0:00:01.039,0:00:05.325
If we evolved from monkeys,[br]why are there still monkeys?

0:00:05.349,0:00:06.728
(Laughter)

0:00:06.752,0:00:08.840
Well, because we're not monkeys,

0:00:08.864,0:00:10.014
we're fish.

0:00:10.038,0:00:11.077
(Laughter)

0:00:11.101,0:00:14.049
Now, knowing you're a fish[br]and not a monkey

0:00:14.073,0:00:18.500
is actually really important[br]to understanding where we came from.

0:00:18.524,0:00:22.261
I teach one of the largest[br]evolutionary biology classes in the US,

0:00:22.285,0:00:26.344
and when my students finally understand[br]why I call them fish all the time,

0:00:26.368,0:00:28.545
then I know I'm getting my job done.

0:00:28.979,0:00:33.613
But I always have to start my classes[br]by dispelling some hardwired myths,

0:00:33.637,0:00:37.684
because without really knowing it,[br]many of us were taught evolution wrong.

0:00:38.849,0:00:42.277
For instance, we're taught[br]to say "the theory of evolution."

0:00:42.944,0:00:46.761
There are actually many theories,[br]and just like the process itself,

0:00:46.785,0:00:50.539
the ones that best fit the data[br]are the ones that survive to this day.

0:00:51.241,0:00:54.384
The one we know best[br]is Darwinian natural selection.

0:00:54.963,0:00:58.923
That's the process by which organisms[br]that best fit an environment

0:00:58.947,0:01:01.167
survive and get to reproduce,

0:01:01.191,0:01:03.857
while those that are less fit[br]slowly die off.

0:01:04.698,0:01:05.874
And that's it.

0:01:05.898,0:01:08.842
Evolution is as simple as that,[br]and it's a fact.

0:01:09.785,0:01:13.785
Evolution is a fact[br]as much as the "theory of gravity."

0:01:14.150,0:01:16.181
You can prove it just as easily.

0:01:16.205,0:01:18.268
You just need to look at your bellybutton

0:01:18.292,0:01:20.458
that you share[br]with other placental mammals,

0:01:20.482,0:01:23.502
or your backbone that you share[br]with other vertebrates,

0:01:23.526,0:01:26.867
or your DNA that you share[br]with all other life on earth.

0:01:27.511,0:01:29.724
Those traits didn't pop up in humans.

0:01:29.748,0:01:32.504
They were passed down[br]from different ancestors

0:01:32.528,0:01:34.677
to all their descendants, not just us.

0:01:35.619,0:01:38.993
But that's not really[br]how we learn biology early on, is it?

0:01:39.017,0:01:42.436
We learn plants and bacteria[br]are primitive things,

0:01:42.460,0:01:45.614
and fish give rise to amphibians[br]followed by reptiles and mammals,

0:01:45.638,0:01:47.421
and then you get you,

0:01:47.445,0:01:50.143
this perfectly evolved creature[br]at the end of the line.

0:01:51.032,0:01:53.766
But life doesn't evolve in a line,

0:01:53.790,0:01:55.426
and it doesn't end with us.

0:01:56.591,0:02:00.051
But we're always shown evolution[br]portrayed something like this,

0:02:00.075,0:02:02.463
a monkey and a chimpanzee,

0:02:02.487,0:02:03.723
some extinct humans,

0:02:03.747,0:02:06.999
all on a forward and steady march[br]to becoming us.

0:02:07.621,0:02:11.216
But they don't become us[br]any more than we would become them.

0:02:11.240,0:02:13.641
We're also not the goal of evolution.

0:02:15.298,0:02:16.799
But why does it matter?

0:02:16.823,0:02:19.695
Why do we need to understand[br]evolution the right way?

0:02:20.560,0:02:24.108
Well, misunderstanding evolution[br]has led to many problems,

0:02:24.132,0:02:28.448
but you can't ask that age-old question,

0:02:28.472,0:02:30.179
"Where are we from?"

0:02:30.203,0:02:33.012
without understanding[br]evolution the right way.

0:02:33.036,0:02:38.892
Misunderstanding it has led[br]to many convoluted and corrupted views

0:02:38.916,0:02:41.963
of how we should treat[br]other life on earth,

0:02:41.987,0:02:43.852
and how we should treat each other

0:02:43.876,0:02:45.542
in terms of race and gender.

