September 15, 2023 • 51 mins
In this episode of The PrimateCast origins, we’re sharing a lecture from primatologist and cognitive ethologist, Patricia Izar from the University of São Paulo.
Pat is one of the eminent Latin American primatologists, and along with her close friends and colleagues Drs. Dorothy Fragaszy and Elisabetta Visalberghi - see episode #68 for more on this from Elisabetta Visalberghi - she’s been studying the incredible tool use behavior of robust capuchins for the past few decades.
Capuchins are one of the very few non-great ape primates that are known to commonly use tools in nature - they use stones and anvils to crack open tough nuts and aquatic invertebrates (Paywall).
Pat walks us through a series of fascinating experiments with these charismatic monkeys - who by the way you can hear make a series of audio-only cameos in the background while she shows our Zoom audience some videos. Her target? Trying to understand what they know about the tools they use and what benefits they gain from using them.
Check out a short documentary about the EthoCebus project, of which Pat is a key member.
Because of her long history of observing and experimenting with wild capuchins, she challenges the idea from laboratory experiments with captive-reared individuals that capuchins don’t understand how or why the tools they use work; a commonly held belief that, unlike humans, monkeys don’t really have a strong sense of the ‘folk physics’ underlying their behavior.
Other topics that come up:
- selecting the best tools to use
- what environmental factors affect when and how capuchins use tools
- how using tools might affect social relationships
- the nutritional benefits of tool use in different seasons
- Have you ever wondered how heavy those stones are?
- playing with perception by providing huge stones that are light as a feather
Pat ends by talking about how this iconic behavior in capuchins can tell us a lot about the evolution of tool use in humans. By studying animals like capuchins, we can learn a lot about the kinds of conditions that are likely to have fostered this cognitively demanding behavior during our evolution.
Although she doesn’t mention it in the lecture, Pat is also a key figure in the profession and development of primatology, both locally in Brazil and internationally. She is currently the President of the Brazilian Society of Primatology, and serves t
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Andrew MacIntosh (00:00):
Welcome to the Primate Cast Origins.
Today's origin story comes fromPatricia Isar and is all about
those amazing tool usingcapuchins of Brazil.
Welcome back to Primate CastOrigins.
(00:41):
We are here from experts in thefield of primatology and beyond
about how they got started andbecame some of the most
influential folks around.
I'm your host, andrew McIntoshfrom Kyoto University's Wildlife
Research Center, and thisepisode is taken from our
International PrimatologyLecture Series Past, present and
Future Perspectives of thefield.
This is the brainchild of DrMichael Huffman and, like Our
(01:02):
Normal Programming, is broughtto you by PsyCASP.
The main goal of the lectureseries is to share the origin
stories of experiencedpractitioners of primatology and
related fields.
To do that, mike Huffman hasinvited a revolving door of
renowned scientists to join uson the program and share their
own stories with us.
The Primate Cast Origins is ourway of sharing those stories
right here on the podcast.
(01:24):
Unlike our normal interviewformat, these lectures are being
done as part of the PsyCASPSeminar in Science Communication
, which is aimed at gradstudents here in the Primatology
and Wildlife Science program atKyoto University.
So what you'll hear is alecture that was recorded in
Zoom and generally includesslides, so there may be
references to visual aids andvideos that are not available in
(01:45):
audio only format.
But for anyone wishing to seethe speakers presenting their
talks, we invite you to checkthose out on the PsyCASP TV
YouTube channel.
Now, in this episode of thePrimate Cast Origins, we're
sharing a lecture fromprimatologist and cognitive
ethologist Professor PatriciaIsar from the University of Sao
Paulo.
Pat is one of the eminent LatinAmerican primatologists and,
(02:07):
along with her close friends andcolleagues, doctors Dorothy
Fricese and ElizabethFisselbergi, who we had
previously in this series before, she's been studying the
incredible tool use behavior ofrobust capuchins for the last
few decades.
Now, capuchins are one of thevery few non-grade eight
primates that are known tocommonly use tools in nature.
They use stones and anvils tocrack open tough nuts and
(02:30):
aquatic invertebrates.
In this lecture, pat walks usthrough a series of fascinating
experiments with thesecharismatic monkeys who, by the
way you can hear, make a seriesof audio only cameos in the
background while she shows Zoomour Zoom audience some videos.
Now her target, trying tounderstand what they know about
the tools they use and whatbenefits they gain from using
them.
Because of her long history ofobserving and experimenting with
(02:53):
wild capuchins, she challengesthe idea which, by the way, came
from laboratory experimentswith captive reared individuals,
that capuchins don't reallyunderstand how or why the tools
they're using actually work.
This is a commonly held beliefthat, unlike humans, monkeys
don't really have a strong senseof the folk physics underlying
their behavior.
Through her talk, she alsoexplores other questions, like
(03:14):
what environmental factorsaffect when and how capuchins
use tools, and how using toolsmight affect social
relationships and, of course,unlock nutritional words that
are not available to themotherwise.
She ends by talking about howthis iconic behavior in
capuchins can tell us a lotabout the evolution of tool use
in humans.
We might be similar in our tooluse capacity to chimpanzees
(03:37):
because we share a commonancestor, but capuchins are way
over there, in another branch ofthe primate family tree, and
there's a whole bunch of otherprimates in between them and us
that are not tool users at all.
So it's fascinating to thinkabout how and why tool use
behavior evolves throughout theanimal kingdom.
Corvids, like crows, areanother famous group of tool
(03:58):
using species that are way offin a different branch of our
family tree.
So we can learn a lot about thekinds of conditions that are
likely to have fostered thiscognitively demanding behavior
tool use during our evolution.
Although she doesn't mention itin the lecture, pat is also a
key figure in the profession anddevelopment of primatology,
both locally in Brazil andinternationally.
(04:19):
She's currently the presidentof the Brazilian Society of
Primatology and serves theInternational Primatological
Society at its VP for Education.
So, with all that said, I'msure you're going to love
hearing about her impressivework on capuchin tool use.
And, as always, here's Dr MikeHuffman with an introduction to
Get Us Started.
Michael Huffman (04:38):
I'd like to welcome all of you again to this
lecture series.
Thanks for coming early in themorning to listen to this.
Some of you in other parts ofthe world may be in the evening,
like it is for Pat, but all ofyou are very welcome and we
really appreciate your watchingthis lecture series.
It's a really great pleasure tohave Pat join us today.
(05:01):
We've been in contact for offand on for quite some time
through journal reviews anddifferent processes like that,
and I'm very much aware of thework she's done, but I've never
probably never heard heractually speak in person.
So this is an exciting momentfor me and I think you'll all
really enjoy what she has toshare.
(05:23):
Coming from my chimpanzeeperspective, when I was first
starting there was a lot of hypeabout chimpanzee tool use and
how advanced they were andthey're the best model for human
evolution of tool use.
But when I started learningmore about the work that the
Capuchin researchers have beendoing, earlier in the series we
(05:45):
had Elisabetta Weisselbergi andshe shared some of her work.
She's a good friend and a closecollaborator with Pat, so I
think we'll learn a lot moreabout Capuchin tool use today.
But in my mind, the work thatthis group in Brazil has been
doing is incredible.
It really really outdoes,outshines the research on
(06:09):
chimpanzee tool use, I thinkbecause they've gone into it so
much more deeply and have lookedat issues that just chimpanzees
haven't done yet.
So I think we all have a lot tolearn from the work that
they're doing, and today is theday that we hear from Pat, so
I'll hand it over to you.
Thank you so much for joiningus today.
Patricia Izar (06:30):
Thank you so much , mike, for this presentation.
Thank you, sasuomo and Andrewalso for all the help here.
I'm very excited to be with youvirtually.
Well, let's go to the lecture.
The title of my lecture todayis on causes and consequences of
(06:52):
tool use lessons learned fromwild Capuchin monkeys.
