Temperament, heredity, and genes | Behavior | MCAT | Khan Academy

Summary

The script explores the concept of temperament in babies, suggesting it's established early and persists into adulthood, indicating a genetic basis. It delves into behavior genetics, explaining how traits like eye color are controlled by genes on DNA. The analogy of a tea bag illustrates how genes can be activated or deactivated by environmental factors, emphasizing the complexity of separating nature versus nurture in shaping behavior. The discussion sets the stage for further exploration of how genetics and environment interact to define who we are.

Takeaways

• 👶 Babies exhibit unique responses and reactions to their environment, which can be categorized as 'easy,' 'difficult,' or 'withdrawn' based on their temperament.
• 🌟 Temperament is a broad term encompassing a person's characteristic emotional reactivity and intensity, and it is more than just personality.
• 🧬 Temperament appears to be well-established before babies interact significantly with their environment, suggesting an innate component.
• 🔗 Studies indicate that temperament tends to persist as individuals age, hinting at a long-term influence on behavior and personality.
• 🧬👶 The idea that temperament is hardwired from birth leads to questions about the genetic basis of personality, gender identity, intelligence, and athletic ability.
• 🧬 Genetics, or heredity, is the transmission of traits from parents to offspring, with genes being the units of heredity that control characteristics like eye color and temperament.
• 🧬 DNA, or deoxyribonucleic acid, is the molecule containing all the instructions for an organism's development and function, including our genetic material.
• 🧬🧬 Genes are segments of DNA that can synthesize proteins, and they are organized into chromosomes, with humans having 46 chromosomes making up their genome.
• 🌐 Most human traits, especially complex ones like intelligence and temperament, are influenced by multiple genes and their interactions with the environment.
• 🌱 The environment plays a crucial role in gene expression, much like hot water brings out the flavor of a tea bag, suggesting a dynamic interplay between nature and nurture.

Q & A

What is the significance of the three babies described in the script?

The three babies represent different temperaments: 'easy', 'difficult', and 'withdrawn'. They illustrate the variability in how babies respond to their environment and caregivers, which is a key concept in understanding temperament.

What does the term 'temperament' refer to in the context of the script?

Temperament refers to a person's characteristic emotional reactivity and intensity, which includes aspects like sociability and shyness. It is a broad term that encompasses traits like predictability in sleeping and feeding patterns.

Why is temperament considered to be established before significant environmental exposure according to the script?

The script suggests that temperaments seem to be well established before babies are exposed to much of their environment, indicating that these traits may have a genetic or innate component.

How does the script describe the persistence of temperament as a person ages?

The script indicates that temperaments are not only established early but also tend to persist as individuals grow older, suggesting a long-term influence on a person's behavior and reactions.

What role does the script suggest that genetics play in determining temperament and other traits?

The script implies that genetics, or the hardwiring component, plays a significant role in determining temperament and other traits, as it discusses the idea of traits being hardwired into us at birth.

How are traits passed from parents to offspring according to the script?

Traits are passed from parents to offspring through heredity, which involves the transmission of genes that control these traits from the father's sperm and the mother's egg.

What is the relationship between genes and chromosomes as explained in the script?

Genes are the units of heredity that are segments of DNA, and they are linked together to form a long strand known as a chromosome. Humans have 46 chromosomes, each containing many genes.

What is the term for the complete set of genetic material in humans?

The complete set of genetic material in humans is referred to as the 'genome', which includes all the chromosomes and genes that make up an individual.

How does the environment interact with genes to influence traits according to the script?

The environment plays a significant role in determining whether genes are active or inactive, thus influencing the expression of traits. The script uses the analogy of a tea bag, where the environment acts like hot water, coaxing out the characteristics of the tea (or traits in the case of genes).

What challenges are mentioned in the script regarding the study of genetics and behavior?

The script highlights the challenge of separating the effects of genes and environment in determining behavior, as both遗传因素 and environmental factors interact in complex ways to shape who we are and how we respond.

What is the purpose of the next video mentioned at the end of the script?

