Linguistics 001, Spring 2010

Evolution of Language: Prospects

Outline

• In the study of biological systems, interesting questions often center on evolution; i.e., on how it is that things came to be as they are

• The same type of reasoning has been applied to (aspects of) cognition, and in particular to the development of language as a human ability

Prospects

• The reading from the bulkpack, by Lewontin, advances a number of arguments to the effect that studying the evolution of cognition (and language) is at best a kind of ‘story-telling’

• In order to understand the force of these objections, which we review below, we will first examine what evolutionary thinking might tell us

Possibilities

• Researchers focussing on arguments that language is a product of evolution (e.g. Pinker and Bloom) try to justify this claim in various ways:– Language is a complex adaptation to the

problem of ‘communication’, and is ‘well-suited’ to this task

– In general, adaptive complexity should be explained through natural selection

Questions

• Two ways of talking about the evolution of cognition– It is interesting in its own right to know how complex

cognitive capacities developed in evolution– Knowing the evolutionary trajectory of a particular

ability like language should shed some light on the question of how the system functions

• The first of these might be a matter of ‘taste’ or interest; the second type says something more specific, and is more contentious for this reason

The Critique

• Lewontin’s paper asks in very general terms how it would be possible to make and test specific claims about the evolution of cognition and e.g. language

• His basic argument is that many claims about evolution of cognition are (1) trivially true, but (2) we don’t know for sure, and (3) it doesn’t seem like we find out

Stories

• It’s possible to simply tell plausible stories about biological properties of organisms.

• In the case of language, there are many such stories; language is required for communication, hunting, evolved because of gossip…

This ‘story-telling’ can involve more or less plausible parts; but ultimately we’re interested in theories that can be tested, and that’s where most of Lewontin’s critique is directed.

Principles of Evolution

• Consider the principles that underlie evolutionary reasoning in general:– Variation: Variation in physiology/anatomy/behavior among

individuals of a species– Heredity: Offspring resemble their parents in traits more

than they do unrelated individuals (typically for genetic reasons)

– Natural Selection: Individuals with certain traits leave more offspring than individuals with other traits, because possessing those traits makes them better able to do what they need to do to survive, reproduce, etc.

Application to Cognition/Language• If, then, one is to provide an argument

about how language evolved, several things have to be done– It must be shown that there is heritable

variation in cognitive capacities– It must be shown that individuals with

greater capacities leave more offspring– Etc.

Problems

• Even when we put aside concerns about heritability etc., there are problems; a crucial one is that we are talking about pre-history:

“Our remote ancestors are not preserved in museum collections, we do not know what kind of heritable variation existed in the past or exists today…and we cannot measure the survival advantage, if any, in our remote ancestors of the ability to do arithmetic.”

Lewontin, p. 111

Specifics

• Some expansions:– We have no ‘close’ relatives (e.g. 7-10 million years to a

common ancestor with chimpanzees, vs. a few thousand for dogs and wolves)

– We are not sure who our ancestors are• Evidence from the fossil record is limited• Inferences about cognitive abilities have to be based on

e.g. cranial capacity (since stone tools are found in a number of hominid types)

– How can these limitations add up to what has to be known for the evolutionary case to be made?

Homology/Analogy

• Another interesting point, which connects with the last lectures on animal communication :– Analogous traits: characteristics similar in

function and form between species, but independent developmentally

– Homologous traits: characteristics connected with each other by unbroken lines of inheritance

• Tails in mammals: in whales, appendages to the spine; in seals, modified hind legs. These are analogous.

For Cognition

• Suppose, then, that we take a comparative perspective on cognition

• How can we tell the difference between analogies and homologies?

• How do we define ‘cognition’ in the first place for comparative investigations, given that different species are specialized for different things?

Connections/Conclusions

• Brain areas have homologues between humans and monkeys/primates, and some functional connections can be studied (e.g. Broca’s in macaques relates to facial movements)

• But it isn’t clear what in a primate brain would be homologous to speech, since primates do not have speech

• Similar considerations apply in the attempts to teach language to non-humans; what we see could very well be analogy, in which case we wouldn’t learn anything about the evolution of language

• What role should “adaptationism” play (if any) in the study of language?