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If we evolved from monkeys,
why are there still monkeys?

2
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(Laughter)

3
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Well, because we're not monkeys,

4
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we're fish.

5
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(Laughter)

6
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Now, knowing you're a fish
and not a monkey

7
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is actually really important
to understanding where we came from.

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I teach one of the largest
evolutionary biology classes in the US,

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and when my students finally understand
why I call them fish all the time,

10
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then I know I'm getting my job done.

11
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But I always have to start my classes
by dispelling some hardwired myths,

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because without really knowing it,
many of us were taught evolution wrong.

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For instance, we're taught
to say "the theory of evolution."

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There are actually many theories,
and just like the process itself,

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the ones that best fit the data
are the ones that survive to this day.

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The one we know best
is Darwinian natural selection.

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That's the process by which organisms
that best fit an environment

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survive and get to reproduce,

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while those that are less fit
slowly die off.

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And that's it.

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Evolution is as simple as that,
and it's a fact.

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Evolution is a fact
as much as the "theory of gravity."

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You can prove it just as easily.

24
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You just need to look at your bellybutton

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that you share
with other placental mammals,

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or your backbone that you share
with other vertebrates,

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or your DNA that you share
with all other life on earth.

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Those traits didn't pop up in humans.

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They were passed down
from different ancestors

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to all their descendants, not just us.

31
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But that's not really
how we learn biology early on, is it?

32
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We learn plants and bacteria
are primitive things,

33
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and fish give rise to amphibians
followed by reptiles and mammals,

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and then you get you,

35
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this perfectly evolved creature
at the end of the line.

36
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But life doesn't evolve in a line,

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and it doesn't end with us.

38
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But we're always shown evolution
portrayed something like this,

39
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a monkey and a chimpanzee,

40
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some extinct humans,

41
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all on a forward and steady march
to becoming us.

42
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But they don't become us
any more than we would become them.

43
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We're also not the goal of evolution.

44
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But why does it matter?

45
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Why do we need to understand
evolution the right way?

46
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Well, misunderstanding evolution
has led to many problems,

47
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but you can't ask that age-old question,

48
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"Where are we from?"

49
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without understanding
evolution the right way.

50
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Misunderstanding it has led
to many convoluted and corrupted views

51
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of how we should treat
other life on earth,

52
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and how we should treat each other

53
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in terms of race and gender.

54
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So let's go back four billion years.

55
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This is the single-celled organism
we all came from.

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At first, it gave rise
to other single-celled life,

57
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but these are still evolving to this day,

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and some would say
the Archaea and Bacteria

59
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that make up most of this group

60
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is the most successful on the planet.

61
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They are certainly going
to be here well after us.

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About three billion years ago,
multicellularity evolved.

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This includes your fungi
and your plants and your animals.

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The first animals to develop
a backbone were fishes.

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So technically,
all vertebrates are fishes,

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so technically, you and I are fish.

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So don't say I didn't warn you.

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One fish lineage came onto land

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and gave rise to, among other things,
the mammals and reptiles.

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Some reptiles become birds,
some mammals become primates,

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some primates become monkeys with tails,

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and others become the great apes,
including a variety of human species.

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So you see, we didn't evolve from monkeys,

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but we do share
a common ancestor with them.

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All the while, life
around us kept evolving:

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more bacteria, more fungi,
lots of fish, fish, fish.

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If you couldn't tell --
yes, they're my favorite group.

78
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(Laughter)

79
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As life evolves, it also goes extinct.

80
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Most species just last
for a few million years.

81
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So you see, most life on earth
that we see around us today

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are about the same age as our species.

83
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So it's hubris,
it's self-centered to think,

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"Oh, plants and bacteria are primitive,

85
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and we've been here
for an evolutionary minute,

86
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so we're somehow special."

87
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Think of life as being this book,
an unfinished book for sure.

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We're just seeing the last
few pages of each chapter.

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If you look out
on the eight million species

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that we share this planet with,

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think of them all being
four billion years of evolution.

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They're all the product of that.

93
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Think of us all as young leaves
on this ancient and gigantic tree of life,

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all of us connected by invisible branches
not just to each other,

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but to our extinct relatives
and our evolutionary ancestors.

96
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As a biologist, I'm still
trying to learn, with others,

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how everyone's related to each other,
who is related to whom.

98
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Perhaps it's better still

99
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to think of us
as a little fish out of water.

100
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Yes, one that learned to walk and talk,

101
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but one that still has
a lot of learning to do

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about who we are and where we came from.

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Thank you.

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(Applause)