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Emma Teeling: The secret of the bat genome

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In Western society, bats are often characterized as creepy, even evil. Zoologist Emma Teeling encourages us to rethink common attitudes toward bats, whose unique and fascinating biology gives us insight into our own genetic makeup.

- Zoologist
Emma Teeling, Director of the Centre for Irish Bat Research, thinks we have a lot to learn from the biology of bats. Full bio

What I want you all to do right now
00:16
is to think of this mammal that I'm going to describe to you.
00:18
The first thing I'm going to tell you about this mammal
00:22
is that it is essential for our ecosystems to function correctly.
00:25
If we remove this mammal from our ecosystems,
00:30
they simply will not work.
00:33
That's the first thing.
00:36
The second thing is that due to the unique sensory abilities
00:37
of this mammal, if we study this mammal,
00:42
we're going to get great insight into our diseases
00:46
of the senses, such as blindness and deafness.
00:50
And the third really intriguing aspect of this mammal
00:54
is that I fully believe that the secret of everlasting youth
00:59
lies deep within its DNA.
01:04
So are you all thinking?
01:08
So,
01:11
magnificent creature, isn't it?
01:13
Who here thought of a bat?
01:16
Ah, I can see half the audience agrees with me,
01:20
and I have a lot of work to do to convince the rest of you.
01:22
So I have had the good fortune for the past 20 years
01:25
to study these fascinating and beautiful mammals.
01:30
One fifth of all living mammals is a bat,
01:34
and they have very unique attributes.
01:38
Bats as we know them have been around on this planet
01:40
for about 64 million years.
01:43
One of the most unique things that bats do
01:47
as a mammal is that they fly.
01:51
Now flight is an inherently difficult thing.
01:54
Flight within vertebrates has only evolved three times:
01:57
once in the bats, once in the birds,
02:01
and once in the pterodactyls.
02:04
And so with flight, it's very metabolically costly.
02:06
Bats have learned and evolved how to deal with this.
02:10
But one other extremely unique thing about bats
02:14
is that they are able to use sound
02:18
to perceive their environment. They use echolocation.
02:21
Now, what I mean by echolocation --
02:25
they emit a sound from their larynx out through their mouth
02:28
or through their nose. This sound wave comes out
02:32
and it reflects and echoes back off objects in their environment,
02:35
and the bats then hear these echoes
02:39
and they turn this information into an acoustic image.
02:42
And this enables them to orient in complete darkness.
02:46
Indeed, they do look very strange. We're humans.
02:50
We're a visual species. When scientists first realized
02:54
that bats were actually using sound to be able to fly
02:57
and orient and move at night, we didn't believe it.
03:01
For a hundred years, despite evidence to show
03:04
that this is what they were doing, we didn't believe it.
03:07
Now, if you look at this bat, it looks a little bit alien.
03:10
Indeed, the very famous philosopher Thomas Nagel
03:14
once said, "To truly experience an alien life form
03:18
on this planet, you should lock yourself inside a room
03:21
with a flying, echolocating bat in complete darkness."
03:25
And if you look at the actual physical characteristics
03:29
on the face of this beautiful horseshoe bat,
03:32
you see a lot of these characteristics are dedicated
03:35
to be able to make sound and perceive it.
03:38
Very big ears, strange nose leaves, but teeny-tiny eyes.
03:41
So again, if you just look at this bat, you realize
03:46
sound is very important for its survival.
03:50
Most bats look like the previous one.
03:53
However, there are a group that do not use echolocation.
03:57
They do not perceive their environment using sound,
04:01
and these are the flying foxes.
04:04
If anybody has ever been lucky enough to be in Australia,
04:06
you've seen them coming out of the Botanic Gardens in Sydney,
04:09
and if you just look at their face, you can see
04:12
they have much, much larger eyes and much smaller ears.
04:16
So among and within bats is a huge variation
04:19
in their ability to use sensory perception.
04:23
Now this is going to be important for what I'm going
04:26
to tell you later during the talk.
04:28
Now, if the idea of bats in your belfry terrifies you,
04:29
and I know some people probably are feeling a little sick
04:34
looking at very large images of bats,
04:37
that's probably not that surprising,
04:41
because here in Western culture,
04:43
bats have been demonized.
04:46
Really, of course the famous book "Dracula,"
04:48
written by a fellow Northside Dubliner Bram Stoker,
04:50
probably is mainly responsible for this.
04:53
However, I also think it's got to do with the fact
04:55
that bats come out at night, and we don't
04:58
really understand them. We're a little frightened by things
05:01
that can perceive the world slightly differently than us.
05:03
Bats are usually synonymous with some type of evil events.
05:07
They are the perpetrators in horror movies,
05:10
such as this famous "Nightwing."
05:13
Also, if you think about it, demons
05:14
always have bat wings, whereas birds, they typically --
05:17
or angels have bird wings.
05:21
Now, this is Western society, and what I hope to do tonight
05:24
is to convince you of the Chinese traditional culture,
05:29
that they perceive bats as
05:34
creatures that bring good luck, and indeed, if you walk
05:36
into a Chinese home, you may see an image such as this.
