Thursday 19 March 2009

Chimps are like humans? Stop monkeying around

This week it was revealed that chimps use sticks to smash open beehives. But there’s nothing remotely ‘human-like’ in such behaviour.

Recent ‘revelations’ about chimp behaviours are forcing us to reconsider whether human beings are unique. Or so we are told.

This week, BBC News reported on a study published in the International Journal of Primatology, which uncovered novel tool-using abilities among wild chimpanzees in central Africa: ‘Cameras have revealed how “armed” chimpanzees raid beehives to gorge on sweet honey’, the BBC reported (1). Scientists found that the primates ‘crafted large clubs from branches to pound the nests until they broke open’ (2).

A few days earlier, the Guardian reported on ‘the loutish behaviour of a stone-throwing chimpanzee at a zoo near the Arctic circle’, which also apparently challenges scientists’ belief that humans are unique; you see, chimps can be yobs, too (3). The discovery that the aggressive chimp had gathered stones over a period of time, in order to throw them later on at unsuspecting spectators – implying some kind of forethought and planning – astounded many scientists.

Mathias Osvath of Lund University in Sweden wrote in the journal Current Biology: ‘Such planning implies advanced consciousness and cognition traditionally not associated with non-human animals.’ He argued that the behaviour of the stone-thrower shows that chimps ‘have a highly developed consciousness, including life-like mental simulations of potential events’: ‘When wild chimps collect stones or go out to war, they probably plan this in advance. I would guess that they plan much of their everyday behaviour.’ Or as the science editor of The Times, Mark Henderson, put it: ‘The extent to which chimp intelligence has been found to approach that of people has surprised even some primatologists.’ (4)

Similarly, in his book The Great Ape Project, Douglas Adams, best known for The Hitchhiker’s Guide to the Galaxy, describes the human-like characteristics of free-living gorillas in Zaire: ‘They look like humans, they move like humans, they hold things in their fingers like humans; the expressions which play across their faces and in their intensely human-looking eyes are expressions which we instinctively feel we recognise as human expressions…’ (5)

It is true that the chimpanzee is the only non-human animal that has been found to use a variety of tools for a variety of purposes in the wild. Unlike monkeys and other apes, chimps use leaves as sponges to soak up drinking water or as umbrellas in heavy rain; they also use leaves to wipe their wounds and use sticks to fish for termites and stones to crack open nuts. Humans are separated from chimpanzees by six million years: not a very long time in evolutionary terms. And, as we are often reminded, we share up to 98.8 per cent of our DNA with these apes, which is the same amount of genetic relatedness as that which exists between horses and zebras, or rats and mice.

So do apes have sophisticated tool-using abilities reminiscent of those possessed by humans? Can they plan and think ahead? Do they have the capacity for cultural learning, where their tool-use is ‘a form of culture that can be taught from one generation to the next’, as The Times argued this week? Do they have the ability to teach one another new skills?

My answer to all these questions is unequivocal: no.

As I argue in my forthcoming book, Just Another Ape?, the fact that we share 98.8 per cent of our genes with chimps does not actually tell us very much. We also share 60 to 70 per cent of our DNA with goldfish and 50 per cent with bananas. It would be rather meaningless to argue that humans are 50 per cent banana-like, or that goldfish are two-thirds human.

One needs to go beyond first impressions and anecdotal evidence in order to establish the differences, and the alleged similarities, between apes and humans. The fact is that the evidence for apes having human-like mental capacities is weak, and getting weaker, as researchers develop more sophisticated ways of investigating what apes can and cannot do. The differences in language, tool-use, self-awareness and insight between apes and humans are vast.

So what do human beings have that apes do not? In his fascinating book The Cultural Origins of Human Cognition, the developmental and comparative psychologist Michael Tomasello puts a persuasive case that the central difference between us and apes is our ability to understand other human beings as intentional beings like ourselves.

Tomasello writes: ‘Imagine a child born alone on a desert island and somehow magically kept alive. What would this child’s cognitive skills look like as an adult - with no one to teach her, no one to imitate, no pre-existing tools, no spoken or written language? She would certainly possess basic skills for dealing with the physical world, but they would not be particularly impressive. She would not invent for herself English, or Arabic numerals, or metal knives, or money. These are the products of collective cognition; they were created by human beings, in effect, putting their heads together… It is because they are adapted for such cultural activities - and not because of their cleverness as individuals - that human beings are able to do so many exceptionally complex and impressive things.’ (6)

This theory suggests that there would come a stage in children’s early development when their knowledge and understanding of the physical world - in relation to things like space, quantity and causality - would be very similar to those of our nearest primate relatives: the great apes. But their skills in ‘social-cultural cognition’ - such as social learning and communication - would already be distinctly human.

