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Spatial abilities of Wild Chimpanzees Pan troglodytes verus

De
103 pages
Sous la direction de Michel Langlais, Christophe Boesch
Thèse soutenue le 11 juin 2010: Université de Leipzig, Bordeaux 2
Malgré la multiplicité des études démontrant le comportement fascinant des animaux dans leur milieu naturel, quelques domaines de recherches demeurent difficiles à aborder. Ainsi, l’étude de certains aspects cognitifs nécessite un certain contrôle sur l’environnement afin de dissocier les influences écologiques et sociales de l’implication cognitive ; par exemple la cognition spatiale incluant la mémoire spatiale, les mécanismes d’orientation spatiale, ainsi que leur implication dans la navigation, tel que par la planification. L’étude de la cognition spatiale des chimpanzés sauvages s’est déroulée dans le Parc national de Taï, une forêt tropicale dense où les ressources potentielles sont abondantes et réparties sur un territoire de 25 km², avec une visibilité d’environ 30 mètres. De plus, les chimpanzés vivent dans une société du type fission-fusion, impliquant de multiples relations sociales. Toutefois, l’enregistrement précis de la position et des activités des chimpanzés, ainsi qu’une carte botanique précise, nous a permis de dissocier les effets écologiques, sociaux et cognitifs afin de mieux comprendre les relations entre ces différents facteurs. Par cette étude, nous montrons que les chimpanzés ont développé un mécanisme permettant une navigation précise grâce à une carte Euclidienne contenant des informations sur la direction et la distances vers des ressources connues. Ce mécanisme est extrêmement adapté et efficace par la connaissance précise de la localisation de milliers de ressources dans leur habitat. Ces capacités permettent d’augmenter leur efficacité en sélectionnant les ressources les plus productives, en les planifiant à l’avance et, de manière plus avancée, en planifiant le parcours le plus court à travers ces différentes ressources durant la journée lorsque la pression sociale requière une meilleure précision dans le choix des ressources. Ces découvertes illustrent d’abord les capacités extraordinaires des chimpanzés, et deuxièmement que les aspects cognitifs peuvent être expliqués dans le milieu naturel des animaux.
-Pan troglodytes verus
-Carte topologique
-Mémoire spatiale
-Simulation de navigation
-Planification spatiale
-TSP
-Carte Euclidienne
Whereas numerous studies demonstrated fascinating behaviour of animals in their natural habitat, some important areas of research were difficult to tackle in the field. This is the case of many studies on cognitive aspects that required controlled environment to dissociate ecological and social influence from cognition. One of these important areas of research is the spatial cognition including spatial memory, spatial orientation mechanisms and the practical use of these abilities to travel efficiently, such as planning skills. This study on spatial cognition in wild chimpanzees took place in Taï National Park, a tropical dense forest where potential food resources are highly abundant in their 25 km² territory, and the visibility is approximately 30 meters. Adding to this complexity, chimpanzees live in a fission-fusion society, maintaining relationships with each other. Nevertheless, with a precise recording of chimpanzee’s location and activities and a precise botanic map of the territory, we were able to dissociate the ecological, social and cognitive effects and understand some relationships between these factors. Here, we showed that wild chimpanzees developed a precise mechanism to navigate efficiently in their large area using a Euclidean map containing accurate information about direction and distance to the known resources. This mechanism is highly adapted and efficient as the chimpanzees have a precise knowledge of the resources location in their area, remembering the location of thousand trees location. These highly developed abilities allowed them to increase their efficiency by selecting the most productive resources, planning them in advanced and on a higher level to plan the shortest path through these major resources during the day when the social pressure induce a higher precision in resource selection. These findings highlight first the outstanding spatial abilities of wild chimpanzees and second that cognition can be better explained in animals’ natural complex environment.
-Pan troglodytes verus spatial memory Euclidean map topological map spatial planning TSP simulation of navigation
Source: http://www.theses.fr/2010BOR21678/document
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Universität Leipzig, Biology Fakultät Université Victor Segalen Bordeaux2
Max Planck Institute for Evolutionary Ecole doctorale de Sciences Sociales
Anthropology

