Tag: genetics

How Does Culture Influence the Way We Use Our Brains? Find Out Here.

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We’ve all heard of “right-brain” and “left-brain” thinkers.

Left-brain thinkers are thought to be more logical and mathematical, while right-brain thinkers tend to lean emotional and artistic.

But are there any links between the way our brains function and our cultures?

We’ve talked a lot about gene-culture coevolution over these past few weeks.

In short, the theory suggests that genetics and culture are interconnected.

This brain imaging study about visual perceptual tasks seems to substantiate that theory.

Individualist vs. Collective 

Psychological research has shown that individualist and collective values are demonstrated in an individual’s view of objects in relation to their context.

Americans, valuing individuality, tend to view the two as independent from each other.

East Asian cultures, which value the collective, view objects as contextually interdependent.

These differences have been shown to impact perception and memory by behavioral scientists.

The Study: How Our Brains Work

A study by the Massachusetts Institute of Technology took a look at whether these cultural tendencies can be measured in brain activity patterns.

Using functional magnetic resonance imaging (fMRI) scans from a group of 20 participants – 10 from East Asia, 10 from the U.S. – McGovern Institute for Brain Research Professor John Gabrieli and his team examined participants’ mental operations.

Participants were asked to compare a sequence of images, and their mental operations were mapped via blood flow changes in the brain.

The images were lines within squares.

Participants were asked to compare each image with the previous image, making judgments based on relative judgments of interdependent objects or absolute judgments of individual objects without context.

For instance, some questions asked whether the lines were proportional to the squares, regardless of size (interdependent); others asked whether the lines were the same length as each other, regardless of the squares (independent of context).

The Results: Confirmed

While the simplicity of the task resulted in no differences in accuracy between the groups, brain activation patterns did differ.

Relative judgments, which have been shown to be harder for Americans, stimulated the brain regions dedicated to mental tasks that demand attention. 

These regions were less active for absolute judgments.

As you might guess, the results for the East Asian group were the opposite, with brain activity becoming more active for absolute judgments and less for relative.

The paper’s lead author, Trey Hedden, said of the study:

“We were surprised at the magnitude of the difference between the two cultural groups, and also at how widespread the engagement of the brain’s attention system became when making judgments outside the cultural comfort zone.”

Even more interesting, questionnaires had been distributed prior to the exam to see how closely each individual identified with their culture, using questions regarding values and norms.

Those individuals who identified more intimately with their culture’s values showed a stronger reactive pattern of brain activity relative to their culture.

This study suggests that our culture – and how closely we individually identify with our culture – can influence the way our minds work.

Pretty heady.

From Mandarin to Italian, How Language Shapes Genetics

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Can you differentiate Mandarin from French or Italian?

Of course, you can. 

The sounds of each of these languages are very different, from hard or soft consonants to long or short vowels.

Due to the dynamic sounds of each mother tongue, you can see the adaptation of different vocal tracts across cultures.

These adaptations have developed across generations according to the languages spoken in countries around the world.

We discussed gene-culture coevolution last week in relation to the human species and speech.

Now, let’s talk about how speech and language have evolved our genetics across cultures.

Physiological Traits Adapt to Language

Speech-related physiological adaptations vary across the human species according to the language spoken.

Some languages, like German or Arabic, require deep guttural sounds due to the harsh consonants.

Others, like Spanish, require speakers to roll their r’s.

One of the ways in which this presents in our physiology was reported by Discover Magazine.

Researchers found that the roof of the mouth differs across cultures, according to how vowel sounds are pronounced. 

Furthermore, these anatomical variations evolve upon each generation, creating an evolution in the language itself and the sounds of speech.

The study’s author, Linguistics Expert Dan Dediu, says, 

“Even small variations in the shape of our vocal tract may affect the way we speak, and this may even be amplified — across generations — to the level of differences between dialects and languages.”

The Study

How did researchers discern this change?

The study looked at over 100 people from several ethnolinguistic groups in Europe, North America, China, and across India.

MRI scans were taken of the hard palate of each participant.

Using the scans and machine learning, computer models formed a picture into the future of the hard palate and the sounds it might produce. 

Five commonly used vowel sounds – the “uh” in sofa,” the “ah” in “hot,” the “oo” in “boot,” the “a” in “bat,” and the long “e” in “feet” – were plugged into the computer model. 

A second generation, mimicking the sounds from the first, showed the amplified pronunciation of each sound – as did 50 generational models after it.

Though the change in the shape of the hard palate over time only impacted pronunciation slightly each generation, the change in the vowel sounds after 50 generations was much more pronounced.

The researchers write that,

“besides culture and environment, quantitative biological variation can be amplified, also influencing language.”

This research begs the question: what will our languages sound like in 50 generations…and how did they sound 50 generations ago?

