Closing the Hominid Gap Ivory Smuggling? Polyester Safari Suits? Glenn C

AUTUMN BOOKS publicly". The audience is thus left to its own imagination: let's see- espionage? Closing the hominid gap ivory smuggling? polyester safari suits? Glenn C. Conroy ordering red wine with fish? While the narrative of the book is a relatively straightforward account of Origins Reconsidered: In Search of What Makes Us Human. By Richard Leakey and discovery and interpretation, a certain Roger Lewin. Doubleday/Little, Brown: 1992. Pp. 375. $25, £18.99. amount of poetic licence creeps into the story. For example, molecular biologists IN the hands of skilled storytellers, the phylogenetic tree, is the level around would be surprised to learn, and David international race to close the 'hominid which most verbal fisticuffs in palaeo Pilbeam would blush to read, that it was fossil gap' has all the excitement, ro anthropology arise. For the most part, Pilbeam's "shift in position" that legiti mance and intrigue of a modern-day Leakey and Lewin spare the reader any mized the field of molecular anthropol Manhattan Project- the only difference dogmatic pronouncements on the first ogy. Similarly, Phillip Tobias might shake is that human-origins research is often level of analysis and quickly get to the his head to read that Raymond Dart portrayed as being more explosive. In more interesting, and of course more "unearthed many hominid fossils be controversial, second and third tween the 1930s and 1950s from four Australopithecus robustus Australopithecus africanus levels. As a refreshing antidote main cave sites in South Africa". As far Sagittal crest (males) No crest to the metastases of cladistic as I am aware, until the fossils dis theology in palaeoanthropology, covered at Makapansgat in the late they place more emphasis on 1940s by Tobias and colleagues rekin . how these discoveries affect our dled his interest in palaeoanthropology, . ·.. notions about human evolution Dart displayed little personal initiative ary grades and the biological in exploring the cave sites of South More robust adaptations shown by each (for Africa (including Taung). Luckily, zygomatics example, australopithecine ver Robert Broom was not so deterred. In Less8 robust zygoma tics sus Homo erectus grades of fact, one might draw the analogy that Differences between these two species ... adaptation). This is the most en Robert Broom was to Dart what Thomas joyable, informative and illumi Huxley was to Darwin. their comfortably chatty and familiar nating aspect of the book (for example, A number of current debates are style, Richard Leakey and Roger Lewin the discussion of maturational patterns reviewed, including the molecular use the recent discoveries of a nearly in Turkana Boy). To a large extent, the evidence for a human-chimpanzee clade complete Homo erectus skeleton (the authors avoid the typical preoccupation and the 'mitochondrial Eve' story. If it is 'Turkana Boy') and a hyper-robust of many palaeoanthropologists with de true, as some molecular anthropologists australopithecine cranium (the 'Black fining direct fossil lineages (although argue, that two such morphologically Skull') as convenient launching pads for Leakey's understandably Kenya this sequel to their successful previous centric view of human evol Australopithecus robustus Australopithecus africanus collaboration, Origins, which was pub ution does peek through at lished in 1977. Leakey's unique personal times). When one considers that Steeper forehead history combined with Lewin's crisp, all known fossil hominoids from engaging writing style results in an en Africa come from only a tiny joyable, fast-paced read. fraction of the present-day land Leakey is described on the dust jacket surface of that continent, it as "the world's most famous living stretches credibility to believe paleoanthropologist", leaving me to pon that any direct ancestors of later der whom the publisher's regard as the humans have yet been found. world's most famous dead palaeoanthro The recent discovery of a .. .lie mainly in dental and cranial features. pologist. The only disappointing aspect Miocene hominoid from north- of the book's production is the poor ern Namibia is a powerful reminder of dissimilar animals as humans and chim choice and marginal quality of the how little we know about the geographic panzees share a more recent common photographs. Inexplicably, there is only distribution of human ancestors. ancestor than two such morphologically one (inadequate) photo each of the To be sure, Origins Reconsidered has similar animals as chimpanzees and Turkana Boy and the Black Skull, many of the elements the public now gorillas, then palaeontologists have little even though they are the centrepieces comes to expect from trade books on choice but to pack up their shovels, of the story. human origins. There are the usual tales throw in the towel, and never again Both discoveries provide important of adventure in remote and dusty places attempt another cladogram based on new insights into human evolution, par and the heavy dose of male bonding (or morphological