The next video is intended to delve deeper into how scientists and psychologists study the effects of environment and genetic background to understand how they ultimately determine our identity and responses.

Outlines

00:00

👶 Temperament and Genetics

The video script discusses the concept of temperament in babies, which is characterized by their unique emotional reactivity and intensity. It describes three types of babies: 'easy', 'difficult', and 'withdrawn'. The script suggests that temperament is established early in life and tends to persist as a person ages. It introduces the idea that temperament might be hardwired into us from birth, hinting at the influence of genetics. The segment also raises questions about the genetic basis of personality, gender identity, intelligence, and athletic ability, setting the stage for a discussion on behavior genetics.

05:03

🧬 Understanding Our Genetic Material

The second paragraph delves into the genetic basis of traits, explaining that genes are segments of DNA that control our characteristics. It describes DNA as deoxyribonucleic acid, the molecule containing all instructions for our development and function. The script uses the analogy of a tea bag to explain how genes can be activated or deactivated by environmental factors. It also discusses how humans inherit 46 chromosomes, with 23 coming from each parent, forming our genome. The genome is likened to a story with 46 chapters, each representing a chromosome. The script highlights that while simple traits like eye color can be traced to specific genes, complex traits involve interactions between multiple genes and the environment.

Keywords

💡Temperament

Temperament refers to a person's characteristic emotional reactivity and intensity, which can include sociability, shyness, and how they respond to their environment. In the video, temperament is described as being established before a baby is significantly exposed to their surroundings, suggesting it is an innate quality. The video uses the example of three babies with different temperaments—easy, difficult, and withdrawn—to illustrate the concept.

💡Heredity

Heredity is the concept of passing traits from parents or ancestors to offspring. It is central to the video's theme of understanding how our characteristics are inherited. The script explains that traits such as eye color and temperament are controlled by genes, which are passed down through the chromosomes we receive from our parents.

💡Genes

Genes are the units of heredity, segments of DNA that are capable of synthesizing a protein. They are responsible for the traits that make us who we are. The video script uses the metaphor of a tea bag to illustrate how genes contain the potential for certain traits but require environmental factors to express them.

💡DNA

DNA, or deoxyribonucleic acid, is the molecule in us that contains all the instructions used in our development and the function of our organisms. It is described as a double helix and is the genetic material that makes up our genes. The video emphasizes that DNA is the blueprint for our traits and characteristics.

💡Chromosomes

Chromosomes are long strands of DNA that are coiled up and contain many genes. Humans have 46 chromosomes, and they are the vehicles through which genes are passed from parents to offspring. The video script explains that we inherit 23 chromosomes from each parent, making up our complete set of genetic content.

💡Genome

The genome refers to the complete set of genetic material in an organism, including all of its genes. The video likens the genome to a story with chapters, where each chapter represents a chromosome and the words represent genes. It is the entire collection of genes that define who we are.

💡Innate

Innate refers to qualities or characteristics that are present from birth, often hardwired into an individual. The video discusses how temperament and certain traits are innate, suggesting that they are established before significant environmental exposure and are hardwired into us.

💡Behavior Genetics

Behavior genetics is the field that studies the genetic component or the hardwiring component to behavior. The video introduces this field as a way to explore how our genetic makeup influences our behavior and characteristics, such as temperament and intelligence.

💡Environmental Factors

Environmental factors are influences from the surroundings that can affect gene expression. The video script uses the tea bag analogy to explain how genes contain potential traits, but it is the environment that can trigger or suppress their expression, much like hot water brings out the flavor of tea.

💡Protein Synthesis

Protein synthesis is the process by which information from DNA is used to create proteins, which are essential for the structure, function, and regulation of the body's tissues and organs. The video mentions that genes are segments of DNA capable of synthesizing proteins, which are crucial for our traits and characteristics.

💡Trait

A trait is a distinguishing quality or characteristic of an organism, such as eye color or temperament. The video script discusses how traits are controlled by genes and are inherited from our parents, contributing to our unique identities.

