9 August 2013,
 0

 

The themes in this post:

 

-       Chimps and Bonobos are the closes relative to hominid and Homo sapiens; they share over 99% of our DNA. Thus, we may gain key insights into our own behavior by investigating our primate relatives.

 

-       Recent reports have highlighted when Chimpanzees consume large amounts of sugar, they engage in hugely aggressive behaviour: monkey hunts and patrolling for other chimpanzees to physically abuse (really!). Hearing these stories made me wonder: if sugar can lead to aggression in chimpanzees, perhaps the same could be the case for human beings?

 

-       Of course, the story is much more complicated. Please read on.

 

 

As our closest living relatives, chimpanzees and their fun loving cousins, bonobos, provide an anthropological gateway to understanding human behaviour. Primatologists argue the study of chimps can bridge a better understanding of our origins, and with that I would largely agree. Researchers at Max Plank have recently discovered humans, bonobos and chimps share about 99% of DNA, and so taking a look at Chimpanzee behaviour may in fact yield some important observations about our human culture and Homo sapiens ever evolving social structures.

 

Despite genetic similarity, chimps and bonobos display wildly different behaviour.  One of the most striking differences lies in how the two groups deal with aggression: Chimpanzees fight, where as Bonobos have copious amounts of sex. Two interesting coping skills.  Yet, when I learned that eating behavior and early food environments could lie at the axis of these different ways of dealing with aggression, I became increasingly curious.

 

Bonobos engage, almost incessantly, in sexual behaviour. Making love is a serious pursuit amongst this distinct clan of the Pan Genus. They seem to prefer sexual contact over violent confrontation even when faced with an outsider. For Bonobos, sex functions to minimize conflict, stress, and also enhances affection. Bonobos have sex for fun, not necessarily to reproduce, and apparently the society is matriarchal. The male’s rank is often determined by his mothers place in society. Bonobos are also playful throughout their lives. No wonder!

 

Making War, on the other hand, seems to be Chimpanzees modus operandi. Chimps are extraordinarily hostile to males from outside communities; theirs is a patriarchal bunch and groups of male Chimps are known to go on patrols for lurking single males that might be trying to make inroads with their females back at base camp. Some monkeys have all the luck. It seems bonobos win, in this case.

 

Researchers speculate the speciation of Bonobos began to happen around 1.5 to 2 million years ago. So, although they have numerous physical similarities with chimps they are recognized as a completely different species. It’s interesting to consider what goes into 1.5 million years of change, and with many things in life, it’s not genetic or necessarily environmental factors that determine destiny, but rather ecology.

 

Geography, and the resulting shift in Chimpanzee ecology, is in important part of this puzzle. The Kasai river that runs along the Congo splits Bonobos from their Chimp cousins; while the environments of the two groups appear to be similar today, 2.5 million years ago, there was thought to be a long drought in what was then called Zaire. The drought in the Congo/Zaire eliminated all the preferred food plants of the Chimpanzees. Those on the north side of the river had to leave. Since chimps are not particularly strong swimmers those left on the south side of the river were free to continue a relatively stress free life, travel in larger more stable parties, make stronger social bonds, and these ultra social apes became Bonobos.  In summary? A lack of food scarcity led to hugely social behaviour, and this ultimately developed into an extremely sexually liberated primate culture.

 

Coming in at second place perhaps only to breathing, feeding is the most important life sustaining activity. Food will affect group size, sociability, and pretty much every dynamic among primate societies (ours included). But, looking at our very own ‘environment of plenty’ and the current obesity crisis (which, you might argue leads to more anti social behaviour than rampant orgies, for example), I’m confused.

 

Chimpanzees, evolving under the evolutionary pressures of scarcity react quite differently to seasonal moments of ad lib food access. In times of plenty, they go on killing sprees. Anecdotal accounts from rangers at Ngogo nature reserve in Uganda have suggested that chimps are more likely to go on border patrols and monkey hunts in the afternoon after eating a lot of ripe, in essence sugary, fruit. So, in the case of Bonobos an environment of plenty has improved social relationships- yet, in the case of Chimpanzees ad lib access to fig fruits elicits… monkey killing.

 

In trying to sort out this conundrum, I reached out to a primatologist. I mentioned my concern about Chimps tendency for patrolling and monkey hunts upon the consumption of ripe fruit. I tried to make parallels with our current icing sugar laden planet, but it was a lost effort.

 

‘In actual fact, while the anecdotal accounts of patrolling and monkey hunting are accurate,’ Dr. Carlson wrote, ‘the aggressive behavior is likely a result of male chimpanzees getting together at the tree base to collect ripe fruit, winding themselves up, and then going out on monkey hunts.’ So it may not be the sugar, but the company that is to blame.

 

The ecology of primates eating behaviour, illustrates a small part of the complexity of our current obesity crisis. It is not one ingredient that can be blamed, nor for that matter one unhealthy social circle. Nor is it the frustrating job, hormones, or your tendency to forget your gym shoes. It’s the collection of all of these factors. The sum, yet again, would seem to be more important than the weight of the parts.

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