Click on the cover to link to OUP's e-catalogue then turn to the biology section.

Interview Podcast with George Miller

Interview Podcast with George Miller
Click on the pic to link to the NOT A CHIMP podcast on Blackwell's Website

Preface to "Not A Chimp: The Hunt For The Genes That Make Us Human"

In many ways, this book is born out of frustration for a professional career in popular science television where ideas about comparative primate cognition, and the similarities and differences between us and our primate relatives, have continually circled me but constantly evaded my grasp in terms of the opportunity to transform them into science documentary. On the plus side, keeping a watching brief for over a quarter of a century on subjects like comparative animal cognition and evolution allows you to watch a great deal of water flow under the bridge. Fashions come and fashions go - specifically, perspectives on the similarity - or otherwise - of human and ape minds.

I remember the first Horizon science documentary about the chimpanzee Washoe, the great ape communicator, using American Sign Language to bridge the species barrier. And, later, Kanzi the bonobo jabbing his lexicon. These were the apes, as Sue Savage-Rumbaugh has put it, that were "on the brink of the human mind".

I remember when the pre-print of Machiavellian Intelligence, by Andrew Whiten and Dick Byrne, plopped onto the doormat of the BBC Antenna science series office in 1988. Suddenly primatology had become a great deal more exciting. Could primates, and especially higher primates like chimpanzees, really be as full of guile, as dastardly, as cunning, and as manipulative as the eponymous Florentine politician? Could they really reach deep into the minds of other individuals to see what they believed and what they wanted, and turn that information into deception?

I remember discussing primate cognition with a young Danny Povinelli, as we sat finger-feeding ourselves shrimp gumbo and new potatoes out of plastic Tupperware containers in a Lafayette restaurant surrounded by an alligator-infested moat, before returning to his kingdom - the New Iberia Research Centre - where the University of Louisiana had lured him back to his native deep South by turning a chimpanzee breeding centre for medical laboratory fodder into a primate cognition laboratory with one of the largest groups of captive chimpanzees in the country. He looked like a kid who had just been thrown the keys to the tuck shop.

In those days Povinelli shared the zeitgeist - spread by Whiten's and Byrne's work, and started by Nick Humphrey and Alison Jolly before them - that, since the most exacting and potentially treacherous environment faced by chimpanzees and other primates was not physical, but the social environment of their peers, they had evolved a form of social cognition very much like our own, in order to deal with it. This was further elaborated into a full-blown "social brain" hypothesis by Robin Dunbar, who related brain neocortex size to social group size throughout the primates and up to man. Povinelli's early work reflects this optimism for the mental life of apes, but both ape-language and ape-cognition research was subjected to a cold douche of searching criticism during the 1990s, and misgivings set in regarding the effectiveness of the experiments that had been constructed to guage ape cognition. Now the worm has turned again, with a number of research groups emerging with bolder and bolder claims for the Machiavellian machinations of primate minds, only to be powerfully countered by the curmudgeonly skepticism, chiefly by Povinelli, that these researchers are merely projecting their mental life onto that of their subjects; that, rather in the frustrating manner of Zeno's arrow that could never quite reach its target because it continually halved its distance to it, no experiment constructed thus far can actually get inside the mind of a chimp and show us exactly what it does and doesn't know, or how much, about the minds of others or the way the physical world works. One influential part of the world of comparative animal cognition talks of a continuum between ape and human minds and shrinks the cognitive distance between us and chimps to almost negligible proportions, while another returns us to the unfashionable idea that human cognition is unique, among the primates, after all.

When I began writing this book the working title was "The 1.6% that makes us human". My aim had always been to scrutinize the impression put about in the popular science media that humans and chimps differ by a mere 1.6% in our genetic code - or even less - and that it therefore makes complete sense that this minuscule genetic difference translates into equally small differences in cognition and behaviour between apes and man. However, contemporary genome science and technology, over the last few years, have dramatically advanced the power and resolution with which scientists can investigate genomes, eclipsing the earlier days of genomic investigation that gave rise to the "1.6% mantra".