Thèse en cotutelle
Kooperatives Promotionsverfahren

PhD theses in Primatology

Emmanuelle Normand

Spatial abilities of Wild Chimpanzees
Pan troglodytes verus

Supervisors: Boesch Christophe / Langlais Michel
th
Defence on 11 June 2010

Jury:
1. Bernard N’Kaoua
2. Martin Schlegel
3. Glyn Goodall
4. Klaus Schilberger

Referres:
1. Paul Garber
2. Klaus Zuberbühler


This thesis is based on the following manuscripts

Normand E., Ban D.S. and Boesch C. (2009) Forest chimpanzees (Pan
troglodytes verus) remember the location of numerous fruit trees. Animal Cognition, DOI
10.1007/s10071-009-0239-7
Normand E. and Boesch C. (2009) Sophisticated Euclidean maps in forest
chimpanzees. Animal Behaviour, 77, 1195–1201.
Normand E. and Boesch C. (submitted) Chimpanzees plan in advance to
visit the most attractive resources. Animal Behaviour.






- 2 - SUMMARY
ACKNOWLEDGEMENTS ...................................................................................................... ..... 5
ABSTRACT ....................................................................................... ........ 7
RESUME ......................................................................................... ......... 8
ZUSAMMENFASSUNG ........................................................................... ..... 9
INTRODUCTION ............................................................................................................... ..... 10
1. The socio-ecological intelligence hypothesis .................................. ..... .10............
2. Captive vs. wild animals’ spatial abilities .................................... ....... .11.......
3. Spatial memory of wild primates .......................................... ....... .12.......
4. Long-term spatial memory .......................................................................... .................. .14.....
5. Spatial orientation mechanism ............................................ ........ .14......
6. Spatial abilities of humans ............................................... ........... .17.
a) Development ........................................................ ............. .17
b) Unfamiliar landscape .................................................. .......... .17...
c) The eco-cultural hypothesis ...................................................................... ............... .17.......
d) Sex differences ...................................................... .............. 18
7. Spatial planning abilities ................................................. ............ 18
8. Challenges and interests of this study ..................................... ....... .2.0.......
STUDY SITE AND SPECIE .................................................................................................... .... 21
1. Research area ......................................................... .............. 21
2. Taï Chimpanzees ....................................................... ............ 21
3. Behavioural data collection .............................................. .......... .2.2..
4. The botanic map .......................................................................................... ........................ 24
THESIS OVERVIEW .............................................................................. ..... 25
1. Spatial Memory of Wild Chimpanzees ...................................... ..... .2.5...........
2. Spatial orientation mechanism: Euclidean maps. .............................. .. .2.5................
3. Planning Abilities of Chimpanzees ................................................................ ............... .2.5......
a. Planning the visit to the most attractive resou r.c.e.s.......................... . .2.5..................
b. Planning daily path ................................................... ............ .2.6
CHAPTER 1: Forest chimpanzees (Pan troglodytess ) vererumember the location of numerous fruit
trees ................................................................................................................................ .......... 27
CHAPTER 2: Sophisticated Euclidean maps in fohriemspt acnzees ............................. .4. 6.........
CHAPTER 3: Chimpanzees plan in advance to v ismit otsht eattractive resources .............. ...... 62
CHAPTER 4 Solving the Travel Salesman Problemso cisia la evolution in Forest Chimpanzees 75
Solving the Travel Salesman Problem is a socilault ioenvo in Forest Chimpanzees ............ ...... 75
GENERAL DISCUSSION ......................................................................... .... 85
- 3 - 1. Original study, innovative results ......................................... ......... .8.5....
2. The results of this study ............................................................................... ........................ 85
a) Do chimpanzees know where the productive fruit s traere? .................... .................... 86
b) Do chimpanzees plan visiting their resources ina nacdev? ...................... .8 6......................
3. The implications of this study on the ecologicpaol thyeses ....................... .8.7.................
a) The complexity of the resources’ spatial distriobnu t.i........................... .8.7..................
b) Spatial orientation mechanism ................................................................. ............ .8.7.........
c) Evolution of primates brains and home range s.iz.e. .......................... .8.9....................
4. Implications of this study on the sociological hthyepsoes .......................... .8.9................
a) Group size influence ................................................... ........... .8.9.
b) Sex differences ......................................................................................... ........................ 90
5. Implication for the socio-ecological hypotheses. ............................... ... .9.0..............
6. Future direction on chimpanzees’ spatial cognit.io.n. ............................ .. .9.1................
REFERENCES ..................................................................................... ...... 93
ANNEXE 1: example of distribution of abundants pterceiee s: ..................................... .1.0. 1.......
ANNEXE 2: example of distribution of rare treies :s p.e.c..................................... . 1.0.2....
ANNEXE 3: The tree species selected for the bmotapn i.c.................................... .1 0..3......

