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TED2018

Prosanta Chakrabarty: Four billion years of evolution in six minutes

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1,125,483 views

Did humans evolve from monkeys or from fish? In this enlightening talk, ichthyologist and TED Fellow Prosanta Chakrabarty dispels some hardwired myths about evolution, encouraging us to remember that we're a small part of a complex, four-billion-year process -- and not the end of the line. "We're not the goal of evolution," Chakrabarty says. "Think of us all as young leaves on this ancient and gigantic tree of life -- connected by invisible branches not just to each other, but to our extinct relatives and our evolutionary ancestors."

- Ichthyologist
Evolutionary biologist and natural historian Prosanta Chakrabarty explores the world in an effort to understand fundamental aspects of biological diversity. Full bio

If we evolved from monkeys,
why are there still monkeys?
00:13
(Laughter)
00:17
Well, because we're not monkeys,
00:18
we're fish.
00:20
(Laughter)
00:22
Now, knowing you're a fish
and not a monkey
00:23
is actually really important
to understanding where we came from.
00:26
I teach one of the largest
evolutionary biology classes in the US,
00:30
and when my students finally understand
why I call them fish all the time,
00:34
then I know I'm getting my job done.
00:38
But I always have to start my classes
by dispelling some hardwired myths,
00:40
because without really knowing it,
many of us were taught evolution wrong.
00:45
For instance, we're taught
to say "the theory of evolution."
00:50
There are actually many theories,
and just like the process itself,
00:54
the ones that best fit the data
are the ones that survive to this day.
00:58
The one we know best
is Darwinian natural selection.
01:03
That's the process by which organisms
that best fit an environment
01:06
survive and get to reproduce,
01:10
while those that are less fit
slowly die off.
01:13
And that's it.
01:16
Evolution is as simple as that,
and it's a fact.
01:17
Evolution is a fact
as much as the "theory of gravity."
01:21
You can prove it just as easily.
01:26
You just need to look at your bellybutton
01:28
that you share
with other placental mammals,
01:30
or your backbone that you share
with other vertebrates,
01:32
or your DNA that you share
with all other life on earth.
01:35
Those traits didn't pop up in humans.
01:39
They were passed down
from different ancestors
01:41
to all their descendants, not just us.
01:44
But that's not really
how we learn biology early on, is it?
01:47
We learn plants and bacteria
are primitive things,
01:51
and fish give rise to amphibians
followed by reptiles and mammals,
01:54
and then you get you,
01:57
this perfectly evolved creature
at the end of the line.
01:59
But life doesn't evolve in a line,
02:03
and it doesn't end with us.
02:05
But we're always shown evolution
portrayed something like this,
02:08
a monkey and a chimpanzee,
02:12
some extinct humans,
02:14
all on a forward and steady march
to becoming us.
02:15
But they don't become us
any more than we would become them.
02:19
We're also not the goal of evolution.
02:23
But why does it matter?
02:27
Why do we need to understand
evolution the right way?
02:28
Well, misunderstanding evolution
has led to many problems,
02:32
but you can't ask that age-old question,
02:36
"Where are we from?"
02:40
without understanding
evolution the right way.
02:42
Misunderstanding it has led
to many convoluted and corrupted views
02:45
of how we should treat
other life on earth,
02:50
and how we should treat each other
02:53
in terms of race and gender.
02:55
So let's go back four billion years.
02:59
This is the single-celled organism
we all came from.
03:02
At first, it gave rise
to other single-celled life,
03:06
but these are still evolving to this day,
03:09
and some would say
the Archaea and Bacteria
03:11
that make up most of this group
03:14
is the most successful on the planet.
03:16
They are certainly going
to be here well after us.
03:18
About three billion years ago,
multicellularity evolved.
03:21
This includes your fungi
and your plants and your animals.
03:25
The first animals to develop
a backbone were fishes.
03:29
So technically,
all vertebrates are fishes,
03:33
so technically, you and I are fish.
03:37
So don't say I didn't warn you.
03:40
One fish lineage came onto land
03:43
and gave rise to, among other things,
the mammals and reptiles.
03:45
Some reptiles become birds,
some mammals become primates,
03:49
some primates become monkeys with tails,
03:53
and others become the great apes,
including a variety of human species.
03:56
So you see, we didn't evolve from monkeys,
04:01
but we do share
a common ancestor with them.
04:03
All the while, life
around us kept evolving:
04:06
more bacteria, more fungi,
lots of fish, fish, fish.
04:09
If you couldn't tell --
yes, they're my favorite group.
04:13
(Laughter)
04:16
As life evolves, it also goes extinct.
04:17
Most species just last
for a few million years.
04:20
So you see, most life on earth
that we see around us today
04:23
are about the same age as our species.
04:26
So it's hubris,
it's self-centered to think,
04:28
"Oh, plants and bacteria are primitive,
04:32
and we've been here
for an evolutionary minute,
04:34
so we're somehow special."
04:37
Think of life as being this book,
an unfinished book for sure.
04:39
We're just seeing the last
few pages of each chapter.
04:44
If you look out
on the eight million species
04:48
that we share this planet with,
04:50
think of them all being
four billion years of evolution.
04:52
They're all the product of that.
04:56
Think of us all as young leaves
on this ancient and gigantic tree of life,
04:59
all of us connected by invisible branches
not just to each other,
05:04
but to our extinct relatives
and our evolutionary ancestors.
05:08
As a biologist, I'm still
trying to learn, with others,
05:12
how everyone's related to each other,
who is related to whom.
05:15
Perhaps it's better still
05:20
to think of us
as a little fish out of water.
05:23
Yes, one that learned to walk and talk,
05:26
but one that still has
a lot of learning to do
05:29
about who we are and where we came from.
05:32
Thank you.
05:35
(Applause)
05:36

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About the speaker:

Prosanta Chakrabarty - Ichthyologist
Evolutionary biologist and natural historian Prosanta Chakrabarty explores the world in an effort to understand fundamental aspects of biological diversity.

Why you should listen

Dr. Prosanta Chakrabarty is an Associate Professor and Curator of Fishes at the Museum of Natural Science and Department of Biological Science at Louisiana State University.

Chakrabarty is a systematist and an ichthyologist studying the evolution and biogeography of both freshwater and marine fishes. His work includes studies of Neotropical (Central and South America, Caribbean) and Indo-West Pacific (Indian and Western Pacific Ocean) fishes. His natural history collecting efforts include trips to Japan, Australia, Taiwan, Madagascar, Panama, Kuwait and many other countries. He has discovered over a dozen new species including new anglerfishes and cavefishes.

The LSU Museum of Natural Science fish collection that Chakrabarty oversees includes nearly half a million fish specimens and nearly 10,000 DNA samples covering most major groups of fishes. He earned his PhD at the University of Michigan and his undergraduate degree is from McGill University in Montreal. He has written two books including A Guide to Academia: Getting into and Surviving Grad School, Postdocs and a Research Job. He was named a TED Fellow in 2016.

More profile about the speaker
Prosanta Chakrabarty | Speaker | TED.com