PhD (Auckland)

Professor
Room: HSB 651
email: rd.gray@auckland.ac.nz
Ph 64 9 377599 ex 88525
My Lab website: http://language.psy.auckland.ac.nz/


Research Interests

My current research spans four areas: language evolution, animal cognition, avian evolution and philosophy of biology. The work on language evolution focuses on the application of phylogenetic methods to questions about human prehistory. The research on animal cognition uses the New Caledonian crow as a model for examining debates about the links between tool manufacture, cognition and cultural evolution. The work on avian evolution uses phylogenetic methods to answer questions origin of groups like penguins and Pelecaniforms and the evolution of their behaviour. My research on the philosophy of biology has focused on the nature/nurture debate and the role developmental systems play in evolution. My work in all these apparently disparate areas is united by a strong emphasis on evolutionary thinking and principles.


Research Projects

1.  Language evolution

Questions about human origins have an enduring fascination. Where did the Polynesians come from? How did Indo-European languages spread over Europe? Genetic and linguistic evidence provide vital clues to solving these mysteries of our past. Recently there have been huge advances in the computational methods used to make inferences from genetic data. Languages evolve in remarkably similar ways to biological species. They split into new languages, mutate, and sometimes go extinct. However, despite these parallels linguists have not commonly used the phylogenetic methods that have revolutionised evolutionary biology in the last twenty years. In other words they have not used an explicit optimality criterion to select the best language tree, nor have they used an efficient computer algorithm to search through the vast number of possible trees for the best tree. This project involves analysing linguistic data using the kind of methods evolutionary biologists have developed to investigate molecular evolution. In the past few years I have examined Indo-European languages but the focus is now shifting to languages in the Pacific (Austronesian languages) and Meso-America.

Gray, R.D. (2005). Pushing the time barrier in the quest for language roots. Science, 309, 2007-2008. [request a pdf]
Gray, R.D. & Atkinson, Q. (2003). Language-tree divergence times support the Anatolian theory of Indo-European origins.  Nature, 426, 435-439. [request a pdf]
Gray, R.D. & F.M. Jordan.  (2000).  Language trees support the express-train sequence of Austronesian expansion.  Nature, 405, 1052-1055. [request a pdf]

2.  Tool manufacture, culture & cognition: New Caledonian crows as a model system. 
(Funded by the Marsden Fund, a collaboration with Dr Gavin Hunt)

Many animals use tools, but tool manufacture is rare. Rarer still is cumulative change in tool manufacture. Chimpanzee and orangutan tool manufacture, for example, is often haphazard, and their tools show no evidence of incremental improvements over time. In contrast, current human technology is the result of a long series of cumulative changes. The ‘ratchet-like’ nature of this technological evolution means that design changes are retained at the population level until new, improved designs arise. This ratchet effect is possible because tool manufacture methods are socially transmitted with sufficient fidelity that individuals do not need to reinvent or recapitulate past inefficient designs. The skills required for the development of this cumulative technology are claimed to include high-fidelity social learning, an understanding of physical relationships and functional properties of objects, and the ability for fine object manipulation. Animals other than humans are generally presumed to lack the necessary neural hardware and cognitive sophistication for cumulative technological evolution.

The New Caledonian crow, Corvus moneduloides, is an ideal model species to examine the links between tool manufacture, social learning and cognition. These crows manufacture two types of tool to facilitate the capture of invertebrates: one from twigs and similar material, and the other from the long barbed edges of Pandanus spp. leaves. The manufacture of pandanus tools provides a unique opportunity for study because a record of tool manufacture is faithfully recorded in ‘counterparts’ or outlines remaining on the leaf edges. Our recent work has revealed that these tools have four features previously thought to be unique to hominids: a high degree of standardization, the use of hooks, “handedness”, and cumulative changes in tool design. We discovered evidence of cumulative changes in a field survey documenting the shapes of 5,550 tools from 21 sites throughout the range of pandanus tools. We found three distinct tool designs: wide tools, narrow tools, and stepped tools. The lack of ecological correlates of the different tool designs and their geographic overlap make it unlikely that they evolved independently. Similarities in the method of manufacture for each design suggest that pandanus tools have gone through a process of cumulative change from a common historical origin.