And let me show you a littlemovie.
We are seeing here a cascudo.
He's the current dominant maleof.
He's an adult male, butCapuchin monkey Is it working?
(07:14):
And or or Makako prego, as wesay in Portuguese.
Capuchin monkey in Portugueseis Makako prego.
He cascudo is crack opening ahard pound nut using a hammer
stone as a tool.
That's cool.
Do is the current.
(07:35):
As I said, he's the currentdominant male of a wild group of
Capuchin monkeys, of course,that lives in this area, the,
the Fazenda Boa Vista.
Fazenda Boa Vista is an arealocated in the north.
Do you see my my arrow here?
Can you see it?
(07:56):
Fazenda Boa Vista is located inthe north eastern region of
Brazil, in the city of Gilboas,in the Piawe state.
What's important here to showto you is more or less in this
region.
This is the echo tone betweenthe sejado and the cutting and
(08:17):
this, as you can see in thispicture and also in this one and
this one.
These are the open woodlandsavanna, like Brazilian beoms
and I'm showing this picture andthis sejado area in the region
of Gilboas in Fazenda, boa Vista.
(08:38):
It's the transition with thecutting which is, in fact, the
semi arid habitat in beyond inBrazil.
So it's a very dry sejado and Iwanted to show this to you
because sometimes, when we thinkabout Brazil monkeys in Brazil
people think about the tropicalforest, the Amazonia and the
(09:01):
Atlantic forest, and this is avery different area.
As you can see here, I firstvisited this area in 2003 with
doctors Dorotifra Gazi andElisabeta Vizalberg that I
mentioned before, my colleaguesand today my very dear friends,
(09:25):
and with them and with thecollaboration of the Olivaida
family, we established thisalready long-term project that
we call the etosebus, oritosebus, to investigate the
ecological, social, cognitiveand developmental factors
(09:46):
associated to use in thispopulation, and I will talk
about it today, all thesefindings.
But I want to emphasize thatthis talk today, my talk today,
is only possible due to thislong-term collaboration among
three women scientists and allthat is involved about being
(10:09):
three women one in the UnitedStates, another one in Italy and
another one in Brazil and alsowith students from all over the
world not only our countries,but we had students from China,
from Israel, from India and withthe local community.
(10:29):
That allowed us to build along-term database that indeed
revolutionized our knowledge onnon-human to use.
First, I think it's important toemphasize that my talk today is
on robust Kapuchin monkeys.
(10:49):
This is a group of eightbiogeographic species that
belong to the genus Sapajos.
These genus, as you can seehere in this map, presents a
wide geographic distributionalmost all over South America,
from Amazonia and AtlanticForest, sejado, kattinga and
(11:12):
Pantanal.
So they occupy these differentbiomes that present distinct
ecological features and theypresent corresponding behavioral
variation in relation to theseecological.
Different ecological featuresin many behavioral domains, from
(11:35):
body posture and locomotion,more bipedal, more when they
walk, more on the ground, alsoin their navigation systems and
in their social systems.
But for the purpose of our talktoday, I want to highlight
(11:57):
their great variation in feedingbehavior.
Kapuchin monkeys are onivorousprimates.
They include a wide variety ofitems to complement their
preferential forgivry, includingmeat.
But they vary not only in thetypes of foods, the items they
(12:21):
eat, but also in their dietcomposition.
So they are mainly forgivores,but in some populations they are
more insectivores and others.
They are even more for livrosthan others, but, most
importantly again, for what weare talking today.
They can extract foods that areinaccessible for most
(12:45):
vertebrates, such as the heartof palm trees, as we can see
here Sapajos nigritos, thespecies that I study in the
Atlantic Forest that I'm nottalking about today, but they
are able to extract the leavesof the palms and eat the heart
of the palms and, of course,they can use tools to crack open
(13:09):
hard foods, including crabs andoysters, as we can see in these
pictures here from the mangrovein Malinian state.
We first described the customaryuse of stone tools in Fazenda
Boavista in 2004, in this paperof 2004.
(13:34):
And you can see in this maphere this is the PIE state and
Gilboés, fazenda Boavista ishere where we first published
this report.
Right after our publication,antonio Moura and Phyllis Lee
published another report here inSerra da Capivara.
(13:54):
So Gilboés, fazenda Boavista,in Gilboés, in Serra da Capivara
, in São Raimundo Nonato, moreor less three kilometers apart.
So is this something about PIEstate?
After these first descriptionsat that time, we're super
(14:19):
surprising.
It was really something thateverybody was oh my god, a
Platini primate using tools.
Oh, we never heard about it.
It was not known fromscientists that they were using
(14:40):
tools in nature.
And after that these firstdescriptions, other reports were
published and today we knowthat several populations along
the central portion of thedistribution of the genus
Sapajos used tools.
(15:01):
But up to now, these reportsthat are here with these
triangles and stars, all thesereports belong or are restricted
to three species Sapajoslibidinosus, as I mentioned, as
in Fazenda Boavista, sapajosflavios and Sapajos chantostenos
(15:23):
.
So among the eight species,three are reported to use tools,
so this could indicate agenetic condition for two use.
Fortunately, these threespecies, in particularly flavios
and chantostenos.
They occur in the more sherryand open biomes of Sejado and
(15:45):
Katzinga, but also in areas offorest.
Flavios and chantostenos,indeed, are species of Atlantic
forest that reach areas ofSejado and Katzinga, and the
forest populations of thesespecies do not use tools.
At least, there are no reportsof eight.
(16:07):
Intensive surveys have beenconducted.
Eduardo Toni and I revealedthese evidence in this paper
published in 2008.
And now our conclusions stillhold true.
We suggested that the evidenceat that time and it's still true
favors the idea thatenvironmental features rather
(16:32):
than cognitive differences amongspecies are related to the
emergence of two use in certainpopulations Indeed.
In a more recent reviewcomparing long-term studies on
seven populations of fourspecies of sapagios that use
(16:54):
tools and do not use tools,briseida Resendri, renata
Ferreira and I addressedexisting hypotheses to explain
variation in the occurrence oftwo use among primate
populations.
More traditionally, feedingtools have been considered a
strategy for extracting embeddedfoods in conditions of fruit
(17:18):
scarcity.
Tools would be a feedingadaptation to the necessity of
finding alternative foods.
It's called the necessityhypothesis.
Later, the idea that two usewould be associated to
availability of time and to ahigher degree of group cohesion,
(17:40):
which are more common featuresmore commonly associated to food
abundance, was introduced.
This is called the opportunityhypothesis.
By comparing our sevenpopulations Briseida, renata and
I, we found evidence that twouse is associated to higher food
(18:02):
availability.
So we found populations that donot use tools and have lower
food availability than thepopulations that use tools and
also related to the availabilityof encased foods, favoring the
opportunity hypothesis.
In the same line, in our studypopulation of Fazenda, boa Vista
(18:27):
, we analyzed two use inrelation to food availability.
This was the PhD of NoemiSpagnaletti.
We compared the frequency oftwo use between two groups, one
of which was slightlyprovisioned with palm nuts and
(18:47):
corn and the other one was notprovisioned, and between the dry
and the wet season.
In fact we conductedcorrelations with rainfall.
The rainfall is reallydifferent between the dry season
it's really dry, zero rainfalland the wet season.
(19:09):
So we did not find there was nodifference between the two
groups, provision andnon-provision, and between
seasons.
There was no correlation withrainfall in the frequency of two
use.
The only correlation we foundit was between two use in the
non-provision group and theavailability of the more
(19:33):
abundant nut, the catalan nut,that these group used to crack,
again favoring the opportunityhypothesis.
Now turning to other findings,our research also contributed to
the study of two cognition inprimates in general.