As with comparative cognitive studies, conclusions on chimp-human similarity and difference in genome research depend crucially on perspective. To look at the complete set of human chromosomes, side by side with chimpanzee chromosomes, at the level of resolution of a powerful light microscope, for instance, is to be overwhelmed by the similarity between them. Overwhelmed with a sense of how close our kinship is with the other great apes. True, our chromosome 2 is a combination of two chimp chromosomes - giving humans a complement of 23 chromosome pairs to 24 in chimps, gorillas and orang-utans - but even here you can see exactly where the two chimp chromosomes have fused to produce one. The banding patterns you visualize by staining the chromosomes match up with astonishing similarity - and that banding similarity extends to many of the other chromosomes in the two genomes. However, look at a recent map of the chromosomes of chimps and humans, aligned side by side, produced by researchers who have mapped all inversions - end-on-end flips of large chunks of DNA - and the chromosomes are all but blotted out by a blizzard of red lines denoting inverted sequence. Now you become overwhelmed by how much structural change has occurred between the two genomes in just 6 million years. True, not all inversions result in changes in the working of genes - but many do - and inversions might even have been responsible for the initial divergence of chimp ancestor from human ancestor.

The extent to which you estimate the difference between chimp and human genomes depends entirely on where you look and how deeply. Modern genomics technology has led us deep into the mine that is the genome and has uncovered an extraordinary range of genetic mechanisms, many of which have one thing in common. They operate to promote variability - they amplify differences between individuals in one species. We now know, for instance, that each human is less genetically identical to anyone else than we thought only three years ago. When we compare human genomes to chimpanzee genomes these mechanisms magnify genetic distance still further. I have tried, in this book, to follow in the footsteps of these genome scientists as they dig deeper and deeper into the "Aladdin's Cave" of the genome. At times the going gets difficult. Scientists, like any explorers, are prone to taking wrong turnings, getting trapped in thickets, and covering hard ground, before breaking through into new insights. I hope that those of you who recoil from genetics with all the visceral horror with which many regard the sport of pot-holing will steel yourselves and follow me as far as I have dared to go into Aladdin's Cave. For only then will you see the riches within and begin to appreciate, as I have, just how limited popular accounts of human-chimpanzee genetic difference really are. Let me try and persuade you that this is a journey, if a little arduous at times, that is well worth taking.

There are a number of scientists around the world who have the breadth and the vision to have begun the task of rolling genetics, comparative animal cognition, and neuroscience into a comprehensive new approach to the study of human nature and this is part, at least, of their story. They strive to describe the nature of humans in terms of the extent to which we are genuinely different to chimpanzees and the other great apes. Somehow, over 6 million years, we humans evolved from something that probably resembled a chimpanzee (though we cannot yet be entirely sure) and the answer to our evolution has to lie in a growing number of structural changes in our genome, versus that of the chimpanzee, that have led to the evolution of a large number of genes that have, effectively, re-designed our brains and led to our advanced and peculiar human cognition.

If you don't believe me, hand this book to your nearest friendly chimpanzee and see what he makes of it!

Thursday, 19 November 2009

The Absent Referent

In NOT A CHIMP I devote a great deal of time discussing whether or not chimps, or any other animal species for that matter, can have any understanding of entities that are invisible - like mental states in the brains of other individuals and physical forces in the natural world - like gravity. I conclude that there is still no reliable evidence that chimps can mind read or have any grasp of "folk" or intuitive physics. Here, in an evol-psych group essay, editor Robert Karl Stonjek adds a third invisible to the array of cognitive powers we humans have and chimps don't - the absent referrant.

The Absent Referent
Robert Karl Stonjek

* * * * Black marks on the asphalt. A child's toy lays broken. * * * *

In their recent paper "Prelinguistic Infants, but Not Chimpanzees, Communicate About Absent Entities", Ulf Liszkowski, Marie Schäfer, Malinda Carpenter, and Michael Tomasello point out that chimps are unable to communicate information about the absent referent.

An experimenter places a favoured object away from baby/chimp subjects. Both are capable of gesturing their desire for the object. Then the object is placed behind a screen. Again, chimp and human subjects can gesture their interest in the object behind the screen.

Now the object is placed in a 'usual' location a few times, so that ape and human become familiar with the usual location of the object. And then the object is removed altogether (the location is now a referent for the absent object). The baby, but not the chimp, will gesture toward the absent referent and try to draw the attention of the experimenter to the missing object.

I speculate that infant chimps may also understand the absent referent but that adult chimps (as in this experiment) will not. I note that some dogs and cats will gesture toward their empty bowls when water or food is absent (my cat will do this when the bowl is running low and it wants the bowl placed outside the door for the night.)