05:40
This is considered the Five Blessings.
05:44
The Chinese word for "bat" sounds like the Chinese word
05:47
for "happiness," and they believe that bats
05:49
bring wealth, health, longevity, virtue and serenity.
05:52
And indeed, in this image, you have a picture of longevity
05:57
surrounded by five bats.
06:00
And what I want to do tonight is to talk to you
06:02
and to show you that at least three of these blessings
06:06
are definitely represented by a bat, and that if we study bats
06:09
we will get nearer to getting each of these blessings.
06:13
So, wealth -- how can a bat possibly bring us wealth?
06:17
Now as I said before, bats are essential for our ecosystems
06:22
to function correctly. And why is this?
06:26
Bats in the tropics are major pollinators of many plants.
06:29
They also feed on fruit, and they disperse the seeds
06:33
of these fruits. Bats are responsible for pollinating
06:36
the tequila plant, and this is a multi-million dollar industry
06:41
in Mexico. So indeed, we need them
06:44
for our ecosystems to function properly.
06:47
Without them, it's going to be a problem.
06:50
But most bats are voracious insect predators.
06:52
It's been estimated in the U.S., in a tiny colony
06:58
of big brown bats, that they will feed
07:01
on over a million insects a year,
07:03
and in the United States of America, right now
07:06
bats are being threatened by a disease known as white-nose syndrome.
07:09
It's working its way slowly across the U.S. and wiping out
07:13
populations of bats, and scientists have estimated
07:16
that 1,300 metric tons of insects a year are now
07:20
remaining in the ecosystems due to the loss of bats.
07:25
Bats are also threatened in the U.S.
07:28
by their attraction to wind farms. Again, right now
07:31
bats are looking at a little bit of a problem.
07:35
They're going to -- They are very threatened
07:36
in the United States of America alone.
07:39
Now how can this help us?
07:42
Well, it has been calculated that if we were to remove bats
07:44
from the equation, we're going to have to then use
07:47
insecticides to remove all those pest insects
07:50
that feed on our agricultural crops.
07:53
And for one year in the U.S. alone, it's estimated
07:56
that it's going to cost 22 billion U.S. dollars,
07:59
if we remove bats. So indeed, bats then do bring us wealth.
08:02
They maintain the health of our ecosystems,
08:07
and also they save us money.
08:09
So again, that's the first blessing. Bats are important
08:12
for our ecosystems.
08:15
And what about the second? What about health?
08:17
Inside every cell in your body lies your genome.
08:21
Your genome is made up of your DNA,
08:26
your DNA codes for proteins that enable you to function
08:29
and interact and be as you are.
08:32
Now since the new advancements in modern molecular technologies,
08:35
it is now possible for us to sequence our own genome
08:39
in a very rapid time and at a very, very reduced cost.
08:43
Now when we've been doing this, we've realized
08:47
that there's variations within our genome.
08:50
So I want you to look at the person beside you.
08:54
Just have a quick look. And what we need to realize
08:57
is that every 300 base pairs in your DNA, you're a little bit different.
08:59
And one of the grand challenges right now
09:04
in modern molecular medicine is to work out
09:06
whether this variation makes you more susceptible to diseases,
09:09
or does this variation just make you different?
09:13
Again, what does it mean here? What does this variation
09:16
actually mean? So if we are to capitalize on all of this
09:19
new molecular data and personalized genomic information
09:23
that is coming online that we will be able to have
09:26
in the next few years, we have to be able to differentiate
09:29
between the two. So how do we do this?
09:32
Well, I believe we just look at nature's experiments.
09:35
So through natural selection, over time,
09:39
mutations, variations that disrupt the function of a protein
09:43
will not be tolerated over time.
09:48
Evolution acts as a sieve. It sieves out the bad variation.
09:51
And so therefore, if you look at the same region
09:55
of a genome in many mammals that have been
09:58
evolutionarily distant from each other
10:01
and are also ecologically divergent, you will get a better
10:04
understanding of what the evolutionary prior of that site is,
10:08
i.e., if it is important for the mammal to function,
10:11
for its survival, it will be the same
10:15
in all of those different lineages, species, taxa.
10:18
So therefore, if we were to do this,
10:22
what we'd need to do is sequence that region
10:26
in all these different mammals and ascertain if it's the same
10:27
or if it's different. So if it is the same,
10:30
this indicates that that site is important for a function,
10:34
so a disease mutation should fall within that site.
10:37
So in this case here, if all the mammals that we look at
10:41
have a yellow-type genome at that site,
10:45
it probably suggests that purple is bad.
10:48
This could be even more powerful if you look at mammals
10:51
that are doing things slightly differently.
10:54
So say, for example, the region of the genome
10:57
that I was looking at was a region that's important for vision.
10:59
If we look at that region in mammals that don't see so well,
11:03
such as bats, and we find that bats that don't see so well
11:06
have the purple type, we know that this is probably
11:10
what's causing this disease.
11:13
So in my lab, we've been using bats to look at two different
11:16
types of diseases of the senses.
11:20
