Pan Africa NewsThe Newsletter of the Committee for the Careand Conservation of Chimpanzees, and the Mahale
Wildlife Conservation Society
ISSN 1884-751X (print), 1884-7528 (online) mahale.main.jp/PAN/

JUNE 2018
P. A. N. EDITORIAL STAFF
Chief Editor:
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Deputy Chief Editor:
Michio Nakamura, Kyoto University, Japan
Associate Editors:
Christophe Boesch, Max-Planck Institute, Germany
Jane Goodall, Jane Goodall Institute, USA
Tetsuro Matsuzawa, Kyoto University, Japan
William C. McGrew, University of St. Andrews, UKJohn C. Mitani, University of Michigan, USA
Vernon Reynolds, Budongo Forest Project, UK
Yukimaru Sugiyama, Kyoto University, Japan
Richard W. Wrangham, Harvard University, USA
Takeshi Furuichi, Kyoto University, Japan
Editorial Secretaries:
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Koichiro Zamma, Nagano College of Nursing, Japan
Eiji Inoue, Toho University, Japan
Takuya Matsumoto, Research Institute for Humanity and Nature,Japan
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VOL. 25, NO. 1

Contents<NOTE >
Masturbation with a Tool by an Infant Male
Chimpanzee
Michio Nakamura				2<NOTE>
Four Cases of Grooming Sessions between
Chimpanzees and Guenons at the Kalinzu Forest
Reserve, Uganda
Takumi Tsutaya, Natsumi Aruga,
Hodaka Matsuo, & Chie Hashimoto		

5<NOTE>
Deposit and Theft? Two Unusual Interactions overWild Plant Food between Adult Chimpanzees in
MahaleTakuya Matsumoto & Hiroko Sakuragi
8<BOOK REVIEW>
Following Fifi. My Adventures among Wild
Chimpanzees: Lessons from Our Closest Relatives(By John Crocker); Among Chimpanzees. Field Notes
from the Race to Save Our Endangered Relatives (By
Nancy J Merrick)William C. McGrew
11<ERRATUM>

13<EDITOR’S NOTE>

14

Pan Africa News, Vol. 25, No.1
Published in June, 2018
Address: c/o Human Evolution Studies,
Dept. of Zoology, Faculty of Science,
Kyoto Univ., Kyoto, 606-8502, JAPANTEL: (+81)75-753-4108
FAX: (+81)75-753-4115
E-mail: pan.editor@gmail.com
URL: http://mahale.main.jp/PAN/
ISSN: 1884-751X (Print), 1884-7528 (Online)1Pan Africa News, 25(1): 2–4 (2018)

Note

Masturbation with a Tool by an Infant Male Chimpanzee
Michio Nakamura
Graduate School of Science, Kyoto University, Japan(E-mail: nakamura@jinrui.zool.kyoto-u.ac.jp)

INTRODUCTION

Here I report a case of “masturbation” with a tool
by a wild infant chimpanzee. More accurately, the infantmale inserted his erect penis into a wadge discarded byan adult male and performed several thrusts, as if he was
copulating with the wadge. The observed “masturbation”
did not involve ejaculation, because infant chimpanzees
are unable to ejaculate. A similar behavior, i.e., rubbing
the penis against a piece of fruit (e.g., orange peel), wasreported for infant male orangutans in captivity (Harrison
1962). There are also some reported cases of captive or
rehabilitant orangutans and chimpanzees stimulating theirown genitals with tools (Dixson 2012).
Masturbation, or self-stimulation of one’s own sexualorgans, is common among humans and nowadays is regarded as useful for healthy sexual development (Kaestle& Allen 2011). Various nonhuman primates are also
known to masturbate (Thomsen et al. 2003; Dixson 2012;
Thomsen & Sommer 2015); therefore, it may be a phylogenetically ancient behavior. However, there are relatively
few studies that focus on masturbation among nonhuman primates in the wild (Thomsen & Soltis 2004). Malechimpanzees (Pan troglodytes) are known to stimulate
their own penises. Although Goodall (1989) noted that
captive chimpanzees sometimes ejaculate by stimulating
their own penises, it had not been observed to result in
ejaculation in the wild conspecifics at Gombe. Similarly,
at Mahale, it is common for males to “fumble with penis,”but without it culminating in ejaculation (Nishida et al.
1999). Such fumbling of penis is done usually by hand (andsometimes by foot), but, thus far, I have found no reportsof such penile-stimulating behaviors with tools, at least inwild chimpanzee populations.

Figure 1. Peace on the back of his mother, Puffy

ten eaten by wadging (i.e., extracting juice by chewing
and compressing the fruits; defined by Goodall 1989; seealso Figure 2). After extracting the juice, the remainder isusually spat out as “a wadge.”
At 14:36 h, Primus and Puffy seemed to have finishedfeeding and started grooming each other on the riverbed,
while Peace sat nearby (Figure 3). Then at 14:47 h, Peacepicked up a wadge of Ficus discarded by Primus and applied it to his genital area, inserting his erect penis into it
and thrusting several times (Figure 4; Video 1 available
at http://mahale.main.jp/PAN/2018/001.html). He successively used several wadges. At 14:52 h, he copulated withan estrus adult female, Omo.