(19:56):
In 2004, when Dorie and Elisa,and also Linda Fedigand,
published the complete Kapuchin,a book that summarized
everything we knew about theCebini, the state of the art on
two use at that time by Kapuchinmonkeys was based on the
(20:18):
laboratory studies with captiveraised monkeys.
The general conclusion was thattwo use was a chance outcome
due to their manipulative andcurious and very active behavior
.
But there was no evidence thatthe monkeys perceived what was
(20:39):
important in materials andactions to achieve this success,
and I quote them in the book.
They said, from therepresentational perspective,
Kapuchins do not appear tounderstand why and how certain
familiar conditions, such as ahole in the surface, influence
(20:59):
the way an object moves across asurface.
This affirmation was alreadychallenged by our first studies
based on naturalisticobservation that strongly
suggested Kapuchins wereselecting particular stones to
(21:20):
use as tools.
Using survey techniques, weanalyzed the features of the
stones the monkeys used, as themonkeys used as anvils and as
hammers, and compared withrandom stones available in the
area.
We analyzed the type of thestone, the frailty, weight,
(21:43):
surface dimensions and heightabove the ground.
We discovered the monkeyspreferred flat surfaces for
anvils, including some woodyanvils, as we can see here in
this picture.
They use much more stone anvils, but some woody anvils as well,
(22:07):
and they preferred hardquartesite stones as hammers.
We also verified that suitableanvils are relatively common in
the area, but suitable Hammersare rare.
These river pebbles are rare inthe region.
(22:31):
Indeed, again still with thenaturalist observation, we
observed that the monkeystransport the hammer stones over
at least small distance.
Let's see this little moviehere.
We can see this juvenile one.
He grab a stone here.
(22:51):
It's a short distance, a meteror less here, but from this data
here you can see that in median, juveniles transport stones to
angels in median from fivemeters and about males 30 meters
(23:13):
.
So we also observed this wasmore important that they
transported heavier stones tocrack open palm nuts than other
foods such as cashew nuts.
So these ladders because thiswas all based on naturalist
(23:35):
observation these ladders tosuggest they were capable of at
least short term planningregarding the choice of the most
adequate two.
So a heavy stone for a piasavaresistant nut and a small stone
for a cashew nut.
But then we went to testexperimentally this idea in the
(23:59):
field, this suggestion that wemade.
We took advantage of this areathat you see here in these
pictures.
This is a natural area wherethere are several end view
stones that the monkeys alwaysuse to crack open nuts there and
we set up our field laboratorythere.
(24:20):
We call that our fieldlaboratory now and during the
time of our experiments weattract the monkeys with water
and palm nuts to the region andfor this experiment we removed
all natural hammer stones fromthe area and provided the
(24:41):
monkeys with nuts and two orthree stones, depending on the
experimental condition that weoffered.
We offered natural stones andsome artificial stones that we
built with the collaboration ofa colleague from the geology
department in the University ofSao Paulo.
(25:02):
So we built these artificialstones that could be large but
empty, and so they would belight and small, very dense ones
that would be heavy, sodifferent from the natural
stones, in which size and weightare correlated the larger the
(25:24):
hammer stone, the heavier it isin natural stones.
So we gave them natural stones,so ascent stones that cracks
easily where they beat thestones and the seed stones that
usually they use as hammers.
And we provided with small andlarge natural stones.
(25:46):
And then we started with theconflicting conditions showing
them, giving them the smallheavy stones and the large light
stones.
We can see here from this graphthat in all conditions, with
(26:09):
the natural stones and theartificial stones, the monkeys
chose significantly, chose thefunctional stone significantly
above expected, by chance, astheir first choice.
It was extremely interestingthat when we first set up the
(26:31):
experiment and they wentstraight to the large with the
artificial stones, then theywent to the large stone first
and they grabbed to leave thestone, expect that stone to be
heavy and then it was light.
So they lost their balance atthe first and they were like
(26:54):
something strong and then theywent and tapped that stone and
they went to the small one andtapped.
So after the first trial, thatwas, they were deceived by our
artificial condition.
They went to the first choicein all other experiments.
(27:16):
So we concluded this isevidence that the monkeys
perceive the affordance of thestone that make it inefficient
too.
In addition, we have shownthrough kinematic analysis,
(27:38):
using videos of nut cracking,that the monkeys also adjust
their body movement according tothe task demand.
This was the PhD of MadhuMangalam.
We show that they crack the lessresistant to cune nut.
I was talking about theOrbignia, the Piazava nut, the
(28:00):
Catulé.
These are very resistant nutsTo cune.
It's the genus astrocarium.
It's a small, rounded, muchless resistant kind of soft palm
nut and not exactly soft butbecause they have to crack, but
much less resistant.
And so they cracked this lessresistant nut by striking a
(28:27):
light stone repeatedly withmoderate force, that is, by not
exceeding a threshold.
We can see here the black barsthe amplitude of the strike for
the to cune nut and the graybars are for the Piazava nut.
(28:48):
So the amplitude is much higherfor the Piazava.
So they not exceed thethreshold for the to cune and
they modulate the kinematicparameters of each strike on the
basis of the condition of thenut, that is, the development of
the fracture following thepreceding strike.
(29:10):
So when they first hear theyperceive that the nut was first
fractured.
They use less amplitude whencracking at a cone.
In contrast, they crack at themore resistant Piazava nut by
(29:30):
striking a headstone with themaximum force that they could
generate, without modulating thekinematic parameters of their
strikes, until the nut cracked.
So it's like they perceive thedifferences of the nuts and that
they adjust their bodymovements to in accordance.
So, in summary of what I saidup to now, our studies have
(29:59):
shown that Kaputin monkeysperceive the affordances of
their materials used as tools,of the nuts they will crack open
and of their body actions, andthat they make at least short
term planning to achieve successwith minimum cost.
This body of evidence showsthat these wild monkeys are
(30:25):
cognitively different from thecaptive raised monkeys that I
mentioned before, that were theobject of that affirmation in
2004 in the complete Kaputin.
We suggest that thesedifferences are the result of
their development, of thedevelopment of these wild
monkeys within the tradition oftwo use.
(30:48):
So I'll show you that usingstone hammers in Boa Vista is a
challenging task.
Hammer stones weigh on averagealmost 1.2 kilos, which is the
weight see here.
I'm not talking about this work, but we, we waited these
monkeys for 13 years, from avery end.
(31:12):
So we have their weight duringtheir development, since they
they are very time.
Here we show in red the females, in blue the males, and we can
see that a stone of 1.2 kilossee here is a three years old
(31:33):
females.
She's already an almost anadult female.
So a stone like that is theweight of an adult females.
Some stones weigh twice afemale that a male can can hold
a fork, even a female.
We saw one female lifting afour kilos stones once.
(31:54):
So it's a very demanding task,it's hard and it takes images.
Here we show that more or lessthis is proficiency in, in that
cracking, and here is the age inmonths.
So it's more or less with five,six years that they are
reaching proficiency, finallyreaching proficiency in this
(32:15):
test.
So the images we see here homeois not cracking, trying to not
back trying.
So the images like homeo, theymust master how to hold the
hammer stone, how to positionthe net.
But ultimately what we show isthat proficiency is best
(32:41):
explained by the decrease ofthese random behaviors that you
see the here he's doing theright behavior, but then he
starts to tap the, to be the,the, the nerds on the stone, and
he turns.
And we age and they decreasemore and more these silly
(33:09):
behaviors and and and this isrelated to to the increase in
proficiency it's like theybecome more focused in what is
really important for success.
So this is achieved byindividual practice with the
material, the stunts and thenuts over the years.
(33:33):
So is this individual learning?
So how the development oftooling skills in immature
capuchins is directly andindirectly affected by the
actions of others, in otherwords, is socially mediated.
These are the results of two anda half years study following 15
(33:59):
individuals younger than sixyears old by a team of four
researchers in two pairs oneobserver registered registering
the behavior of the focalimmature and the other
registering the neighbors, theactivity of neighbors within 10
meters radius.
