History 101 (2020–…): Season 1, Episode 10 - Genetics - full transcript

September 2012.

Under a parking lot
in the English city of Leicester,

archaeologists find
a mysterious skeleton,

its spine oddly twisted.

DNA from the bones confirms

these are the mortal remains
of Richard III, king of England.

His funeral,
530 years after he was killed in battle.

What's more, most portraits show him
with dark hair and eyes.

But his DNA reveals Richard III

likely had fair hair as a child
and blue eyes.

Genetics can be full of surprises.



DNA is the blueprint to life,

the stuff that determines
nearly everything about you,

from how you look
to whether or not you're a thrill-seeker.

But that just takes up 1.2% of your DNA.

Scientists still don't know
what's in the remaining 98.8%.

Our closest evolutionary relatives,

chimpanzees,

share 96% of the same DNA as us.

But we also share
about 60% of the same DNA...

...as bananas.

The ability to read DNA

is arguably one of the most important
technological advances

of the 20th century.

But, in our rush to understand
and manipulate DNA,



are we sowing
the seeds of our own destruction?

Are we unleashing
a real Frankenstein's monster?

For centuries,

humans have known that we get
more than our looks from our parents.

But no one ever knew how.

By the 1950s, biologists know

that DNA exists
and that it contains the code of life.

This is a close-up
of the DNA molecule,

magnified more than 100,000 times.

Unbelievable as it seems,

we can transfer heredity
through the substance of DNA.

Well, gee, what kind of stuff is DNA?

In 1952,
when British chemist Rosalind Franklin

uses X-rays to magnify DNA,

she makes a startling discovery.

DNA is actually shaped like a spiral.

A year later,

Franklin's photo lands on the desk
of James Watson and Francis Crick,

who realize what they're seeing is
actually a double helix...

which helps them work out
DNA's molecular structure.

So what is this stuff?

DNA stands for deoxyribonucleic acid.

Let's break it down.

Inside every cell in your body,

in the nucleus, you'll find the genome,

twenty-three pairs
of squiggly chromosomes.

Half are from your mother,

half from your father.

And each chromosome contains
a folded-up spiral ladder strand of DNA.

That ladder is made up
of just four molecular bases

that always connect in pairs.

Adenine and thymine,

and then cytosine and guanine.

And certain sequences of those letters,
what we call genes,

tell the cell to create certain proteins,

the molecules responsible
for every function in your body.

DNA can be found in every living thing.

But it's also incredibly complex.

And it could end up
fundamentally changing

our understanding of life

if only we can unlock its secrets.

In the 1960s,

before anyone fully understands
how DNA operates,

scientists get an idea.

If they study families
that share a unique genetic trait,

they should be able to locate

that trait on their shared chromosomes.

Over the next few decades,

geneticists start combing through
the DNA of families

with inherited diseases.

One example is Huntington's disease,

a rare neurological disorder
that only shows up in adults.

So parents often pass it down
to their children

before they even know they have it.

My daughter,
she's at risk from the illness as well.

She's only 14.

And hopefully, one day,
there will be a cure for her.

In 1983,

researchers begin work on isolating
where the disease is on the genome,

and they eventually discover

a gene marker for Huntington's
on chromosome four.

It means they can spot the disease
before its symptoms show,

so adults can know if they're putting
their future children at risk.

One of the many researchers

rushing to isolate genetic diseases is

British scientist Alec Jeffreys.

But in 1984, he realizes something else.

Certain stretches of DNA
produce a pattern,

rather like a bar code,
that's unique to each person.

All it takes is a microscopic amount
of DNA from any body tissue,

and scientists should be able
to distinguish

and identify that individual.

He calls it "DNA fingerprinting."

And it will revolutionize
the way crimes are solved.

In the summer of 1986,

the body of 15-year-old Dawn Ashworth
is found in a wooded area

in Leicestershire.

Dawn was subjected
to a horrific sexual attack,

and I have no doubt that the person
who committed that was

a very sick-minded individual indeed.

