Name: 【TED】Paul Ewald: Can we domesticate germs? (Paul Ewald: Can we domesticate germs?)
Uploaded: 2018-01-01T17:04:45.000Z
Duration: 19 min 19 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...

Adverbs of degree

What I'd like to do is just drag us all down into the gutter,

Adverbs of manner

and actually all the way down into the sewer

Transition words & phrases

And when evolutionary biologists talk about design,

they really mean design by natural selection.

And that brings me to the title of the talk,

"Using Evolution to Design Disease Organisms Intelligently."

And I also have a little bit of a sort of smartass subtitle to this.

I really think that this subtitle explains

what somebody like me, who's sort of a Darwin wannabe,

sort of coming into this field of health sciences and medicine.

It's really not a very friendly field for evolutionary biologists.

but you see a lot of people who are sort of defending their turf,

and may actually be very resistant, when one tries

So, all of the talk today is going to deal with two general questions.

One is that, why are some disease organisms more harmful?

And a very closely related question, which is,

how can we take control of this situation once we understand

How can we make the harmful organisms more mild?

And I'm going to be talking, to begin with, as I said,

And the focus when I'm talking about the diarrheal organisms,

as well as the focus when I'm talking about any organisms

is to think about the problem from a germ's point of view,

And in particular, to think about a fundamental idea

which I think makes sense out of a tremendous amount of variation

And that idea is that from the germ's-eye point of view,

disease organisms have to get from one host to another,

and often they have to rely on the well-being of the host

that don't rely on host mobility at all for transmission.

And when you have that, then evolutionary theory tells us

that natural selection will favor the more exploitative,

So, natural selection will favor organisms

If instead transmission to another host requires host mobility,

then we expect that the winners of the competition

So, if the pathogen doesn't need the host to be healthy and active,

the winners in the competition are those that exploit the hosts

But if the host needs to be mobile in order to transmit the pathogen,

then it's the benign ones that tend to be the winners.

So, I'm going to begin by applying this idea to diarrheal diseases.

Diarrheal disease organisms get transmitted in basically three ways.

They can be transmitted from person-to-person contact,

or they can be transmitted through the water.

And when they're transmitted through the water,

unlike the first two modes of transmission,

these pathogens don't rely on a healthy host for transmission.

A person can be sick in bed and still infect tens, even hundreds

To sort of illustrate that, this diagram emphasizes that

somebody's going to be taking out the contaminated materials.

They're going to wash those contaminated materials,

and then the water may move into sources of drinking water.

People will come in to those places where you've got

The whole point is that a person who can't move

when diarrheal disease organisms are transported by water,

we expect them to be more predator-like, more harmful.

So, one way you can test is just look at all diarrheal bacteria,

and see whether or not the ones that tend to be

more transmitted by water, tend to be more harmful.

Now I put those names in there just for the bacteria buffs,

there's a lot of them here, I can tell --

the main point here is that those data points

all show a very strong, positive association between

the degree to which a disease organism is transmitted by water,

how much death they cause per untreated infection.

So this suggests we're on the right track.

But this, to me, suggests that we really need

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【TED】Paul Ewald: Can we domesticate germs? (Paul Ewald: Can we domesticate germs?)

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