The Myth of Spanish King Ferdinand, the Lisping King & the True Gene-Culture Coevolution of Speech

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There is a common myth in Spain that King Ferdinand was born with a lisp.

As the story goes, this speech impediment led to the Spanish pronunciation of “z” and “c” with the soft “th” sound, as Ferdinand’s courtiers imitated his lisp.

Photographer: Kunsthistorisches Museum Wien, Bilddatenbank.

This Spanish pronunciation of “z” as “th” differs from the “z” as “s” spoken in western Spanish-speaking countries.

In reality, the “s” sound exists in the Spanish language; it is just not applied to “z” or “c” (the latter, when followed by “i” or “e”). 

Thus, it follows that the differences in pronunciation across Spanish-speaking cultures are not due to a lisping king, but rather to the natural regional differences that develop in living languages.

In the same way that American pronunciation of English varies from British pronunciation, peculiarities of living languages emerge across many groups, regions, countries, etc.

While King Ferdinand’s story is nothing but an urban legend, culture and genetics really do work together to create physiological differences related to speech.

Here’s how.

Genes & Culture Interact

Herbert Gintis’ paper titled, “Gene–culture coevolution and the nature of human sociality,” defines the gene-culture coevolution theory as follows:

“Gene–culture coevolution is the application of sociobiology, the general theory of the social organization of biological species, to humans—a species that transmits culture in a manner that leads to quantitative growth across generations.”

Cultural differences have produced changes in brain size, body size, and other aspects of human anatomy across the human species.

Last week, we talked about how genes and culture worked together to alter our diet – specifically, our ability to consume milk products – and how that ability varies across cultures according to their cultural history.

In the same way, gene-culture coevolution has symbiotically shaped human speech and communication.

Speech & Communication

Gintis goes on to explain how gene-culture coevolution is readily apparent in the physiological evolution of human speech and facial communication.

He writes that genetic alterations that improve speech are propagated due to the increasing importance human society places on communication. 

In early humans, speech production was facilitated by the evolution of regions in the motor cortex, including the adaptation of muscles and nerves in the tongue, larynx, and mouth that help produce speech.

Other physical attributes that have adapted over time in humans to improve speech include a low larynx in the throat, a shorter oral cavity, and the hypoglossal canal of the tongue, all of which both help produce sounds.

The Wernicke’s and Broca’s regions in the cerebral cortex are either absent or are very small in other primates; they’re large in humans, enabling comprehension and speech.

Human facial musculature is also more highly developed, allowing the eyes and lips to impart nonverbal communication.

Considering the development of these attributes that facilitate speech in humans, you can see that genes and culture have worked closely together to evolve the human species.

Next week, we’ll talk about how these physiological aspects of speech differ across cultures.

Your Ancestors Couldn’t Drink Milk, But You Can: Here’s Why

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Got milk?

Your ancestors didn’t.

About 10 millennia ago, human adults couldn’t drink milk.

The BBC article, “How Human Culture Influences Our Genetics,” outlines why the human adults of today are more lactose tolerant, while those of yesteryear were not.

Lactose tolerance – or intolerance – is genetic.

Prior to dairy farming, only children could manage to chug a glass of milk without getting sick. 

When some cultures began dairy farming, a genetic mutation created an ability amongst adults to digest milk properly.

This mutation was passed on to offspring over time.

Last week, we discussed how culture is outpacing genetics when it comes to human evolution.

This is one example where culture may not have outpaced genetics but still worked symbiotically to evolve a tolerance to milk through natural selection.

Lactose Tolerance Today

As mentioned, those cultures with a background in dairy farming are significantly more lactose tolerant today, because they’ve developed the related gene.

This is another example of how culture impacts biological evolution.

That gene effectively produces the enzyme, lactase, which breaks down lactose (the sugar found in dairy products) in the small intestine.

Cultures with a higher prevalence of lactose intolerance see lesser production of lactase in infancy.

Upwards of 70 percent of adults from East Asian and West African cultures suffer lactose intolerance, along with those of Greek, Italian, Jewish, and Arab heritage.

On the opposite end of the spectrum, those cultures with high lactose tolerance include Northern European cultures, particularly those of the Nordic region. 

The populations of Sweden and Finland have a reported tolerance of 74 percent and 82 percent, respectively.

These tolerance levels might be related to the immigration of lactose tolerant groups to these regions, rather than a background in dairy farming, as the cultures aren’t historically rooted in the production or consumption of milk.

But these countries may be the exception that proves the rule.

As anthropologist and co-author of The 10,000-Year Explosion: How Civilization Accelerated Human Evolution, Henry Harpending, writes:

“Which came first, the cattle or the mutation, you can’t tell. If the mutation had not occurred, there wouldn’t be so much dairying. But if people who could digest lactose didn’t have cattle, the mutation would have had no advantage.”

The Cow or the Milk

Although we may not know what came first – the cow or the milk tolerance – we can spot some aspects of “survival of the fittest” in the evolution of these cultures.

