- Hello everyone, and welcome
to the very first episode
of Lunch Break Science.
I'm Arielle Johnson from
the Leakey Foundation,
a nonprofit committed to funding
human evolution research,
and sharing discoveries
in programs like this one.
Here with us today we have,
Leakey Foundation Grantee,
Dr. Zarin Machanda.
Zarin, we're really excited
to have you here today.
It's just wonderful to have
such a phenomenal scientist
for our very first event.
Zarin is joining us from Massachusetts,
where she is stint
Professor of Anthropology,
at Tufts University.
She also studies a large
chimpanzee community
at Kibale National Park in Uganda.
She is director of the
Kibale Chimpanzee project.
Today she'll be discussing
her work on the relationships
and communication of chimpanzees.
Before we start Zarin, what
is it about chimpanzee?
I mean they're really fascinating animal,
but why are there so specially
important to study when we
consider human evolution?
- I mean I think...
Hey Arielle, thank you
so much for having me.
And I'm really honored to be
the first in your series here,
which I'm really excited about.
I love studying chimps.
I think they...
From the moment that I started
working with them more than
20 years ago actually,
it's really hard not to
spend time with chimpanzees
and not see aspects of humanity in them.
And obviously many of you know,
that chimpanzees and humans are...
Chimpanzees are humans
closest living relative
along with bonobos.
And we share approximately
98 to 99% of our DNA
in common with this species.
And so that means that we
shared this last common ancestor
with them probably about six
to eight million years ago.
And so they're an
incredibly important species
along with bonobos, in telling us about
the evolution of our own species.
So things that we have in common
with chimps are likely are
often things that we probably
have a shared history with.
Things where we see differences
between chimps and humans
are things that we then might
have to start to understand
from that split with the
last common ancestor.
So, really data from chimps
and bonobos, and a lot of the
other great apes are really
crucial pieces of information
for understanding our own species.
- Well, I'm really looking
forward to your talk.
Before we get started though,
as a reminder to those
of you watching us live
on YouTube, Facebook or Twitter,
you can leave questions
in the comments for Zarin
at any time during the talk,
and we'll loop back to the end at the end
and get as many of those
answered as possible.
I wanna thank Anna Gordon Getty
and Camilla and George Smith
whose generous support has made
Lunch Break Science possible.
We really, really just thank them so much.
Now I'm going to turn
over the floor to you,
the virtual floor.
- Great, thanks again Arielle.
And I'm really excited today
to tell you a little bit more
about some of the research
that we've conducted at our
project Kibale Chimpanzee
Project in Uganda,
along with work of other colleagues,
to really try to understand
chimpanzee communication.
And not just vocal communication,
but all sorts of ways that chimpanzees
share information with each other.
And I always like to start
talks about chimpanzee
communication by actually telling
you a little bit about one
of my favorite chimpanzee
vocalizations called a Pant-hoot.
And this is one of my favorite calls.
It's one of the calls that when
we're out in the forest with
the chimpanzees, we hear it
actually quite frequently.
So it's a commonly given signal,
and it's really, it can be quite loud.
And so we'll hear it even from far away
from a mile or two away in the forest.
And, it's a really
interesting talk and call,
and I'll talk a little bit more
about what the sound means.
But in many ways, when we hear this call,
a lot of times it's a
signal of excitement.
So chimpanzees are giving it
when they come together after
having not seen each other for
a long time or when something
very socially exciting is happening.
So in some ways it's not
exactly a chimpanzee hello,
but it's a way to say I'm
very excited to be here.
So the call is called a Pant-Hoot,
but it can actually be
broken down into four stages.
So the call starts with the
Pant, and this is kind of just
like heavy breathing.
So it sounds a little bit like, (panting)
And then, remember
they're getting excited.
So it gets louder and faster.
And we call this the Build-Up phase
and it sounds a little bit
like, (panting heavily)
And then, there's the Hoot part,
and the Hoot part is the
loudest part of the call.
It's really that crescendo of this call.
And what I think is kind of
fun about the hoot is that it
can often be like really
individually distinctive.
And so if we hear the hoot
part, we can often tell
which individual is
hooting just by this part.
