Name: 31.なぜ多くの種が存在するのか？生物多様性に影響を与える要因 (31. Why So Many Species? The Factors Affecting Biodiversity)
Uploaded: 2021-01-14T04:53:01.000Z
Duration: 48 min 28 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Prof: Now today I am going to talk about biodiversity

and whether or not it's something we should be worried

like the extinction crisis which is being caused by human

And I don't want you to forget this extremely simple idea here,

that the impact of humans on the environment basically is a

function of how many people there are on the planet,

times the average amount that each of those people consumes,

multiplied perhaps by some fudge factor to express good or

And I think that the Greeks probably could have written that

It's nothing that is particularly surprising.

Nevertheless it is striking to me that this half of the

equation, the upper half of the equation,

has pretty much disappeared from public discourse on this

pushback from various groups that see any discussion of the

population problem as inevitably involving contraception or

And it's also a pushback from the poor countries of the world,

"You can't come down here and tell us what to do after

you've all gone and screwed up your own environment.

Let us get on with our own lives, and that's not our

The impact of humans on the environment of the planet is

basically a function of how many people there are on the planet

You will find in the literature on things about biodiversity

problems, extinction problems, an awful lot of fairly refined,

You will find people applying cutting edge ecological theory

But, by way of introduction, I never want you to forget that

the problem of human impact on the other species on the planet

is not a problem that we can really solve with scientific

We can only solve it by understanding the incentives

that people encounter to have more babies,

or fewer babies, and the incentives that they

encounter to consume more or to consume less.

If any of you think this is simple, just think of what's

The people of the world are trying to stimulate consumption.

And that flies right in the face of the environmental

I don't think there's any easy answer on that.

Prof: Right, Bob Wyman teaches a class on

By the way, let me just take one of Bob's slides,

If you go around the planet and you ask people how many babies

indicates that they want about two-thirds of what they actually

And that suggests that the easiest way to solve the

population problem is not to do anything Draconian,

but just to give every woman on the planet control of her own

Okay, I just wanted to make sure I got that message across

Now today I'm going to discuss extinctions, and I am going to

do it from ecological, economical, evolutionary and

And within the ecological literature this is an old

chestnut, and basically back oh say about

thirty to fifty years ago there was intuition that suggested

that the more diverse an ecosystem was the more stable it

And people like stability, they don't like to be hit by

surprises, and so diversity would be good because it

Then Bob May showed that more diverse communities can be less

That's not a necessary logical connection, that more diverse

things are more stable; sometimes more diverse

Since then there have been a lot of experiments.

More recent theory shows that sometimes diversity can increase

and I think it's one where we have to be modest and say that,

"You know, in any particular circumstance

Stability itself is a fairly abstract term,