This is the PhD of your not ashard.
(34:22):
This method allowed us toanalyze the focal monkeys
behavior with nuts and stonesand its presence near and use in
relation to the start,continuation and end of cracking
by other members of the group.
We have shown that.
I will show the little moviesas just to illustrate on what
(34:46):
I'm showing in the graphs.
We have shown that the imagesmanipulate nuts and debris, the
debris, the debris, more oftenwhen they can see and hear
others, other members of thegroup, nuts cracking.
See here these gray bars showwhen there's nuts cracking
(35:09):
activity in the group.
So they manipulated more ofthese nuts and debris when there
is activity in the group.
And it's the opposite withother objects they manipulate
less when there is activity ofnuts cracking in the group.
Then we also show that theymanipulate.
(35:35):
This is Homeo.
Again, they manipulate nuts anddebris more often when they are
near an anvil here, more whenthey are near an anvil than when
they are away.
Again, it's the opposite withother objects, even in the
(35:55):
absence of others.
So the artifacts also affecttheir practice.
And finally, we have also shownthat the images stay near an
anvil more often when there isactivity on.
(36:17):
Others are nuts cracking thanwhen there is no nuts cracking
activity.
We can see here even near.
In fact I will show later thatthey are nuts.
The adults are not supertolerant of the others when they
are nut cracking, but see howclose Aserola is of her mother,
amore is of her mother here, andso they stay near, more near
(36:42):
the anvil when there is practice.
So, in conclusion, both theactual observation of the
activity of others and theartifacts of this activity the
nut leftovers and stonesfacilitate the practice of
percussing nuts and stones froma very early age.
(37:04):
In Fazena, boavista, artifactsleft behind when cracking nuts
facilitated the practice byimages, and adults cracking at
those sites draw their attentionto these artifacts.
Recently we have shown that theolder the monkeys get, what I'm
(37:26):
showing here is the reuse ofstones previously used by a
conspecific, and they have shownthat these reuse also increases
with age.
The older the monkeys get, themore they reuse the stones
previously used by a conspecific.
(37:47):
So we suggest that for theputings, the stones acquire
their two value with thepractice.
This was the PhD of AndresBallestados Adia and I want to
show you this move of a veryyoung one, olivia.
She just throw the function ofa stone.
She's very young, so an adultuse that stone.
(38:09):
And then she goes there and shethrow that one and she starts
to play with the nuts and in awhile she will play with the
sandstone.
See, grab the sandstones andstart to play, and soon others
will come here and do the same.
(38:30):
So when they are older thenthey will start to reuse the
functional stone.
Finally, we show that thetradition of nut cracking with
stones in Fazenda, boavistaaffects learning processes by
influencing memory and attentionof younger monkeys.
(38:52):
When others we see here in thisred bar the first red bar when
others start to crack nuts, theyoungsters immediately start to
manipulate and percuss nuts.
But, what is important, theysustain this behavior for longer
after the nut cracking ends.
(39:14):
Here we can see one minuteafter two minutes, three minutes
, even eight minutes after theend of this activity, there is
still one or other immaturemanipulating nuts and stones,
and this is significantlydifferent from other foods that
(39:35):
they manipulate.
So social influence on learningaffects not only what's learned
but the learning process itself.
Just a little movie Over hereis Giatobá, a former dominant
male who just cracked eightalready.
(39:56):
Now he's leaving and present,present at that time a young
juvenile.
He's now a grown up already.
He tries to manipulate someother young crime and he tries
(40:20):
to percuss the nut Again.
There's no activity anymore.
See, no sound of nut cracking,just others crying.
And he stays there.
Now, now, really.
(40:50):
So nut cracking has otherconsequences on the life of
these kapuchin monkeys.
It enhances competition forfood sources, what is evident by
the decreased tolerance ofdominant female starboard
subordinates in two sites.
Here I'm showing thisassociation index between pairs
(41:14):
of individuals, of females ofdifferent hanking or high high
hanking, high, middle hanking,the different diets and in fruit
trees, in palm trees and in thetwo sites.
And we can see here for bothstudied group, the unprovision
and the provision, theassociation index between
(41:37):
females is significantly lowerin two sites compared to the
other food sites, even azappable food sites that the
individuals can monopolize, andthis is related also to an
(41:57):
increased contest competition.
We see more direct, not actualaggression but formal, but we
see direct competition in twosites, much more than it would
be expected by the time theyspend there.
And this is probably related tothe rigid, linear female
(42:21):
dominance hierarchy, very stableover the years, that we
observed in Fazenda Boavista andwhat is very different from
what we observed in the other myother study populations in
Atlantic Forest where dominancerelations between females are
almost absent, they are almostegalitarian.
(42:42):
So they are loose dominancerelations in these populations
that do not use too.
So we suggest that to useincreased linearity of the
dominance hierarchy so affectsthe social structure of the
group and in fact we found asimilar effect of decreased
spatial association whencomparing the spatial
(43:05):
association of the entire group,not only females, including the
males of all ages.
We use the same database of twoand a half years we compiled
for the study of Yonet on thedevelopment of two youths that
we had the data on the identityof imaturs and we were in the
(43:26):
neighbors and we were able tobuild the association networks.
Considering the activity nutcracking are others and location
on the end view or outside theend views we build the
association networks and we sawthat the association networks
during nut cracking on the endviews were less dense and more
(43:50):
modular than during otheractivities in other locations.
So if this is such a difficultfood source to obtain, that
increases the possibility ofgetting a grass it's hard to
acquire why the monkeys are soattracted to it.
(44:10):
We have just shown that thekernel of palm nuts obtained
with the aid of toolssignificantly increases the diet
quality of caputin monkeys inFazenda, boa Fista.
This was published last yearusing a nutritional ecology
study based on daily focalfollows of individual monkeys.
(44:34):
That was the PhD of my student,lucas Peternelli dos Santos.
We compared days when themonkeys used tools to crack open
palm nuts versus days when theydid not use tools.
On days when they crack openpalm nuts with tools, they
(44:55):
acquired higher levels of fat,carbohydrate and energy, lower
levels of, I would say,non-digestible fibers.
(45:15):
When they use tools, then whenthey do not use tools and these
fibers decrease the absorptionof nutrients.
And they also acquired a morebalanced diet in terms of the
ratio between the non-proteinenergy intake and protein
ingested on days when they usedtools versus the days when they
(45:39):
did not use tools.
So two use did not increase theamount of food, not increased
diet quantity, but increasedtheir diet quality.
So, in summary, what we learnedfrom these wild caputin monkeys
(46:03):
from Fazenda Boa Fista is thattwo use is a tradition that
emerges in populations that relyon stractive foraging, coupled
with ecological contexts thatfavor manipulation and practice
with two materials.
This is a skill acquiredthrough a long process of
(46:28):
practice that is stimulated bythe activity of skilled
conspecific and by the artifactsof this activity.
Two use has importantconsequences for the life of
these caputins.
It contributes substantially toimprove their diet and, as such
a rich source, it increaseswithin group competition for
(46:53):
food, affecting patterns ofsociety.
Finally, I think our findingsmay illuminate causes and
consequences of two use inancestral hominins.
For a long time, two use and twomaking were considered a
(47:16):
feature of the genus Homo and ithas been linked to brain growth
and its social and life historycorrelates and the increase in
meat eating.
We now have sufficient evidenceof two use in hominins much
prior to the genus Homo andperhaps even two making, as we
(47:40):
can see in this just publishedpaper.
In science they are showingthese two sites in Kenya of the
genus Paranthropus and thesesites are dated almost three
(48:01):
million years ago.
So this is really really a nodeto use, and perhaps even two
making that they were using toextract bone marrow.
So to understand the evolutionof these two use as a feeding
adaptation that predates theappearance of the genus Homo.