Cultures with higher lactose tolerance were historically able to survive famine at a higher rate and may have even made for stronger warriors, due to bone health.

In his research on the subject, Professor Daniel Wegmann of the University of Fribourg in Switzerland, concludes:

“Over the past 3,000 years, lactase-persistent individuals had more children or, alternatively, those children had better chances of survival than those without this trait.”

We can only expect lactose tolerance to grow even more within the next 3,000 years.

Does Culture Drive Human Behavior More Than Genetics?

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Biologists say that behavior is ultimately determined by natural selection.

This is because genetic structures are constructed according to the mental processes and learned patterns and responses to different environments.

As Richerson and Boyd, authors of Not By Genes Alone: How Culture Transformed Human Evolution, note: physiological changes that shape behavior are evolutionary.

Take bird migration, for instance.

Instead of passing winter in harsh environments, birds have acquired their migratory behavior according to evolutionary physiological reactions.

The brain has formed evolutionary strategies across time to send hormonal signals that trigger annual migration to warmer climates.

So, while genes may determine the traits and behaviors best suited to the environment, the environment has helped shape these genes. 

Where does culture come into play?

Culture is part of the environment, especially where humans are concerned.

Culture Drives Human Evolution

Taking the environment’s impact on evolution a step further, in a study by the University of Maine, culture was found to drive human evolution even more so than genetics.

According to the 2021 study by researchers, Tim Waring and Zach Wood, humans adapt to their environment and challenges in their environment via culture – in the form of learned knowledge, skills, and practices –more effectively and at a faster pace than through genetics.

One reason for this “special evolutionary transition” is that the cultural transfer of knowledge is flexible and fast when compared to genetic transfer.

Waring notes that:

“Gene transfer is rigid and limited to the genetic information of two parents, while cultural transmission is based on flexible human learning and effectively unlimited with the ability to make use of information from peers and experts far beyond parents.”

This results in a stronger adaptation via cultural evolution than genetic evolution allows.

The researchers also argue that culture’s group-oriented nature produces more group-oriented evolution as well.

Ways in Which Humans Have Evolved

How have humans evolved via culture?

Humans have adapted in several key ways over the millennia.

These include:

  • Capacity for social learning
  • Predisposition to be cooperative
  • Capacity to collaborate
  • Diminishing aggression

Genetics and culture work together to adapt behaviors, but as Waring and Wood’s research suggests, culture is becoming even more influential on the evolution of human behavior.

As Waring concludes:

“This research explains why humans are such a unique species…We are slowly becoming ever more cultural and ever less genetic.”

Maybe She’s Born with It: Genetic Versus Acquired Behaviors

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Last week, we talked about the evolution of color perception.

Why were traditional societies without the color “blue” in their vocabulary? Was it due to their culture? Or their genetics?

That’s exactly what researchers Paul Kay and Brent Berlin set out to investigate.

Inferiority

As discussed in our last post, the scientific community previously assumed that the so-called genetic inferiority of “primitive” societies resulted in a lack of color perception – and thus a lack of color language.

It was only in 1969 that Kay and Berlin took a deeper look.

In researching the languages of twenty ethnic groups, they collected the groups’ color descriptions, using twenty different color chips. In this way, they systematically compared these groups’ color vocabulary.

Their Findings

Primary colors were identified across nearly every culture, which suggests that color language is unrelated to retina development or genetics.

Evolutionary research also confirms that the eyes of Hebrews and ancient Greeks possessed the same color vision as they do today.

What Does This Mean?

This means that color language is a cultural norm; there is no difference in our genetics, our vision or our perceived color spectrum.

The difference is only in the language. And while some cultures differentiate distinct separations between certain colors, others don’t.

One example: Blue

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Take a look at this color spectrum.

In the Russian language, what English speakers call “light blue” qualifies as a different color from “dark blue.”

“Goluboy” and “siniy” in Russian, respectively.

Both light and dark blue are the same color in English, just two different shades of that color.

In fact, Russians may be more on point than the Brits on this differentiation. The wavelengths of light and dark blue differ as much as light blue and green.

So, equating dark and light blue makes as much physiological sense as calling light blue green and vice versa.

Now, consider early Russian scientists or linguists studying the English language.

The absence of vocabulary between what they saw as two distinct colors – goluboy and siniy -would certainly have made the English language – and, therefore, the British – seem primitive and uncivilized.

The Russians may have viewed their lacking color vocabulary as a lack of color perception and, therefore, genetic inferiority.

Civilized/Uncivilized

So, does color vocabulary (and the assumed “color perception” that accompanies it) make one culture more civilized than the other?

Of course not.

Whether your language lumps light and dark blue together or it differentiates between the two – or whether you have the color “blue” in your language at all – no color vocabulary is inferior to the other.

We’ll talk more about this next week.