characters. But do ticularly the Homo erectus skeleton. Most 'male bondage' as Dan Quayle once in molecular anthropologists overstate their evolutionary hypotheses can be broken advertently called it). Palaeoanthropol case? Vince Sarich once tweaked the down into three analytical levels: the ogists have elevated the 'don't get mad, collective noses of palaeoanthropologists cladogram, the phylogenetic tree and the get even' school of scientific journalism by writing that "one no longer has the scenario. Unlike cladograms and phyla to an art form and the reader does not option of considering a fossil specimen grams, scenarios are not diagrams but, have to wait long before Leakey and older than about eight million years a rather, historical narratives that describe colleague Alan Walker return the favour hominid no matter what it looks like". not only phylogenetic relationships but by effectively 'slam-dunking' Donald However, let us remember that the hu also the ecological and evolutionary Johanson. Leakey teases his audience a man genome contains some three billion forces that most directly influence the bit by lamenting that his personal and base pairs, so that even 'good' DNA org<misms under discussion. The scen professional relationship with Johanson sequence data of 10 kilobase pairs cover ario, being more hypothetical and began to deteriorate for unspecified only a small fraction of the genome. interpretive than the cladogram or reasons he considers "best not discussed Given the recent 'mitochondrial Eve' NATURE · VOL 360 · 26 NOVEMBER 1992 393 © 1992 Nature Publishing Group AUTUMN BOOKS fiasco in which flaws in statistical pro utterly harmless sense of 'higher-level' or cedures and maximum parsimony analy Common-sense 'emergent' in which solidity is a higher sis of the mitochondrial DNA data using level emergent property of H 20 mol the PAUP computer program have been consciousness ecules when they are in a lattice struc noted and the conflicting molecular evi ture (ice)", but he goes on to deny the dence about whether the chimpanzee Stuart Sutherland reducibility of consciousness to brain gorilla-human trichotomy is really re function. But if solidity can be reduced solved, or even resolvable, one 'genio The Rediscovery of the Mind. By John R. to the behaviour of molecules, why can glossus in vestibule' rejoinder to Sarich Searle. MIT Press: 1992. Pp. 270. not consciousness similarly be reduced to might be that "one no longer has the $22.50, £19.95 (hbk); £9.95 (pbk). the behaviour of the brain of which it is option of considering chimpanzees more (Pbk not yet available in the US.) an emergent property? Searle's answer is closely related to humans than to gorillas tortuous. He claims that solidity original no matter how good the molecular evi JusT as the mini-skirt comes and goes ly meant the feeling produced by a solid dence superficially appears to be"! in women's clothing, so does conscious object: the reduction applies not to this To his credit, Leakey is not hung up ness fluctuate in fashion for philos feeling but to the property of the object on giving fossils specific names and ophers. In the past few years, book that gives rise to the feeling. This argu seems to understand, unlike many of his shops have been graced or despoiled by ment does not work: if the solidity of an peers, that just because one gives a shelf-loads of tomes devoted to the sub object can be reduced to the behaviour specific name to a fossil does not neces ject. Almost all have been turgid and of its molecules and if the relation be sarily"mean that one has described a real obscurantist. Now, with The Rediscovery tween consciousness and the brain is biological species. The biological species of the Mind we have a clear, well written analogous to that between the solidity of concept is only operative in organisms and cogently argued account, which is an object and the state of its molecules, where reproductive behaviour can be marked by that unfashionable quality, then surely consciousness should be re examined in nature (or the laboratory). common sense. In standing up for the ducible to brain states. The contention Species-specific morphological distinc existence of consciousness as a fact, John that consciousness is merely an emergent tions can only be codified after species Searle attacks with pleasing acerbity the property of brain states cannot therefore are so identified. The process does not loonier beliefs of those who have be sustained. It is no use Searle arguing, work the other way round. One cannot attempted to deny it. For example, of as he does, that such phenomena as first observe differences in fossils and the Churchlands, who claim that mental magnetism were irreducible before Max then claim that these differences define terms have been invented by ordinary well and similarly that one day we will true biological species because, as is well people to explain behaviour ("folk have a theory that shows how conscious known, morphological differentiation psychology") and therefore have no ness emerges from the brain.

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