Discussion

Probably, no one would doubt that so called “sextoys,” which some human males use for masturbation,
are “tools” in the broader sense. The wadges into which

Observation

The observation was made on the M group chimpanzees at the Mahale Mountains National Park, Tanzania (forthe research site, see Nakamura et al. 2015). The “masturbation” event was recorded for a two-year old infant malenamed Peace, first born of Puffy (Figure 1). Puffy wasborn in the M group and has an elder maternal brother (i.e.,
uncle to Peace), Primus, who is the current alpha male ofthe M group.
On September 15th 2016, I was conducting ad libitum
observations by following a party of chimpanzees sincemorning. At 11:04 h, I saw Puffy and Peace descending
to the rocky riverbed of the Kasiha Valley. Many chimpanzees of the M group were feeding on Saba comorensis
and Ficus vallis-choudae fruits along the valley while
they slowly moved downstream. The Ficus fruits are of-

Figure 2. An adult male eating Ficus vallis-choudae fruits
by wadging

2

Pan Africa News, 25(1): 2–4 (2018)
Dubuc et al. 2013), these studies clearly showed that thedefined behaviors of these males did sometimes lead to
ejaculation. On the other hand, in the case of Mahale
chimpanzee males (including sexually mature ones),
Nishida (2008) emphasizes that their penile fumbling “isnot masturbation” because it completely lacks ejaculation.
Considering that male masturbation requires ejaculation,
as stated in the study by Nishida, the observed subject(Peace) cannot be stated to have masturbated.
Some authors say that it is inappropriate to call contact to/with sexual organs by infant primates as sexual(Mizuhara 1981). On the other hand, Takenoshita (2009)
argues that some behaviors can be sexual even without
ejaculation. It is difficult to discern whether or not an
infant chimpanzee, which cannot ejaculate, had sexualpleasure by stimulating his own penis. At least, when achimpanzee infant male inserts his erect penis into thevagina of a female and thrusts it (without ejaculation),
the behavior is called “copulation” (e.g., Hasegawa 1990),
the same term used for a mature male’s almost identicalsexual behavior. Hence, Peace’s behavior may be regarded
as sexual, despite lacking ejaculation. Peace copulatedwith an estrous female following his behavior involving
wadges; hence, it seems that motivation underlying thisbehavior might have been similar to that underlying copulation with a female.

Figure 3. Primus (left) and Puffy (right) grooming eachother while Peace sits in front

Peace inserted his penis apparently have the same function with those of “sex toys” even though the wadges Acknowledgments
I would like to thank the Tanzania Commission for Science
were not purposefully made for that function. The wadges
had just been discarded; therefore, they seem to have had and Technology, the Tanzania Wildlife Research Institute, andthe Tanzania National Parks for the permissions to conduct
moderate warmth, moisture, and softness that may give field research at Mahale. I would also like to thank Dr. Ruth
more pleasurable stimuli than those made with a hand or Thomsen, Dr. Kazuhiko Hosaka, and an anonymous reviewer
with rubbing his penis against ground. The wadges are for their helpful comments and suggestions on the earlier manualso manipulable objects and thus meet the criteria of ani- script. The study was supported by the MEXT/JSPS kakenhi
JP15H04429, #4903 JP17H06381, and JP26284138.
mal “tools” (Shumaker et al. 2011).
According to Morris (1971), the word masturbation
appears to be a corruption of manu-stuprare, or “to defile with the hand,” thus itprimarily implies using a hand. Definitionsof masturbation by macaque (Macacaspp.) males also include “manual rubbing”(Thomsen & Soltis 2004) or “manual manipulations” (Dubuc et al. 2013). However,these cases may simply reflect the use ofa hand or hands being observed, and if wethink of human and nonhuman ape masturbation using tools, the use of hand may
not necessarily be a condition of the definition of masturbation.
Some may consider that male masturbation potentially leads to ejaculation(though it may sometimes end before ejaculation). The fact that discussions of malemasturbation are often done in strong connection with sperm competition (Thomsen
et al. 2003) also implies that ejaculationis thought of as a basic and fundamental
component of this behavior. Althoughbehavioral definitions of male primate
masturbation do not usually require ejacu- Figure 4. Peace inserting his penis into a wadge and thrusting (still images
lation to occur (Thomsen & Soltis 2004; taken from video)3

Pan Africa News, 25(1): 2–4 (2018)
Press, Cambridge.
Nishida T 2008. [Society of Chimpanzees.] Tōhō Shuppan,
Tokyo, in Japanese.
Nishida T, Kano T, Goodall J, McGrew WC, Nakamura M
1999. Ethogram and ethnography of Mahale chimpanzees.
Anthropol Sci 107:141–188.

References

Dixson AF 2012. Primate Sexuality. Oxford University Press,
Oxford.
Dubuc C, Coyne SP, Maestripieri D 2013. Effect of mating activity and dominance rank on male masturbation
among free-ranging male rhesus macaques. Ethology 119:1006–1013.

https://doi.org/10.1537/ase.107.141

Shumaker RW, Walkup KR, Beck BB 2011. Animal Tool
Behavior: The Use and Manufacture of Tools by Animals.
The Johns Hopkins University Press, Baltimore.
Ta ke nosh it a Y 20 09. [Sex by Japa ne se ma ca que s:“Proceptivity” observed in homosexual behaviors.] In:[Anthropology of Sex.] Okuno K, Shiino W, Takenoshita Y(eds), Shunpū-sha, Tokyo, pp. 3–34, in Japanese.
Thomsen R, Soltis J 2004. Male masturbation in free-ranging
Japanese macaques. Int J Primatol 25:1033–1041.