But the absent referent is much more than this in humans. The absent referent acquires a property attributable to the referent that is absent. The imagery at the head of this essay conjures an image of a child hit by a motor car, even though there is no evidence of such an event. The lost wedding ring that is replaced by a new one is not the same because of the absent referent. 'Qualia' can be thought of as the referent which is absent (properties implied by the target object).

Humans not only see or have knowledge of the referent which is absent, they perceive its vestige as a property of the thing from which it is absent. We say that grandpa's walking stick reminds us of him, but we also perceive something of grandpa in the walking stick which is why we want to keep it. If it were just a reminder then a replica would be sufficient.

Tools may be a simple as a particularly shaped stone. But the stone tool takes on a special character when the ability to perceive the absent referent has evolved. The use of the tool remains with that tool, we see it (the absent referent). If we gained status at the time of using the tool, then that status remains with the tool as an additional absent referent. The tool takes on those qualities ~ status and utility ~ even though the tool is not being used. Thus humans readily kept tools and defended the possession of them in the same way they defend any other aspect of their status.

Words can be characterised as having a denotation (the bland dictionary meaning) and a connotation (the feeling the word evokes, its inner meaning or personal meaning to us). The connotation is the absent referent ~ the thing that the word refers to, even when the thing is not present. The feeling behind every word, that which gives the word meaning, can be traced back to the absent referent that the baby described above 'sees' when pointing to the place where the favoured object usually sits ~ the chimp does not 'see' it.

Not all words map directly onto concrete objects or actions. There is a long and complex cognitive road between the simplest absent referent and the full language we currently use. But the same root form gives rise to art, music, language, the concept of future and past, religion and all else that makes up human culture. Absent referents can be manipulated as abstract or symbolic forms.

As mentioned earlier, I think it is highly probable that the precursor of humans with language would have had absent referent capability as children and this would have been a necessary part of playing behaviour. When the ability to model the absent referent entered adulthood, probably due to a single gene mutation, we had the genesis of all that is uniquely human.

Symbolic Gestures And Spoken Language Are Processed By A Common Neural System

Excellent paper by a team which includes Pat Gannon. I cannot do better than to reproduce the abstract and for those of you more interested, and not able to source PNAS normally through a university library system, this is one of their open access articles - its free!


Symbolic gestures, such as pantomimes that signify actions (e.g., threading a needle) or emblems that facilitate social transactions (e.g., finger to lips indicating “be quiet”), play an important role in human communication. They are autonomous, can fully take the place of words, and function as complete utterances in their own right. The relationship between these gestures and spoken language remains unclear. We used functional MRI to investigate whether these two forms of communication are processed by the same system in the human brain. Responses to symbolic gestures, to their spoken glosses (expressing the gestures' meaning in English), and to visually and acoustically matched control stimuli were compared in a randomized block design. General Linear Models (GLM) contrasts identified shared and unique activations and functional connectivity analyses delineated regional interactions associated with each condition. Results support a model in which bilateral modality-specific areas in superior and inferior temporal cortices extract salient features from vocal-auditory and gestural-visual stimuli respectively. However, both classes of stimuli activate a common, left-lateralized network of inferior frontal and posterior temporal regions in which symbolic gestures and spoken words may be mapped onto common, corresponding conceptual representations. We suggest that these anterior and posterior perisylvian areas, identified since the mid-19th century as the core of the brain's language system, are not in fact committed to language processing, but may function as a modality-independent semiotic system that plays a broader role in human communication, linking meaning with symbols whether these are words, gestures, images, sounds, or objects.

Wednesday, 18 November 2009

Right-Handed Chimps Provide Clues To The Origin Of Human Language

More good news for those scientists who support the idea that human language evolved from the use of intentional gestures. Bill Hopkins, and French colleagues, have been recording communicative gestures in chimps for years and have found a highly significant bias to use of the right hand in communicative gestures used in contexts like attention getting, shared excitation, threat, aggression, greeting, reconciliation, and overtures to play. This, of course, implies left lateralization of the brain for these gestures. As the scientists conclude: "This finding provides additional support to the idea that speech evolved initially from a gestural communication system in our ancestors. Moreover, gestural communication in apes shares some key features with human language, such as intentionality, referential properties and flexibility of learning and use."