TEDWomen 2015
Marlene Zuk: What we learn from insects' sex lives
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Readability: 3.6
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In this enlightening, funny talk, Marlene Zuk shares just some of the ways that insects are truly astonishing -- and not least for the creative ways they have sex.
Marlene Zuk - Evolutionary biologist
Marlene Zuk studies insect behavior -- and how humans use animal behavior to think about how we behave ourselves. Full bio
Marlene Zuk studies insect behavior -- and how humans use animal behavior to think about how we behave ourselves. Full bio
Double-click the English transcript below to play the video.
00:13
So, people are more afraid of insects
than they are of dying.
than they are of dying.
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(Laughter)
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At least, according to a 1973
"Book of Lists" survey
"Book of Lists" survey
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which preceded all those online best,
worst, funniest lists that you see today.
worst, funniest lists that you see today.
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Only heights and public speaking
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exceeded the six-legged
as sources of fear.
as sources of fear.
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And I suspect if you had put
spiders in there,
spiders in there,
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the combinations of insects and spiders
would have just topped the chart.
would have just topped the chart.
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Now, I am not one of those people.
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I really love insects.
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I think they're interesting and beautiful,
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and sometimes even cute.
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(Laughter)
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And I'm not alone.
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For centuries, some
of the greatest minds in science,
of the greatest minds in science,
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from Charles Darwin to E.O. Wilson,
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have drawn inspiration from studying
some of the smallest minds on Earth.
some of the smallest minds on Earth.
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Well, why is that?
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What is that keeps us
coming back to insects?
coming back to insects?
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Some of it, of course, is just the sheer
magnitude of almost everything about them.
magnitude of almost everything about them.
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They're more numerous
than any other kind of animal.
than any other kind of animal.
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We don't even know how many species
of insects there are,
of insects there are,
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because new ones
are being discovered all the time.
are being discovered all the time.
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There are at least a million,
maybe as many as 10 million.
maybe as many as 10 million.
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This means that you could have
an insect-of-the-month calendar
an insect-of-the-month calendar
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and not have to reuse a species
for over 80,000 years.
for over 80,000 years.
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(Laughter)
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Take that, pandas and kittens!
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(Laughter)
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More seriously, insects are essential.
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We need them.
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It's been estimated
that 1 out of every 3 bites of food
that 1 out of every 3 bites of food
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is made possible by a pollinator.
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Scientist use insects to make fundamental
discoveries
discoveries
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about everything from the structure
of our nervous systems
of our nervous systems
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to how our genes and DNA work.
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But what I love most about insects
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is what they can tell us
about our own behavior.
about our own behavior.
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Insects seem like they do
everything that people do.
everything that people do.
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They meet, they mate,
they fight, they break up.
they fight, they break up.
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And they do so with what looks
like love or animosity.
like love or animosity.
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But what drives their behaviors is really
different than what drives our own,
different than what drives our own,
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and that difference
can be really illuminating.
can be really illuminating.
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There's nowhere where that's more true
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than when it comes to one
of our most consuming interests -- sex.
of our most consuming interests -- sex.
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Now, I will maintain.
and I think I can defend,
and I think I can defend,
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what may seem like a surprising statement.
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I think sex in insects is more
interesting than sex in people.
interesting than sex in people.
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(Laughter)
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And the wild variety that we see
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makes us challenge
some of our own assumptions
some of our own assumptions
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about what it means to be male and female.
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Of course, to start with,
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a lot of insects don't need
to have sex at all to reproduce.
to have sex at all to reproduce.
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Female aphids can make little, tiny clones
of themselves without ever mating.
of themselves without ever mating.
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Virgin birth, right there.
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On your rose bushes.
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(Laughter)
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When they do have sex,
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even their sperm is more
interesting than human sperm.
interesting than human sperm.
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There are some kinds of fruit flies
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whose sperm is longer
than the male's own body.
than the male's own body.
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And that's important because the males
use their sperm to compete.
use their sperm to compete.
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Now, male insects do compete with weapons,
like the horns on these beetles.
like the horns on these beetles.
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But they also compete
after mating with their sperm.
after mating with their sperm.
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Dragonflies and damselflies have penises
that look kind of like Swiss Army knives
that look kind of like Swiss Army knives
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with all of the attachments pulled out.
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(Laughter)
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They use these formidable devices
like scoops,
like scoops,
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to remove the sperm from previous males
that the female has mated with.
that the female has mated with.
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(Laughter)
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So, what can we learn from this?