- 4 - ACKNOWLEDGEMENTS

I thank the ‘Ministère de la Recherche Scientifique et de l’Enseignement Supérieur ’ and
the ‘Ministère de l’Environnement, des Eaux et Forêts’ of Côte d’Ivoire, the Director of the
“Office Ivoirien des Parcs et Réserves” (OIPR), Col Kahiba Lambert, and the Director of the
OIPR South-West Zone, Cdt Adama Tondossama, for permission to conduct this study. I would
also like to thank the OIPR officers for their constant effort in protecting the Taï National Park.
I would like to express my deepest gratitude to Prof. Christophe Boesch, my supervisor
from the Max Planck Institute in Leipzig, first for allowing me to have this experience at the Taï
Chimpanzee Project, and second for his constant assistance and advice since my Master. This
thesis would not have been possible without his trust. A very special thanks goes out to Michel
Langlais, my supervisor from the School of Cognitive Sciences in Bordeaux, whose expertise,
understanding and patience added considerably to my research.
I would also thank the ‘Centre Suisse de Recherches Scientifiques’ (CSRS) in Abidjan
for their constant availability: I would particularly like to thank Olivier Girardin, Gueladio Cissé
and Bassirou Bonfoh, as well as their respective wives who were all always helpful and cheerful
towards me. All the students and the employees of the CSRS were at all times very welcoming,
transforming my short stays at the centre into unforgettable memories. I address special thanks to
Andres Tschannen and Dorothy Newman for our in-depth resourceful discussion held over many
dinners at the center…
I would like to address special thanks to the many assistants of the Taï Chimpanzee
Project who helped in the data collection for my study. I especially Jonas Tahoo, François Yro
and Jean-Baptiste Mihi Nahan who all helped me achieve the very challenging task of mapping
the trees in the chimpanzees’ territory. I would also like to thank Nestor Gouyan Bah and Nicaise
Oulaï for their help in the data collection on the chimpanzees. I am also very grateful to the other
assistants of the Taï Chimpanzee Project who all added their special touch in making the Taï
forest a real paradise during my stay as well as all the assistants of the Taï Monkey Project and
the “Centre de Recherche en Écologie Tropicale”. I especially thank my friends Yasmin
Moëbius, Cristina Gomes and Sabrina Locatelli who shared this wonderful time with me in the
forest.
I am grateful to Dervla Dowd, Dorothy Newman, Mimi Arandjelovic and Carolyn
Rowney for improving the English of the manuscripts and this thesis. Thanks also goes out to
those who provided me with statistical advice at times of critical need: Roger Mundry and
- 5 - Damien Caillaud. This thesis would not have been possible without the support in a number of
ways from all the administrative and research staff at the Max Planck Institute, as well as from
the students who largely contributed with their feedback during the field meetings.
During the time I was managing the Taï Chimpanzee Project, I received the constant help
from Zouh Paul and for that I am very grateful. I also thank the local authorities of the village
around Taï for their understanding and support, as well as the Chiefs of the villages close to the
research area for providing their help in raising awareness about the conservation of the flora and
fauna in the Taï National Park.
I recognize that this research would not have been possible without the financial
assistance of the French ministry of Research and the Max Planck Institute.
I would also like to express my love and gratitude to my family and friends for the
support they provided me through my studies.
Lastly, it was an honour for me to meet the chimpanzees of the south group and I am
forever indebted to them for allowing my presence in their amazing community for 6 years.