https://doi.org/10.1111/eth.12146

Goodall J 1989. Glossary of Chimpanzee Behaviors. Jane
Goodall Institute.
Hasegawa T 1990. [Mystery of promiscuous society: Sexual
life of chimpanzees.] In: [Cultural Historiography ofMonkeys.] Nishida T, Izawa K, Kano T (eds), Heibon-sha,
Tokyo, pp. 371–388, in Japanese.
Harrisson B 1962. A study of orang-utan behaviour in thesemi-wild state 1959–60. Int Zoo Yearb 3: 57–68.

https://doi.org/10.1023/B:IJOP.0000043350.75897.89

https://doi.org/10.1111/j.1748-1090.1962.tb03396.x

Thomsen R, Soltis J, Teltscher C 2003. Sperm competition and the function of male masturbation in nonhuman primates. In: Sexual Selection and Reproductive
Competition in Primates. Jones CB (ed), American Societyof Primatologists, Norman, pp. 437–453.
Thomsen R, Sommer V 2015. Masturbation (nonhumanprimates). In: The International Encyclopedia of Human
Sexuality (First Edition). Whelehan P, Bolin A (eds),
Wiley-Blackwell, Boston.

Kaestle CE, Allen KR 2011. The role of masturbation in
healthy sexual development: Perceptions of young adults.
Arch Sex Behav 40: 983–994.
https://doi.org/10.1007/s10508-010-9722-0

Mizuhara H 1981. [Notes on Behavioral Theory of Japanese
Macaques.] Dōbutsu-sha, Tokyo, in Japanese.
Morris D 1971. Intimate Behaviour: A Zoologist’s Classic
Study of Human Intimacy. Random House, New York.
Nakamura M, Hosaka K, Itoh N, Zamma K 2015. Mahale
Chimpanzees: 50 Years of Research. Cambridge University

https://doi.org/10.1002/9781118896877.wbiehs289

Received: 4 October 2017
Accepted: 1 February 20184

Pan Africa News, 25(1): 5–7 (2018)

Note

Four Cases of Grooming Sessions between Chimpanzees andGuenons at the Kalinzu Forest Reserve, Uganda
Takumi Tsutaya1,2, Natsumi Aruga3, Hodaka Matsuo3, & Chie Hashimoto3
1 Graduate School of Science, Kyoto University, Kyoto, Japan
2 Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan
2 Primate Research Institute, Kyoto University, Aichi, Japan(E-mail: tsutayatakumi@gmail.com)

INTRODUCTION

Detailed Observation
On December 2, 2015, a chimpanzee mother (Ida)
was the subject of focal animal sampling from 10:34 h at aMusanga-dominant secondary forest. Her offspring (Iku,
a 10-year-old female; Iyo, a 5-year-old female; and Iliya,
a 2-year-old male) were accompanied by Ida, but Iku wasout of the observers’ sight for most of the observation
period. Other chimpanzees were not observed, and their
voices were not heard during the observation period. Aftereating fruits of Musanga, Ida made day bed at 10:49 hand rested until the end of the observation period. Aroundnoon, a solitary male red-tailed monkey (RT1) approachedwithin 30 m and started feeding on the fruits of Musanga.
Around 13:00 h, Iyo and Iliya moved to a Funtumia africana tree located 10 m away from Ida’s tree and possibly started interacting with RT1. We estimated RT1 as asolitary (i.e., individual who does not belong to a specificgroup) because we did neither see nor hear the presence ofother red-tailed monkeys during the observation.
At 13:08 h, the first author observed RT1’s tail next
to Iyo and Iliya at the F. africana tree and started recording a video from 13:10:07 h (Video 1 available online at
http://mahale.main.jp/PAN/2018/003.html). Iyo was on
the adjacent branch (< 1 m away) with RT1, and Iliya
was on a different branch, approximately 1 m above. RT1
seemed to request grooming by posing his shoulder, hip,cheek, tail, or back mostly to Iyo and sometimes to Iliya.
Iyo groomed at least the hip, cheek, tail, and back of RT1
by hand and mouth (Figure 1). Iyo held RT1’s tail andinspected it for more than 10 s. Iliya touched RT1 but did
not groom him. Self-scratching was observed by both Iyo
and RT1. After a sudden movement by RT1, Iyo and Iliya
moved to another branch in the same tree at 13:15:04 h.
No grooming from RT1 was observed.
After this grooming interaction, no grooming wasobserved, but Iyo and Iliya shook branches on which RT1
was sitting (see Video 2 from 13:18:21 h, Video 3 from
13:21:15 h, and Video 4 from 13:24:00 h available online
at http://mahale.main.jp/PAN/2018/003.html). Iyo madeday bed and rested in it (Video 3). Finally, RT1 moved
5 m from Iliya on the same tree, after Iliya shook a RT1’s
branch at 13:24:50 h (Video 4). From 13:24:49 h, Iyo andIliya played with each other. At 13:26:15 h, RT1 moved toanother tree and left the chimpanzees.
Throughout the interaction, Ida was observed by aInteractions between wild chimpanzees and other primates have mostly been studied in terms of hunting (e.g.,
Boesch & Boesch 1989). On the other hand, affiliativeinteractions have been less studied. Although a few cases
on affiliative interactions have been reported, evidence
is mostly anecdotal and sporadic. Young chimpanzees
frequently play with and sometimes engage in grooming with young baboons in Gombe, Tanzania (Goodall
1986; Teleki 1973). Grooming of a red-tailed monkey bya subadult female chimpanzee was observed in Budongo,
Uganda (John & Reynolds 1997).
Here four cases of affiliative interactions (i.e., grooming) between wild chimpanzees and sympatric guenons
in the Kalinzu Forest Reserve, Uganda, are reported.
One case is described in detail, and the other three othercases are succinctly described. Although these cases are
anecdotal, they contribute to understand typical affiliativeinteractions between wild chimpanzees and sympatricguenons.