To test this hypothesis, researchers at the Max Planck Institute for Evolutionary Anthropology in Germany gave a battery of tests to a large number of chimpanzees, orang-utans and human two-year-olds (7). They found that the young children who had been walking and talking for about a year performed at a similar level to chimpanzees on tasks of physical cognition - such as judging space and quantities and understanding causality - but outstripped both chimpanzees and orang-utans on tasks of social cognition, such as understanding the intentions of others and learning through imitation.

In one of the social learning tests, the experimenter showed the apes and human children how to open a plastic tube in order to retrieve a reward inside. The children watched the experimenter and imitated the solution. The apes, on the other hand, tried to smash open the tube, or used their teeth to pull its contents out. Some scientists argue that even by one year of age, children’s performance on imitation tasks goes way beyond that of apes: they are already able to appreciate that other beings have intentions and also that they have particular goals.

Researchers at the Institute for Psychology at the Hungarian Academy of Sciences showed a group of 14-month-old infants a new way to switch on a light with their forehead (8). In one example shown to the children, the female experimenter’s hands were free when she turned on the light with her head; in the other example, her hands were occupied: she was holding a blanket around her shoulders. The researchers found that the children only imitated the actions of the experimenter if her action was considered to be intentional. So if the female experimenter’s hands were free when she used her head to turn on the light, the infants imitated her actions exactly. But when her hands were occupied - holding on to the blanket - the children did not tend to imitate her actions, instead opting for the more straightforward alternative of using their hands to switch the light on.

So rather than simply imitating the actions of a model, pre-verbal children will consider whether there is a reason for carrying out a task in a particular way. If the female experimenter used her head to carry out the task when her hands were free, the infants must have assumed that the use of her head was intentional and therefore that it must serve some purpose; thus they copied the action.

In an experiment by Andrew Meltzoff, co-director of the University of Washington Institute for Learning and Brain Sciences, children were shown an adult trying, but failing, to perform certain actions (9). In one example, the experimenter picked up a stick tool and tried, but failed, to push in the button on a box in order to activate a buzzer inside. Meltzoff’s aim was to determine whether children interpreted the model’s behaviour in purely physical terms, or whether they were able to look beyond the ‘literal body movements’ to see the underlying goal of the act. The results indicated that children can indeed infer the adult’s goal by watching the failed attempts: they performed the same acts that the adults had intended to carry out.

Young children’s imitation is clearly guided by an understanding of other people’s goals and intentions. Their imitation may or may not involve matching the actions of another person to achieve a particular goal, depending on whether they perceive that person’s action as having been intentional or unintentional. It is this understanding of other beings as having intentions which, according to Tomasello, ‘forms the basis for children’s initial entry into the world of culture’ (10).

He writes: ‘The outcome is that each child who understands her [fellows] as intentional/mental beings like herself… can now participate in the collectivity known as human cognition, and so say (following Isaac Newton) that she sees as far as she does because she “stands on the shoulders of giants”.’

Video: Goualougo chimpanzee
honey pounding

It is this ability for cultural learning that sets human beings apart from all other animals. Even the most enthusiastic proponent of ape and human equivalence would have to admit that apes’ skills have not led to any significant changes in the way they live their lives. Human societies, on the other hand, have become ever-more complex. In his 1876 pamphlet The Part Played by Labour in the Transition from Ape to Man, Friedrich Engels argued that each generation has been able to build on the abilities of earlier generations, so that our work becomes ‘different, more perfect and more diversified’. Engels wrote: ‘Agriculture was added to hunting and cattle raising; then came spinning, weaving, metalworking, pottery and navigation. Along with trade and industry, art and science finally appeared.’ (11)

And as the cognitive archaeologist Steven Mithen argued in his book The Prehistory of the Mind, since the birth of agriculture around 10,000 years ago, events have flashed past ‘at bewildering speed’. ‘People create towns and then cities. In no more than an instant carts have become cars and writing tablets word processors.’ (12).

On the face of it, due to regional variations in chimpanzees’ use of tools, one might possibly put the case for chimps being capable of some form of cultural transmission of behaviour; in other words, learning from one another. Yet this still begs the question of why their tool-use does not progress and improve from one generation to the next.

