biological and cultural foundations of human language: insights from computer simulations nick...
Post on 20-Dec-2015
214 views
TRANSCRIPT
![Page 1: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/1.jpg)
Biological and cultural foundations of human language: Insights from computer simulations
Nick ChaterDivision of Psychology and Language Sciences
UCL
Morten ChristiansenFlorencia Reali
Andrea Baronchelli
Romualdo Pastor-Satorras
![Page 2: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/2.jpg)
Overview
• 1. A brain adapted for language?
• 2. Co-evolution of genes and language? Simulating the Baldwin effect
• 3. Diverging human populations
• 4. Functional features can become genetically embedded
• 5. Conclusions
![Page 3: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/3.jpg)
1. A brain adapted for language?
![Page 4: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/4.jpg)
Could brains be adapted for language?
• Language seems extremely complex
• And to have many highly specific and incredibly subtle properties
• How can children figure it out, while linguists can’t?
• That is, how is language acquisition possible?
• Perhaps the triggering of a genetically coded language-specific faculty?– language instinct– language organ– language acquisition device– language module
![Page 5: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/5.jpg)
A language-specific faculty implies the brain is adapted for language, just as it adapted for vision
• The visual environment today
• Visual environment of evolutionary adaptation
Strangely similar…
![Page 6: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/6.jpg)
• The linguistic environment today
• Linguistic environment of evolutionary adaptation
Roar!
“…the cat sat on the mat…”
Strangely dissimilar…
![Page 7: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/7.jpg)
But perhaps language and the language faculty co-evolved via the Baldwin effect (Pinker & Bloom, 1990)
• Driving acquired traits into the genes--– It may work for ostrich calluses– perhaps it works for language
![Page 8: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/8.jpg)
2. Co-evolution of genes and language? Simulating the Baldwin effect
![Page 9: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/9.jpg)
• “Language” is a string of features
• Genes can express bias or neutrality on each feature: “fixed” .95 bias to red: “fixed” .95 bias to blue:“learnable”: unbiased
• “Genome”:
The Baldwin effect: A very simple simulation
• Trial and error learning
• Only the fastest learners “reproduce”
• And create the next generation by sexual recombination and mutation
• Do the genes begin to adapt to the language???
![Page 10: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/10.jpg)
The Baldwin effect in action
![Page 11: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/11.jpg)
But co-evolution requires genetic adaptation to a varying language
• Can language change lead language genes?
• Potential problem:– Language changes very fast, in relation to genetic change
• So what happens when language and genes can both change?
![Page 12: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/12.jpg)
Same speed for language and genetic mutation rate
![Page 13: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/13.jpg)
Languages changes twice as fast
![Page 14: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/14.jpg)
Language changes 10 times as fast
No Baldwin effect
No coevolution
“Learnable” genes win out
![Page 15: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/15.jpg)
Genes cannot catch a linguistic “moving target”
Chater, N., Reali, F. & Christiansen, M.H. (2009). Restrictions on biological adaptation in language evolution. PNAS, 106, 1015-1020.
![Page 16: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/16.jpg)
Joint work with Andrea Baronchelli, Romualdo Pastor-Satorras, Morten Christiansen, in prepartion
3. Diverging human populations
![Page 17: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/17.jpg)
Once populations are split, co-evolution will be specific to the local linguistic environment
Joint work with Andrea Baronchelli, Romualdo Pastor-Satorras, Morten Christiansen (in prep)
If language-gene coevolution occurred, it had better stop, once populations diverge
But wide geographical separation occurred early, w.r.t., to presumed time-scale for language
(And even geographically nearby groups show very fast linguistic change)
Test with population splitting simulations...
No co-evolution beyond this point!
![Page 18: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/18.jpg)
Case 1: Language change is fast
• No coevolution
• Neutral “genes” dominate
• No UG
![Page 19: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/19.jpg)
Case 2: Language change is slow
• Lots of local coevolution; few neutral genes
• Genetic divergence precisely mirrors linguistic divergence;
• No UG
![Page 20: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/20.jpg)
4. Functional features can become genetically embedded
![Page 21: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/21.jpg)
But non-arbitrary features of language may become genetically assimilated
• Because non-arbitrary features will be stable under cultural evolution– Compositionality
– Large vocabulary
– Layers of both phonology and syntax
• And hence may provide a viable target for biological evolution...
![Page 22: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/22.jpg)
Non-arbitrary features of language can become genetically assimilated
![Page 23: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/23.jpg)
Genes cannot catch a linguistic “moving target”
Christiansen, Reali & Chater (submitted)
![Page 24: Biological and cultural foundations of human language: Insights from computer simulations Nick Chater Division of Psychology and Language Sciences UCL](https://reader036.vdocuments.site/reader036/viewer/2022062516/56649d425503460f94a1d389/html5/thumbnails/24.jpg)
5. Conclusions
• No co-evolution of genes for arbitrary features of language– Incompatible with classical UG in linguistics (but there is not necessarily
a clash with minimalism metatheory)
• Co-evolution of functional features of language might occur (but not required to explain functional universals)
• Language evolution is primarily cultural evolution: language evolves to be easy to learn and process
Language is shaped by the brain