OBSERVATIONSKalinzu Forest Reserve
The Kalinzu Forest Reserve is located in western
Uganda (30°07′E, 0°17′S) and covers an area of 137 km²(Hashimoto 1998). Ecological and behavioral studies onwild chimpanzees in the Kalinzu Forest Reserve havebeen conducted since 1992. Six sympatric primate species have been identified in the reserve: eastern chimpanzee (Pan troglodytes schweinfurhii), blue monkey(Cercopithecus mitis), red-tailed monkey (C. ascanius),
L’Hoest’s monkey (C. lhoesti), Abyssinian black-andwhite colobus (Colobus guereza), and olive baboon (Papio
anubis) (Hashimoto 1998). The two dominant tree species
in the Kalinzu Forest Reserve are Parinari excelsa, a primary forest species, and Musanga leo-errerae, a secondary forest species, and several Ficus trees are also found(Hashimoto 1998). The fruits of Musanga and Ficus areimportant food sources for primates in the Kalinzu Forest
Reserve (Tashiro et al. 1999).
The studied group of chimpanzees was the M-group(Hashimoto 1998), which has been continuously studied
since 1997. There are approximately 100 individuals inthis group, and most group members have been identified(Hashimoto et al. 2015).

5

Pan Africa News, 25(1): 5–7 (2018)

Figure 1. Iyo grooms a solitary male red-tailed monkey (RT1).

Other Three Cases
Although detailed data are not available, three additional cases of affiliative interactions between chimpanzees and solitary guenons were observed in the Kalinzu
Forest Reserve. These guenons were estimated as solitary
because we did neither see nor hear the presence of theother monkeys during the observation.
The second author observed that a chimpanzee
mother (Nono) groomed her older offspring (Noe, an
11-year-old female). Her younger offspring (Nobita, a5-year-old male) played alone within 2 m from Nono. A
solitary male blue monkey (BM1) approached within 10
m to these chimpanzees at 13:42 h on June 30, 2015. BM1
approached within 2 m to Nono at 13:52 h and touched
Nono by hand to groom her several times from 13:55 h
to 13:58 h. Nobita swayed a branch behind Nono toward
BM1, and Noe drove away BM1 at 13:59 h. No otherchimpanzees were present within the observer’s sight.
The third author observed a solitary red-tailed monkey (RT2) approaching a resting mother–infant pair ofchimpanzees. Although RT2 posed his back to the infant
within < 1 m, possibly to request grooming, the mothersubsequently drove RT2 away. No other chimpanzees
were present within the observer’s sight.
The last author observed Minny (a juvenile female
chimpanzee) grooming a solitary male blue monkey(BM2) on a Ficus saussureana tree for more than 1 h.
Minny traveled with Gai (a nulliparous adult female) during the observation day. BM2 requested grooming by
posing his back to Minny. BM2 did not groom the chimpanzees. No other chimpanzees were present within theobserver’s sight.

offspring, and all actor of guenon side is solitary male.
Because adult chimpanzees tend to be aggressive to otherspecies (Ross et al. 2009), guenons probably avoid groupsof chimpanzees, especially groups of adult male chimpanzees (but see Hosaka & Ihobe 2015). However, immature
chimpanzees have a relatively small body size, and thus
guenons may be able to approach non-adult chimpanzees
without fear of lethal aggression.
Solitary guenon males seem to spontaneously approach isolated mother–offspring pairs and small groupsof female chimpanzees and request grooming from them.
One possible reason for this behavior is hygiene. Freeland(1981) reported that a pet male red-tailed monkey gets
8.2 ticks per hour as a result of nine walks in the Kibale
forest, Uganda. Because some parts of the body are difficult to reach and groom, grooming by other individuals
is important to keep the whole body clean. Red-tailed
and blue monkeys create one-male social group. Adult
males are intolerant of each other and do not form “bachelor groups” in these species (Struhsaker 1980; Butynski1982). Because of such social structures, solitary male
red-tailed and blue monkeys need to be groomed by otherspecies. It has been reported that solitary male red-tailed
monkeys sometimes travel with groups of red colobus(Colobus badius) in the Kibale Forest, Uganda and are
groomed by members of the group (Struhsaker 1981). The
last author observed a solitary male red-tailed monkey
travel with and be groomed by a group of Abyssinian
black-and-white colobus in the Kalinzu Forest Reserve. It
is possible that solitary male red-tailed and blue monkeys
approach isolated mother–offspring chimpanzee pairs
with the expectation of being groomed.
Because the observations reported here are anecdotal,collecting quantitative data on affiliative interactions willbe crucial to further understand inter-species relationships
between sympatric primates.

DISCUSSIONACKNOWLEDGMENTS

local research assistant. She was resting in her bed about
10 m away from the F. africana tree and was totally
ignorant.

Most actors of chimpanzee side are mother andWe thank local research assistants for helping our field-

6

Pan Africa News, 25(1): 5–7 (2018)
Reserve, Uganda. Primates 56:301–305.

work. We are grateful to Yasuko Tashiro, Moe Go, Hiroshi
Ihobe, Ikki Matsuda, Mina Isaji, Hiroyuki Takemoto, Takeshi
Furuichi, members of Laboratory of Human Evolution Studies,and a reviewer for helpful comments on this study. This work
was supported in part by Grants-in-Aid for Scientific Research(KAKENHI: 15J00464) from the Japan Society for the
Promotion of Science.

https://doi.org/10.1007/s10329-015-0478-y

Hosaka K, Ihobe H 2015. Interspecific relationships. In:
Mahale Chimpanzees: 50 years of Research. Nakamura M,
Hosaka K, Itoh N, Zamma K (eds), Cambridge University
Press, Cambridge, pp. 213–224.
John T, Reynolds V 1997. Budongo Forest chimpanzee
grooms a redtailed monkey. Pan Afr News 4:6.
https://doi.org/10.5134/143349

REFERENCES

Ross SR, Holmes AN, Lonsdorf EV 2009. Interactions
between zoo-housed great apes and local wildlife. Am J
Primatol 71:458–465.