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(Laughter)
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All right, it is not a lesson in the sense
of us imitating them
of us imitating them
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or of them setting
an example for us to follow.
an example for us to follow.
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Which, given this,
is probably just as well.
is probably just as well.
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And also, did I mention sexual cannibalism
is rampant among insects?
is rampant among insects?
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So, no, that's not the point.
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But what I think insects do,
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is break a lot of the rules
that we humans have about the sex roles.
that we humans have about the sex roles.
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So, people have this idea that nature
dictates kind of a 1950s sitcom version
dictates kind of a 1950s sitcom version
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of what males and females are like.
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So that males are always
supposed to be dominant and aggressive,
supposed to be dominant and aggressive,
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and females are passive and coy.
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But that's just not the case.
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So for example, take katydids,
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which are relatives of crickets
and grasshoppers.
and grasshoppers.
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The males are very picky
about who they mate with,
about who they mate with,
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because they not only transfer
sperm during mating,
sperm during mating,
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they also give the female
something called a nuptial gift.
something called a nuptial gift.
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You can see two katydids
mating in these photos.
mating in these photos.
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In both panels,
the male's the one on the right,
the male's the one on the right,
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and that sword-like appendage
is the female's egg-laying organ.
is the female's egg-laying organ.
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The white blob is the sperm,
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the green blob is the nuptial gift,
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and the male manufactures
this from his own body
this from his own body
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and it's extremely costly to produce.
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It can weigh up to a third
of his body mass.
of his body mass.
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I will now pause for a moment
and let you think about
and let you think about
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what it would be like if human men,
every time they had sex,
every time they had sex,
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had to produce something
that weighed 50, 60, 70 pounds.
that weighed 50, 60, 70 pounds.
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(Laughter)
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Okay, they would not be able
to do that very often.
to do that very often.
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(Laughter)
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And indeed, neither can the katydids.
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And so what that means
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is the katydid males are very choosy
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about who they offer
these nuptial gifts to.
these nuptial gifts to.
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Now, the gift is very nutritious,
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and the female eats it
during and after mating.
during and after mating.
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So, the bigger it is,
the better off the male is,
the better off the male is,
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because that means more time for his sperm
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to drain into her body
and fertilize her eggs.
and fertilize her eggs.
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But it also means that the males
are very passive about mating,
are very passive about mating,
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whereas the females
are extremely aggressive and competitive,
are extremely aggressive and competitive,
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in an attempt to get as many of these
nutritious nuptial gifts as they can.
nutritious nuptial gifts as they can.
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So, it's not exactly
a stereotypical set of rules.
a stereotypical set of rules.
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Even more generally though,
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males are actually not all that important
in the lives of a lot of insects.
in the lives of a lot of insects.
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In the social insects --
the bees and wasps and ants --
the bees and wasps and ants --
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the individuals that you see every day --
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the ants going back and forth
to your sugar bowl,
to your sugar bowl,
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the honey bees that are flitting
from flower to flower --
from flower to flower --
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all of those are always female.
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People have had a hard time getting
their head around that idea for millennia.
their head around that idea for millennia.
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The ancient Greeks knew that there was
a class of bees, the drones,
a class of bees, the drones,
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that are larger than the workers,
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although they disapproved
of the drones' laziness
of the drones' laziness
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because they could see that
the drones just hang around the hive
the drones just hang around the hive
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until the mating flight --
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they're the males.
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They hang around until the mating flight,
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but they don't participate
in gathering nectar or pollen.
in gathering nectar or pollen.
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The Greeks couldn't figure out
the drones' sex,
the drones' sex,
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and part of the confusion was that they
were aware of the stinging ability of bees
were aware of the stinging ability of bees
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but they found it difficult to believe
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that any animals that bore such a weapon
could possibly be a female.
could possibly be a female.
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Aristotle tried to get involved as well.
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He suggested, "OK, if the stinging
individuals are going to be the males ..."
individuals are going to be the males ..."
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Then he got confused,
because that would have meant
because that would have meant
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the males were also taking care
of the young in a colony,
of the young in a colony,
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and he seemed to think
that would be completely impossible.
that would be completely impossible.
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He then concluded that maybe
bees had the organs of both sexes
bees had the organs of both sexes
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in the same individual,
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which is not that far-fetched,
some animals do that,
some animals do that,
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but he never really
did get it figured out.
did get it figured out.
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And you know, even today,
my students, for instance,
my students, for instance,
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call every animal they see,
including insects, a male.
including insects, a male.