What alarms the neighborhood
is that, three years earlier, the body

of 15-year-old murder victim Lynda Mann
was found just half a mile away.

Do they have a serial killer on the loose?

Detectives give Dr. Jeffreys

DNA samples recovered from both victims,

and he proves
their suspicions are correct.

It's the same man.

You can seen that the patterns
in this track and this track

are, in fact, identical.

And therefore, it led us to the conclusion

that this semen has originated
from the same man,

and therefore,
the two murders are connected.

But to investigators' surprise,

the sample doesn't match the suspect
they already have in custody.

You can see that the pattern
from his blood stain is

quite different from that...

got from the semen that was taken
from the vagina swabs from both girls.

So police
start collecting DNA samples

from over 5,000 men living in the area,

until they finally find a match.

And Colin Pitchfork
becomes the first person

ever to be convicted
based on DNA evidence.

DNA fingerprinting becomes
the greatest advance

in forensics since actual fingerprinting.

By 1990, the use of DNA in police work

explodes all around the world.

Since it was launched,

America's national DNA index of criminals,
called CODIS,

has helped
in more than 465,000 investigations.

The chances of two unrelated individuals
matching is one in 30 billion.

That's almost four times
the world's population.

CODIS contains
nearly 14 million offender DNA profiles.

As of October 2019, 367 convicted people

have been exonerated through DNA.

Throughout the 80s,

even before scientists fully understand
how it works,

DNA is already proving useful
for uncovering disease and solving crimes.

But to really understand DNA, in 1990,

scientists embark on one
of the most ambitious projects ever,

creating a map of the human genome.

It's no small feat.

The human genome contains
about 3.2 billion base pairs.

If you wrote out the entire sequence,
it would fill 800 copies of the Bible.

If you stretch the DNA in one cell
all the way out,

it would be about six feet long.

But all the DNA
from the 37 trillion cells in your body

would stretch across the solar system
and back again.

The effort to map the genome will end up
costing around $2.7 billion.

Not so expensive
for the secret to all of life.

Americans spend at least ten times more
on pizza per year.

But even as some geneticists
are struggling to decode DNA,

others don't want to wait.

They decide to start manipulating it.

Take a gene from one living thing
that has the trait you want

and insert it into the DNA
of another living thing

during reproduction.

And voilà, you've artificially engineered
that genetic trait.

The technique proves especially good
at boosting the efficiency of food crops.

It will be possible to grow crops
that have no cholesterol in the oil.

We'll be able to grow crops
with higher vitamin content.

In 1994, geneticists make
a backwards copy of the gene

that ripens tomatoes

and create new tomatoes
that don't ripen too quickly.

Other crops are modified
to be genetically resistant to pests.

They're called
"genetically modified organisms,"

GMOs.

And soon, they're everywhere.

As of 2018,

the top five countries growing GMOs
in terms of crop area

are the United States, Brazil, Argentina,

Canada, and India.

Twelve countries in Africa
are now testing crops

that have been modified
for drought tolerance,

saline tolerance, and enhanced nutrients.

In the US, up to 92% of corn is
genetically engineered...

and 94% of soybeans.

Estimates are that more than 75%
of processed foods on supermarket shelves,

from soda to soup to condiments,
have some genetically altered ingredients.

But as people begin to realize

the extent to which their food
is genetically modified,

there are concerns.

What exactly are we eating?

Some of this, likely,

comes from soy
which has been genetically modified.

So what's the big deal,
genetically modified? Well, we don't know.

There's no scientific consensus
as to whether these foods are okay or not.

And yet we are putting them
into infant formula,

something we give to babies
from the first day of their lives.

And yet they contain ingredients
that have never been tested for safety.

For now, there is
no scientific evidence

that swapping out a plant's genes
makes food harmful in any way.

But simply interfering with nature

at such a basic level
makes people nervous.

Are geneticists messing with forces
they don't fully understand?

When scientists start tinkering

with the DNA of animals,
the debate intensifies.