(48:22):
Of course it's important tostudy the living apes, as Mike
did with the chimpanzees inTanzania as a case of common
ancestry, but it's alsoimportant to study the more
distant robust kaputin monkeysthat offer a possibility to
(48:45):
study a convergence.
The appearance of two usingdistant clades allow us to
search for factors associated tothis feature.
For example, our results on thenutritional significance of
tools for kaputins suggestsusing natural stone tools in
(49:07):
feeding may have improved thediet quality of hominins much
prior to the appearance of Homoand maybe also of this may be
associated to this cascade ofrelated social consequences that
are now attributed to the genusHomo.
So I think this is an important, an additional importance
(49:31):
contribution of our study.
And with that I end my talk.
I would like to thank you againa lot, a lot, for this
invitation to be here.
I thank all the fundingagencies that made this
long-term study possible, thepermits and all the students, as
(49:53):
I said, the laboratory, and ifyou have other questions after
today, you can contact me here.
Thank you very much.
Welcome to the Primate Cast Origins.
Today's origin story comes fromPatricia Isar and is all about
those amazing tool usingcapuchins of Brazil.
Welcome back to Primate CastOrigins.
(00:41):
We are here from experts in thefield of primatology and beyond
about how they got started andbecame some of the most
influential folks around.
I'm your host, andrew McIntoshfrom Kyoto University's Wildlife
Research Center, and thisepisode is taken from our
International PrimatologyLecture Series Past, present and
Future Perspectives of thefield.
This is the brainchild of DrMichael Huffman and, like Our
(01:02):
Normal Programming, is broughtto you by PsyCASP.
The main goal of the lectureseries is to share the origin
stories of experiencedpractitioners of primatology and
related fields.
To do that, mike Huffman hasinvited a revolving door of
renowned scientists to join uson the program and share their
own stories with us.
The Primate Cast Origins is ourway of sharing those stories
right here on the podcast.
(01:24):
Unlike our normal interviewformat, these lectures are being
done as part of the PsyCASPSeminar in Science Communication
, which is aimed at gradstudents here in the Primatology
and Wildlife Science program atKyoto University.
So what you'll hear is alecture that was recorded in
Zoom and generally includesslides, so there may be
references to visual aids andvideos that are not available in
(01:45):
audio only format.
But for anyone wishing to seethe speakers presenting their
talks, we invite you to checkthose out on the PsyCASP TV
YouTube channel.
Now, in this episode of thePrimate Cast Origins, we're
sharing a lecture fromprimatologist and cognitive
ethologist Professor PatriciaIsar from the University of Sao
Paulo.
Pat is one of the eminent LatinAmerican primatologists and,
(02:07):
along with her close friends andcolleagues, doctors Dorothy
Fricese and ElizabethFisselbergi, who we had
previously in this series before, she's been studying the
incredible tool use behavior ofrobust capuchins for the last
few decades.
Now, capuchins are one of thevery few non-grade eight
primates that are known tocommonly use tools in nature.
They use stones and anvils tocrack open tough nuts and
(02:30):
aquatic invertebrates.
In this lecture, pat walks usthrough a series of fascinating
experiments with thesecharismatic monkeys who, by the
way you can hear, make a seriesof audio only cameos in the
background while she shows Zoomour Zoom audience some videos.
Now her target, trying tounderstand what they know about
the tools they use and whatbenefits they gain from using
them.
Because of her long history ofobserving and experimenting with
(02:53):
wild capuchins, she challengesthe idea which, by the way, came
from laboratory experimentswith captive reared individuals,
that capuchins don't reallyunderstand how or why the tools
they're using actually work.
This is a commonly held beliefthat, unlike humans, monkeys
don't really have a strong senseof the folk physics underlying
their behavior.
Through her talk, she alsoexplores other questions, like
(03:14):
what environmental factorsaffect when and how capuchins
use tools, and how using toolsmight affect social
relationships and, of course,unlock nutritional words that
are not available to themotherwise.
She ends by talking about howthis iconic behavior in
capuchins can tell us a lotabout the evolution of tool use
in humans.
We might be similar in our tooluse capacity to chimpanzees
(03:37):
because we share a commonancestor, but capuchins are way
over there, in another branch ofthe primate family tree, and
there's a whole bunch of otherprimates in between them and us
that are not tool users at all.
So it's fascinating to thinkabout how and why tool use
behavior evolves throughout theanimal kingdom.
Corvids, like crows, areanother famous group of tool
(03:58):
using species that are way offin a different branch of our
family tree.
So we can learn a lot about thekinds of conditions that are
likely to have fostered thiscognitively demanding behavior
tool use during our evolution.
Although she doesn't mention itin the lecture, pat is also a
key figure in the profession anddevelopment of primatology,
both locally in Brazil andinternationally.
(04:19):
She's currently the presidentof the Brazilian Society of
Primatology and serves theInternational Primatological
Society at its VP for Education.
So, with all that said, I'msure you're going to love
hearing about her impressivework on capuchin tool use.
And, as always, here's Dr MikeHuffman with an introduction to
Get Us Started.
Michael Huffman (04:38):
I'd like to welcome all of you again to this
lecture series.
Thanks for coming early in themorning to listen to this.
Some of you in other parts ofthe world may be in the evening,
like it is for Pat, but all ofyou are very welcome and we
really appreciate your watchingthis lecture series.
It's a really great pleasure tohave Pat join us today.
(05:01):
We've been in contact for offand on for quite some time
through journal reviews anddifferent processes like that,
and I'm very much aware of thework she's done, but I've never
probably never heard heractually speak in person.
So this is an exciting momentfor me and I think you'll all
really enjoy what she has toshare.
(05:23):
Coming from my chimpanzeeperspective, when I was first
starting there was a lot of hypeabout chimpanzee tool use and
how advanced they were andthey're the best model for human
evolution of tool use.
But when I started learningmore about the work that the
Capuchin researchers have beendoing, earlier in the series we
(05:45):
had Elisabetta Weisselbergi andshe shared some of her work.
She's a good friend and a closecollaborator with Pat, so I
think we'll learn a lot moreabout Capuchin tool use today.
But in my mind, the work thatthis group in Brazil has been
doing is incredible.
It really really outdoes,outshines the research on
(06:09):
chimpanzee tool use, I thinkbecause they've gone into it so
much more deeply and have lookedat issues that just chimpanzees
haven't done yet.
So I think we all have a lot tolearn from the work that
they're doing, and today is theday that we hear from Pat, so
I'll hand it over to you.
Thank you so much for joiningus today.
Patricia Izar (06:30):
Thank you so much , mike, for this presentation.
Thank you, sasuomo and Andrewalso for all the help here.
I'm very excited to be with youvirtually.
Well, let's go to the lecture.
The title of my lecture todayis on causes and consequences of
(06:52):
tool use lessons learned fromwild Capuchin monkeys.
And let me show you a littlemovie.
We are seeing here a cascudo.
He's the current dominant maleof.
He's an adult male, butCapuchin monkey Is it working?
(07:14):
And or or Makako prego, as wesay in Portuguese.
Capuchin monkey in Portugueseis Makako prego.
He cascudo is crack opening ahard pound nut using a hammer
stone as a tool.
That's cool.
Do is the current.
(07:35):
As I said, he's the currentdominant male of a wild group of
Capuchin monkeys, of course,that lives in this area, the,
the Fazenda Boa Vista.
Fazenda Boa Vista is an arealocated in the north.
Do you see my my arrow here?
Can you see it?
(07:56):
Fazenda Boa Vista is located inthe north eastern region of
Brazil, in the city of Gilboas,in the Piawe state.
What's important here to showto you is more or less in this
region.
This is the echo tone betweenthe sejado and the cutting and
(08:17):
this, as you can see in thispicture and also in this one and
this one.
