Sci-Ed Update 255

Were ribosomes the first organelle? Thinking styles, aphantasia, thinking about art, hearing issues are common, and what about weight loss drugs? Those stories and a lot more in this new issue!

Feb 28, 2023

How the Brain Creates Your Taste in Art

Using a combination of machine learning and neuroimaging data, researchers revealed a neural basis for aesthetic appreciation.

An area in the front of the brain known as the medial prefrontal cortex (mPFC) is responsible for assigning a subjective value to them. Image is in the public domain

It has been said that there is no accounting for taste. But what if taste can actually be accounted for, and what if the things doing the accounting are the neural networks inside your brain?
In a new paper published in Nature Communications, a team of Caltech researchers show how they have revealed the neural basis for aesthetic preferences in humans using a combination of machine learning and brain-scanning equipment.
The work took place in the lab of John O’Doherty, Caltech’s Fletcher Jones Professor of Decision Neuroscience, and builds on research published by that lab in 2021. In that previous research, scientists trained a computer to predict volunteers’ taste in art by feeding it data about which paintings the volunteers liked and which they disliked. With enough training, the computer became adept at correctly guessing if a person would like a Monet or a Rothko, for example.

Why Do We Have Eyebrows and Other Types of Facial Hair?

The evolutionary reasons for having facial hair aren’t as clean cut as you might imagine. Find out why humans have eyebrows, eyelashes and beards.

(Credit: Kolonko/Shutterstock)

We humans seem to have an on-again, off-again relationship with facial hair.
Prehistoric cave drawings reveal the myriad tools our ancient ancestors used to shave: shark’s teeth, sharpened flints and even clam shells. Nowadays, beards are back in style and people are taking a razor to their brows, instead.
But is there a reason we evolved to have these hairy baubles in the first place? And, if so, what evolutionary advantage might we be throwing away for the sake of staying on trend?
Turns out, researchers have a lot to say on the matter. Get their answers to why we have eyebrows, what eyelashes are for and why we grow beards.

The world is built for people with perfect hearing — but 83% of people don't have it

Maria Fabrizio / Special to NPR

“Hearing varies because our brains vary,” said Travis Threats, professor and chair of the department of speech, language and hearing sciences at St. Louis University. “People with so-called ‘normal hearing’ are still not perceiving things the same way. … There are a lot of subtleties of how we hear and how we're able to interpret sound.”

Threats added that the process of transforming those external factors into something the brain can understand is extremely complicated.

“The more steps you have in any process … there are more things that can go wrong,” he said. “But there are also more things that can shine.”

These subtle differences in our hearing, including how we perceive and interpret sound, is what Andrew Hugill calls aural diversity.

Aural Diversity Infographic

This infographic is made available under the Creative Commons BY-ND License.

Aural Diversity begins with the simple observation that everybody hears differently. Yet the assumption in most hearing and listening situations is that we all hear the same. This infographic is a high-level map of the complexity of aural diversity, which is subject to many universal variations and includes animal and machine, as well as human, listening.

Fat, Sugar, Salt … You’ve Been Thinking About Food All Wrong

Scientists are asking tough questions about the health effects of ultra-processed diets. The answers are complicated—and surprising.

Photo: Getty Images

IN THE LATE 2000s, Carlos Monteiro noticed something strange about the food that Brazilian people were eating. The nutritionist had been poring over three decades’ worth of data from surveys that asked grocery shoppers to note down every item they bought. In more recent surveys, Monteiro noticed, Brazilians were buying way less oil, sugar, and salt than they had in the past. Despite this, people were piling on the pounds. Between 1975 and 2009 the proportion of Brazilian adults who were overweight or obese more than doubled.
This contradiction troubled Monteiro. If people were buying less fat and sugar, why were they getting bigger? The answer was right there in the data. Brazilians hadn’t really cut down on fat, salt, and sugar—they were just consuming these nutrients in an entirely new form. People were swapping traditional foods—rice, beans, and vegetables—for prepackaged bread, sweets, sausages, and other snacks. The share of biscuits and soft drinks in Brazilians’ shopping baskets had tripled and quintupled, respectively, since the first household survey in 1974. The change was noticeable everywhere. When Monteiro first qualified as a doctor in 1972, he’d worried that Brazilians weren’t getting enough to eat. By the late 2000s, his country was suffering with the exact opposite problem.

Weight Loss Drugs Aren’t A Quick Fix

The popularity of drugs like Ozempic and a new pediatric recommendation that encourages fat teens to get weight-loss surgery show we still view fatness as a moral flaw that needs extreme intervention.