- 6 - ²
ABSTRACT

Whereas numerous studies demonstrated fascinating behaviour of animals in their natural
habitat, some important areas of research were difficult to tackle in the field. This is the case of
many studies on cognitive aspects that required controlled environment to dissociate ecological
and social influence from cognition. One of these important areas of research is the spatial
cognition including spatial memory, spatial orientation mechanisms and the practical use of these
abilities to travel efficiently, such as planning skills.
This study on spatial cognition in wild chimpanzees took place in Taï National Park, a
tropical dense forest where potential food resources are highly abundant in their 25 km territory,
and the visibility is approximately 30 meters. Adding to this complexity, chimpanzees live in a
fission-fusion society, maintaining relationships with each other. Nevertheless, with a precise
recording of chimpanzee’s location and activities and a precise botanic map of the territory, we
were able to dissociate the ecological, social and cognitive effects and understand some
relationships between these factors.
Here, we showed that wild chimpanzees developed a precise mechanism to navigate
efficiently in their large area using a Euclidean map containing accurate information about
direction and distance to the known resources. This mechanism is highly adapted and efficient as
the chimpanzees have a precise knowledge of the resources location in their area, remembering
the location of thousand trees location. These highly developed abilities allowed them to increase
their efficiency by selecting the most productive resources, planning them in advanced and on a
higher level to plan the shortest path through these major resources during the day when the
social pressure induce a higher precision in resource selection. These findings highlight first the
outstanding spatial abilities of wild chimpanzees and second that cognition can be better
explained in animals’ natural complex environment.






- 7 - ²
RESUME

Malgré la multiplicité des études démontrant le comportement fascinant des animaux
dans leur milieu naturel, quelques domaines de recherches demeurent difficiles à aborder. Ainsi,
l’étude de certains aspects cognitifs nécessite un certain contrôle sur l’environnement afin de
dissocier les influences écologiques et sociales de l’implication cognitive ; par exemple la
cognition spatiale incluant la mémoire spatiale, les mécanismes d’orientation spatiale, ainsi que
leur implication dans la navigation, tel que par la planification.
L’étude de la cognition spatiale des chimpanzés sauvages s’est déroulée dans le Parc
national de Taï, une forêt tropicale dense où les ressources potentielles sont abondantes et
réparties sur un territoire de 25 km, avec une vis ibilité d’environ 30 mètres. De plus, les
chimpanzés vivent dans une société du type fission-fusion, impliquant de multiples relations
sociales. Toutefois, l’enregistrement précis de la position et des activités des chimpanzés, ainsi
qu’une carte botanique précise, nous a permis de dissocier les effets écologiques, sociaux et
cognitifs afin de mieux comprendre les relations entre ces différents facteurs.
Par cette étude, nous montrons que les chimpanzés ont développé un mécanisme
permettant une navigation précise grâce à une carte Euclidienne contenant des informations sur
la direction et la distances vers des ressources connues. Ce mécanisme est extrêmement adapté et
efficace par la connaissance précise de la localisation de milliers de ressources dans leur habitat.
Ces capacités permettent d’augmenter leur efficacité en sélectionnant les ressources les plus
productives, en les planifiant à l’avance et, de manière plus avancée, en planifiant le parcours le
plus court à travers ces différentes ressources durant la journée lorsque la pression sociale
requière une meilleure précision dans le choix des ressources. Ces découvertes illustrent d’abord
les capacités extraordinaires des chimpanzés, et deuxièmement que les aspects cognitifs peuvent
être expliqués dans le milieu naturel des animaux.