Boesch C, Boesch H 1989. Hunting behavior of wild chimpanzees in the Taï National Park. Am J Phys Anthropol
78:547–73.

https://doi.org/10.1002/ajp.20675

https://doi.org/10.1002/ajpa.1330780410

Struhsaker TT 1980. Comparison of the behaviour and ecology of red colobus and redtail monkeys in the Kibale Forest,
Uganda. Afr J Ecol 18:33–51.

Butynski TM 1982. Harem-male replacement and infanticidein the blue monkey (Cercopithecus mitus stuhlmanni) in
the Kibale Forest, Uganda. Am J Primatol 3:1–22.

https://doi.org/10.1111/j.1365-2028.1980.tb00269.x

https://doi.org/10.1002/ajp.1350030102

Struhsaker TT 1981. Polyspecific associations among tropicalrain-forest primates. Z Tierpsychol 57:268–304.

Freeland WJ 1981. Functional aspects of primate grooming.
Ohio J Sci 81:173–177.
Goodall J 1986. The Chimpanzees of Gombe: Patterns of
Behavior. Belknap Press, Cambridge.
Hashimoto C 1998. Chimpanzees of the Kalinzu Forest,
Uganda. Pan Afr News 5:6–8.

https://doi.org/10.1111/j.1439-0310.1981.tb01928.x

Tashiro Y, Furuichi T, Hashimoto C 1999. A preliminary
report of the feeding ecology of chimpanzees in the
Kalinzu forest reserve, Uganda: fecal analysis and habitatuse. Primate Res 15:179–185, in Japanese with English
summary.

https://doi.org/10.5134/143364

Hashimoto C, Isaji M, Koops K, Furuichi T 2015. First records of tool-set use for ant-dipping by Eastern chimpanzees (Pan troglodytes schweinfurthii) in the Kalinzu Forest

https://doi.org/10.2354/psj.15.179

Teleki G 1973. The omnivorous chimpanzee. Sci Am 228:
32–42.

Received: 16 December 2017
Accepted: 23 March 20187

Pan Africa News, 25(1): 8–10 (2018)

Note

Deposit and Theft? Two Unusual Interactions over Wild Plant
Food between Adult Chimpanzees in Mahale
Takuya Matsumoto1,2,3 & Hiroko Sakuragi1,4
1 Japan Society for the Promotion of Science (JSPS) Research Fellow
2 Graduate School of Science, Kyoto University, Japan
3 Research Institute for Humanity and Nature, Japan
4 Wildlife Research Center, Kyoto University, Japan(E-mail: matsumoto@chikyu.ac.jp)

INTRODUCTION

using her teeth and placed one half in CT’s right foot. CT
kept holding the half with the same foot, while XP kept
the other half in her left hand. CT kept peering at XP’s
mouth and did not show interest in the fragment handed
by XP. After XP finished eating the first half, she tookback the half in CT’s foot, all the while CT kept peering at
her. Then, XP divided the retrieved half into quarters andhad CT hold one quarter with his foot again. After finishing her portion, XP took back the quarter from CT’s footand ate it. At 15:55 h, XP put the last piece of fruit in her
mouth while CT continued to peer. XP left the site chewing; CT left 30 s later. Forty seconds after CT moved fromthe site, he obtained a lemon fruit for himself.

Food sharing is assumed to be one of the most important behaviors in the process of human evolution (e.g.,
Isaac 1978). Therefore, its occurrence and characteristics
have been studied extensively across primates (McGrew
1975; Jaeggi & van Schaik 2011). Among chimpanzees(Pan troglodytes), the most genetically closest species
to humans (Homo sapiens), food sharing is commonly
observed, and relevant data on several populations havebeen well documented and analyzed (Hosaka 2015).
Food sharing among chimpanzees can often be observed between mothers and infants. Studies suggest that
infants learn food items through food sharing from theirmothers (e.g., Nishida & Turner 1996). Most of the fooditems shared among non-kin adults include meat and cultivated food (Boesch & Boesch 1989; Hockings et al. 2007;
Ohashi 2007). Sharing of wild plant food among adults israre. Boesch & Boesch (1989) defined six types of foodtransfer interactions (focusing on meat) and suggested thatmost are characterized by passive sharing (but see Gilby
2006 for active sharing occurring relatively more often
among Gombe chimpanzees). A recipient shows begging
behavior and takes a part of the food without any facilitation or resistance from the “possessor”, who is defined as
an individual in physical contact with the food (McGrew
1975; Jaeggi & van Schaik 2011).
The present study reports two cases of wild plantfood sharing among chimpanzees. The events are seemingly similar to those reported by Nakamura & Itoh(2001). However, the cases shown here had notable differences from typical food sharing interactions observed in
chimpanzees. The subjects were adult chimpanzees (P. t.
schweinfurthii) of the M group at the Mahale Mountains
National Park, Tanzania (see Nakamura et al. (2015) for
details on the study site and chimpanzee group).