And so a lot of times the
food can be kind of like,
like I said, it's very loud,
so I'm gonna make a loud sound,
but it can be a little bit like, (hooting)
or it could be even more like
just kind of a really screamy
kinda sound like, (hooting)
kind of like that.
And it's important to
remember if you're teaching
small children to do this.
They only hoot maybe a few
times like three or four
or five times they don't keep screaming.
And it's also important to
remind them that they eventually
stopped screaming and enter stage four,
which is the Let down, just
the last part of the call
where they're relaxing and
it's a little bit like,
(hooting)
So I'm gonna Pant-Hoot for you.
If you put it all together,
it a little bit like this,
which is, (pant-hooting)
So that's my, not necessarily
very accurate Pant-Hoot
a chimpanzee would not necessarily
think that I was a chimp,
but I think you hopefully
could hear all four parts,
and now I'm gonna just
actually play a video
so you can hear and see
what chimpanzees look like
when they're pant hooting.
And the thing about this video
to just pay attention to,
you'll actually see two
chimps together, pant hooting.
And then if you wait till
after they Pant-Hoot,
you'll hear other chimps
farther away responding to them.
(chimpanzees pant hooting)
So hopefully now you know what
real chimpanzees sound like
when they're pant hooting.
Now I said that this call
actually has a lot of,
kind of meaning for chimpanzees.
And there are a lot of hidden meanings
in many ways to these pant-hoots.
And this is some of the
work that we've done
at Kibale Chimpanzee Project,
especially the work of a
colleague Pablo Fredrick,
who focused on this call for his research.
And we've done a lot of
studies to try to figure out
kinda some of these hidden meanings.
And one of the things that we
know from a male pant-hoots
in particular, is that they do actually
signify social status.
So high ranking males
have slightly different
pant-hoot structures,
than low ranking males.
So if you are a chimpanzee,
you are likely able
to figure out some
aspects of the individual
who's pant hooting from just
the sound of their call.
And interestingly, we also
know that testosterone levels
actually vary with the pant-hoot.
So different males who have
different high testosterone have
slightly different sounding pant-hoots.
And that goes hand in
hand with social status.
Since we know that testosterone
and rank also co-vary with one another.
Now, interestingly, we've
also found that chimpanzees
who pant-hoot together,
like you saw in that video,
are often ones that have
stronger social bonds.
So potentially this joint pant hooting
where they do it together,
what we call chorus
might be a signal to the other
chimpanzees or to each other
of a strong social bond.
And actually when they pant-hoot together,
what's really interesting is,
each chimpanzee might have
kind of an individual sounding
pant-hoot on their own,
but when they pant hoot
together in chorus,
they actually modify their sound
so that it's more similar to one another.
Which I think is maybe again,
some kind of signal of their social bond.
And I think the last kinda
hidden thing about pant-hoots
that I think is really
interesting is, that different
communities of chimpanzees actually have
slightly different sounding pant-hoots.
And so essentially if you
are a chimp in the forest
and you hear a pant-hoot,
it's likely that you're able
to tell whether that chimpanzee
is a friendly member of your
community, or potentially a
member of a neighboring and
not so friendly community.
So there's a lot of stuff that we can tell
just by the sounds that chimpanzees make.
But this study...
The study of how we actually
figure out what chimpanzees
are saying to each other,
can be quite difficult.
What we can do is, we have
this longterm field site
where we're able to collect
just tons, and tons,
and tons of data, and
try to piece together
what some of these sounds mean.
But another way...
But that takes years and years.
So we have 33 years of data
and some of our data tables
have five million rows of data.
So I mean, it's an immense
collection of data.
But there are other ways that
we can actually figure out
what chimpanzee communication means,
by actually doing experiments.
And here's actually a study
that I was involved with.
It was led by Anne Marijke Schel,
along with Simon Townsend,
Klaus Zuberbühler
and Katie Slocombe.
And this is a study we did at Bojangles,
where we actually tried
to figure out an aspect...
Something about chimpanzees vocalizations.
Especially these alarm calls
that they give to snakes.
And so, what we did was actually
a real experiment in the field
and how we did this is we hit
a snake, we actually found
a snake skin that we
stuffed to make it look
very alive and real.