In 1996, Scottish scientists

take the nucleus
of a white-faced sheep's udder cell

and inject it into the egg cell
of a black-faced sheep,

then implant the egg
into a surrogate mother.

One hundred and fifty days later,

the surrogate gives birth
to a white-faced lamb,

an exact genetic copy of the mom
who donated her udder cell.

Dolly the sheep is an instant celebrity,

the first mammal cloned

from an adult cell,
a genetic twin to her mother.

If scientists can successfully clone
a sheep like Dolly,

then what about other forms of life?

The question is now being asked,

will they ultimately be able
to clone human beings?

The same technique
does prove successful for cloning monkeys,

but what about humans?

It'd be one thing to modify the genes
of a baby with a deadly disease,

but will people start designing
their children,

making sure they have a higher IQ

or a certain eye color?

Scientists can now take cells

from a human embryo
smaller than a pinhead...

and use them to grow
genetically identical healthy body organs,

ones that could later replace sick ones.

But meddling with human embryos
proves extremely controversial.

The use of, uh... uh...

embryos to clone...

is wrong.

We should not,
as a society, grow life...

to destroy it.

Human cloning is flat-out banned

in more than two dozen countries,
but not the US.

And the debate rages on.

Meanwhile,
after a full decade of research,

geneticists finally present the world
with their first draft of a map

of the entire human genome.

President Bill Clinton makes
the announcement.

With this profound new knowledge,
humankind is on the verge of gaining

immense new power to heal.

Genome science will have a real impact
on all our lives.

And even more
on the lives of our children.

It quickly accelerates
new findings.

Genes are isolated
with links to type 2 diabetes,

cardiovascular disease,
schizophrenia, and more.

In a page out of science fiction,

people can now find out

if they're likely to get certain diseases
before they happen,

and they start acting on it.

In early 2013, actress Angelina Jolie

announces her decision
to have a double mastectomy.

A defective BRCA1 gene

puts her at an 87% risk
of developing breast cancer.

The procedure reduces the odds to 5%.

I've been very happy just to see
the discussion

about women's health expanded,
and that means the world to me.

And... and after losing my mom
to these issues, I'm very grateful for it.

With celebrities
raising awareness,

more people start wanting to know
about their own DNA,

what diseases might be lurking there,

and what it might tell them
about their genetic past.

In 2015, 23andMe,
named after the number of chromosomes,

becomes the first FDA-approved company

to sell genetic testing
directly to consumers.

DNA home kits become
gift-wrapped bombshells.

Some discover long-lost siblings.

Many people, excited about the technology,

start uploading their genetic profiles

to sites that allow you to search
for long-lost relatives.

It introduces another thorny issue...

privacy.

Law enforcement agencies quickly see
the potential of this new DNA development

to catch more criminals.

In early 2018,

California homicide detectives upload
crime scene DNA of a suspect known

as the Golden State Killer.

Searching nearly one million profiles,

they get hits on several distant relatives
of their suspect.

The matches are enough
to lead them to a name,

Joseph DeAngelo.

And that April,

the 72-year-old former police officer
is charged with the murders of 12 people.

It was always gonna be DNA
that solved this case.

There's gonna be discussions
about privacy

and public nature of these databases,
like there is on everything. That's fine.

Those are discussions
for other people to have.

Um, our need is to solve crimes.

But it raises
difficult questions:

What if scientists discover
a genetic predisposition

for criminal activity,

and the authorities decide to act on it?

What if government agencies
start rounding up people

with a particular undesirable trait?

Your DNA holds all your secrets
about your past and your possible future.

What might your employer do,
or your future significant other,

if they knew your predisposition
to certain diseases?

What if we start discriminating
against people

for their unseen genetic traits?

We may have opened this Pandora's box

before fully understanding
the consequences.

And let's not forget that 98.8%
of the genome we still don't understand.

Manipulating DNA could give us longer,
healthier, and even more enriching lives,

but it could also launch us
into a dark new era.

Humanity's curiosity can take us
to some dangerous places.

With genetics, our endless quest
to know more and to control our lives

may just take us a step too far.