These are the open woodlandsavanna, like Brazilian beoms
and I'm showing this picture andthis sejado area in the region
of Gilboas in Fazenda, boa Vista.
(08:38):
It's the transition with thecutting which is, in fact, the
semi arid habitat in beyond inBrazil.
So it's a very dry sejado and Iwanted to show this to you
because sometimes, when we thinkabout Brazil monkeys in Brazil
people think about the tropicalforest, the Amazonia and the
(09:01):
Atlantic forest, and this is avery different area.
As you can see here, I firstvisited this area in 2003 with
doctors Dorotifra Gazi andElisabeta Vizalberg that I
mentioned before, my colleaguesand today my very dear friends,
(09:25):
and with them and with thecollaboration of the Olivaida
family, we established thisalready long-term project that
we call the etosebus, oritosebus, to investigate the
ecological, social, cognitiveand developmental factors
(09:46):
associated to use in thispopulation, and I will talk
about it today, all thesefindings.
But I want to emphasize thatthis talk today, my talk today,
is only possible due to thislong-term collaboration among
three women scientists and allthat is involved about being
(10:09):
three women one in the UnitedStates, another one in Italy and
another one in Brazil and alsowith students from all over the
world not only our countries,but we had students from China,
from Israel, from India and withthe local community.
(10:29):
That allowed us to build along-term database that indeed
revolutionized our knowledge onnon-human to use.
First, I think it's important toemphasize that my talk today is
on robust Kapuchin monkeys.
(10:49):
This is a group of eightbiogeographic species that
belong to the genus Sapajos.
These genus, as you can seehere in this map, presents a
wide geographic distributionalmost all over South America,
from Amazonia and AtlanticForest, sejado, kattinga and
(11:12):
Pantanal.
So they occupy these differentbiomes that present distinct
ecological features and theypresent corresponding behavioral
variation in relation to theseecological.
Different ecological featuresin many behavioral domains, from
(11:35):
body posture and locomotion,more bipedal, more when they
walk, more on the ground, alsoin their navigation systems and
in their social systems.
But for the purpose of our talktoday, I want to highlight
(11:57):
their great variation in feedingbehavior.
Kapuchin monkeys are onivorousprimates.
They include a wide variety ofitems to complement their
preferential forgivry, includingmeat.
But they vary not only in thetypes of foods, the items they
(12:21):
eat, but also in their dietcomposition.
So they are mainly forgivores,but in some populations they are
more insectivores and others.
They are even more for livrosthan others, but, most
importantly again, for what weare talking today.
They can extract foods that areinaccessible for most
(12:45):
vertebrates, such as the heartof palm trees, as we can see
here Sapajos nigritos, thespecies that I study in the
Atlantic Forest that I'm nottalking about today, but they
are able to extract the leavesof the palms and eat the heart
of the palms and, of course,they can use tools to crack open
(13:09):
hard foods, including crabs andoysters, as we can see in these
pictures here from the mangrovein Malinian state.
We first described the customaryuse of stone tools in Fazenda
Boavista in 2004, in this paperof 2004.
(13:34):
And you can see in this maphere this is the PIE state and
Gilboés, fazenda Boavista ishere where we first published
this report.
Right after our publication,antonio Moura and Phyllis Lee
published another report here inSerra da Capivara.
(13:54):
So Gilboés, fazenda Boavista,in Gilboés, in Serra da Capivara
, in São Raimundo Nonato, moreor less three kilometers apart.
So is this something about PIEstate?
After these first descriptionsat that time, we're super
(14:19):
surprising.
It was really something thateverybody was oh my god, a
Platini primate using tools.
Oh, we never heard about it.
It was not known fromscientists that they were using
(14:40):
tools in nature.
And after that these firstdescriptions, other reports were
published and today we knowthat several populations along
the central portion of thedistribution of the genus
Sapajos used tools.
(15:01):
But up to now, these reportsthat are here with these
triangles and stars, all thesereports belong or are restricted
to three species Sapajoslibidinosus, as I mentioned, as
in Fazenda Boavista, sapajosflavios and Sapajos chantostenos
(15:23):
.
So among the eight species,three are reported to use tools,
so this could indicate agenetic condition for two use.
Fortunately, these threespecies, in particularly flavios
and chantostenos.
They occur in the more sherryand open biomes of Sejado and
(15:45):
Katzinga, but also in areas offorest.
Flavios and chantostenos,indeed, are species of Atlantic
forest that reach areas ofSejado and Katzinga, and the
forest populations of thesespecies do not use tools.
At least, there are no reportsof eight.
(16:07):
Intensive surveys have beenconducted.
Eduardo Toni and I revealedthese evidence in this paper
published in 2008.
And now our conclusions stillhold true.
We suggested that the evidenceat that time and it's still true
favors the idea thatenvironmental features rather
(16:32):
than cognitive differences amongspecies are related to the
emergence of two use in certainpopulations Indeed.
In a more recent reviewcomparing long-term studies on
seven populations of fourspecies of sapagios that use
(16:54):
tools and do not use tools,briseida Resendri, renata
Ferreira and I addressedexisting hypotheses to explain
variation in the occurrence oftwo use among primate
populations.
More traditionally, feedingtools have been considered a
strategy for extracting embeddedfoods in conditions of fruit
(17:18):
scarcity.
Tools would be a feedingadaptation to the necessity of
finding alternative foods.
It's called the necessityhypothesis.
Later, the idea that two usewould be associated to
availability of time and to ahigher degree of group cohesion,
(17:40):
which are more common featuresmore commonly associated to food
abundance, was introduced.
This is called the opportunityhypothesis.
By comparing our sevenpopulations Briseida, renata and
I, we found evidence that twouse is associated to higher food
(18:02):
availability.
So we found populations that donot use tools and have lower
food availability than thepopulations that use tools and
also related to the availabilityof encased foods, favoring the
opportunity hypothesis.
In the same line, in our studypopulation of Fazenda, boa Vista
(18:27):
, we analyzed two use inrelation to food availability.
This was the PhD of NoemiSpagnaletti.
We compared the frequency oftwo use between two groups, one
of which was slightlyprovisioned with palm nuts and
(18:47):
corn and the other one was notprovisioned, and between the dry
and the wet season.
In fact we conductedcorrelations with rainfall.
The rainfall is reallydifferent between the dry season
it's really dry, zero rainfalland the wet season.
(19:09):
So we did not find there was nodifference between the two
groups, provision andnon-provision, and between
seasons.
There was no correlation withrainfall in the frequency of two
use.
The only correlation we foundit was between two use in the
non-provision group and theavailability of the more
(19:33):
abundant nut, the catalan nut,that these group used to crack,
again favoring the opportunityhypothesis.
Now turning to other findings,our research also contributed to
the study of two cognition inprimates in general.
(19:56):
In 2004, when Dorie and Elisa,and also Linda Fedigand,
published the complete Kapuchin,a book that summarized
everything we knew about theCebini, the state of the art on
two use at that time by Kapuchinmonkeys was based on the
(20:18):
laboratory studies with captiveraised monkeys.
The general conclusion was thattwo use was a chance outcome
due to their manipulative andcurious and very active behavior
.
But there was no evidence thatthe monkeys perceived what was
(20:39):
important in materials andactions to achieve this success,
and I quote them in the book.
They said, from therepresentational perspective,
Kapuchins do not appear tounderstand why and how certain
familiar conditions, such as ahole in the surface, influence
(20:59):
the way an object moves across asurface.
This affirmation was alreadychallenged by our first studies
based on naturalisticobservation that strongly
suggested Kapuchins wereselecting particular stones to
(21:20):
use as tools.
Using survey techniques, weanalyzed the features of the
stones the monkeys used, as themonkeys used as anvils and as
hammers, and compared withrandom stones available in the
area.
We analyzed the type of thestone, the frailty, weight,
(21:43):
surface dimensions and heightabove the ground.