Case 2, on July 19, 2015 (observed by TM and HS)
At 12:37 h, an adult female, BD, was found holding
four fruits of Tabernaemontana pachysiphon (two bunches with two fruits each) on a tree. Another adult female,
RJ, rushed to BD and tried to pull the fruits toward herself. BD screamed, apparently resisting; however, RJ succeeded in snatching a bunch. BD started to eat a fruit of
the other bunch while RJ placed the bunch snatched fromBD at her feet. RJ then pulled the fruit that BD was eating
using both hands and started to feed on it (for details of
the event after then, see Video 1 available online at http://mahale.main.jp/PAN/2018/004.html). Both BD and RJ
held the fruit, although only RJ was able to eat it. Aftera while, BD moved slightly away from RJ and the fruits.
After finishing the first fruit, RJ started to eat the second
fruit from the bunch. A while later, BD re-approached,then touched and peered at the fruit that RJ was eating.
RJ seemed to share a small piece once by mouth-to-mouthtransfer. BD tried to pull the fruit toward herself andeat it; however, RJ resisted by biting BD’s arm and face
(Figure 1). RJ started to eat the third fruit, which allowed
BD to have the second’s leftover. However, most edible
portions of the second fruit had been consumed by RJ.
BD peered at the third fruit that RJ was eating, but RJ did
not share. At 12:44 h, BD left the site. RJ continued feeding and ate all four fruits. There were no individuals otherthan BD, RJ and RJ’s infant in the vicinity.

OBSERVATIONS

Case 1, on February 4, 2013 (observed by TM)
At 15:51 h, an adult female, XP, obtained a lemon(Citrus limon) fruit and started to feed. XP placed herright hand on the ground behind her to hold herself up as
she sat cross-legged with her 3-month-old infant sleeping
on her lap. XP peeled the lemon with her left hand andteeth; twenty seconds later, an adult male, CT, approachedand sat beside XP on her left, peering at her mouth. WhenXP finished peeling the lemon, she divided it into halves

DISCUSSION

Although some studies operationally define possession as being in physical contact with the item (McGrew

8Pan Africa News, 25(1): 8–10 (2018)accounted for 31.0% (44 out of 142 captures) of contests
over prey following capture in chimpanzee predation on
mammals during the 1991–1994 period (Hosaka et al.
2001). T. pachysiphon fruits might have been as attractive
to RJ as meat that she snatched it in Case 2.
No data are available on the social rank of BD and
RJ. Both immigrated to the M group at the same period in2010 (Hayakawa et al. 2011) and have often traveled in thesame nomadic party. Furthermore, BD has taken care (e.g.,
carrying) of RJ’s infant frequently (Sakuragi, unpublisheddata). It is notable that this forceful food transfer occurred
between relatively close individuals.
Previous studies on chimpanzee food sharing havefocused on meat sharing and have found that possessors gain fitness benefits from sharing (e.g., Gilby 2006).
However, the two cases shown in this study reveal thatfood-related interactions in chimpanzees are quite diverse. The first case especially calls for reevaluation of thepossessor–recipient dichotomy regarding food transfer.
It is difficult to reach any general conclusion from thesetwo cases alone; more detailed descriptions and analyses
of interactions related to food transfer are required to elucidate the concept of “possession” of food in chimpanzee
societies.

Figure 1: An adult female, RJ (right), exhibited threatening
behavior toward an adult female, BD (left), which tried totake back the Tabernaemontana pachysiphon fruit.

1975; Jaeggi & van Schaik 2011), Case 1 in the present
study raises a question to this definition. CT kept peering
at the piece of lemon that XP was eating while apparently
showing no interest in the fragment handed by her. XP
took the lemon fruit back from CT’s foot as if from her
own and ate the entire fruit by herself. Both individuals
seemed to share the awareness that the fruit held by CT
belonged to XP, even though the individual in physicalcontact with it was CT, not XP. XP had only one handavailable for handling the fruit, for three of her limbs
were occupied: legs with her sleeping infant, arm forholding herself up. It seems plausible that XP may haveused CT’s foot so as not to get dirt on the surface by placing it on the ground. She would have used her own foot tohold a peeled fruit if her feet had not been occupied. This
rare behavior of XP may lead to a better understandingof plant food sharing in terms of social significance asfollows.
If CT was motivated simply to feed on lemon, he
could have easily done so on his own in the same area.
However, he chose to stay beside XP and continued topeer at her mouth. Interestingly, he did not recognize
the piece of fruit that XP put in his foot as having beenshared, or given, by her. Within 1 h before this event, CT
had groomed XP for approximately 10 min unilaterally
and followed XP intermittently, showing his strong motivation to interact with XP. These observations suggestthat it was important for CT to receive from XP what she
was eating, not what she put aside when eating. Case 1
supports the suggestion by Slocombe & Newton-Fisher(2005) that plant food sharing between adults may notalways be explained by nutritional benefits, but by social
significance.
Food sharing in Case 2 can be interpreted as a forceful event because (1) BD resisted by screaming and attempted to reclaim the food and (2) RJ showed a threatening attitude toward BD. This can be assumed as theft,
which is one of the 6 types of food transfer interactions
defined by Boesch & Boesch (1989). The availability of
T. pachysiphon fruits is not so high because chimpanzees
check and try to select ripe fruits. Thus, these fruits may
have been so attractive that RJ took them from BD. Theft

ACKNOWLEDGMENTS

Permission to conduct this research was provided by the
Tanzania Wildlife Research Institute (TAWIRI), Tanzania
Commission for Science and Technology (COSTECH), andTanzania National Parks (TANAPA). We are grateful to theMahale Mountains National Park (MMCRP) and MahaleGombe Wildlife Research Centre (MGWRC) for logistic
support. We thank all our research colleagues and local assistants of the Mahale Mountains Chimpanzee Research Project(MMCRP) for their continuous help and support. The present study was financially supported by MEXT KAKENHI(#24255010); JSPS KAKENHI (#14J00562 & #16J03218); andthe Leading Graduate Program in Primatology and Wildlife
Science, Kyoto University.