And we actually hit it
under a bunch of leaves.
And then, it was attached
to a fishing wire
that the chimps couldn't see.
And so when a chimp actually
approached this hidden snake,
we actually would pull on the fishing wire
to reveal the snake, and then we would see
or hear the reaction, we
would record the reaction
of the chimp especially
the calls that they gave.
So I'm gonna play two
videos, one is actually taken
from the front of like
looking at the chimp
as it's approaching.
And this is a chimpanzee where,
you'll see actually once a snake is...
You'll hear Anna Marijke
voice over and you'll see
her, the chimpanzee approach the snake,
she'll kinda jump back and
give these calls called Woos,
and then she'll give another
call called a Waa bark.
And then the second video
after that is gonna play
the view from behind, where you see
the chimp that's next in, who happens
to be her adult male son.
And you'll see how kind of she calls back
to that individual.
So let's play the first video.
- [Anna] Now be seeing the snake,
wooing,
wooing,
wooing.
- And so you could hear
those woos that she gave
they're called soft woos.
Now, in the second video you'll see,
like I said from the back,
and you'll hear these
waa barks that she gives
as an alarm call.
- [Man] (mumbles)is on
my side wooing, wooing.
(chimpanzees waa barking)
- So you heard those waa barks.
So this is a really kind
of interesting question
that we were asking.
And about those particular calls,
but one of the very early
views of animal communication
was that the calls that animals gave,
especially in response to kind
of this kind of a predator
or some kind of danger, these alarm calls,
were just kind of automatic responses.
So in the same way that if you fall spider
and you might go, aah without really
kind of having any
intentionality behind them.
And so one of the things that
we wanted to do is actually
show whether or not the sounds
that chimpanzees were making,
whether they were capable of
intentional communication.
And what we found over
running this experiment
countless times, is that the
first sound that chimpanzees
make that, woo, woo that soft woo,
does seem to be kind of
just an automatic response.
But those waa barks, those
alarm calls that they give,
that you heard, are actually things that
they give more likely, the
more likely to give them
if the chimpanzee behind them
is a friend or a relative.
And if the chimpanzee behind
them isn't neither of those,
they often just don't
give that alarm call.
And that suggests that chimpanzees
have some kind of control.
They look to see who's behind
them, and they give a call
depending on who that individual is.
And so that actually does tell us
that chimpanzee communication,
at least this vocal communication,
meets the key criteria for intentionality.
And that is something that humans
and chimpanzees have in
common with one another.
That kind of shared...
That's something that we probably
share and it has probably
a deep evolutionary history in that sense.
Now, so we have a lot of information
about vocal communication,
but chimpanzees actually
communicate in all sorts of other ways.
So I'm gonna show a video
of two males on the left is
Kakama who's our alpha
male, on the right is Makoko
and you'll see them actually
doing something that male
chimpanzees do often,
which is groom each other.
(birds tweeting)
So this is a behavior when
we're out in the forest,
we will see much more frequently
among male, male dyads
than we do among female, female dyads.
And so, to us grooming is
probably some sort of signal
of friendship or a strong social bond.
So this is kind of an example
of a signal that is given
that's not necessarily vocal,
but is probably communicating
trust or some kind of affiliation.
And we actually know that grooming
reinforces these long-term
and short-term social bonds.
So again, this is not necessarily
like chimpanzees saying
to each other with words
or with vocalizations
"High on your buddy."
But it is a way of communicating
that with each other.
Now there are other kinds of signals,
non-vocal signals that chimpanzees give.
And I'm gonna show you another video
and I'll kinda talk about
those signals afterwards.
So here's another video of
a chimpanzee up in a tree,
and you will see them
scratching themselves and...
Pay attention to what happens.
(birds tweeting)
So, hopefully what you saw
was there were scratching,
and then those two individuals
approached and actually
raised their hands up above their head
and then started grooming each other.
Now there are a couple
of unknown questions here
in our research program that
we don't really understand.
But one thing, that we would
love to know is whether
or not that scratching,
is kind of a signal
to say to another chimp,
can you come grew me?
Or would you like to grow me?
Or help, I actually would really
love it if you groomed me.
So that's something that
we don't really know.
