How animals, bugs and plants are evolving in cities
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0:01 - 0:03This is where I grew up.
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0:03 - 0:05A small village near the city of Rotterdam
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0:05 - 0:07in the Netherlands.
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0:08 - 0:12In the 1970s and 1980s,
when I was a teenager, -
0:12 - 0:13this area was still a quiet place.
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0:13 - 0:18It was full of farms and fields
and swampland, -
0:18 - 0:22and I spent my free time there,
enjoying myself, -
0:22 - 0:24painting oil paintings like this one,
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0:24 - 0:27collecting wildflowers, bird-watching
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0:27 - 0:30and also collecting insects.
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0:30 - 0:32And this was one of my prized finds.
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0:32 - 0:34This is a very special beetle,
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0:34 - 0:36an amazing beetle called an ant beetle.
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0:36 - 0:39And this is a kind of beetle
that lives its entire life -
0:39 - 0:41inside an ant's nest.
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0:41 - 0:44It has evolved to speak ant.
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0:45 - 0:47It's using the same chemical signals,
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0:47 - 0:50the same smells as the ants do,
for communicating, -
0:50 - 0:54and right now, this beetle
is telling this worker ant, -
0:54 - 0:56"Hey, I'm also a worker ant,
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0:56 - 0:58I'm hungry, please feed me."
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0:58 - 0:59And the ant complies,
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0:59 - 1:02because the beetle is using
the same chemicals. -
1:02 - 1:04Over these millions of years,
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1:04 - 1:09this beetle has evolved a way
to live inside an ant society. -
1:10 - 1:11Over the years,
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1:11 - 1:12when I was living in that village,
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1:12 - 1:16I collected 20,000 different beetles,
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1:16 - 1:19and I built a collection
of pinned beetles. -
1:19 - 1:23And this got me interested,
at a very early age, in evolution. -
1:23 - 1:29How do all those different forms,
how does all this diversity come about? -
1:30 - 1:33So I became an evolutionary biologist,
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1:33 - 1:35like Charles Darwin.
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1:35 - 1:39And like Charles Darwin,
I also soon became frustrated -
1:39 - 1:43by the fact that evolution is something
that happened mostly in the past. -
1:43 - 1:47We study the patterns that we see today,
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1:47 - 1:50trying to understand the evolution
that took place in the past, -
1:50 - 1:54but we can never actually see it
taking place in real time. -
1:54 - 1:56We cannot observe it.
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1:56 - 1:58As Darwin himself already said,
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1:58 - 2:01"We see nothing of these slow
changes in progress, -
2:01 - 2:05until the hand of time
has marked the lapse of ages." -
2:06 - 2:07Or do we?
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2:08 - 2:10Over the past few decades,
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2:10 - 2:14evolutionary biologists
have come to realize that sometimes, -
2:14 - 2:19evolution proceeds much faster
and it can actually be observed, -
2:19 - 2:23especially when the environment
changes drastically -
2:23 - 2:26and the need to adapt is great.
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2:27 - 2:29And of course, these days,
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2:29 - 2:32great environmental changes
are usually caused by us. -
2:32 - 2:36We mow, we irrigate, we plow, we build,
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2:36 - 2:39we pump greenhouse gases
into the atmosphere -
2:39 - 2:41that change the climate.
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2:41 - 2:43We release exotic plants and animals
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2:43 - 2:45in places where they didn't live before,
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2:45 - 2:51and we harvest fish and trees and game
for our food and other needs. -
2:52 - 2:58And all these environmental changes
reach their epicenter in cities. -
2:59 - 3:03Cities form a completely new habitat
that we have created. -
3:03 - 3:07And we clothe it in brick and concrete
and glass and steel, -
3:07 - 3:09which are impervious surfaces
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3:09 - 3:12that plants can only root in
with the greatest difficulty. -
3:13 - 3:16Also in cities, we find
the greatest concentrations -
3:16 - 3:18of chemical pollution,
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3:18 - 3:21of artificial light and noise.
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3:21 - 3:24And we find wild mixtures
of plants and animals -
3:24 - 3:27from all over the world
that live in the city, -
3:27 - 3:29because they have escaped
from the gardening -
3:29 - 3:31and aquarium and pet trade.
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3:32 - 3:35And what does a species do
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3:35 - 3:39when it lives in a completely
changed environment? -
3:40 - 3:44Well, many, of course, go, sadly, extinct.
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3:44 - 3:46But the ones that don't go extinct,
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3:47 - 3:49they adapt in spectacular ways.
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3:50 - 3:53Biologists these days
are beginning to realize -
3:53 - 3:57that cities are today's
pressure cookers of evolution. -
3:57 - 4:00These are places
where wild animals and plants -
4:00 - 4:03are evolving under our eyes very rapidly
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4:03 - 4:07to suit these new, urban conditions.
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4:07 - 4:10Exactly like the ant beetle did
millions of years ago, -
4:10 - 4:13when it moved inside an ant colony.