We discovered the monkeyspreferred flat surfaces for
anvils, including some woodyanvils, as we can see here in
this picture.
They use much more stone anvils, but some woody anvils as well,
(22:07):
and they preferred hardquartesite stones as hammers.
We also verified that suitableanvils are relatively common in
the area, but suitable Hammersare rare.
These river pebbles are rare inthe region.
(22:31):
Indeed, again still with thenaturalist observation, we
observed that the monkeystransport the hammer stones over
at least small distance.
Let's see this little moviehere.
We can see this juvenile one.
He grab a stone here.
(22:51):
It's a short distance, a meteror less here, but from this data
here you can see that in median, juveniles transport stones to
angels in median from fivemeters and about males 30 meters
(23:13):
.
So we also observed this wasmore important that they
transported heavier stones tocrack open palm nuts than other
foods such as cashew nuts.
So these ladders because thiswas all based on naturalist
(23:35):
observation these ladders tosuggest they were capable of at
least short term planningregarding the choice of the most
adequate two.
So a heavy stone for a piasavaresistant nut and a small stone
for a cashew nut.
But then we went to testexperimentally this idea in the
(23:59):
field, this suggestion that wemade.
We took advantage of this areathat you see here in these
pictures.
This is a natural area wherethere are several end view
stones that the monkeys alwaysuse to crack open nuts there and
we set up our field laboratorythere.
(24:20):
We call that our fieldlaboratory now and during the
time of our experiments weattract the monkeys with water
and palm nuts to the region andfor this experiment we removed
all natural hammer stones fromthe area and provided the
(24:41):
monkeys with nuts and two orthree stones, depending on the
experimental condition that weoffered.
We offered natural stones andsome artificial stones that we
built with the collaboration ofa colleague from the geology
department in the University ofSao Paulo.
(25:02):
So we built these artificialstones that could be large but
empty, and so they would belight and small, very dense ones
that would be heavy, sodifferent from the natural
stones, in which size and weightare correlated the larger the
(25:24):
hammer stone, the heavier it isin natural stones.
So we gave them natural stones,so ascent stones that cracks
easily where they beat thestones and the seed stones that
usually they use as hammers.
And we provided with small andlarge natural stones.
(25:46):
And then we started with theconflicting conditions showing
them, giving them the smallheavy stones and the large light
stones.
We can see here from this graphthat in all conditions, with
(26:09):
the natural stones and theartificial stones, the monkeys
chose significantly, chose thefunctional stone significantly
above expected, by chance, astheir first choice.
It was extremely interestingthat when we first set up the
(26:31):
experiment and they wentstraight to the large with the
artificial stones, then theywent to the large stone first
and they grabbed to leave thestone, expect that stone to be
heavy and then it was light.
So they lost their balance atthe first and they were like
(26:54):
something strong and then theywent and tapped that stone and
they went to the small one andtapped.
So after the first trial, thatwas, they were deceived by our
artificial condition.
They went to the first choicein all other experiments.
(27:16):
So we concluded this isevidence that the monkeys
perceive the affordance of thestone that make it inefficient
too.
In addition, we have shownthrough kinematic analysis,
(27:38):
using videos of nut cracking,that the monkeys also adjust
their body movement according tothe task demand.
This was the PhD of MadhuMangalam.
We show that they crack the lessresistant to cune nut.
I was talking about theOrbignia, the Piazava nut, the
(28:00):
Catulé.
These are very resistant nutsTo cune.
It's the genus astrocarium.
It's a small, rounded, muchless resistant kind of soft palm
nut and not exactly soft butbecause they have to crack, but
much less resistant.
And so they cracked this lessresistant nut by striking a
(28:27):
light stone repeatedly withmoderate force, that is, by not
exceeding a threshold.
We can see here the black barsthe amplitude of the strike for
the to cune nut and the graybars are for the Piazava nut.
(28:48):
So the amplitude is much higherfor the Piazava.
So they not exceed thethreshold for the to cune and
they modulate the kinematicparameters of each strike on the
basis of the condition of thenut, that is, the development of
the fracture following thepreceding strike.
(29:10):
So when they first hear theyperceive that the nut was first
fractured.
They use less amplitude whencracking at a cone.
In contrast, they crack at themore resistant Piazava nut by
(29:30):
striking a headstone with themaximum force that they could
generate, without modulating thekinematic parameters of their
strikes, until the nut cracked.
So it's like they perceive thedifferences of the nuts and that
they adjust their bodymovements to in accordance.
So, in summary of what I saidup to now, our studies have
(29:59):
shown that Kaputin monkeysperceive the affordances of
their materials used as tools,of the nuts they will crack open
and of their body actions, andthat they make at least short
term planning to achieve successwith minimum cost.
This body of evidence showsthat these wild monkeys are
(30:25):
cognitively different from thecaptive raised monkeys that I
mentioned before, that were theobject of that affirmation in
2004 in the complete Kaputin.
We suggest that thesedifferences are the result of
their development, of thedevelopment of these wild
monkeys within the tradition oftwo use.
(30:48):
So I'll show you that usingstone hammers in Boa Vista is a
challenging task.
Hammer stones weigh on averagealmost 1.2 kilos, which is the
weight see here.
I'm not talking about this work, but we, we waited these
monkeys for 13 years, from avery end.
(31:12):
So we have their weight duringtheir development, since they
they are very time.
Here we show in red the females, in blue the males, and we can
see that a stone of 1.2 kilossee here is a three years old
(31:33):
females.
She's already an almost anadult female.
So a stone like that is theweight of an adult females.
Some stones weigh twice afemale that a male can can hold
a fork, even a female.
We saw one female lifting afour kilos stones once.
(31:54):
So it's a very demanding task,it's hard and it takes images.
Here we show that more or lessthis is proficiency in, in that
cracking, and here is the age inmonths.
So it's more or less with five,six years that they are
reaching proficiency, finallyreaching proficiency in this
(32:15):
test.
So the images we see here homeois not cracking, trying to not
back trying.
So the images like homeo, theymust master how to hold the
hammer stone, how to positionthe net.
But ultimately what we show isthat proficiency is best
(32:41):
explained by the decrease ofthese random behaviors that you
see the here he's doing theright behavior, but then he
starts to tap the, to be the,the, the nerds on the stone, and
he turns.
And we age and they decreasemore and more these silly
(33:09):
behaviors and and and this isrelated to to the increase in
proficiency it's like theybecome more focused in what is
really important for success.
So this is achieved byindividual practice with the
material, the stunts and thenuts over the years.
(33:33):
So is this individual learning?
So how the development oftooling skills in immature
capuchins is directly andindirectly affected by the
actions of others, in otherwords, is socially mediated.
These are the results of two anda half years study following 15
(33:59):
individuals younger than sixyears old by a team of four
researchers in two pairs oneobserver registered registering
the behavior of the focalimmature and the other
registering the neighbors, theactivity of neighbors within 10
meters radius.
This is the PhD of your not ashard.
(34:22):
This method allowed us toanalyze the focal monkeys
behavior with nuts and stonesand its presence near and use in
relation to the start,continuation and end of cracking
by other members of the group.
We have shown that.
I will show the little moviesas just to illustrate on what
(34:46):
I'm showing in the graphs.
We have shown that the imagesmanipulate nuts and debris, the
debris, the debris, more oftenwhen they can see and hear
others, other members of thegroup, nuts cracking.
See here these gray bars showwhen there's nuts cracking
(35:09):
activity in the group.
So they manipulated more ofthese nuts and debris when there
is activity in the group.
And it's the opposite withother objects they manipulate
less when there is activity ofnuts cracking in the group.
Then we also show that theymanipulate.
(35:35):
This is Homeo.
Again, they manipulate nuts anddebris more often when they are
near an anvil here, more whenthey are near an anvil than when
they are away.
