representative of creativity, happiness, and freedom. The personality traits of this color can be fun, playful, cheerful, nurturing, and productive. Read more about color psychology and personalities <a href="https://bigthink.com/mind-brain/color-personality-psychology?rebelltitem=2#rebelltitem2" target="_self">here</a>.</p>
Study reveals which colors best suit which emotions around the globe<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDYzMTk5OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyODc4OTg5OH0.bY-pu-MFNivdJLDJuBp9TBKrhwuy7hngUa1aIWxQMVw/img.jpg?width=1245&coordinates=0%2C93%2C0%2C94&height=700" id="33fff" class="rm-shortcode" data-rm-shortcode-id="1a5d7bb00dac94bd6201616789fb4882" data-rm-shortcode-name="rebelmouse-image" alt="concept of color psychology how colors make us feel color emotions" />
Certain colors are globally ties to certain emotions, the study reveals.
Image by agsandrew on Shutterstock<p>In this particular survey, participants were asked to fill out an online questionnaire which involved assigning 20 emotions to 12 different color terms. They were also asked to specify the intensity with which they associated the color term with the emotion.</p><p><strong>Certain colors are globally linked to certain emotions, the study reveals.</strong></p><p>The results of this study showed a few definite correlations between colors and emotions throughout the globe. Red, for example, is the only color that is strongly associated with both negative (anger) and positive (love) feelings. Brown, on the other end of the spectrum, is the color that triggers the fewest emotions globally.<br></p><p>The color white is closely associated with sadness in China, while purple is what is closely associated with sadness in Greece. This can be traced back to the roots of each culture, with white being worn at funerals in China and dark purple being the Greek Orthodox Church's color of mourning. </p><p>Yellow is more associated with joy, specifically in countries that see less sunshine. Meanwhile, its association with joy is weaker in areas that have greater exposure to sunshine. </p><p><a href="https://www.sciencedaily.com/releases/2020/09/200910150247.htm" target="_blank">According to Dr. Oberfeld-Twistel</a>, it is difficult to say exactly what the causes for global similarities and differences are. "There is a range of possible influencing factors: language, culture, religion, climate, the history of human development, the human perceptual system."</p>