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Why nature vs. nurture is ‘zombie idea’ we need to kill
Why do some people still believe that behavior is caused solely by genes or environment? A new paper offers some answers.
- Despite the fact that scientists have long known that behavior is caused by complex interactions between genes and environment, the debate still persists in the culture today.
- A new paper outlines three reasons why this debate persists, and why behavior isn't special — it abides by the same evolutionary processes as other traits.
- The authors say rejecting the false nature-nurture dichotomy can help kill this "zombie idea."
Which determines traits like sexual orientation, intelligence and behavior: genes or environment?
Many modern debates center on this question, from the #MeToo movement to transgender rights, to academic performance, to crime. But is the nature-nurture conversation even worth having? After all, it was more than three decades ago that the American biochemist Daniel Koshland wrote in an editorial published in Science, "The debate on nature and nurture in regard to behavior is basically over. Both are involved."
Now, a paper recently published in BioScience argues it's finally time to kill the "zombie" that is the nature-nurture debate. The authors—Marlene Zuk and Hamish G. Spencer of the University of Otago's Department of Zoology—note that behaviors aren't determined solely by genes or environment.
Zuk and Spencer divide their argument into three parts.
Behavior is not special in its evolution
Behavior, the authors write, evolves in the same manner as other traits. People often mistakenly think that behavior — particularly human behavior — exists apart from the principles of evolution, in a separate realm from other characteristics, such as height.
The authors note the Venus flytrap as an example.
"The motor cells that close the trap need exactly two signals within 20 seconds to activate. Then, at least three—not one, not four—flicks of a trigger hair are needed to signal the production of digestive enzymes. Only then can successful consumption of the prey commence."
Does this precise predatory process count as behavior? It's a tricky question, sure. But the authors raise it because:
"If we can't draw a hard and fast line separating behavior from other traits, then the same rules apply to both, and behavior evolves the same way that leg length or other physical characteristics do. That is an important conclusion, because it means that we can't invoke culture as a get-out-of-evolution-free card."
Behavior is not explained solely by genes or environment
That might be obvious enough. But the authors also argue that behaviors aren't even the result of an additive combination of the two. In other words, you can't look at a world-class sprinter and say that their skill comes from 68 percent genetics, 32 percent environment.
Rather, behaviors stem from the complex and fluid interaction between the two.
"The effect of an organism's genes depends on the organism's environment and does so just as much as the effect of an organism's environment depends on its genes," the authors write. "Genes and environment interact. The philosopher of science Evelyn Fox Keller calls this the entanglement of genotype and environment, which also conveys the inextricable nature of the relationship between the two."
Genes do not code for behavior
Zuk and Spencer suggest that the way people talk about genes tends to confuse the public about the role genetics play in influencing behavior. For example, you might read a study saying that scientists have "found the gene for" intelligence, criminality, or whatever trait.
"What scientists mean when they talk about a gene for a trait is that variation at that gene (e.g., differences in the DNA sequence of that gene) leads, in a certain range of environments, to variation in that trait, and the concept involved is one called heritability," the authors write.
But a gene for a trait does not act as an off-on switch that produces behavior.
"The crucial point is that, regardless of the heritability of a trait, a change in the range of environments (or, for that matter, the genetic variation affecting the trait) can change the heritability. Everything is context dependent."
Killing the zombie
So, why do we need to kill the nature-nurture zombie? Zuk and Spencer suggest that these misguided beliefs can cause us to think certain behaviors are inevitable. For example, if people with anorexia read articles saying the condition is caused solely by genetics, they might feel like there's nothing they can do to improve their health. In this way, people may feel like they have an "out" to continue these behaviors, when, in reality, environmental interventions could benefit them.
Similarly, the belief that genes determine traits like intelligence or social mobility may influence public officials not to spend as much money on certain public programs. In this way, the nature-nurture dichotomy causes people to do nothing at all.
The authors say it's time to break our conceptual link between genetics and fate.
"A rejection of that equivalence, along with a view of the nature of the entanglement of genes and the environment, would be real progress, and just might kill the zombie."
- The Pessimistic Brain: Wired to Be Negative? - Big Think ›
- Why Some Apples Fall Far From The Tree - Big Think ›
- Where Does Happiness Come From: Nature or Nurture? - Big Think ›
A Harvard professor's study discovers the worst year to be alive.
- Harvard professor Michael McCormick argues the worst year to be alive was 536 AD.
- The year was terrible due to cataclysmic eruptions that blocked out the sun and the spread of the plague.
- 536 ushered in the coldest decade in thousands of years and started a century of economic devastation.
The past year has been nothing but the worst in the lives of many people around the globe. A rampaging pandemic, dangerous political instability, weather catastrophes, and a profound change in lifestyle that most have never experienced or imagined.
But was it the worst year ever?
Nope. Not even close. In the eyes of the historian and archaeologist Michael McCormick, the absolute "worst year to be alive" was 536.