Mithen argues that apes do not have the ability to imitate – and neither are they very good at innovating (13). The fact that some chimp groups do not use sticks to fish for termites does not necessarily tell us anything about cultural transmission, he argues, but instead indicates the limitations of their intelligence. ‘The failure of Tai chimpanzees to use termite sticks is most likely to arise simply from the fact that no individual within the group has ever thought of doing such a thing, or discovered it accidentally, or managed to learn from another chimp before that chimp forgot how to do it, or passed away with his great tool-use secret. This is not cultural behaviour; it is simply not being very good at thinking about making and using physical objects. It is the absence of technical intelligence.’ (14)

His argument is persuasive, especially when one considers that primatologists have not found any technological advances in chimpanzees’ tool-use over more than 40 years of observations in the wild. Instead, ‘each generation of chimpanzees appears to struggle to attain the technical level attained by the previous generation’ (15). In an attempt to understand why, if apes really do have cognitive abilities similar to humans they show so little evidence of using these abilities in the wild, evolutionary psychologist Richard Byrne argues that: ‘[One possibility] is that apes know so very much less than humans that even having the rudiments of human non-linguistic cognition does not produce much that we recognise as intelligent.’ (16)

While apes are still struggling to crack open nuts, or retrieve honey from beehives, humans have made life-changing inventions such as the internal combustion engine, the harnessing of electricity, the creation of life-saving vaccines and x-rays, and much, much more. While apes are still struggling to communicate in the here and now, humans have invented the alphabet and other forms of written symbols and ever-more impressive means to disseminate the written word, from the invention of paper and ink to the typewriter and the internet. While apes are living in groups the same size as the ones they lived in several million years ago, human beings have created cities, nation states, governments and global economic institutions.

Investigations into what apes can and cannot do may provide some insight into the evolutionary origins of our unique abilities. But it cannot tell us very much, if anything, about what it means to be human. Rather, today’s increasingly shrill claims that apes and other animals are ‘just like us’ reveals the degraded view some people have of human beings. The sentimentalised view of animals is very often coupled with a nightmarish vision of human destructiveness. That is why, in Just Another Ape?, I will focus on the differences between human beings and apes - in order to show just how exceptional human beings really are.

(1) ‘Armed’ chimps go wild for honey, BBC News, 18 March 2009

(2) ‘Armed’ chimps go wild for honey, BBC News, 18 March 2009; Flexible and Persistent Tool-using Strategies in Honey-gathering by Wild Chimpanzees, International Journal of Primatology, 12 March 2009

(3) Chimp who threw stones at zoo visitors showed human trait, says scientist, Guardian, 9 March 2009

(4) ANALYSIS: Chimp with malice on mind, The Times (London), 10 March 2009

(5) Adams, D. (1993), ‘Meeting a Gorilla’ in The Great Ape Project, eds. P. Cavalieri and P. Singer (London: Fourth Estate), p21.

(6) How Are Humans Unique?, New York Times, 25 May 2008

(7) Herrmann, E et al (2007), ‘Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis’, Science, 317 (5843), pp.1360-1366.

(8) Gergely, G., Bekkering, H., & Király, I. (2002). ‘Rational imitation in preverbal infants’, Nature, 415, 755.

(9) Meltzoff, A (1995), ‘Understanding the intentions of others: Re-enactment of intended acts by 18-month-old children’. Developmental Psychology 31, 838-850.

(10) Tomasello, M. (1999) The Cultural Origin of Human Cognition (Cambridge, MA: Harvard University Press), p8.

(11) Engels, F. (1982) The Part Played by Labour in the Transition from Ape to Man, Moscow: Progress Publishers, p10.

(12) Mithen, S. (1998), The Prehistory of the Mind: A Search for the Origins of Art, Religion and Science, (London: Phoenix), p21.

(13) Mithen, S. (1998), The Prehistory of the Mind: A Search for the Origins of Art, Religion and Science, (London: Phoenix).

(14) Mithen, S. (1998), The Prehistory of the Mind: A Search for the Origins of Art, Religion and Science, (London: Phoenix), p83-p84.

(15) Mithen, S. (1998), The Prehistory of the Mind: A Search for the Origins of Art, Religion and Science, (London: Phoenix), p84.

(16) Byrne, R. (2006), The Thinking Ape: evolutionary origins of intelligence, (Oxford: Oxford University Press), p159.

First published by spiked