Universal Darwinism?

1. Universal Darwinism? • We know that biological evolution requiresreplication with variation, plus natural selection for useful traits • But Dawkins suggests that evolution will ALWAYS happen when these preconditions are met • This evolution might not be biological!

2. Breeding ideas? • It may seem silly to think of an idea, or a form of behaviour, breeding… • BUT breeding = creating a new copy • Whenever an idea is spread to another mind, a new copy of the information in that idea is created • … so we can say that whenever someone hears a new idea or learns a new behaviour, that idea has successfully reproduced

3. How do ideas reproduce? • Imitation • Animals very bad at this • Humans very good at this • We readily imitate the behaviours of others • Linguistic behaviours • Fashions, hobbies, crazes

4. The evolution of culture • So ideas reproduce (with variation) … • Are ideas selected? • Yes! • What ideas will get selected? • i.e. What ideas will tend to spread? • Ideas which are good at spreading themselves!

5. Enter the meme • Dawkins in The Selfish Gene: • “meme” as the unit of imitation • (just as “gene” is the unit of biological inheritance) • suggested that memes can evolve • groups of memes making up “idea animals” • Theory elaborated by Blackmore (1999) and others (e.g. the philosopher Dennett) • Key point: memes are selected for their usefulness to themselves, not to us! • Memes as parasites?

6. What is co-evolution? • As we have seen, species evolve by natural selection to fit their environment… • … but part of that environment may be other organisms! • Organisms can evolve to become dependent on one another (symbiosis)

7. Co-evolution in nature • Intestinal bacteria • Insects pollinating flowers • The eukaryotic cell • … and many other examples

8. Co-evolution can also occur in situations where one organism is parasitic on another • bacteria specialize to invade other species, which in turn evolve defenses • consider case of malaria, which may account for the persistence of the sickle-cell gene in some human populations

9. We might also consider co-evolution of different genes, at separate loci, within a single species • For example, consider the stick insect, where genes that lead to the development of a body appearance that resembles a twig co-evolve with genes that lead to behavior that reinforces the camouflage

10. Language as co-evolution Deacon and Blackmore In this case we will consider co-evolution between genes and memes within a single species, rather than co-evolution between two species

11. What has this got to do with language? • If we put these two ideas together… • … we can see language as a bundle of behaviours, an “idea animal” • Its habitat is the human brain • It has evolved to fit that habitat • Can we explain the origin and / or acquisition of language in these terms?

12. Blackmore (1999) • Blackmore on the Big Brain: it evolved to allow us to store and spread memes better • Blackmore on the origin of language: • What is language for? – she concludes it is for spreading memes • Co-evolution: • language (made of memes) is evolving… • But our genes are evolving to fit our memes (inc. language) too

13. Deacon (1997) • Deacon: key to language is symbol use • Control of social/sexual relationships • Language evolves to fit its environment • Its environment is the brain of the child • Language has therefore evolved to become easy for a child to learn • Deacon: this explains language acquisition • Our brains have also evolved to accommodate language (co-evolution)

14. Summary • Two theories based on language evolving to inhabit us, rather than us evolving to use language • Blackmore: meme theory • Deacon: language evolving to fit child’s brain • Both theories involve co-evolution • Language and brain/body have evolved together, becoming co-dependent/symbiotic

15. Word of warning • Both Deacon and Blackmore’s theories are relatively new… • … and fairly controversial • They are only favoured by a minority of linguists • e.g. the Chomskyans oppose this view