And it's an active research question.
The other thing that is kinda
interesting is that behavior
that you saw, where they
were clapping their hands
above their heads.
That's something that we
call high-arm grooming
and to date, we have actually
studied this fairly well.
We actually don't know
a lot about the function
of that behavior.
We don't really know why they're doing it.
It's something that some chimpanzees,
our chimpanzees do it a lot.
Other chimpanzee communities
don't do it at all.
So we have a lot of unanswered questions
in this kind of area.
We're not really sure what it signals
or why they're doing it.
So we do have a lot of
unanswered questions
with chimpanzees.
Now, there are other
signals that chimpanzees
give that really have to do with dominance
and social structure.
So one that we see very
commonly among male chimpanzees
is Piloerection, where a male chimpanzee
will kind of puff up all
of their hair on their body
to make them look really,
really big and strong.
So that's kind of a non-vocal signal
of dominance and strength.
But we also, sorry, have other
kind of vocal signals of dominance.
And what I'm gonna show you here,
is our alpha male Kakama,
who you see on the screen.
And he's actually gonna walk
past a low ranking male,
and you'll actually hear the
low ranking male give a really
emphatic vocalization called a pant grunt.
And this is a signal that
we see from low ranking
individuals, to high ranking individuals,
and it's one of the ways that
we can actually construct
the dominance hierarchy.
Oh, I'm not sure if the video is playing.
(chimpanzees pant grunting)
So you saw that really emphatic like,
low ranking individual.
Basically it's a signal like,
please don't beat me up.
I know I'm low ranking, please,
please don't beat me up.
So we have a lot of communication
just to kind of really
strengthen or establish
this dominance hierarchy.
And this is something that
we see among males a lot.
And the other thing that males
will do as kind of a signal
is do dominance displays.
And so I'll show you another
video where you'll actually
see a number of males, kind of puffed up
and they kind of just
run through the group
or the community...
Run through the area that other
chimps are in all puffed up,
throwing branches, making lots of noise,
trying to make themselves
look big and impressive
and establish themselves as intimidating
high ranking individual.
(chimpanzees pant grunting)
And I know that video can
be a little bit dizzying
because you're trying to
follow these running chimps
through the forest.
But I think it also gives
you, a little bit of a taste
of what it's like to
be in the wild with us.
And sometimes it's just complete
chaos and there's all this
undergrowth and the chimps
are and running around.
But, that's a very that
behavior that I showed you
this dominance display is
something that we see frequently
among adult males who are trying
to establish themselves as
big high ranking imposing individuals.
Now, one of the things
that you may have noticed
is that a lot of the communication
that I've talked about
with these dominance
displays, and Piloerection,
and pant grunts are really
kind of focused on adult males.
And it's true that there are
a lot of adult sex differences
where male chimpanzees are
bigger, they're more aggressive,
they're more social,
which is why we see grooming among them.
And females are often just kinda
more often with their offspring.
They're smaller, they're less aggressive,
but I don't want you to leave this talk,
thinking that females don't
communicate or have their own
special ways of communicating.
And one of the things that we
actually see with females is,
again, a non-vocal signal,
but female chimpanzees
are, when they're around
the time of ovulation, will
actually have a swelling
of their genital tissue.
And these are called sexual swellings.
And you can see a nice example
of a sexual swelling here.
And this is not something
that they have all the time.
This is just something
that they have around
the time of ovulation.
It lasts for about 10 days.
And this is in many ways
a signal to other males
and potentially to other females
of their reproductive status,
and that they're ready
to copulate and mate with males.
And it's also not just a visual signal.
And you can tell it's kind
of like a pretty profound
visual signal, It's bright
pink, and it's pretty obvious,
but it may also be an olfactory signals.
So when females...
Females will often get inspected by males
who will kind of touch the
swelling and sniff the swelling,
and that's actually still a
little bit of an unanswered
question about what they're smelling,
what they're trying to smell,
or they try and pick up some
kind of olfactory Q about
the levels of their hormones
or something like that.
That's something that we
still don't know a lot about.
And of course we have a lot
of kind of communication
between mothers and babies.
We do have some work that
has shown that mothers kinda
signal to babies when it's time to leave,
when they're ready to go
and do something else.