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And when I tell them
that the ferocious army-ant soldiers
that the ferocious army-ant soldiers
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with their giant jaws,
used to defend the colony,
used to defend the colony,
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are all always female,
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they seem to not quite believe me.
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(Laughter)
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And certainly all of the movies --
Antz, Bee Movie --
Antz, Bee Movie --
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portray the main character
in the social insects as being male.
in the social insects as being male.
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Well, what difference does this make?
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These are movies. They're fiction.
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They have talking animals in them.
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What difference does it make
if they talk like Jerry Seinfeld?
if they talk like Jerry Seinfeld?
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I think it does matter,
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and it's a problem that actually
is part of a much deeper one
is part of a much deeper one
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that has implications
for medicine and health
for medicine and health
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and a lot of other aspects of our lives.
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You all know that scientists
use what we call model systems,
use what we call model systems,
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which are creatures --
white rats or fruit flies --
white rats or fruit flies --
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that are kind of stand-ins
for all other animals, including people.
for all other animals, including people.
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And the idea is
that what's true for a person
that what's true for a person
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will also be true for the white rat.
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And by and large,
that turns out to be the case.
that turns out to be the case.
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But you can take the idea
of a model system too far.
of a model system too far.
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And what I think we've done,
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is use males, in any species,
as though they are the model system.
as though they are the model system.
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The norm.
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The way things are supposed to be.
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And females as a kind of variant --
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something special that you only study
after you get the basics down.
after you get the basics down.
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And so, back to the insects.
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I think what that means
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is that people just couldn't see
what was in front of them.
what was in front of them.
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Because they assumed that the world's
stage was largely occupied by male players
stage was largely occupied by male players
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and females would only have
minor, walk-on roles.
minor, walk-on roles.
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But when we do that, we really miss out
on a lot of what nature is like.
on a lot of what nature is like.
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And we can also miss out on the way
natural, living things, including people,
natural, living things, including people,
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can vary.
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And I think that's why we've used males
as models in a lot of medical research,
as models in a lot of medical research,
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something that we know now to be a problem
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if we want the results to apply
to both men and women.
to both men and women.
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Well, the last thing
I really love about insects
I really love about insects
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is something that a lot of people
find unnerving about them.
find unnerving about them.
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They have little, tiny brains
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with very little cognitive ability,
the way we normally think of it.
the way we normally think of it.
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They have complicated behavior,
but they lack complicated brains.
but they lack complicated brains.
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And so, we can't just think of them
as though they're little people
as though they're little people
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because they don't do things
the way that we do.
the way that we do.
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I really love that it's difficult
to anthropomorphize insects,
to anthropomorphize insects,
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to look at them and just think of them
like they're little people
like they're little people
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in exoskeletons, with six legs.
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(Laughter)
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Instead, you really have to accept them
on their own terms,
on their own terms,
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because insects make us question
what's normal and what's natural.
what's normal and what's natural.
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Now, you know, people write fiction
and talk about parallel universes.
and talk about parallel universes.
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They speculate about the supernatural,
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maybe the spirits of the departed
walking among us.
walking among us.
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The allure of another world
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is something that people say is part of
why they want to dabble in the paranormal.
why they want to dabble in the paranormal.
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But as far as I'm concerned,
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who needs to be able to see dead people,
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when you can see live insects?
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Thank you.
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(Applause)
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ABOUT THE SPEAKER
Marlene Zuk - Evolutionary biologistMarlene Zuk studies insect behavior -- and how humans use animal behavior to think about how we behave ourselves.
Why you should listen
Marlene Zuk is a biologist and writer who researches animal behavior and evolution, mostly using insects as subjects. Zuk is interested in the ways that people use animal behavior to think about human behavior, and vice versa, as well as in the public's understanding of evolution. She teaches graduate and undergraduate courses in the Department of Ecology, Evolution and Behavior at the University of Minnesota -- including a seminar called “What’s the Alternative to Alternative Medicine?”
In addition to publishing numerous scientific articles, Zuk has published four books for a general audience: Sexual Selections: What We Can and Can’t Learn About Sex from Animals; Riddled with Life: Friendly Worms, Ladybug Sex, and the Parasites That Make Us Who We Are; Sex on Six Legs: Lessons on Life, Love and Language from the Insect World; and most recently, Paleofantasy: What Evolution Really Tells Us About Sex, Diet and the Way We Live.
Marlene Zuk | Speaker | TED.com