Name: An evolutionary perspective on human health and disease | Lara Durgavich
Uploaded: 2020-10-26T18:26:14.000Z
Duration: 15 min 28 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Transcriber: Ivana Korom Reviewer: Krystian Aparta

When I was approximately nine weeks pregnant with my first child,

I found out I'm a carrier for a fatal genetic disorder

is that one of the two copies of chromosome number 15

Because I still have one normal copy of this gene,

But if a baby inherits this mutation from both parents,

if both copies of this particular gene don't function properly,

that progressively shuts down the central nervous system

For many pregnant women, this news might produce a full-on panic.

But I knew something that helped keep me calm

when I heard this bombshell about my own biology.

whose ancestry isn't Eastern European Jewish like mine,

of also being a carrier for the Tay-Sachs mutation.

individuals who have one normal copy of the gene

is about one out of 27 people among Jews of Ashkenazi descent, like me,

only one in about 300 people carry the Tay-Sachs mutation.

Thankfully, it turned out I was right not to worry too much.

and we now have two beautiful and healthy children.

I was aware of the unusually high rate of Tay-Sachs in the Ashkenazi population.

But it wasn't until a few years after my daughter was born

when I created and taught a seminar in evolutionary medicine at Harvard,

The process of evolution by natural selection

So how did this defective gene persist at all?

And why is it found at such a high frequency

The perspective of evolutionary medicine offers valuable insight,

humans' evolutionary past has left our bodies vulnerable

it demonstrates that natural selection doesn't always make our bodies better.

But as I hope to illustrate with my own story,

understanding the implications of your evolutionary past

When I started investigating Tay-Sachs using an evolutionary perspective,

The unusually high rate of the Tay-Sachs mutation

may relate to advantages the mutation gave this population

"I'm sorry, did you just suggest that this disease-causing mutation

Certainly not for individuals who inherited two copies of the mutation

may have been more likely to survive, reproduce

This idea that there can be circumstances in which heterozygotes are better off

Evolutionary biologists call this phenomenon

are more common among some African and Asian populations

or those with ancestry from these tropical regions.

In these geographic regions, malaria poses significant risks to health.

The parasite that causes malaria, though,

can only complete its life cycle in normal, round red blood cells.

By changing the shape of a person's red blood cells,

the sickle cell mutation confers protection against malaria.

People with the mutation aren't less likely to get bitten

by the mosquitoes that transmit the disease,

but they are less likely to get sick or die as a result.

is therefore the best possible genetic option

Carriers are less susceptible to malaria,

because they make some sickled red blood cells,

but they make enough normal red blood cells

that they aren't negatively affected by sickle cell anemia.

the defective gene I carry won't protect me against malaria.

But the unusual prevalence of the Tay-Sachs mutation