- 8 - ZUSAMMENFASSUNG

Trotz zahlreicher Studien, die das faszinierende Verhalten von Wildtieren in ihrer
natürlichen Umwelt dokumentieren, bleiben einige Studienfelder schwer erfassbar. So ist zum
Beispiel bei der Erforschung von bestimmten kognitiven Aspekten die Rücksichtnahme auf den
Umweltfaktor erforderlich, damit Umwelt- und Sozialeinfluss von den kognitiven Faktoren
unterschieden werden können. Zu diesen Untersuchungsfeldern gehört die Raumkognition,
welche das Raumgedächtnis, die Mechanismen der Raumorientierung sowie deren effizientes
Nutzen durch die Schimpansen, z.B. durch ihre Fähigkeit zum Planen, einschließt.
Die vorgestellte Studie über Raumkognition bei wild lebenden Schimpansen wurde im
Nationalpark von Tai durchgeführt, das heißt, in einem dichten tropischen Wald, wo potentielle
Ressourcen bei einer Sichtweite von ungefähr 30 Metern auf einem 25 qm großen Areal
reichlich verteilt sind. Hinzu kommt, dass Schimpansen in einer Fission-Fusion
Gesellschaftsstruktur leben, die vielfache soziale Beziehungen fördern. Jedoch, mit einer
genauen Registrierung der räumlichen Lage und der Aktivitäten der Schimpansen und anhand
einer präzisen botanischen Karte des Gebiets, konnten wir die Umwelt-, Sozial- und kognitiven
Effekte gegeneinander abgrenzen und somit die zwischen diesen unterschiedlichen Faktoren
bestehenden Beziehungen erfassen.
In dieser Studie zeigen wir, dass Schimpansen einen besonderen Mechanismus zur
Raumorientierung auf ihrem Gebiet entwickelt haben. Dabei verfügen sie über eine euklidische
Mind-Karte mit präzisen Informationen über Richtungen und Entfernungen zu den bekannten
Ressourcen. Durch ein genaues Wissen über die Verteilung der Nahrungsressourcen auf ihrem
Gebiet ist dieser Mechanismus hoch effizient. Dank dieser Fähigkeiten werden Schimpansen
immer effizienter, indem sie die ergiebigsten Ressourcen auswählen, dabei planende Fähigkeiten
einsetzen und weiterhin indem sie an einem Tag die kürzeste Strecke zu den verschiedenen
Ressourcen ausmachen, wenn der soziale Druck höchste Präzision in der Wahl der
Nahrungsressourcen erfordert.
Diese Erkenntnisse erhellen zuallererst die außergewöhnlichen Fähigkeiten der wild
lebenden Schimpansen und beweisen, dass sich kognitive Mechanismen bei wild lebenden
Tieren in ihrer natürlichen Umwelt besser erklären lassen.


- 9 - INTRODUCTION


1. The socio-ecological intelligence hypothesis
“It is my Hypothesis that the extreme diversity of plant foods in tropical forests and the
manner in which they are distributed in space and time have been a major selective force in the
development of advanced cerebral complexity in certain higher primates.” Milton 1981.

Living in a tropical forest involves coping with a complex environment containing an
unpredictable spatial and temporal distribution of resources. Animals in their natural habitat have
to deal with various constraints relative to their particular behavioural, social and ecological
adaptations. Primates face a daily challenge to locate food resources during seasonal food
scarcity (Anderson et al., 2005), beware of various predators, and all this, with respect to their
social organization. These socio-ecological constraints have been proposed as being good
parameters to explain the evolution of brain size or intelligence. One such theory is the
ecological intelligence hypothesis proposed by Clutton-Brock and Harvey (1980) and Milton
(1981). It claims that the ecological complexity of primates’ environments is the factor that
favoured the evolution of intelligence. Moreover, the development of high cognitive abilities
could have been favoured in frugivorous primates by the dispersed and unpredictable food
resources that necessitate complex extraction manipulation (Milton, 1981; Boesch & Boesch-
Achermann, 2000).
The second approach is the Machiavellian intelligence hypothesis, also called the social
intelligence hypothesis and argues that the complexity of social networks relative to group size
constrained the evolution of brain size to memorise and develop social and cognitive skills to
manage relationships (Dunbar, 1998, 2003; Whiten & Byrne, 1997).
Both propositions have been tested under an evolutionary perspective measuring
correlation between primate brain and ecological (Clutton-Brock & Harvey, 1980; Mace et al.,
1980; Milton, 1981) or social parameters (Humphrey, 1976; Dunbar, 1998, Stephan et al, 1981).
Among the results showing correlation of brain size/weight or different brain parts with either
ecological or social factors, we retain the more recent research of Barton (1996) confirming the
positive correlation between the neocortex volume of primates and social group size in general
- 10 -