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4:13 - 4:18We now find animals and plants
that have moved inside the human colony -
4:18 - 4:20and are adapting to our cities.
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4:20 - 4:22And in doing so,
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4:22 - 4:23we're also beginning to realize
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4:23 - 4:27that evolution can actually
proceed very fast. -
4:27 - 4:30It does not always take
the long lapse of ages; -
4:30 - 4:33it can happen under our very eyes.
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4:34 - 4:37This, for example,
is the white-footed mouse. -
4:37 - 4:41This is a native mammal
from the area around New York, -
4:41 - 4:44and more than 400 years ago,
before the city was built, -
4:44 - 4:46this mouse lived everywhere.
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4:46 - 4:50But these days, they are stuck
in little islands of green, -
4:50 - 4:56the city's parks, surrounded by a sea
of tarmac and traffic. -
4:57 - 5:02A bit like a modern-day version
of Darwin's finches on the Galapagos. -
5:04 - 5:06And like Darwin's finches,
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5:06 - 5:10the mice in each separate park
have started evolving, -
5:10 - 5:13have started to become
different from each other. -
5:13 - 5:16And this is my colleague,
Jason Munshi-South, -
5:16 - 5:17from Fordham University,
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5:17 - 5:19who is studying this process.
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5:19 - 5:23He is studying the DNA
of the white-footed mice -
5:23 - 5:25in New York City's parks,
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5:25 - 5:29and trying to understand
how they are beginning to evolve -
5:29 - 5:31in that archipelago of islands.
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5:31 - 5:34And he's using a kind of
DNA fingerprinting, and he says, -
5:34 - 5:36"If somebody gives me a mouse,
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5:36 - 5:38doesn't tell me where it's from,
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5:38 - 5:39just by looking at its DNA,
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5:39 - 5:42I can tell exactly
from which park it comes." -
5:42 - 5:45That's how different they have become.
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5:45 - 5:49And Jason has also discovered
that those changes, -
5:49 - 5:50these evolutionary changes,
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5:51 - 5:53are not random, they mean something.
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5:53 - 5:56For example, in Central Park,
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5:57 - 5:59we find that the mice have evolved genes
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5:59 - 6:02that allow them to deal
with very fatty food. -
6:03 - 6:05Human food.
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6:05 - 6:08Twenty-five million people
visit Central Park each year. -
6:08 - 6:11It's the most heavily visited park
in North America. -
6:11 - 6:13And those people leave behind snack food
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6:13 - 6:16and peanuts and junk food,
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6:16 - 6:18and the mice have started feeding on that,
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6:18 - 6:21and it's a completely different diet
than what they're used to, -
6:21 - 6:22and over the years,
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6:22 - 6:26they have evolved to suit
this very fatty, very human diet. -
6:27 - 6:29And this is another city slicker animal.
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6:29 - 6:32This is the European garden snail.
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6:32 - 6:33A very common snail,
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6:33 - 6:37it comes in all kinds of color variations,
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6:37 - 6:40ranging from pale yellow to dark brown.
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6:41 - 6:43And those colors are completely determined
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6:43 - 6:45by the snail's DNA.
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6:46 - 6:50And those colors also determine
the heat management of the snail -
6:50 - 6:52that lives inside that shell.
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6:53 - 6:56For example, a snail
that sits in the sunlight, -
6:56 - 6:57in the bright sun,
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6:57 - 6:59if it has a pale yellow shell,
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6:59 - 7:05it doesn't heat up as much as a snail
that sits inside a dark brown shell. -
7:05 - 7:09Just like when you're sitting
in a white car, you stay cooler -
7:09 - 7:12than when you're sitting
inside a black car. -
7:12 - 7:15Now there is a phenomenon called
the urban heat islands, -
7:15 - 7:18which means that in the center
of a big city, -
7:18 - 7:21the temperature can be
several degrees higher -
7:21 - 7:22than outside of the big city.
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7:22 - 7:24That has to do with the fact
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7:24 - 7:27that you have these concentrations
of millions of people, -
7:27 - 7:29and all their activities
and their machineries, -
7:29 - 7:30they generate heat.
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7:30 - 7:34Also, the wind is blocked
by the tall buildings, -
7:34 - 7:38and all the steel and brick
and concrete absorb the solar heat -
7:38 - 7:40and they radiate it out at night.
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7:40 - 7:43So you get this bubble of hot air
in the center of a big city, -
7:43 - 7:47and my students and I figured
that maybe those garden snails, -
7:47 - 7:50with their variable shells,
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7:50 - 7:54are adapting to the urban heat islands.