Why was 536 so bad? You could certainly argue that 1918, the last year of World War I when the Spanish Flu killed up to 100 million people around the world, was a terrible year by all accounts. 1349 could also be considered on this morbid list as the year when the Black Death wiped out half of Europe, with up to 20 million dead from the plague. Most of the years of World War II could probably lay claim to the "worst year" title as well. But 536 was in a category of its own, argues the historian.
It all began with an eruption...
According to McCormick, Professor of Medieval History at Harvard University, 536 was the precursor year to one of the worst periods of human history. It featured a volcanic eruption early in the year that took place in Iceland, as established by a study of a Swiss glacier carried out by McCormick and the glaciologist Paul Mayewski from the Climate Change Institute of The University of Maine (UM) in Orono.
The ash spewed out by the volcano likely led to a fog that brought an 18-month-long stretch of daytime darkness across Europe, the Middle East, and portions of Asia. As wrote the Byzantine historian Procopius, "For the sun gave forth its light without brightness, like the moon, during the whole year." He also recounted that it looked like the sun was always in eclipse.
Cassiodorus, a Roman politician of that time, wrote that the sun had a "bluish" color, the moon had no luster, and "seasons seem to be all jumbled up together." What's even creepier, he described, "We marvel to see no shadows of our bodies at noon."
...that led to famine...
The dark days also brought a period of coldness, with summer temperatures falling by 1.5° C. to 2.5° C. This started the coldest decade in the past 2300 years, reports Science, leading to the devastation of crops and worldwide hunger.
...and the fall of an empire
In 541, the bubonic plague added considerably to the world's misery. Spreading from the Roman port of Pelusium in Egypt, the so-called Plague of Justinian caused the deaths of up to one half of the population of the eastern Roman Empire. This, in turn, sped up its eventual collapse, writes McCormick.
Between the environmental cataclysms, with massive volcanic eruptions also in 540 and 547, and the devastation brought on by the plague, Europe was in for an economic downturn for nearly all of the next century, until 640 when silver mining gave it a boost.
Was that the worst time in history?
Of course, the absolute worst time in history depends on who you were and where you lived.
Native Americans can easily point to 1520, when smallpox, brought over by the Spanish, killed millions of indigenous people. By 1600, up to 90 percent of the population of the Americas (about 55 million people) was wiped out by various European pathogens.
Like all things, the grisly title of "worst year ever" comes down to historical perspective.
A simple trick allowed marine biologists to prove a long-held suspicion.
- It's long been suspected that sharks navigate the oceans using Earth's magnetic field.
- Sharks are, however, difficult to experiment with.
- Using magnetism, marine biologists figured out a clever way to fool sharks into thinking they're somewhere that they're not.
For some time, scientists have suspected that sharks belong among the growing number of animals known to navigate using Earth's magnetic field. Testing anything with a shark, though, requires some care.
The key was selecting the right candidate. Keller and his colleagues chose the bonnethead shark, Sphyrna tiburo, a small critter that summers at Turkey Point Shoal off the coast of the Florida State University Coastal and Marine Laboratory with which Keller is affiliated.
Bonnetheads elsewhere have been known to complete 620-mile roundtrip migrations. As the lab's Dean Grubbs puts it, "That's not bad for a shark that is only two to three feet long. The question is how do they find their way back to that same estuary year after year." There's a report of a great white shark migrating between two locations, one in South Africa and another in Australia, year after year.
The research is published in Current Biology.
Keller and his team rounded up 20 local juvenile bonnetheads and transported them into a holding tank at the marine lab. For the tests, the researchers simulated three real-world magnetic fields. As the various magnetic fields were activated, the sharks' movements were captured by GoPro cameras and their average swimming orientations calculated by software.
The first simulation, serving as a control, mimicked the magnetic field of the nearby shoal from which the sharks had been captured. When this field was activated, the sharks essentially acted like they were "home," just swimming around as they do.
A second field was the magnetic equivalent of a location 600 kilometers south of the lab within the Gulf of Mexico. When this field was activated, the sharks, apparently mistaking themselves for being far south in the Gulf, began swimming northward toward the shoal.
The opposite occurred with a field standing in for a location in continental North America 600 km north of their home shoal — the sharks began swimming southward.
"For 50 years," says Keller, "scientists have hypothesized that sharks use the magnetic field as a navigational aid. This theory has been so popular because sharks, skates, and rays have been shown to be very sensitive to magnetic fields. They have also been trained to react to unique geomagnetic signatures, so we know they are capable of detecting and reacting to variation in the magnetic field."
His team's experiments confirm what's long been suspected, Keller says: "Sharks use map-like information from the geomagnetic field as a navigational aid. This ability is useful for navigation and possibly maintaining population structure."
A machine learning system lets visitors at a Kandinsky exhibition hear the artwork.
Have you ever heard colors?
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.
A new study suggests that private prisons hold prisoners for a longer period of time, wasting the cost savings that private prisons are supposed to provide over public ones.