We're looking at blindness. Now why would you do this?
11:24
Three hundred and fourteen million people are visually impaired, and
11:27
45 million of these are blind. So blindness is a big problem,
11:32
and a lot of these blind disorders come from inherited diseases,
11:35
so we want to try and better understand
11:39
which mutations in the gene cause the disease.
11:42
Also we look at deafness. One in every 1,000
11:45
newborn babies are deaf, and when we reach 80,
11:49
over half of us will also have a hearing problem.
11:53
Again, there's many underlying genetic causes for this.
11:56
So what we've been doing in my lab
12:00
is looking at these unique sensory specialists, the bats,
12:03
and we have looked at genes that cause blindness
12:06
when there's a defect in them,
12:08
genes that cause deafness when there's a defect in them,
12:10
and now we can predict which sites are most likely to cause disease.
12:12
So bats are also important for our health,
12:17
to enable us to better understand how our genome functions.
12:20
So this is where we are right now,
12:25
but what about the future?
12:27
What about longevity?
12:29
This is where we're going to go, and as I said before,
12:31
I really believe that the secret of everlasting youth
12:35
lies within the bat genome.
12:38
So why should we be interested in aging at all?
12:39
Well, really, this is a picture drawn from the 1500s
12:44
of the Fountain of Youth. Aging is considered
12:46
one of the most familiar, yet the least well-understood,
12:50
aspects of all of biology, and really,
12:53
since the dawn of civilization, mankind has sought to avoid it.
12:56
But we are going to have to understand it a bit better.
13:01
In Europe alone, by 2050, there is going to be
13:04
a 70 percent increase of individuals over 65,
13:07
and 170 percent increase in individuals over 80.
13:11
As we age, we deteriorate, and this deterioration
13:15
causes problems for our society, so we have to address it.
13:18
So how could the secret of everlasting youth actually lie
13:23
within the bat genome? Does anybody want to hazard
13:27
a guess over how long this bat could live for?
13:30
Who -- put up your hands -- who says two years?
13:34
Nobody? One? How about 10 years?
13:37
Some? How about 30?
13:41
How about 40? Okay, it's a whole varied response.
13:45
This bat is myotis brandtii. It's the longest-living bat.
13:48
It lived for up to 42 years,
13:52
and this bat's still alive in the wild today.
13:54
But what would be so amazing about this?
13:57
Well, typically, in mammals there is a relationship
13:59
between body size, metabolic rate,
14:04
and how long you can live for, and you can predict
14:07
how long a mammal can live for given its body size.
14:09
So typically, small mammals live fast, die young.
14:12
Think of a mouse. But bats are very different.
14:16
As you can see here on this graph, in blue,
14:19
these are all other mammals, but bats
14:21
can live up to nine times longer than expected
14:24
despite having a really, really high metabolic rate,
14:26
and the question is, how can they do that?
14:29
There are 19 species of mammal that live longer
14:32
than expected, given their body size, than man,
14:35
and 18 of those are bats.
14:38
So therefore, they must have something within their DNA
14:41
that ables them to deal with the metabolic stresses,
14:46
particularly of flight. They expend three times more energy
14:49
than a mammal of the same size,
14:53
but don't seem to suffer the consequences or the effects.
14:54
So right now, in my lab, we're combining
14:58
state-of-the-art bat field biology, going out and catching
15:01
the long-lived bats, with the most up-to-date,
15:05
modern molecular technology to understand better
15:08
what it is that they do to stop aging as we do.
15:11
And hopefully in the next five years, I'll be giving you a TEDTalk on that.
15:16
Aging is a big problem for humanity,
15:19
and I believe that by studying bats, we can uncover
15:23
the molecular mechanisms that enable mammals
15:26
to achieve extraordinary longevity. If we find out
15:29
what they're doing, perhaps through gene therapy,
15:32
we can enable us to do the same thing.
15:35
Potentially, this means that we could halt aging or maybe even reverse it.
15:38
Just imagine what that would be like.
15:43
So really, I don't think we should be thinking of them
15:47
as flying demons of the night, but more as our superheroes.
15:50
And the reality is that bats can bring us so much benefit
15:55
if we just look in the right place. They're good for our ecosystem,
15:58
they allow us to understand how our genome functions,
16:01
and they potentially hold the secret to everlasting youth.
16:04
So tonight, when you walk out of here and you look up
16:07
in the night skies, and you see this beautiful flying mammal,
16:10
I want you to smile. Thank you. (Applause)
16:13
Translated by Joseph Geni
Reviewed by Morton Bast

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About the speaker:

Emma Teeling - Zoologist
Emma Teeling, Director of the Centre for Irish Bat Research, thinks we have a lot to learn from the biology of bats.

Why you should listen

One-fifth of all mammals in the world are bats -- so why are they so stigmatized in Western culture? Dr. Emma Teeling believes that these fascinating creatures have a lot to teach us, with their uniquely high metabolic rates and surprisingly long lifespans. Teeling studies mammalian phylogenetics and comparative genomics, with particular expertise in bat biology and the bat's genetic signatures of survival.

More profile about the speaker
Emma Teeling | Speaker | TED.com