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7:54 - 7:56Maybe in the center of a city,
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7:56 - 7:59we find that the shell color is evolving
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7:59 - 8:02in a direction to reduce
overheating of the snails. -
8:02 - 8:06And to study this, we started
a citizen-science project. -
8:06 - 8:09We built a free smartphone app,
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8:09 - 8:11which allowed people
all over the Netherlands -
8:11 - 8:14to take pictures of snails
in their garden, in their street, -
8:14 - 8:16also in the countryside,
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8:16 - 8:19and upload them to a citizen
science web platform. -
8:19 - 8:22And over a year, we got 10,000 pictures
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8:22 - 8:25of snails that had been photographed
in the Netherlands, -
8:25 - 8:28and when we started analyzing the results,
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8:28 - 8:31we found that indeed,
our suspicions were confirmed. -
8:31 - 8:34In the center of the urban heat islands,
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8:34 - 8:40we find that the snails have evolved
more yellow, more lighter-colored shells. -
8:42 - 8:45Now the city snail and the Manhattan mouse
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8:45 - 8:51are just two examples
of a growing list of animals and plants -
8:51 - 8:54that have evolved to suit
this new habitat, -
8:54 - 8:57this city habitat that we have created.
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8:58 - 9:01And in a book that I've written
about this subject, -
9:01 - 9:02the subject of urban evolution,
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9:02 - 9:04I give many more examples.
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9:04 - 9:06For example, weeds that have evolved seeds
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9:06 - 9:10that are better at germinating
on the pavement. -
9:10 - 9:13Grasshoppers that have evolved a song
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9:13 - 9:17that has a higher pitch
when they live close to noisy traffic. -
9:18 - 9:23Mosquitoes that have evolved
to feed on the blood of human commuters -
9:23 - 9:25inside metro stations.
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9:25 - 9:28And even the common city pigeon
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9:28 - 9:31that has evolved ways to detox themselves
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9:31 - 9:35from heavy-metal pollution
by putting it in their feathers. -
9:36 - 9:38Biologists like myself,
all over the world, -
9:38 - 9:41are becoming interested
in this fascinating process -
9:41 - 9:42of urban evolution.
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9:42 - 9:46We are realizing that we're really
at a unique event -
9:46 - 9:48in the history of life on earth.
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9:48 - 9:51A completely new ecosystem
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9:51 - 9:56that is evolving and adapting
to a habitat that we have created. -
9:57 - 9:59And not just academics --
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9:59 - 10:03we're also beginning to enlist
the millions of pairs of hands -
10:03 - 10:05and ears and eyes
that are present in the city. -
10:05 - 10:08Citizen scientists, schoolchildren --
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10:08 - 10:09together with them,
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10:09 - 10:12we are building
a global observation network -
10:12 - 10:17which allows us to watch this process
of urban evolution taking place -
10:17 - 10:18in real time.
-
10:19 - 10:23And at the same time,
this also makes it clear to people -
10:23 - 10:26that evolution is not
just some abstract thing -
10:26 - 10:28that you need to travel
to the Galapagos to study, -
10:28 - 10:33or that you need to be a paleontologist
to understand what it is. -
10:33 - 10:36It's a very ordinary biological process
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10:36 - 10:40that's taking place
all the time, everywhere. -
10:40 - 10:42In your backyard,
in the street where you live, -
10:42 - 10:44right outside of this theater.
-
10:45 - 10:49But there is, of course,
a flip side to my enthusiasm. -
10:49 - 10:51When I go back to the village
where I grew up, -
10:52 - 10:57I no longer find those fields and swamps
that I knew from my youth. -
10:57 - 10:58The village has now been absorbed
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10:58 - 11:01by the growing
conglomeration of Rotterdam, -
11:01 - 11:04and instead, I find shopping malls
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11:04 - 11:07and I find suburbs and bus lanes.
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11:07 - 11:10And many of the animals and plants
that I was so accustomed to -
11:10 - 11:14have disappeared,
including perhaps that ant beetle. -
11:15 - 11:19But I take comfort in the fact
that the children growing up -
11:19 - 11:21in that village today
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11:21 - 11:24may no longer be experiencing
that traditional nature -
11:24 - 11:26that I grew up with,
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11:26 - 11:28but they're surrounded
by a new type of nature, -
11:28 - 11:30a new type of ecosystem,
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11:30 - 11:34that, to them, might be just as exciting
as the old type was to me. -
11:34 - 11:38They are living in a new,
modern-day Galapagos. -
11:38 - 11:41And by teaming up with citizen scientists
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11:41 - 11:45and with evolutionary
biologists like myself, -
11:45 - 11:48they might become the Darwins
of the 21st century, -
11:48 - 11:51studying urban evolution.
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11:51 - 11:52Thank you.
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11:52 - 11:55(Applause)
- Title:
- How animals, bugs and plants are evolving in cities
- Speaker:
- Menno Schilthuizen
- Description:
-
In cities, evolution occurs constantly, as countless plants, animals and insects adapt to human-made habitats in spectacular ways. Evolutionary biologist Menno Schilthuizen calls on peculiar beings such as fast food-loving mice and self-cooling snails to illustrate the ever-transforming wonders of urban wildlife -- and explains how you can observe this phenomenon in real-time, thanks to a global network of enthusiastic citizen scientists.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 12:07
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Ivana Korom edited English subtitles for How animals and plants are evolving in cities |