Olive Burd / BuzzFeed News; Getty Images

Since the CDC declared obesity an epidemic in 1999, physicians, scientists, and researchers have been attempting to make sense of the reasons Americans are larger than we’ve ever been. Many reasons have been tossed around: In 1999, then–CDC director Jeffrey P. Koplan blamed a steady decline in physical activity, to which he offered a multitiered remedy: counseling obese patients in doctors’ offices, offering healthy food choices and opportunities to exercise in schools and workplaces, and building more sidewalks and bike paths in urban areas.
Since then, the United States has tried everything from implementing fresher, healthier menus in primary schools to shaming fat people to classifying obesity as a disease, but nothing has actually stopped Americans from gaining weight. … Dr. Fatima Cody Stanford, an obesity doctor at Mass General Hospital and professor at Harvard Medical School, challenges the way we’ve been taught to think about obesity as a disease. As she notes, it’s not about “willpower” or simply “diet or exercise.” … In Stanford’s view, the brain controls how much food the body needs to eat and how much it stores within the body.
She also argues that obesity is genetic: In other words, if you were born to fat parents, then there’s a 50-85% likelihood of being fat even if you change your diet, exercise, sleep well, and manage your stress. Obesity, then, isn’t a moral failure; it’s more complex than that, and yet, Wegovy and its counterpoint, Ozempic, are being touted as possible solutions for this ever-growing epidemic.
Rather than focusing simply on metabolism, these drugs are designed to connect the brain and the stomach while also suppressing the appetite. They are also touted as effective medications: Ozempic, Wegovy, and other medications prescribed for obesity are said to induce a weight loss of 15 to 22% of overall body weight. Most people begin at .25 milligrams a week and, depending on each patient’s side effects, they go up to .5 milligrams after a month. Eventually, over time, patients go up to 2.4 milligrams, which is the highest dose with the biggest payoff. The average weight loss at that level is 15 to 17% and one-third of those patients have 20% weight loss.
Of course, there’s a catch 22: Once you stop taking the medication, most people regain the weight they’ve lost.

How Should We Think About Our Different Styles of Thinking?

Some people say their thought takes place in images, some in words. But our mental processes are more mysterious than we realize.

My head isn’t entirely word-free; like many people, I occasionally talk to myself in an inner monologue. (Remember the milk! Ten more reps!) On the whole, though, silence reigns. Blankness, too: I see hardly any visual images, rarely picturing things, people, or places. Thinking happens as a kind of pressure behind my eyes, but I need to talk out loud in order to complete most of my thoughts. My wife, consequently, is the other half of my brain. If no interlocutor is available, I write. When that fails, I pace my empty house, muttering. I sometimes go for a swim just to talk to myself far from shore, where no one can hear me. My minimalist mental theatre has shaped my life. I’m an inveterate talker, a professional writer, and a lifelong photographer—a heady person who’s determined to get things out of my head, to a place where I can apprehend them.
I’m scarcely alone in having a mental “style,” or believing I do. Ask someone how she thinks and you might learn that she talks to herself silently, or cogitates visually, or moves through mental space by traversing physical space. I have a friend who thinks during yoga, and another who browses and compares mental photographs. I know a scientist who plays interior Tetris, rearranging proteins in his dreams. My wife often wears a familiar faraway look; when I see it, I know that she’s rehearsing a complex drama in her head, running all the lines. She sometimes pronounces an entire sentence silently before speaking it out loud.

Mindi Fried on Teaching & Learning with Aphantasia

In Episode 133, Dr. Mindi Fried joins us to discuss her experience of aphantasia, the inability to picture thoughts and memories in the mind’s eye, and how that affects how she teaches and learns anatomy and physiology. This is a chat that will increase our awareness of the huge and sometimes invisible diversity that exists among our students.

To listen to this episode, click on the player (if present) or this link→ theAPprofessor.org/podcast-episode-133.html

How did life begin? One key ingredient is coming into view

A Nobel-prizewinning scientist’s team has taken a big step forward in its quest to reconstruct an early-Earth RNA capable of building proteins.

Billions of years ago, before there were beasts, bacteria or any living organism, there were RNAs. These molecules were probably swirling around with amino acids and other rudimentary biomolecules, merging and diverging, on an otherwise lifeless crucible of a planet.
Then, somehow, something special emerged: a simple machine, a pocket made of RNAs, with the ability to place amino acids next to one another and maybe link them into chains. This was the macromolecule that would gradually evolve into the ribosome, the RNA–protein complex responsible for translating genetic information into proteins. Its birth — the details of which remain hypothetical — would have created a fundamental shift in this prebiotic, RNA-dominated world, providing a key ingredient to all life as we know it. Ada Yonath, a structural biologist at the Weizmann Institute of Science in Rehovot, Israel, and her team first conceptualized this ‘protoribosome’ idea nearly two decades ago, after she and others determined the structure of the modern ribosome, a feat that later secured Yonath a share of the 2009 Nobel Prize in Chemistry.

Kevin Patton comment→ Hmm, I wonder if I should ask my students to get into small groups and work out which organelle was the first to appear—and why. I bet that’d get them thinking!

The A&P Professor Science & Education Updates