To date we only have circumstantial evidence that New Caledonian crows transmit tool-making knowledge via social learning. These crows live in small family units where juveniles have ample opportunity to learn foraging techniques. The social learning and reasoning abilities of other Corvus species are well documented. The high fidelity in the shape of tool design at sites makes individual trial-and-error learning unlikely. Similarly, the evidence that crows might have some grasp of the functional properties of their tools is also only inferential. Our aims are to:
1. test whether crows socially transmit tool knowledge with high fidelity.
2. test whether crows understand the functional properties of their tools.

Hunt, G.R. & Gray, R.D. (2004).  The crafting of hook tools by wild New Caledonian crows. Proceedings of the Royal Society London B (Suppl.), 271, S88-S90. [request a pdf]
Hunt, G.R. & Gray, R.D. (2003).  Diversification and cumulative evolution in New Caledonian crow tool manufacture.  Proceedings of the Royal Society, London B., 270, 867-874.
Hunt, G.R., M.C. Corballis, & R.D. Gray (2001). Laterality in tool manufacture by crows. Nature, 414, 707. [request a pdf]

3.  The behaviour and evolution of New Zealand birds. 
This work uses mitochondrial DNA sequences to construct phylogenies for avian groups such as penguins, petrels, and Pelecaniformes. These phylogenies are then used to test hypotheses about behavioural and ecological evolution. To date this work has shown that seabird behavioural and ecological characters are remarkably phylogenetically informative. For example, some penguin displays are homologues that have persisted for over 50 million years. I am currently testing hypotheses about the sequential evolution of complex displays, and examining whether certain classes of behavioural characters consistently contain more phylogenetic information than others.

Kennedy, M.R., Holland, B.R., Gray, R.D., and Spencer, H.G. (2005). Untangling long branches: Identifying conflicting phylogenetic signals using spectral analysis, Neighbor-Net, and consensus networks. Systematic. Biology. 54(4), 620–633. [request a pdf]
Kennedy, M.R., R.D. Gray, & H.G. Spencer. (2000). The phylogenetic relationships of the shags and cormorants:  Can sequence data resolve a disagreement between behavior and morphology? Molecular Phylogenetics and Evolution, 17(3), 345-359. [request a pdf]
Kennedy, M.R., H.G. Spencer, & R.D. Gray. (1996). Hop, step, and gape: Do the social displays of the Pelecaniformes reflect phylogeny? Animal Behaviour, 51, 273-291. [request a pdf]

4.  Developmental systems theory. 
Developmental Systems Theory is an attempt to do biology without the problematic nature/nurture dichotomy that has plagued researchers in the biological and social sciences for decades. My work has focused on a critique of the concept of genetic information and a reworking of the way we conceptualise inheritance to include extragenetic factors.

Gray, R.D. (2001). Selfish genes or developmental systems? In: Thinking about Evolution: Historical, Philosophical and Political Perspectives: Festschrift for Richard Lewontin. R. Singh, K. Krimbas, D. Paul and J. Beatty. Cambridge, Cambridge University Press, pp. 184-207.

Oyama, S., P.E. Griffiths, & R.D. Gray (eds.). (2001). Cycles of Contingency: Developmental Systems and Evolution. Cambridge, MIT Press.