REFERENCES

Boesch C, Boesch H 1989. Hunting behavior of wild chimpanzees in the Taï National Park. Am J Phys Anthropol
78:547–573.
https://doi.org/10.1002/ajpa.1330780410

Gilby IC, 2006. Meat sharing among the Gombe chimpanzees: Harassment and reciprocal exchange. Animal Behav
71:953–963.
https://doi.org/10.1016/j.anbehav.2005.09.009

Hayakawa T, Nakashima M, Nakamura M 2011. Immigrationof a large number of adolescent female chimpanzees into
the Mahale M group. Pan Afr News 18:8–10.
https://doi.org/10.5134/143527

Hockings KJ, Humle T, Anderson JR, Biro D, Sousa C,
Ohashi G, Matsuzawa T 2007. Chimpanzees share forbidden fruit. PLOS One 2:e886.
https://doi.org/10.1371/journal.pone.0000886

Hosaka K 2015. Hunting and food sharing. In: Mahale
Chimpanzees 50 Years of Research. Nakamura M, Hosaka
K, Itoh N, Zamma K (eds), Cambridge University Press,
Cambridge, pp. 274–290.
Hosaka K, Nishida T, Hamai M, Matsumoto-Oda A, Uehara
S 2001. Predation of mammals by the chimpanzees ofthe Mahale Mountains, Tanzania. In: All Apes Great andSmall. Galdikas BMF, Briggs NE, Sheeran LK, Shapiro
GL, Goodall J (eds), Springer, Boston, pp. 107–130.
Isaac G 1978. The food-sharing behavior of protohumanhominids. Sci Am 238:90–108.
https://doi.org/10.1038/scientificamerican0478-90

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Jaeggi AV, van Schaik CP 2011. The evolution of food sharing in primates. Behav Ecol Sociobiol 65:2125.

Nishida T, Turner LA 1996. Food transfer between motherand infant chimpanzees of the Mahale Mountains National
Park, Tanzania. Int J Primatol 17:947–968.

https://doi.org/10.1007/s00265-011-1221-3

McGrew WC 1975. Patterns of plant food sharing by wild
chimpanzees. In: Contemporary Primatology. Kondo S,
Kawai M, Ehara A (eds), Karger, Basel, pp. 304–309.
Nakamura M, Hosaka K, Itoh N, Zamma K (eds) 2015.
Mahale Chimpanzees 50 Years of Research. Cambridge
University Press, Cambridge.

https://doi.org/10.1007/BF02735296

Ohashi G 2007. Papaya fruit sharing in wild chimpanzees at
Bossou, Guinea. Pan Afr News 14:14–16.
https://doi.org/10.5134/143471

Slocombe KE, Newton-Fisher NE 2005. Fruit sharing
between wild adult chimpanzees (Pan troglodytes schweinfurthii): A socially significant event? Am J Primatol
65:385–391.

https://doi.org/10.1002/ajpa.23293

Nakamura M, Itoh N 2001. Sharing of wild fruits among
male chimpanzees: Two cases from Mahale, Tanzania. Pan
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https://doi.org/10.1002/ajp.20123

Received: 8 February 2018
Accepted: 15 April 201810

Pan Africa News, 25(1): 11–12 (2018)

BOOK REVIEW

Following Fifi: My Adventures among Wild Chimpanzees:
Lessons from Our Closest Relatives
By John Crocker
New York: Pegasus Books, 269 pp.
Published in 2017
ISBN: 978-1-68177-568-5, $27.95 (USA), hardback

Among Chimpanzees: Field Notes from the Race to Save Our
Endangered Relatives
By Nancy J Merrick
Boston: Beacon Press, 254 pp.
Published in 2014
ISBN: 978-0-8070-8074-0, $18.00 (USA), paperback

William C McGrew
School of Psychology and Neuroscience, University of St Andrews, Scotland, UK(E-mail: wcm2@st-and.ac.uk)

In the early 1970s, under the leadership of Prof. David
Hamburg, Stanford University had a programme that sent
to Tanzania small batches of undergraduates majoringin human biology. At Gombe they spent months acting
as research assistants in ongoing studies of chimpanzees
and baboons. On the chimpanzee front, most students
focussed on the mother–infant study, collecting detailed
data on the daily lives of female apes with dependent offspring. Two of these students, Nancy Merrick and John
Crocker, went on to become physicians, and now, decades later, each has written a memoir, and Jane Goodall
has supplied a foreword to each book. Their books are
enlightening (for after all, how often do such young persons get such a golden opportunity?), but the results arevery different. (Necessary disclosure: I was at Gombe at
the same period in 1972–73 as these two authors, so myfirst-hand knowledge may be similarly impressionistic totheirs.)
Crocker’s is the more focussed of the two, going into
depth, in a three-part structure. Part One is a detailed
recollection of his experience, from arrival at Gombe onwards, for eight months in the field. It covers the first 104
pages, and Chapter 3 is a graphic account of a typical day
in the life of a student researcher doing focal-subject follows of chimpanzee mothers and offspring. He captures
the nuances of the experience, as well as the data collection. In the process, he formed a close friendship with
one of the Tanzanian field assistants, Hamisi Matama, tothe unusual extent that they later ending up going up Mt.
Kilimanjaro together. Part Two describes how Crocker,
as a family physician in Seattle, makes use of ‘lessons
learned’ about parental nurturing, as acquired from timespent with Fifi, one of Gombe’s most famous and influential individual chimpanzees. He shows how the simple
basics of intimate interaction as practiced by our nearest

