- 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
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
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
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.
Tailbone
Coccyx.
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.
Fangs?
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
Hiccups
Sure: https://t.co/DjMZB1XidG
— Stephen Roughley (@SteBobRoughley) 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
Ear hair
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
Nervous laughter
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
Um, yipes.
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.
As part of a new exhibition, the worlds of culture and technology collide, bringing sound to the colors of abstract art pioneer Wassily Kandinsky.
Kandinsky had synesthesia, where looking at colors and shapes causes some with the condition to hear associated sounds. With the help of machine learning, virtual visitors to the Sounds Like Kandinsky exhibition, a partnership project by Centre Pompidou in Paris and Google Arts & Culture, can have an aural experience of his art.
An eye for music
Kandinsky's synesthesia is thought to have heavily influenced his painting. Seeing yellow summoned up trumpets, evoking emotions like cheekiness; reds produced violins portraying restlessness; while organs representing heavenliness he associated with blues, according to the exhibition notes.
Virtual visitors are invited to take part in an experiment called Play a Kandinsky, which allows them to see and hear the world through the artist's eyes.
Kandinsky's synesthesia is thought to have heavily influenced his 1925 painting Yellow, Red, Blue.Image: Guillaume Piolle/Wikimedia Commons
In 1925, the artist's masterpiece, "Yellow, Red, Blue", broke new ground in the world of abstract art, guiding the viewer from left to right with shifting shapes and shades. Almost a century after it was painted, Google's interactive tool lets visitors click different parts of the artwork to journey through the artist's description of the colors, associated sounds and moods that inspired the work.
But Google's new toy is not the only tool developed to enhance the artistic experience.
Artist Neil Harbisson has developed an artificial way to emulate Kandinsky by turning colors into sounds. He has a rare form of color blindness and sees the world in greyscale. But a smart antenna attached to his head translates dominant colors into musical notes, creating a real-world soundtrack of what's in front of him. The invention could open up a new world for people who are color blind.
Reprinted with permission of the World Economic Forum. Read the original article.
The United States of America, land of the free, is home to 5 percent of the world's population but 25 percent of its prisoners. The cost of having so many people in the penal system adds up to $80 billion per year, more than three times the budget for NASA. This massive system exploded in size relatively recently, with the prison population increasing by six-fold in the last four decades.
Ten percent of these prisoners are kept in private prisons, which are owned and operated for the sake of profit by contractors. In theory, these operations cost less than public prisons and jails, and states can save money by contracting them to incarcerate people. They have a long history in the United States and are used in many other countries as well.
However, despite the pervasiveness of private contractors in the American prison system, there is not much research into how well they live up to their promise to provide similar services at a lower cost to the state. The little research that is available often encounters difficulties in trying to compare the costs and benefits of facilities with vastly different operations and occasionally produces results suggesting there are few benefits to privatization.
A new study by Dr. Anita Mukherjee and published in the American Economic Journal: Economic Policy joins the debate with a robust consideration of the costs and benefits of private prisons. Its findings suggest that some private prisons keep people incarcerated longer and save less money than advertised.
Mississippi Blues
The study focuses on prisons in Mississippi. Despite its comparatively high rate of incarceration, Mississippi's prison system is very similar to that of other states that also use private prisons. Demographically, its system is representative of the rest of the U.S. prison system, and its inmates are sentenced for similar amounts of time.
The state attempts to get the most out of its privatization efforts, as a 1994 law requires all contracts for private prisons in Mississippi to provide at least a 10 percent cost savings over public prisons while providing similar services. As a result, the state seeks to maximize its savings by sending prisoners to private institutions first if space if available.
While public and private prisons in Mississippi are quite similar, there are a few differences that allow for the possibility of cost savings by private operators — not the least of which is that the guards are paid 30 percent less and have fewer benefits than their publicly employed counterparts.
The results of privatization
The graph depicts the likelihood of release for public (dotted line) vs. private (solid line) prison inmates. At every level of time served, public prisoners were more likely to be released than private prisoners.Dr. Anita Mukherjee
The study relied on administrative records of the Mississippi prison system between 1996 and 2013. The data included information on prisoner demographics, the crimes committed, sentence lengths, time served, infractions while incarcerated, and prisoner relocation while in the system, including between public and private jails. For this study, the sample examined was limited to those serving between one and six years and those who served at least a quarter of their sentence. This created a primary sample of 26,563 bookings.
Analysis revealed that prisoners in private prisons were behind bars for four to seven percent longer than those in public prisons, which translates to roughly 85 to 90 extra days per prisoner. This is, in part, because those in private prison serve a greater portion of their sentences (73 percent) than those in public institutions (70 percent).
This in turn might be due to the much higher infraction rate in private prisons compared to public ones. While only 18 percent of prisoners in a public prison commit an infraction, such as disobeying a guard or possessing contraband, the number jumps to 46 percent in a private prison. Infractions can reduce the probability of early release or cause time to be added to a sentence.
It's unclear why there are so many more infractions in private prisons. Dr. Mukherjee suggests it could be the result of "harsher prison conditions in private prisons," better monitoring techniques, incentives to report more of them to the state before contract renewals, or even a lackadaisical attitude on the part of public prison employees.
What does all this cost Mississippi?
The extra time served eats 48 percent of the cost savings of keeping prisoners in a private facility. For example, it costs about $135,000 to house a prisoner in a private prison for three years and $150,000 in the public system. But longer stays in private prisons reduce the savings from $15,000 to only $7,800.
As Dr. Mukherjee remarks, this cost is also just the finance. Some things are a little harder to measure:
"There are, of course, other costs that are difficult to quantify — e.g., the cost of injustice to society (if private prison inmates systematically serve more time), the inmate's individual value of freedom, and impacts of the additional incarceration on future employment. Abrams and Rohlfs (2011) estimates a prisoner's value of freedom for 90 days at about $1,100 using experimental variation in bail setting. Mueller-Smith (2017) estimates that 90 days of marginal incarceration costs about $15,000 in reduced wages and increased reliance on welfare. If these social costs were to exceed $7,800 in the example stated, private prisons would no longer offer a bargain in terms of welfare-adjusted cost savings."
It is possible that the extra time in jail provides benefits that counter these costs, such as a reduced recidivism rate, but this proved difficult to determine. Though it was not statistically significant, there was some evidence that the added time actually increased the rate of recidivism. If that's true, then private prisons could be counterproductive.