0:02:47.253,0:02:50.260
So let's go back four billion years.

0:02:50.927,0:02:54.051
This is the single-celled organism[br]we all came from.

0:02:54.075,0:02:57.400
At first, it gave rise[br]to other single-celled life,

0:02:57.424,0:02:59.916
but these are still evolving to this day,

0:02:59.940,0:03:02.130
and some would say[br]the Archaea and Bacteria

0:03:02.154,0:03:04.004
that make up most of this group

0:03:04.028,0:03:06.151
is the most successful on the planet.

0:03:06.175,0:03:08.651
They are certainly going[br]to be here well after us.

0:03:09.500,0:03:13.180
About three billion years ago,[br]multicellularity evolved.

0:03:13.204,0:03:16.315
This includes your fungi[br]and your plants and your animals.

0:03:17.021,0:03:20.790
The first animals to develop[br]a backbone were fishes.

0:03:21.385,0:03:25.306
So technically,[br]all vertebrates are fishes,

0:03:25.330,0:03:28.693
so technically, you and I are fish.

0:03:28.717,0:03:30.415
So don't say I didn't warn you.

0:03:31.526,0:03:33.607
One fish lineage came onto land

0:03:33.631,0:03:37.537
and gave rise to, among other things,[br]the mammals and reptiles.

0:03:37.561,0:03:41.885
Some reptiles become birds,[br]some mammals become primates,

0:03:41.909,0:03:44.670
some primates become monkeys with tails,

0:03:44.694,0:03:49.487
and others become the great apes,[br]including a variety of human species.

0:03:49.511,0:03:51.887
So you see, we didn't evolve from monkeys,

0:03:51.911,0:03:54.062
but we do share[br]a common ancestor with them.

0:03:54.824,0:03:57.744
All the while, life[br]around us kept evolving:

0:03:57.768,0:04:01.710
more bacteria, more fungi,[br]lots of fish, fish, fish.

0:04:01.734,0:04:04.321
If you couldn't tell --[br]yes, they're my favorite group.

0:04:04.345,0:04:05.346
(Laughter)

0:04:05.370,0:04:08.307
As life evolves, it also goes extinct.

0:04:08.331,0:04:11.618
Most species just last[br]for a few million years.

0:04:11.642,0:04:14.395
So you see, most life on earth[br]that we see around us today

0:04:14.419,0:04:16.614
are about the same age as our species.

0:04:16.958,0:04:20.260
So it's hubris,[br]it's self-centered to think,

0:04:20.284,0:04:22.855
"Oh, plants and bacteria are primitive,

0:04:22.879,0:04:25.117
and we've been here[br]for an evolutionary minute,

0:04:25.141,0:04:26.584
so we're somehow special."

0:04:27.172,0:04:31.489
Think of life as being this book,[br]an unfinished book for sure.

0:04:32.085,0:04:35.418
We're just seeing the last[br]few pages of each chapter.

0:04:36.386,0:04:38.648
If you look out[br]on the eight million species

0:04:38.672,0:04:40.297
that we share this planet with,

0:04:40.321,0:04:44.839
think of them all being[br]four billion years of evolution.

0:04:44.863,0:04:46.582
They're all the product of that.

0:04:47.386,0:04:52.218
Think of us all as young leaves[br]on this ancient and gigantic tree of life,

0:04:52.242,0:04:56.543
all of us connected by invisible branches[br]not just to each other,

0:04:56.567,0:04:59.853
but to our extinct relatives[br]and our evolutionary ancestors.

0:05:00.499,0:05:03.856
As a biologist, I'm still[br]trying to learn, with others,

0:05:03.880,0:05:07.075
how everyone's related to each other,[br]who is related to whom.

0:05:08.831,0:05:11.109
Perhaps it's better still

0:05:11.133,0:05:14.829
to think of us[br]as a little fish out of water.

0:05:14.853,0:05:17.773
Yes, one that learned to walk and talk,

0:05:17.797,0:05:20.146
but one that still has[br]a lot of learning to do

0:05:20.170,0:05:22.841
about who we are and where we came from.

0:05:23.348,0:05:24.499
Thank you.

0:05:24.523,0:05:28.501
(Applause)