Highlights

Babies exhibit unique reactions and responses to their environment, which can be characterized as easy, difficult, or withdrawn.

Temperament is a broad term encompassing a person's characteristic emotional reactivity and intensity, including sociability and shyness.

Temperament appears to be well established before babies are significantly exposed to their environment.

Studies suggest that temperament is persistent as a person ages, with inhibited or withdrawn children likely to remain so into adulthood.

The concept of temperament being hardwired at birth leads to questions about the genetic basis of personality and gender identity.

Behavior genetics is a field that explores the genetic component or hardwiring aspect of behavior.

Heredity involves passing traits from parents or ancestors to offspring, which are controlled by genes.

Genes are segments of DNA that can synthesize a protein and are the units of heredity.

DNA, or deoxyribonucleic acid, contains all the instructions for an organism's development and function.

Humans have 46 chromosomes, which are long strands of DNA containing many genes.

Each person receives 23 chromosomes from each parent, contributing to their unique genetic makeup.

The genome is the complete collection of genes in an organism, which determines its characteristics.

Simple traits like eye color can be traced to specific genes, while complex traits involve groups of genes.

Genes can be active or inactive, and the environment plays a role in determining their expression.

The interaction between genes and the environment is crucial in understanding how traits affect behavior.

The analogy of a tea bag and hot water is used to explain how genes require environmental factors to express traits.

Future discussions will delve into how scientists disentangle the effects of genes and environment on behavior.

Transcripts

All right.

So here we have three babies.

And if you've been around babies very much,

you know that babies are often pretty

unique in the way that they respond

and the way that they react to their parents

and to other people and to their environment.

And so we might give this baby on the left

here a big old grin.

And we could say that this baby is really cheerful and really

relaxed and fairly predictable in its sleeping

and in its feeding.

And we might characterize this baby as easy.

And then we have this baby in the middle,

and maybe we'll give it a real sad face here.

And maybe this baby is really irritable or intense

or less predictable in its sleeping and in its feeding.

And we might characterize this baby as pretty difficult.

And then we have this baby on the end,

and maybe we'll just give it a really flat affect.

Maybe we can't tell if she's smiling or if she's frowning.

But maybe this little girl is kind of resistant to change

and maybe withdrawn from new people or new scenarios.

And we might characterize her as withdrawn.

And there are other ways that we might differentiate

between these and other children.

But we call these differentiations temperament.

And temperament is a pretty broad term

and is actually quite difficult to define.

But to get your intuition rolling,

you might be thinking words like "personality."

But temperament is really a little bit broader than that.

And we might say that it's a person's

characteristic emotional reactivity and intensity.

So maybe words like their "sociability"

or their "shyness."

But the real interesting thing about temperament

is that, as psychologists study this idea,

they find that temperaments seem to be pretty well established

before babies are exposed to much of their environment.

And even more interesting, to me at least,

is that as these studies continue,

and as psychologists continue to look at this temperament,

it seems to be fairly persistent as a person ages.

So I'll write, "persists."

And what I mean by that is that maybe this inhibited

or withdrawn child on the right here,

this little girl, as she grows up,

studies have found that she is more

likely to be inhibited and withdrawn as an adult.

And so combined, these two ideas-- this idea

that the temperament is fairly established at birth

and that it also persists as people age-- leads

us to believe that, really, this temperament,

this idea that kind of defines us, is fairly hardwired into us

at birth.

And so that leads us to develop further curiosities.

If our temperament is hardwired into us,

what about our personality?

Is that hardwired into us?

And is it persistent as we age?

And how about our gender identity?

Does that come predetermined and hardwired?

And are there are certain folks that are hardwired, maybe,

to have higher intelligence or to be geniuses or even

super athletes?

Well, hopefully we can dissect some of these ideas,

or at least begin to dig into them as we talked about--

really a field, called behavior genetics, looking

at the genetic component or the hardwiring component

to behavior.

So when we talk about hardwiring, what we're really

talking about is heredity.

And heredity is the idea of passing traits

from parents or ancestors to offspring.

There's the father.