Selected Publications

Atkinson, Q.D., Gray, R.D. and Drummond, A.J. (in press). Bayesian coalescent inference of major human mtDNA haplogroup expansions in Africa. Proceedings of the Royal Society London B [request a pdf]

Atkinson, Q.D., Gray, R.D. and Drummond, A.J. (2008). mtDNA variation predicts population size in humans and reveals a major Southern Asian chapter in human prehistory. Molecular Biology and Evolution, 25, 468-474.  [request a pdf]

Greenhill, S.J., Blust, R. and Gray, R.D. (2008). The Austronesian Basic Vocabulary Database: From bioinformatics to lexomics. Evolutionary Bioinformatics, 4, 271–283

Holzhaider, J.C., Campbell, V.M., Hunt, G.R. and Gray, R.D. (2008). Do wild New Caledonian crows (Corvus moneduloides) attend to the functional properties of their tools? Animal Cognition, 11, DOI 10.1007/s10071-007-0108-1 [request a pdf]

O’Brien, M. J., Lyman, R. L., Collard, M., Holden, C. J., Gray, R. D. and Shennan, S. J. (2008). Phylogenetics and the evolution of cultural diversity. In: Cultural Transmission and Archaeology: Issues and Case Studies, M. J. O’Brien (ed), Society for American Archaeology Press, Washington, D.C., pp. 39-58.  [request a pdf]

Nicholls, G.K. and Gray, R.D. (2008). Dated ancestral trees from binary trait data and its application to the diversification of languages. Journal of the Royal Statistical Society, Series B, 70(3), 545–566. [request a pdf]

Taylor, A.H., Hunt, G.R., Medina, F.S., and Gray, R.D. (2008). Do New Caledonian crows solve physical problems through causal reasoning? Proceedings of the Royal Society London B, DOI 10.1098/rspb.2008.1107  [request a pdf]

Cnotka, J., Gunturkun, O., Rehkamper, G., Gray, R.D. and Hunt, G.R. (2008). Extraordinary large brains in tool-using New Caledonian crows (Corvus moneduloides). Neuroscience Letters, 433(3), 241-245. [request a pdf]

Hunt, G.R., Abdelkrim, J., Anderson, M.G., Holzhaider, J.C., Marshall, A.J., Gemmell, N. and Gray, R.D. (2007). Innovative pandanus-tool folding by New Caledonian crows. Australian Journal of Zoology, 55, 291-298. [request a pdf]

Hunt, G.R. and Gray, R.D. (2007). Genetic assimilation of behaviour does not eliminate learning and innovation. Behavioral and Brain Sciences, 30(4), 412-413. [request a pdf]

Gray, R.D., Greenhill, S.J, and Ross, R.M. (2007). The pleasures and perils of Darwinzing culture (with phylogenies). Biological Theory, 2(4), 360-375. [request a pdf]

Taylor, A.H., Hunt, G.R., Holzhaider, J.C., and Gray, R.D. (2007). Spontaneous metatool use by New Caledonian crows. Current Biology, 17, 1504-1507. [request a pdf]

Atkinson, Q.D. & Gray, R.D. (2006). How old is the Indo-European language family? Progress or more moths to the flame? In: Phylogenetic Methods and the Prehistory of Languages. Forster, P & Renfrew, C. (eds). Cambridge: The McDonald Institute for Archaeological Research, pp. 91-109. [request a pdf]

Holden, C.J. & Gray, R.D. (2006). Exploring Bantu linguistic relationships using trees and networks. In: Phylogenetic Methods and the Prehistory of Languages. Forster, P & Renfrew, C. (eds). Cambridge: The McDonald Institute for Archaeological Research, pp. 19-31. [request a pdf]

Nicholls, G.K. & Gray, R.D. (2006). Quantifying uncertainty in a stochastic dollo model of vocabulary evolution. In: Phylogenetic Methods and the Prehistory of Languages. Forster, P & Renfrew, C. (eds). Cambridge: The McDonald Institute for Archaeological Research, pp. 161-171. [request a pdf]

Hunt, G.R. and Gray, R.D. (2007). Parallel tool industries in New Caledonian crows. Biology Letters, 3, 173-175.  [request a pdf]

Hunt, G.R., Lambert, C and Gray, R.D. (2007). Cognitive requirements for tool use by New Caledonian crows (Corvus moneduloides). New Zealand Journal of Zoology, 34 (1), 1-7 [request a pdf]

