Today, the British Sunday Times reported that the chimpanzee has just been knocked off the top of the "IQ tree". What that tree is, and whether that includes another primate species likely to lay claim to that title - homo sapiens - is unclear (I assume it doesn't). The article said:
"ORANG-UTANS have been named as the world’s most intelligent animal in a study that places them above chimpanzees and gorillas, the species traditionally considered closest to humans.
The study found that out of 25 species of primate, orang-utans had developed the greatest power to learn and to solve problems.
The controversial findings challenge the widespread belief that chimpanzees are the closest to humans in brainpower. They also suggest that the ancestry of orang-utans and humans may be more closely entwined than had been thought."
James Lee, a Harvard psychologist quoted by the article as an author of the study making these claims apparently said, “It is even possible that an orang-utan-like forager occupied a pivotal link in the chain of descent leading to man.”
Well, good on the orang-utan, of which I'm very fond. And it's great that some prominence is being given to them when orang-utans are endangered as never before due to encroachment onto their home habitats in the swampy jungles of Sumatra and Borneo. One of the tragic ironies about growing interest in renewable alternatives to fossil fuels is increased demand for palm oil, which is accelerating the destruction of the homes of these amazing human relatives to make way for palm oil plantations. (Orang-utan means "man of the forest" or "man of the woods" in Malay and Indonesian.)
By way of background, most people are aware that we share most of our DNA with the common chimpanzee (Pan troglodytes). Less well known is that there is another species of chimpanzee that's just as closely related to us, one that vaguely resembles Pan troglodytes, but which socially is completely different from both. I'm talking about the bonobo, or Pan paniscus. In fact, until the late 1920s, scientists didn't even have an inkling that bonobos were a different species from common chimps given their resemblance, and referred to the few museum specimens as pygmy chimpanzees.
Chimps and bonobos form a common genus: Pan. Our human lineage diverged from Pan only about 5.5 million years ago according to DNA comparisons. (In fact, some scientists argue that we're closely enough related in genes and time to chimps and bonobos that we should be regarded as a single genus: Homo.) Gorillas split around 7.5 million years ago and orang-utans an estimated 14 million years ago, much longer than our other relatives among the great apes - even if not that long in overall evolutionary terms.
In view of that, Lee's study would seem to indicate that the remarkable growth in mental faculties that are a hallmark of the higher primates must have started a very long time ago - perhaps much longer than conventionally thought.
Nevertheless, in reporting on Lee's study, one part of the Sunday Times article read as follows:
"He also found that the single most important factor in deciding a species’ intelligence was simply the size of its brain: “The correlation of brain size with mental ability found in humans appears to extend throughout the primate order.”"
Really? Well, if brain size translated into brain power, what about elephants and whales, which each have brains very large in total weight and size? I suspect Lee has been misrepresented here, and that he's referring to part of the brain called the neocortex. This is the bit that handles complex social relationships and is a recent addition in evolutionary terms, developing on the outer surface of the brain over time in response to the pressures of social living as these increased among our ancestors over millions of years.
Evolutionary psychologist Robin Dunbar and others at Liverpool University have compared relative neocortex size among the higher primates. The results are unambiguous: we have the biggest neocortex area by far, which figures as humans have the most complex social relationships and the largest social group sizes (although even we tend to max out at around 150 in terms of the sustained social relationships we can handle. Aurélia Merçay and I wrote a little about this and its implications for negotiating in chapter 7 of DHA's third volume, "Thinking Outside the Box" at left).
It's slightly surprising that orang-utans have come out on top among non-human primates in their abilities to carry out mental tasks because they're generally considered less sociable than chimps and bonobos. But then there's a lot we didn't realize about the way they lived until very recently, thanks to pioneering field work by the Dutch primatologist Carel van Schaik and his colleagues. Their definitive reports of tool use and, crucially, proto-cultural transmission of tool use among wild orang-utan populations astounded the scientific world in late 2005.
The ways primate species live socially is significant. Although chimps and bonobos are superficially similar in appearance and are species of the same genus, for instance, they live completely differently in social terms and also manage problems of conflict and achieve reconciliation in very different ways. (If chimps are from Mars, bonobos are from 'Boogie Nights'.)
Common chimps and bonobos live in larger and more complex social groups than orang-utans. If orang-utans are turning out to be much more mentally capable than previously imagined, there might also be things about their social life we've missed, given the difficulty of studying them in their dense and remote jungle habitats.
So what? Well, as another Dutch primatologist Frans de Waal explained in books such as "Chimpanzee Politics" and "Our Inner Ape", bonobos and common chimps have a lot to teach us about understanding the roots of human aggression and practical conflict resolution.
Not least about coalition politics, at which both species could show more than a thing or two to many an experienced human diplomat or politician. For example, de Waal documented machinations for power among competing males in a captive chimpanzee colony in the Netherlands in the 1970s that resulted in the death of one and which would have given Machiavelli a run for his money in terms of subtlety and complexity. (In the early 1990s, Newt Gingrich, U.S. House Speaker, was reportedly so impressed with "Chimpanzee Politics" that he made it required reading for his junior colleagues in Congress.)
As in humans, xenophobia, rape and murder have been documented in common chimps, which, by inference, has fuelled pessimism about 'Man, the warlike ape'. Yet good news is that our other equally close cousin, the bonobo, seems much more effective in resolving conflict and dealing with and preventing violence, which contradicts this gloomy view. It also seems to be no coincidence that coalitions of females hold the reins of power in bonobo society.
I wouldn't be surprised if orang-utans also have something useful to teach us about conflict and reconciliation, just as chimpanzee and bonobo studies are already doing. A lot is being learned about the role of emotions and gender, the origins of human morality and the influence of social hierarchies to fuel or restrain violence by placing our species within the context of our cousins, the other great apes.
Which is good news for us if we don't drive them to extinction first.
John Borrie
References
"Chimps Knocked Off Top of the IQ Tree", Sunday Times (15 April 2007): http://www.timesonline.co.uk/tol/news/uk/article1654998.ece
R.I.M. Dunbar, "Co-evolution of Neocortical Size, Group Size and Language in Humans", Behavioural and Brain Sciences, 1993: 16, pp. 681-735.
Frans de Waal, "Chimpanzee Politics: Power and Sex Among Apes" (rev. edn) (Baltimore: the John Hopkins University Press: 2000), "Our Inner Ape: the Best and Worst of Human Nature" (London: Granta: 2005)
International Herald Tribune/New York Times, "In Search of the Smart Orangutan" (16 November 2005), available here.
Image courtesy of Wikipedia under the GNU Free Documentation License.
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