Again, it's the opposite withother objects, even in the
(35:55):
absence of others.
So the artifacts also affecttheir practice.
And finally, we have also shownthat the images stay near an
anvil more often when there isactivity on.
(36:17):
Others are nuts cracking thanwhen there is no nuts cracking
activity.
We can see here even near.
In fact I will show later thatthey are nuts.
The adults are not supertolerant of the others when they
are nut cracking, but see howclose Aserola is of her mother,
amore is of her mother here, andso they stay near, more near
(36:42):
the anvil when there is practice.
So, in conclusion, both theactual observation of the
activity of others and theartifacts of this activity the
nut leftovers and stonesfacilitate the practice of
percussing nuts and stones froma very early age.
(37:04):
In Fazena, boavista, artifactsleft behind when cracking nuts
facilitated the practice byimages, and adults cracking at
those sites draw their attentionto these artifacts.
Recently we have shown that theolder the monkeys get, what I'm
(37:26):
showing here is the reuse ofstones previously used by a
conspecific, and they have shownthat these reuse also increases
with age.
The older the monkeys get, themore they reuse the stones
previously used by a conspecific.
(37:47):
So we suggest that for theputings, the stones acquire
their two value with thepractice.
This was the PhD of AndresBallestados Adia and I want to
show you this move of a veryyoung one, olivia.
She just throw the function ofa stone.
She's very young, so an adultuse that stone.
(38:09):
And then she goes there and shethrow that one and she starts
to play with the nuts and in awhile she will play with the
sandstone.
See, grab the sandstones andstart to play, and soon others
will come here and do the same.
(38:30):
So when they are older thenthey will start to reuse the
functional stone.
Finally, we show that thetradition of nut cracking with
stones in Fazenda, boavistaaffects learning processes by
influencing memory and attentionof younger monkeys.
(38:52):
When others we see here in thisred bar the first red bar when
others start to crack nuts, theyoungsters immediately start to
manipulate and percuss nuts.
But, what is important, theysustain this behavior for longer
after the nut cracking ends.
(39:14):
Here we can see one minuteafter two minutes, three minutes
, even eight minutes after theend of this activity, there is
still one or other immaturemanipulating nuts and stones,
and this is significantlydifferent from other foods that
(39:35):
they manipulate.
So social influence on learningaffects not only what's learned
but the learning process itself.
Just a little movie Over hereis Giatobá, a former dominant
male who just cracked eightalready.
(39:56):
Now he's leaving and present,present at that time a young
juvenile.
He's now a grown up already.
He tries to manipulate someother young crime and he tries
(40:20):
to percuss the nut Again.
There's no activity anymore.
See, no sound of nut cracking,just others crying.
And he stays there.
Now, now, really.
(40:50):
So nut cracking has otherconsequences on the life of
these kapuchin monkeys.
It enhances competition forfood sources, what is evident by
the decreased tolerance ofdominant female starboard
subordinates in two sites.
Here I'm showing thisassociation index between pairs
(41:14):
of individuals, of females ofdifferent hanking or high high
hanking, high, middle hanking,the different diets and in fruit
trees, in palm trees and in thetwo sites.
And we can see here for bothstudied group, the unprovision
and the provision, theassociation index between
(41:37):
females is significantly lowerin two sites compared to the
other food sites, even azappable food sites that the
individuals can monopolize, andthis is related also to an
(41:57):
increased contest competition.
We see more direct, not actualaggression but formal, but we
see direct competition in twosites, much more than it would
be expected by the time theyspend there.
And this is probably related tothe rigid, linear female
(42:21):
dominance hierarchy, very stableover the years, that we
observed in Fazenda Boavista andwhat is very different from
what we observed in the other myother study populations in
Atlantic Forest where dominancerelations between females are
almost absent, they are almostegalitarian.
(42:42):
So they are loose dominancerelations in these populations
that do not use too.
So we suggest that to useincreased linearity of the
dominance hierarchy so affectsthe social structure of the
group and in fact we found asimilar effect of decreased
spatial association whencomparing the spatial
(43:05):
association of the entire group,not only females, including the
males of all ages.
We use the same database of twoand a half years we compiled
for the study of Yonet on thedevelopment of two youths that
we had the data on the identityof imaturs and we were in the
(43:26):
neighbors and we were able tobuild the association networks.
Considering the activity nutcracking are others and location
on the end view or outside theend views we build the
association networks and we sawthat the association networks
during nut cracking on the endviews were less dense and more
(43:50):
modular than during otheractivities in other locations.
So if this is such a difficultfood source to obtain, that
increases the possibility ofgetting a grass it's hard to
acquire why the monkeys are soattracted to it.
(44:10):
We have just shown that thekernel of palm nuts obtained
with the aid of toolssignificantly increases the diet
quality of caputin monkeys inFazenda, boa Fista.
This was published last yearusing a nutritional ecology
study based on daily focalfollows of individual monkeys.
(44:34):
That was the PhD of my student,lucas Peternelli dos Santos.
We compared days when themonkeys used tools to crack open
palm nuts versus days when theydid not use tools.
On days when they crack openpalm nuts with tools, they
(44:55):
acquired higher levels of fat,carbohydrate and energy, lower
levels of, I would say,non-digestible fibers.
(45:15):
When they use tools, then whenthey do not use tools and these
fibers decrease the absorptionof nutrients.
And they also acquired a morebalanced diet in terms of the
ratio between the non-proteinenergy intake and protein
ingested on days when they usedtools versus the days when they
(45:39):
did not use tools.
So two use did not increase theamount of food, not increased
diet quantity, but increasedtheir diet quality.
So, in summary, what we learnedfrom these wild caputin monkeys
(46:03):
from Fazenda Boa Fista is thattwo use is a tradition that
emerges in populations that relyon stractive foraging, coupled
with ecological contexts thatfavor manipulation and practice
with two materials.
This is a skill acquiredthrough a long process of
(46:28):
practice that is stimulated bythe activity of skilled
conspecific and by the artifactsof this activity.
Two use has importantconsequences for the life of
these caputins.
It contributes substantially toimprove their diet and, as such
a rich source, it increaseswithin group competition for
(46:53):
food, affecting patterns ofsociety.
Finally, I think our findingsmay illuminate causes and
consequences of two use inancestral hominins.
For a long time, two use and twomaking were considered a
(47:16):
feature of the genus Homo and ithas been linked to brain growth
and its social and life historycorrelates and the increase in
meat eating.
We now have sufficient evidenceof two use in hominins much
prior to the genus Homo andperhaps even two making, as we
(47:40):
can see in this just publishedpaper.
In science they are showingthese two sites in Kenya of the
genus Paranthropus and thesesites are dated almost three
(48:01):
million years ago.
So this is really really a nodeto use, and perhaps even two
making that they were using toextract bone marrow.
So to understand the evolutionof these two use as a feeding
adaptation that predates theappearance of the genus Homo.
(48:22):
Of course it's important tostudy the living apes, as Mike
did with the chimpanzees inTanzania as a case of common
ancestry, but it's alsoimportant to study the more
distant robust kaputin monkeysthat offer a possibility to
(48:45):
study a convergence.
The appearance of two usingdistant clades allow us to
search for factors associated tothis feature.
For example, our results on thenutritional significance of
tools for kaputins suggestsusing natural stone tools in
(49:07):
feeding may have improved thediet quality of hominins much
prior to the appearance of Homoand maybe also of this may be
associated to this cascade ofrelated social consequences that
are now attributed to the genusHomo.
So I think this is an important, an additional importance
(49:31):
contribution of our study.
And with that I end my talk.
I would like to thank you againa lot, a lot, for this
invitation to be here.
I thank all the fundingagencies that made this
long-term study possible, thepermits and all the students, as
(49:53):
I said, the laboratory, and ifyou have other questions after
today, you can contact me here.
Thank you very much.
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