And then we'll have a mother.

And we said these parents are passing traits.

So let me draw that.

They're passing traits.

And as a review, traits are essentially

the distinguishing qualities or characteristics

that compose us.

Maybe a better word would be our "attributes," so things

like our eye color, or even our temperament.

And these inherited traits that we get from our mother

and from our father-- these characteristics that

define us-- are actually controlled by genes.

And so as I get a little bit deeper into the biology,

I need a better picture, and I've

pre-drawn an image that will help me talk about some

of these ideas.

But genes are actually the little, individual units

of heredity.

They're actually segments of DNA,

right here, that's capable of synthesizing a protein.

So this strand, this double helix, is DNA.

And let me write that real big for us.

And DNA is-- I guess continue in what is now becoming almost

a vocabulary lesson-- but DNA is deoxyribonucleic acid.

And it's actually a molecule in us

that contains all the instructions used

in our development and in the function of our organisms

and, really, in the function of our personage.

But it contains all of our genetic material.

That's what DNA is-- our genetic material.

So, many of these genes, these little units

of heredity right here, are linked together

to form a long strand of DNA called a chromosome.

So we have maybe a gene there, and maybe a gene here,

and a lot of little genes link together as we go down.

But they form this long strand of DNA,

and it coils up really tightly.

And this long strand-- all of this whole structure right

here-- is one strand of DNA coiled up called a chromosome.

And as humans, we have 46 chromosomes

full of genes that make us who we are.

And we get 23 of these chromosomes from our father,

through his sperm, and 23 of these chromosomes

from our mother, through her egg.

And in the end, we end up with this nice collection

of genetic content-- 46 chromosomes in its entirety--

that resides in almost every single cell in our body right

here in the nucleus.

And we refer to this collection of genes, compiled

in this list of chromosomes, as our genome.

So I guess it's kind of like this-- we have approximately

30,000 genes, and if we consider them to be words in a story,

that story would be about as long as The Old Man in the Sea

by Ernest Hemingway-- so kind of a short novel.

But continuing that theme, I guess

that story would have 46 chapters,

and the title of that entire story would be our "Genome."

So our genome is really just this entire collection

of genes that make us who we are.

Some of the more simple traits can

be traced fairly specifically to certain genes,

like eye color or hair color.

Relatively simple traits can be traced back to specific genes.

We can actually see which genes are

controlling those specific traits.

But most of our traits-- especially the complicated ones

like intelligence or happiness or aggressiveness

or all of those characteristics that

play into our temperament, the ones that

are heavy hitters in our behavior--

are traced back to groups of genes.

And those groups of genes are actually

interacting with each other and with our environment.

You see, these genes can either be active or inactive.

And the environment actually plays a major role

in turning them on or off, determining whether they're

going to code for these proteins or not code for these proteins.

And so you can think of this idea like a tea bag.

Let me draw a cup here.

And in this cup we have a tea bag here.

So we've got this tea bag.

It's kind of hanging off the side

right there with its label.

And in this tea bag are all of the makings

for the tea that we're going to drink.

And so all of the little leaves, and all of the things

that are characteristic of this tea,

and all the makings of the tea-- so its flavor, it's caffeine,

its smell-- are contained within this little tea bag.

But they're actually coaxed into expression

as hot water is poured over it.

So as water gets poured over it, especially hot water,

it pulls from these leaves the flavor.

And it pulls the caffeine out, and it pulls that aroma.

And that tea that was contained in this bag

begins to spread and express itself in this glass

so that we can enjoy it.

And while all of the contents were originally

contained-- everything about the tea, its characteristics,

were determined by that tea bag--

ultimately its expression was dependent on the hot water.

And so what becomes really challenging

is separating the effects of our genes and our environment

and ultimately determining which ones,

and to what degree, these genes and these traits

end up affecting our behavior.

But I'm running out of time in this video,

and so in the next video, I'm going

to talk about how, as scientists, psychologists

begin to tease apart these effects of environment

and our genetic background in ultimately determining

who we are and how we respond.