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!

Friday, 21 May 2010

Somatosensation In Social Perception

Meanwhile, in the same number of the same journal - Nature Reviews Neuroscience - one of the doyens of human mirror neurons - Christian Keysers - reports finding evidence for the firing of mirror neurons in the somatosensory cortices - those parts of the brain that receive and process incoming information from our sense organs - ears, eyes, touch sensors etc. etc. "Studies that measure brain activity while participants witness the sensations, actions and somatic pain of others consistently show vicarious activation in the somatosensory cortices", they say, in the abstract.

Mirrors, Mirrors Everywhere?

The debate over whether or not mirror neurons really exist, and whether or not they have been satisfyingly proved to exist in humans rumbles on. One bug-bear is the lack of direct observations of neurons firing in humans due to the inability of investigators to push probes into human brains except in very rare cases where brains are already being investigated for things like Parkinsons Disease. However, in this breezy piece in Nature Reviews Neuroscience, Leonie Walberg reports on some work where recordings of single-cell activity have been made, from several areas of human brain, that behave with mirror neuron properties.

The authors, she says, report activity in patients with implanted electrodes when they observed or executed grasping actions and facial expressions. Recordings were made from medial frontal cortex (which includes the anterior cingulate cortex, an important component of the 'social brain'), medial temporal cortex (which includes the amygdala - another important 'social brain'structure, and the hippocampus).

"Of the 68 'matching cells' detected, 33 showed increased firing during both the observation and execution of a particular action and 21 cells showed decreased firing in both conditions. Interestingly, in the remaining 14 neurons, the firing rate increased in one condition but decreased in the other."

The authors speculate that the decreased firing in some cells, which is not the classical mirror neuron condition, may have a role in suppressing execution of observed actions to ensure that we do not imitate every action we see. However this observation seems destined to further fuel the rather rancorous debate over mirror neurons being all things to all people. After all, mirror neurons were first reported in monkeys - a species that is very poor at imitation, whereas humans, if anything, over-imitate.

Thursday, 20 May 2010

Two More "Brain-builder" Proteins

In my chapter BRAIN-BUILDERS I recount the tale of how the discovery of two genes responsible for microcephaly - ASPM and Microcephalin - has an evolutionary dimension in that both genes have accumulated substantial sequence evolution since the split from the common ancestor. Both genes affect the plane of the spindle in mitotic cell division of neuron progenitor cells such that cells can be kept in the totipotent state for longer - squeezing proliferation power out of the neuro-epithelium. Now a group of scientists at the Picower Institute at MIT have discovered two more proteins - Cdk5rap2 and pericentrin - that work together to regulate neural growth in the developing brain. Loss of function of these proteins, they report, causes microcephaly and osteodysplastic primordial dwarfism. Their normal action takes place in the developing neocortex and their mode of action was discovered using "knock out' mice.

Wednesday, 19 May 2010

Birds And Mammals Share A Common Brain Circuit For Learning

In my chapter CLEVER CORVIDS I point out that recent research comparing avian and mammalian brains has demonstrated that parts of both are derived from the same embryonic structures, which suggests that bird brains are not "bird-brains" after all. Here research on neurons in a part of the basal ganglia of the zebra finch - so-called area X which is involved in the learning of song - bear strong comparison to neural structures in the corresponding part of mammalian brains - the striatum and globus pallidus. As the scientists concerned are quoted saying: "Our results strongly suggest that the same brain circuits underlie learning in birds and mammals, despite the superficial differences in anatomy".

Creativity Linked To Mental Health

In the final chapter of NOT A CHIMP I talk about fresh research that has breathed life into much older ideas about the link between mania and creativity. Here a group of Scandinavian scientists carry the story still further with the discovery that highly creative people and schizophrenics have similar profiles of dopamine D2 receptors in the brain - particularly the thalamus (which acts as a filter for incoming material from the senses which is then passed on to neo-cortical structures for advanced processing). Schizophrenics and creatives have a lower density of D2 receptors in the thalamus, suggesting that this causes the thalamus to be less strict in its signal filtering. There is therefore a higher flow of signals from the thalamus which might, says the article, "be a possible mechanism behind the ability of healthy highly creative people to see numerous uncommon connections in a problem-solving situation and the bizarre associations found in the mentally ill".

As lead scientist Fredrik Ullen, explains: "Thinking outside the box might be facilitated by having a somewhat less intact box (the thalamus)".

Tuesday, 18 May 2010

Anthropocentrism - Born Or Made?

In the book, and in many of my recent posts, I have ground on about our innate human propensity for attributing human cognition to animals - anthropomorphism - and the way it bedevils comparative cognitive research. But where does such an ingrained cognitive bias come from? Are we born with it, or do we acquire it during child development? Most psychologists have assumed that anthropocentrism - favouring a human vantage point when it comes to comparing us to the animals and them to us - is a default position hardwired into babies and thence young children, but recent research, reported here, by a team of scientists from Northwestern University, challenges that view. They maintain that 3 year- olds do not have this anthropocentric bias, but, that by the time URBAN children are 5+, they do. The conclusion is that anthropocentrism is thrust upon developing children by the attitudes they are surrounded by as they grow up, and the biased way animal behaviour is represented in the media - tv programmes and kiddies books etc.