living relations can be applied to the day-to-day practiceof family medicine. This is a modest application of suchknowledge, by comparison with more prominent andnewsworthy aspects of modelling the evolutionary origins
of human behaviour, such as aggression, technology, social structure, diet, etc., but insights abound. Part Three ofthe book is Crocker’s return to Tanzania and Gombe, 36
years later, in 2009, accompanied by his eldest son. Theirjourney combines curiosity about what has happened in
the meantime to Gombe and the chimpanzees, introducing
his son to the African bush, but most importantly, reunionwith Hamisi, and introduction to his family, after decades
apart. This is done most movingly and contributes to theoverall feel-good tone of the book.
The book is illustrated with 37 good colour plates
from past and present and has a useful 9-page index.
However, it gives no scientific references, even to Jane
Goodall’s basic work, so that readers who want such background information must look elsewhere (see below).
Merrick’s is a much more wide-ranging effort, although the two authors have much in common. She too
gives a personal, detailed account of her student time at
Gombe in 1972, taking part in the same study of motherinfant pairs as did Crocker. Her account of her first day
in the field shows her to be an articulate story-teller. This
opportunity for comparison of that research project in action is unusual, for example, in terms of allowing a sort ofinter-observer reliability. She too later takes her family toAfrica, for many of the same reasons, and her response to‘progress’ (that is, the development of tourism) at Gombe
provides a useful and confirmatory judgement. But
Merrick goes on to make several trips and not just to see
chimpanzees; an abortive trip to Karisoke to meet with
Dian Fossey must have been frustrating. Her accounts ofsmuggling a young chimpanzee out of Gombe and of the11Pan Africa News, 25(1): 11–12 (2018)
Gombe kidnapping by rebels from Zaire make compelling
reading.
The book then opens up in a variety of ways thatend of being an overall ‘state of the union’ assessment of
Pan troglodytes. Wild chimpanzees, especially those infragmented forest segments, such as at Bulindi, Uganda,
get coverage that otherwise is scarce, by comparison withpopulations in well-known national parks. Refuges forconfiscated or orphanned chimpanzees, both in Africa
and in the West, get coverage, as do zoological gardens,
especially Los Angeles Zoo (although its Mahale exhibit,
which has no connection to the wild chimpanzees of western Tanzania, is not explained). All the major conserva-

tion problems facing wild chimpanzees are aired, such as
the bush meat trade, and Merrick provides a useful list of
10 things that an individual person can do to help in ameliorating them.
The book has a useful 10-page index and nine pagesof chapter-by-chapter endnotes, in the form of references.
Disappointingly, it has no photographs, and the single illustration, a map, is problematic, failing to name Burkina
Faso and denying chimpanzees to Niger.
In summary, both books have much to offer as firstperson accounts by committed and insightful observers
taking a long-term view. Anyone wondering what it was
like to be a student in Gombe’s heyday of the 1970s willlearn more here than from any other source.
Received: 13 February 2018
Accepted: 14 March 201812

Pan Africa News, 25(1): 13 (2018)

Erratum

A Female Bonobo Sleeping on the Ground after Daytime Birthand its Implications
Heungjin Ryu
Pan Africa News 24(2), 9–13 (2017)

Owing to a technical error, corresponding e-mail address was typed incorrectly as
ryu.heungjin.26v@st.kyoto-u.ac.jp instead of ryu.heungjin.26v@kyoto-u.jp in the print and the KURENAI versions.
This error has been corrected in the HTML version at http://mahale.main.jp/PAN/24_2/24(2)_01.html.

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Pan Africa News, 25(1): 14 (2018)

Editor’s Note

Starting 7 May 2018, Pan Africa News (PAN) has adopted the “Online First” service that enables submitted manuscripts to be published online at http://mahale.main.jp/PAN/online_first.html, before print publication following peer review and acceptance. Along with this change, we have adopted a new format of PDF
and print version of PAN in which each paper begins at the top of a new page.
The adoption of the Online First service means that the deadlines of manuscripts are virtually no longer
necessary. If you wish to publish your manuscript in PAN, you should submit it anytime. It could be published online ahead of print within a month if your communication with a reviewer proceeds fast and smoothly. Appropriate numbers of pooled Online First papers are selected to be compiled into a print issue twice per
year in June and December.
Finally, please note that DOI (Digital Object Identifier) of each paper is not available at the time of online
first publication, because we chose the system where DOIs are assigned by Crossref to all PAN papers published in the course of a year only once per year in December. Thus, in the year following print publication,
you can search for DOIs of published PAN papers at free DOI lookup in the Crossref website (https://www.
crossref.org/guestquery/). For the detail about how to get DOI, please see the Instructions to Authors at http://mahale.main.jp/PAN/instruction.html.
We hope that you like this new service. We look forward to receiving your good research and conservation about chimpanzees and bonobos as submissions to PAN!
Kazuhiko Hosaka, on behalf of the PAN Editorial TeamA 6-year-old male, Omali (left), and a 7-year-old female, Upepo (right), playing with each other. Phototaken by Kazuhiko Hosaka on 17 August 2017 at Mahale Mountains National Park, Tanzania.

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