Losing Ten Pounds to Gain Knowledge
Frans B. M. de Waal
Living Links, Yerkes Primate Center
Emory University, Atlanta, USA

Last summer, I spent ten days in the Mahale Mountains National Park. I had been warned that the chimpanzees are often up in the mountains in August, far away from Kansyana, the base camp, and that sometimes they are not seen at all during this time. But upon arrival in the camp with Dr. Toshisada Nishida, while we were still unpacking our bags, it was my luck to hear them hooting in the distance. Most of the M-group chimpanzees were coming down the mountain, making their appearance the very same afternoon, banging the life out of some poor metal sheds near the camp. This was my very first sight of wild chimpanzees, because even though I have visited field sites of other primates (such as orangutans, muriquis, various macaques, olive baboons, and gibbons), chimpanzees somehow had escaped me. This is rather embarrassing for someone considered an expert on the species. So, when Dr. Nishida mentioned that he was close to retirement, and that 2003 would be the perfect year to stop by in Tanzania, I did not think twice.

I saw chimps every day, often groups of them, and ran after them up and down the mountain, losing about 1 pound per day. I am not used to expend so much energy simply to see my animals. I observe them in captivity, often in zoos, or conduct behavioral experiments, such as at the Yerkes Primate Center. There my chimpanzees live in outdoor enclosures that obviously prevent much of the behavior seen in the field. I have no trouble explaining why captive work is and will always remain essential for a full understanding of ape behavior, yet at the same time it is obvious that only studies in their natural habitat can tell us what their behavior is for. Questions about social and cognitive evolution require field data, and here I was at one of the premier sites with one of the true pioneers, who had started out about forty years ago on this very same spot. My visit taught me nothing but respect for the persistence and hard work that goes into collecting scientific information on wild apes.

I will not go into details of life in the camp, which I soon began to call the Mahale Sheraton owing to its exorbitant luxury, nor of the food we ate and warm beer we drank. The main thing was to get up at 6 AM, eat a quick breakfast, and get going as soon as it was light. The chimpanzees needed to be found, and the camp had several young scientists and many trackers to help with this. If chimps were silent, retiring types, finding them in the morning in such a vast stretch of forest might be impossible, but fortunately these animals are about the noisiest in the world. Their reliance on vocalizations was in fact what struck me most. I am familiar with all of the varied calls of the species, but had never realized how much the life of wild chimpanzees is totally built around these. When you follow an individual such as Alofu, a prime adult male, you see him stand still and listen to chimpanzees in the distance all the time. You can see him decide between different courses of action: reply with his own calls; move towards the source of the sounds (sometimes in a great hurry leaving me struggling through tangled vines), or act as if what he heard is of no importance. The forest is alive with calls, some nearby some faint in the distance, and social life is lived to a large degree in a world of vocalizations. This is not true in captivity, or only to a limited degree, because there the apes can almost always see each other, and are never far away.

Several fights broke out. I am used to follow these scenes in the greatest possible detail noting who supports whom, the exact aggression intensity in every dyad, and of course follow-up behavior, such as reconciliation. Forget about this in Mahale: a fight means that you are surrounded by the screams of invisible chimpanzees, lots of shaking bushes and trees, and an occasional brief appearance of a participant out of the undergrowth. Obviously, field workers become very good at gaining a fuller picture from bits and pieces of information, but it undeniably is a process of reconstruction.

I was excited to recognize and photograph many of the known cultural patterns of the Mahale chimpanzees, such as hand-clasp grooming, leaf-clipping, and the riverbed display. The latter was first described for Ntologi (the legendary previous alpha male of M-group), who used to dislodge large boulders from a dry riverbed during displays. Alofu, who in his younger years may have watched Ntologi, gave similar displays full of strength and rhythm. Of special interest to me was the well-documented hand-clasp grooming (1), since we know this pattern also from one of our captive groups (2). McGrew et al. (3) were right to stress that cultural primatologists should not only look for group-specific customs, but also for variation within each custom. The hand-clasp of M-group is different than ours. When our chimpanzees lift their arms above their heads during grooming, their hands firmly clasp, whereas in M-group one sees no clasping at all, only two “hanging” hands resulting from a mutual leaning of wrists (Figure 1).

Even though the scientists and trackers scrupulously avoided any direct interaction with the chimpanzees, which seems a wise strategy, I could see how the apes reacted differently to people they knew compared with the occasional tourists crossing our path with their guides. Relationships of mutual trust develop. I remember walking an entire day behind Pinky, a female carrying a three-year-old daughter. The daughter could not sit still, sometimes rolling on her back on her mother’s back, and kept staring at me. She ended up playing a game where she would sit in the path untill I got within a few steps, then race to catch up with mom, jumping onto her, only to drop to the ground again and wait for the next encounter with the bipedal ape following her. She must have sensed that I am a chimp friend.

Chimpanzee politics were also to be seen, even though I must say that I would never have understood much of it without the background information provided by Dr. Nishida. The alpha male, Fanana, had been on safari for two weeks with an attractive female. During his protracted absence, the beta male, Alofu, impressed everybody with his displays. He often had Kalunde by his side. Kalunde is the oldest male, only about half the size of the prime adult males: at the age of about forty, he has shrunk (Figure 2). As usual in chimpanzees, these over-the-hill characters are real political schemer. Kalunde often groomed Alofu, and displayed along with him. Until Fanana returned, that is. This was the day on which I followed Alofu. I didn’t know what was the matter with him, but he traveled up, then down, then up, the mountain, and did this so many times that our follow became the most protracted physical exercise I have ever engaged in. Alofu often touched his own nipples, a behavior I know as self-reassurance in bonobo males. He must have been totally nervous about Fanana’s return, and indeed in the days thereafter there existed obvious tensions due to the fact that Alofu failed to pant-grunt to Fanana. I don’t know how this worked itself out, but it was fascinating to see how Kalunde switched camps. One moment the old male would be grooming Fanana, the next moment he would be hanging out with Alofu, as if he was trying to guess which side it would be best for him to be on.

I was literally baptized as a field worker while watching a hunt, standing under a tree in which several adult males and swollen females were dividing the carcass of a red Colobus monkey. We learned about the hunt through hooting and screams of chimpanzees mixed with the shrieks of monkeys. Following the laws of gravity, the diarrhea of one of the males during the commotion caused me to enter a rather smelly phase of my career. I am not complaining. It was a thrill for me to see al of this, having read countless descriptions. Nothing beats the real experience. All I had to do afterwards was take a “shower” in the Sheraton.


  1. Nakamura M 2002. Grooming hand-clasp in Mahale M group chimpanzees: Implications for culture in social behaviours. In: Behavioural Diversity in Chimpanzees and Bonobos. Boesch C, Hohmann G, Marchant LF (eds), Cambridge University Press: Cambridge. pp 71-83.
  2. de Waal FBM, Seres M 1997. Propagation of handclasp grooming among captive chimpanzees. Am J Primatol 43: 339-346.
  3. McGrew WC, Marchant LF, Scott SE, Tutin CEG 2001. Intergroup differences in social custom of wild chimpanzees: The grooming hand-clasp of the Mahale Mountains, Tanzania. Curr Anthropol 42: 148-153.

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