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So infectious disease, right?
Infectious disease are still
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the main cause of human suffering
and death around the world.
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Every year, millions of people die
of diseases such as TB, malaria, HIV,
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around the world, and even
in the United States every year,
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thousands of Americans die
of seasonal flu.
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Now of course, humans,
we are creative. Right?
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We have come up with ways to protect
ourselves against these diseases.
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We have drugs and vaccines.
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And, you know, we're conscious.
We learn from our experiences
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and come up with creative solutions.
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We used to think we're alone in this,
but now we know we're not.
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We're not the only medical doctors.
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Now we know that there's a lot of animals
out there that can do it too.
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Most famous, perhaps, chimpanzees.
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Not so much different from us,
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they can use plants
to treat their intestinal parasites.
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But the last few decades have shown us
that other animals can do it too:
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elephants, porcupines,
sheep, goats, you name it.
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And even more interesting than that
is that recent discoveries are telling us
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that insects and other little animals
with smaller brains
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can use medication too.
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The problem in infectious diseases,
as we all know,
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is that pathogens continue to evolve,
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and a lot of the drugs
that we have developed
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are losing their efficacy.
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And therefore, there is this great need
to find new ways to discover drugs
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that we can use against our diseases.
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Now, I think that we
should look at these animals,
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and we can learn from them
how to treat our own diseases.
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As a biologist, I have been studying
monarch butterflies for the last 10 years.
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Now, monarchs are extremely famous
for their spectacular migrations
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from the U.S. and Canada
down to Mexico every year,
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where millions of them come together,
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but it's not why I started studying them.
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I study monarchs because they get sick.
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They get sick like you.
They get sick like me.
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And I think what they do
can tell us a lot about drugs
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that we can develop for humans.
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Now, the parasites
that monarchs get infected with
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are called ophryocystis elektroscirrha,
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a mouthful.
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What they do is they produce spores,
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millions of spores
on the outside of the butterfly
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that are shown as little specks
in between the scales of the butterfly.
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And this is really detrimental
to the monarch.
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It shortens their lifespan,
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it reduces their ability to fly,
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it can even kill them
before they're even adults.
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Very detrimental parasite.
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As part of my job, I spend a lot of time
in the greenhouse growing plants,
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and the reason for this is that monarchs
are extremely picky eaters.
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They only eat milkweed as larvae.
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Luckily, there are several
species of milkweed that they can use,
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and all these milkweeds
have cardenolides in them.
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These are chemicals that are toxic.
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They're toxic to most animals,
but not to monarchs.
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In fact, monarchs
can take up the chemicals,
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put it in their own bodies,
and it makes them toxic
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against their predators, such as birds.
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And what they do, then,
is advertise this toxicity
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through their beautiful
warning colorations
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with this orange, black, and white.
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So what I did during my job
is grow plants in the greenhouse,
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different ones, different milkweeds.
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Some were toxic, including
the tropical milkweed,
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with very high concentrations
of these cardenolides.
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And some were not toxic.
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And then I fed them to monarchs.
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Some of the monarchs were healthy.
They had no disease.
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But some of the monarchs were sick,
and what I found is that
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some of these milkweeds are medicinal,
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meaning they reduce the disease symptoms
in the monarch butterflies,
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meaning these monarchs can live longer
when they are infected
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when feeding on these medicinal plants.
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And what I found is I had this idea,
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and a lot of people said
it was a crazy idea,
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but I thought, what if monarchs
can use this, right?
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What if they can use these plants
as their own form of medicine?
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What if they can act as medical doctors?
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So my team and I
started doing experiments,
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and the first types of experiments,
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we had caterpillars,
and gave them a choice:
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medicinal milkweed versus
non-medicinal milkweed.
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And then we measured how much they ate
of each species over their lifetime.
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And the result, as so often
in science, was boring:
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50 percent of their food was medicinal,
50 percent was not.
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These caterpillars didn't do
anything for their own welfare.
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So then we moved on to adult butterflies,
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and we started asking the question
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whether it's the mothers
that can medicate their offspring.
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Can the mothers lay their eggs
on medicinal milkweed
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that will make their
future offspring less sick?
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We have done these experiments now
over several years,
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and always get the same results.
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What we do is we put
a monarch in a big cage,
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a medicinal plant on one side,
a non-medicinal plant on the other side,
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and then we measure the number of eggs
that the monarchs lay on each plant.
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And what we find when we do that
is always the same:
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what we find is that the monarchs
strongly prefer the medicinal milkweed.
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In other words,
what these females are doing
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is they're laying 68 percent
of their eggs in the medicinal milkweed.
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Intriguingly, what they do
is they actually transmit the parasites
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when they're laying the eggs.
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They cannot prevent this.
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They can also not medicate themselves.
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But what these experiments tell us
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is that these monarchs, these mothers,
can lay their eggs on medicinal milkweed
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that will make their
future offspring less sick.
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Now, this is is a really
important discovery, I think,
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not just because it tells us
something cool about nature,
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but also because it may tell us something
more about how we should find drugs.
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Now, these are animals that are very small
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and we tend to think of them
as very simple.
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They have tiny little brains,
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yet they can do this
very sophisticated medication.
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Now, we know that even today,
most of our drugs
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derive from natural products,
including plants,
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and in indigenous cultures,
traditional healers
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often look at animals to find new drugs.
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In this way, elephants have told us
how to treat stomach upset,
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and porcupines have told people
how to treat bloody diarrhea.
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What I think is important though
is to move beyond
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these large-brained mammals
and give these guys more credit,
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these simple animals, these insects
that we tend to think of
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as very, very simple
with tiny little brains.
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The discovery that these animals
can also use medication
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opens up completely new avenues,
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and I think that maybe one day,
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we will be treating human diseases
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with drugs that were first
discovered by butterflies,
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and I think that is an amazing opportunity
worth pursuing.
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Thank you so much.
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(Applause)