autumn books

768 NATURE | VOL 425 | 23 OCTOBER 2003 | www.nature.com/nature

ferring to debate the logic of the enterprisewithin linguistic theory. They have tended toignore findings from studies of acquisitionthat are inconsistent with their favourite theories. In short, they have not recognizedthat describing a language is not the same as describing the process by which peopleacquire it.

By contrast, in the past few decades,psycholinguists have documented many ofthe facts of acquisition. They have examinedwhat speech children hear, studied theprocesses for learning complex systems,and identified factors that influence devel-opment.But they have also generally ignoredchanges in syntactic theories — descriptionsof the rules that govern language — and theassociated issue of just what is innate aboutlanguage in humans.

Tomasello has added a new perspective tothese debates from the psycholinguistic side,based on his work with primates as well aschildren. He has brought together a numberof the topics that psycholinguists haveworked on: language studied as a system forcommunication, the relationships betweenlanguage, memory and attention, how infer-ences about meaning are made in context,choices of conceptual perspective — thedecision to call a dog a “dog” rather than an“animal” — how common ground is built up in communication, and how a speaker’sintentions are interpreted. He emphasizesthat language is essentially social and that itrelies not only on vocabulary and linguisticconstructions, but also on non-linguisticelements such as gesture and gaze.

He starts from the premise that childrenacquire language by attending closely to thelanguage they hear. To do that, they mustanalyse speakers’ intentions and find anypatterns in the language that speakers use.Tomasello argues that children acquire constructions in the same way as they dowords: they have to learn both, and just asthey slowly build up their vocabulary, theyalso slowly build up a repertoire of construc-tions. Words, in fact, are stepping-stones to constructions. For instance, children first use a verb like “want” only with “that”(“want that”), then with a following verb(“wanna go”), and only later still with a direct object and following verb (“want him[to] go out”). They build up larger construc-tions by combining smaller ones. BecauseTomasello looks at speaker intentions as wellas patterns of use, he integrates the cognitiveand the social in language development fromthe start.

Researchers have always assumed thatchildren acquire vocabulary by learning,but many have argued that learning alonecan’t explain children’s acquisition of theregularities of language that can be described in rules for syntax and morphology. Acqui-sition of these, propose Steven Pinker andothers, depends on innate language-specific

the acquisition of complex informationabout an organism’s environment implies selection to better store and use the informa-tion. The evolution of extra-large brains and corresponding intelligence in dolphinsand primates illustrates that convergence.Conway Morris stops short of saying thatanother species has yet evolved the sophisti-cated language of humans, but suggests that“waiting in the wings of the theatre of con-sciousness are other minds stirring, poisedon the threshold of articulation”. These areprovocative words and, whether or not oneagrees with his conclusions, the examples are fascinating and indicate a prodigiousknowledge of the scattered literature on convergent evolution.

Given this rampant convergence here onEarth, Conway Morris believes that “extra-terrestrials with nervous systems will hear,see, and smell in very much the same way as we do, and if that is so will also possiblyhave similar mental processes”. So where arethese ETs? Alas, he doubts that they exist.Conway Morris and Gould both think thatwe humans might be alone, but for differentreasons. For Gould,“the awesome improba-bility of human evolution” derives from contingency in adaptive evolution. ConwayMorris argues that if our planet were evenslightly different from the way it actually is,then life might not have emerged. His argu-ment is based on the difficulties of getting life started, on the failure of scientists to synthesize life from scratch, and on someunusual features of Earth and our Solar System. He even suggests that intelligencemight never have evolved here had not a cataclysmic impact jettisoned the Moon intoits orbit. This sounds rather like Gould’s historical contingency, except that ConwayMorris emphasizes physical events creatingopportunities for life to emerge and adapt,whereas Gould emphasized the idiosyncraticnature of adaptation itself.

The tension between inevitability andloneliness leads Conway Morris towards ahigher objective, which is to re-establish“notions of awe and wonder” in evolutionand thus “allow a conversation with religioussensibilities”. He dismisses Fred Hoyle’s“strange ideas about the origins of biologicalcomplexity” but admits a grudging respectfor Hoyle’s remark that the Universe is a “set-up job”. Conway Morris’s metaphysicalvision occasionally becomes overwrought,as when he says: “Not only is the Universestrangely fit to purpose, but so, too, as I haveargued throughout this book, is life’s abilityto navigate its solutions.” Whatever ConwayMorris may think about the Universe and itspredispositions, Life’s Solution invokes thestandard darwinian explanation of adap-tation by natural selection for life’s ability to navigate.

I recommend this book to anyone grap-pling with the meaning of evolution and

our place in the Universe, and to biologistsinterested in adaptation and constraints.I am obliged, however, to caution readersabout the deprecating way in which ConwayMorris sometimes refers to evolutionistswhose views he opposes. He is especially dismissive of Gould, who died a year ago:readers interested in their conflict can readan exchange elsewhere (Natural History 107,48–55; 1998). Conway Morris’s antagonismto Gould becomes more puzzling when one reads — in a chapter titled “Towards atheology of evolution?” — of his disdain for“ultra-Darwinists” and “genetic fundamen-talism”, as these were also frequent targets ofGould’s pen. But while Gould argued for theseparation of science and religion, ConwayMorris is searching for common ground.

