Sean B. Carroll

And one of my favorite examples is the influence of salmon in western rivers on tree growth. And you're like, what? Yes, trees need salmon. So who would have thought that?

And one of my favorite examples is the influence of salmon in western rivers on tree growth. And you're like, what? Yes, trees need salmon. So who would have thought that?

And one of my favorite examples is the influence of salmon in western rivers on tree growth. And you're like, what? Yes, trees need salmon. So who would have thought that?

Let's start with one rule, which is really some animals are more important than others, or if you want to use the Orwell saying, are more equal than others. There's sort of a poetic description sometimes of nature, that everything matters and everything has its role. But it turns out that some creatures have a really outsized role in the diversity and stability of their ecosystems.

Let's start with one rule, which is really some animals are more important than others, or if you want to use the Orwell saying, are more equal than others. There's sort of a poetic description sometimes of nature, that everything matters and everything has its role. But it turns out that some creatures have a really outsized role in the diversity and stability of their ecosystems.

Let's start with one rule, which is really some animals are more important than others, or if you want to use the Orwell saying, are more equal than others. There's sort of a poetic description sometimes of nature, that everything matters and everything has its role. But it turns out that some creatures have a really outsized role in the diversity and stability of their ecosystems.

When ecologists started to discover this, it was even to their own surprise, well, the consequences are great. So that if you think about, for example, people may be familiar with the story of both the

When ecologists started to discover this, it was even to their own surprise, well, the consequences are great. So that if you think about, for example, people may be familiar with the story of both the

When ecologists started to discover this, it was even to their own surprise, well, the consequences are great. So that if you think about, for example, people may be familiar with the story of both the

eradication and then the later reintroduction of wolves in the yellowstone ecosystem so in the early part of the 20th century there was a great effort to eliminate wolves virtually everywhere in the lower 48 states you know because they were Disliked by humans, their effect on livestock, they were scary, et cetera, et cetera.

eradication and then the later reintroduction of wolves in the yellowstone ecosystem so in the early part of the 20th century there was a great effort to eliminate wolves virtually everywhere in the lower 48 states you know because they were Disliked by humans, their effect on livestock, they were scary, et cetera, et cetera.

eradication and then the later reintroduction of wolves in the yellowstone ecosystem so in the early part of the 20th century there was a great effort to eliminate wolves virtually everywhere in the lower 48 states you know because they were Disliked by humans, their effect on livestock, they were scary, et cetera, et cetera.

What we didn't understand what we were doing was we were taking a creature that had a really outsized impact on the stability and diversity of its ecosystem. We were taking it out of the picture and this had huge consequences. One of those consequences we can still see all over the place, which is, for example, the enormous numbers of deer that are in many states.

What we didn't understand what we were doing was we were taking a creature that had a really outsized impact on the stability and diversity of its ecosystem. We were taking it out of the picture and this had huge consequences. One of those consequences we can still see all over the place, which is, for example, the enormous numbers of deer that are in many states.

What we didn't understand what we were doing was we were taking a creature that had a really outsized impact on the stability and diversity of its ecosystem. We were taking it out of the picture and this had huge consequences. One of those consequences we can still see all over the place, which is, for example, the enormous numbers of deer that are in many states.

those deer in turn have enormous consequences on uh plant diversity because they mow down the plants and forests etc etc so the discovery that some creatures have these outsized effects um was a surprise it's sort of they were about these sort of hidden connections in in ecosystems and then we understand that if we can replace some of these things maybe we can reverse

those deer in turn have enormous consequences on uh plant diversity because they mow down the plants and forests etc etc so the discovery that some creatures have these outsized effects um was a surprise it's sort of they were about these sort of hidden connections in in ecosystems and then we understand that if we can replace some of these things maybe we can reverse

those deer in turn have enormous consequences on uh plant diversity because they mow down the plants and forests etc etc so the discovery that some creatures have these outsized effects um was a surprise it's sort of they were about these sort of hidden connections in in ecosystems and then we understand that if we can replace some of these things maybe we can reverse

some of the some of the changes that um some of the unwanted changes that have happened in places so it's i give you the wolf example but you know in the tide pools on the pacific coast that certain starfish in the serengeti it's the wildebeest that the massive numbers of wildebeest just munching the grass have an enormous impact on the diversity and stability of that ecosystem.

some of the some of the changes that um some of the unwanted changes that have happened in places so it's i give you the wolf example but you know in the tide pools on the pacific coast that certain starfish in the serengeti it's the wildebeest that the massive numbers of wildebeest just munching the grass have an enormous impact on the diversity and stability of that ecosystem.