But just to kind of come
back to this idea of chimps
and humans and how related we are.
I'm gonna show you a video
of a mother kinda interacting
with her baby, and I just had
a baby about three months ago.
And so this is kind of very obvious to me.
But I feel like there's a lot
in this video where you can
just see the mom, both
being completely exhausted
with having this baby around her,
but also playing with this baby
nibbling on the baby's toes
and just kind of this interaction,
I find reminds me a lot
about my own interactions
with my children.
(birds tweeting)
- [Man] He's bitting his ear.
(birds tweeting)
- So I hope you learned a little bit
about chimpanzee communication,
both vocal and non-vocal today.
I would like to say a big, thank you,
not only to you for coming
to watch this today,
but also to all of our staff
in Uganda who collect the data.
And a big thank you to the
Leakey Foundation who has
not only funded my own work personally,
including my PhD dissertation,
but also is such a great
supporter of longterm research
for wild primates.
And it's been an amazing
support over the...
They've been an amazing support over
the last 30 plus years for our project.
And if you'd like to learn
more about our project,
I'd encourage you to follow
us on Facebook or on Twitter.
And I'm very happy to answer
any questions that you have.
So, the question from someone
who I actually know John,
is do chimpanzees alarm
call in response to snakes,
to enemies or lesser allies
within the same community,
or do they only alarm call
to close friends or family members?
So chimpanzees will I
mean, obviously they...
When you do this kind of project,
they certainly are not only alarm calling
to just their friends or family members.
They sometimes will alarm
call to other individuals,
and they will do this
I mean, that's the...
So we had to do this experiment.
I think we did it about 40 different times
with different individuals.
And we specifically were just
looking at their response
to snakes cause we could control that.
But certainly they give waa barks
in response to other things.
We just didn't kind of, we didn't test...
We didn't do the experiment with,
in response to non sneak things.
But waa barks are given in response
to kind of other stimuli including,
when they hear neighboring
chimps from another community.
So from, oh, that question disappeared
before I could read all of it.
So from, oh, and it
disappeared again I'm sorry.
So, from Alex.
How much attention do the
chimps give to you as observers?
Do you think there's a
difference in behavior
because of observing them?
It's a wonderful question.
So actually, we have, the
chimpanzees actually pay so little
attention to us as observers.
And part of this is because,
we've been doing this for so long,
that after 33 years of being in the field,
a lot of the chimpanzees in
the group that we study have
kind of had humans observing them
since the day they were born.
Obviously not all of them because
the females come in at adolescents.
But, so one of the things...
So, my feeling of being in the forest
is that the chimpanzees
don't pay attention to us.
They almost barely look at us,
unless we do something like
fall down or, make a
loud noise by accident.
We try to wear muted clothing.
We try not to talk very loudly.
We try not to eat in front
of them so they're not,
thinking about us as sources of food.
Chimpanzees are actually a
little bit different than
gorillas in this respect.
So if you spent time
with Mountain gorillas,
you'll have kind of a
different experience where they
actually do kind of carefully watch you.
I don't think that our presence
either with the gorillas or
with the chimps actually
affects their behavior too much.
But so yeah, now I think this is part
of the process habituation.
The one time that we probably
do have maybe an effect on
them is if they're interacting
with a neighboring community
of chimps who are not
habituated to human observation,
then I think then it
can be a little bit...
Then we probably scare away
the neighboring community of chimps.
We probably are like a secret weapon
for our chimps in that sense.
But that doesn't happen
very frequently, so...
Any other questions?
- Yeah, that's about all of the time
we have today for questions.
I'm sure if any of you
submit questions afterwards,
that Zarin would be happy
to answer them maybe.
Again, thank you so much Zarin,
that was an amazing way
to kick off our series.
If you'd like to learn more
about Zarin Machandas research,
the Leakey Foundation, and how
you can help support research
like hers, and programs like this.
Please feel free to visit
us@leakeyfoundation.org
for more information.
Next Thursday, we meet yet another amazing
Leakey Foundation
scientist, Lauren Schroeder.
And hear about what it takes to study
the skulls of early humans.
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Until next week, stay
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Bye everyone.