Conway Morris derides the “almost gleeful abasement of humans” by ultra-Darwinists, and claims that Darwin himself“retreated into a gloomy agnosticism”. Butthe closing passage of The Origin of Speciesis far from gloomy: “There is grandeur in this view of life, with its several powers having been originally breathed into a fewforms or into one; and that … from so simple a beginning endless forms most beautiful and most wonderful have been,and are being,evolved.”In the second editionDarwin inserted three words (italicizedhere): “… breathed by the Creator”. In Life’s Solution, Conway Morris has perhapsexplained why, in his view of life, the secondedition might be preferable to the first. ■

Richard E. Lenski is in the Department ofMicrobiology and Molecular Genetics,Michigan State University, East Lansing,Michigan 48824, USA.

Listen, learn and constructConstructing a Language: A Usage-Based Theory of Language Acquisitionby Michael Tomasello Harvard University Press: 2003. 388 pp.$45, £29.95

Eve V. Clark

In 1965, Noam Chomsky posited that lin-guistic theory should be able to account for how children acquire a first language.In so doing, he triggered debates that havelasted ever since. What is innate? What andhow much language do children hear? Are children’s errors corrected? Do children usetwo different mechanisms for learninggrammar: one for regularities in syntax andmorphology that can be described withrules, another for irregular forms?

But few linguists have spent much timelooking at language acquisition itself, pre-

© 2003 Nature Publishing Group

autumn books

NATURE | VOL 425 | 23 OCTOBER 2003 | www.nature.com/nature 769

capacities. These capacities, argue research-ers, are shared by all languages and includeinnately given word classes.

But in Tomasello’s view, acquiring a firstlanguage entails mastering more than itsgrammar. It means learning to use the language to communicate, using the sameresources that adult speakers do. The child’sabstraction of grammatical rules, as sketchedout in Chomsky’s proposal, remains animportant part of this task but, as Tomasellopoints out, it is unclear how quickly childrenidentify such rules.

Tomasello presents a wealth of obser-vation and argument in support of hisapproach. He appeals to recent linguisticsresearch on constructions in syntax, and topsychological research on children’s under-standing of intentions and beliefs in others,on joint attention in communication, and onfunction-based distributional analyses andanalogy in learning. He makes a compellingcase for his view of acquisition as an alterna-tive both to those linguistic accounts thathave focused on grammar and on how muchis innate, and to current ‘connectionist’accounts by Jeffrey Elman and his colleaguesthat focus on the forms learnt but not on theirmeanings. He argues against the idea thatthere are different mechanisms for learningrule-based and irregular forms of language,and in favour of a single mechanism for

learning both words and constructions.And,like many biologists, he cautions againstassuming innateness without examining thealternatives.

Tomasello should make us think more,and more carefully, about language in socialas well as cognitive terms,and to consider theroles of attention, memory and learning inthe process of acquisition. But he also leavesmany questions unanswered. For example,what are the units of language being learnt?How should one define them — the notionof clause, for example? When do childrenlearn to rely on conventions — that “dog”designates the category of dogs in English,but “chien”does so in French? Did languagesevolve in the kinds of settings where adultsand infants first establish joint attention?How do children learn the meanings ofwords and constructions? How is the choiceof a conceptual perspective by the speaker —“that dog” or “that animal” — related to thebuild-up of common ground in conversa-tion? How do children get rid of errors such as “comed” (for “came”) or “me throw”(for “I want to throw it”) in their speech? Are they attentive to corrections from adults,and if so, how? Are they, in fact, exposed toenough information about constructions toallow for learning?

These are all empirical questions thatmust be taken seriously. How children

acquire language can no longer be presentedas a thought-experiment about the languagethat is the product of acquisition: it demandsconcrete data and theory about the processof acquisition. ■

Eve V. Clark is in the Department of Linguistics,Stanford University, Stanford,California 94305-2150, USA.

Changing the worldNiche Construction: TheNeglected Process in Evolutionby F. John Odling-Smee, Kevin N. Laland & Marcus W. FeldmanPrinceton University Press: 2003. 486 pp.$75, £49.95 (hbk); $39.50, £26.95 (pbk)

Laurent Keller

“Niche construction changes our concep-tion of the evolutionary process … andshould be regarded, after natural selection,as a second major participant in evolution.”So argue the authors of this book as early aspage 2. But what exactly is niche construc-tion? And if it’s really so important, howcould evolutionary biologists have neglectedit for so long?

The concept of niche construction is relatively simple. All living creatures,through both their metabolism and theirbehaviour, actively change and control theworld in which they live. Organisms choosehabitats and resources; they construct nests,holes,burrows,webs or pupal cases; and theymodify the chemical environment in whichthey live. These alterations, which occur atscales ranging from the extremely local to the global, inevitably modify some of theselection pressures acting on the organisms.And it is precisely this — the effects of anorganism on its own environment — thatthe authors believe to be the important component that has been neglected by theconventional theory of evolution.

The concept that organisms bring aboutimportant changes in their environment thatmay in turn affect their fitness is not com-pletely new, however. Charles Darwin hadalready made several potent observations tothis effect. For example, in On the Origin ofSpecies he states: “When a species, owing tohighly favourable circumstances, increasesinordinately in numbers in a small tract,epidemics — at least this seems generally to occur with our game animals — oftenensue: and here we have a limiting checkindependent of the struggle for life.” Thisobservation is strongly reminiscent of one in Niche Construction in which the authorsdiscuss how large-scale human aggregationresulting from the construction of villages,towns and cities may create new health hazards such as the spread of epidemics.

In the 1980s, several scientists pointed

© 2003 Nature Publishing Group