Hunt, G.R., Rutledge, R.B. and Gray, R.D. (2006). The right tool for the job: What strategy do wild New Caledonian crows use in food extraction tasks? Animal Cognition, 9, 307-316 [request a pdf]

Hunt, G.R. and Gray, R.D. (2006). Tool manufacture by New Caledonian crows: chipping away at human uniqueness. Acta Zoologica Sinica 52 (Suppl.), 622-625. [request a pdf]

Hunt, G.R., M.C. Corballis, and R.D. Gray. (2006). Design complexity and strength of laterality are correlated in New Caledonian crows’ pandanus tool manufacture. Proceedings of the Royal Society London B, 73, 1127-1133. [request a pdf]

Atkinson, Q.D. & Gray, R.D. (2005). Are accurate dates an intractable problem for historical linguistics? In Mapping our Ancestry: Phylogenetic Methods in Anthropology and Prehistory. Eds. C. Lipo, M. O’Brien, S. Shennan & M. Collard. Aldine (Chicago), pp. 269-296. [request a pdf]

Atkinson, Q. and Gray, R.D. (2005).  Curious parallels and curious connections: Phylogenetic thinking in biology and historical linguistics. Systematic Biology, 54(4), 513-526.

Atkinson, Q., Nicholls, G. and Gray, R.D. (2005).  From words to dates: water into wine, mathemagic or phylogenetic inference? Transactions of the Philological Society, 103(2), 193-219. [request a pdf]

Bryant, D, Filimon, F, & Gray, R.D. (2005). Untangling our past: Languages, Trees, Splits and Networks. In: The Evolution of Cultural Diversity: Phylogenetic Approaches. Editors: R. Mace, C. Holden, S. Shennan. London: UCL Press, pp. 69-85.

Greenhill, S. & Gray, R.D. (2005). Testing dispersal hypotheses: Pacific settlement, phylogenetic trees and Austronesian languages. In: The Evolution of Cultural Diversity: Phylogenetic Approaches. Editors: R. Mace, C. Holden, S. Shennan. London: UCL Press, pp. 31-52.

Gray, R. D. (2005). Pushing the time barrier in the quest for language roots. Science, 309, 2007-2008.

Griffiths, P.E. & R.D. Gray. (2005).  Three ways to misunderstand developmental systems theory.  Biology and Philosophy, 20, 417–425. [request a pdf]

Kennedy, M.R., Holland, B.R., Gray, R.D., and Spencer, H.G. (2005). Untangling long branches: Identifying conflicting phylogenetic signals using spectral analysis, Neighbor-Net, and consensus networks. Systematic Biology, 54(4), 620–633. [request a pdf]

Griffiths, P.E. & R.D. Gray. (2004). The Developmental Systems Perspective: Organism-enviromnent systems as units of development and evolution.  In The Evolutionary Biology Of Complex Phenotypes.  M. Pigliucci & K. Preston (eds.).  Chicago, University of Chicago Press, pp. 419-431.

Hunt, G.R. and Gray, R.D. (2004).  Direct observations of pandanus-tool manufacture and use by a New Caledonian crow (Corvus moneduloides). Animal Cognition, 7, 114-120. [request a pdf]

Hunt, G.R. and Gray, R.D. (2004).  The crafting of hook tools by wild New Caledonian crows. Proceedings of the Royal Society London B (Suppl.), 271, S88-S90. [request a pdf]

Gray, R.D. and Atkinson, Q. (2003).  Language-tree divergence times support the Anatolian theory of Indo-European origins.  Nature, 426, 435-439. [request a pdf]

Gray, R.D., M. Heaney, S. Fairhall. (2003). Evolutionary Psychology and the challenge of adaptive explanation. In: From Mating to Mentality: Evaluating Evolutionary Psychology. K. Sterelny and J. Fitness (eds). Psychology Press (London & New York), pp. 247-268. [request a pdf]

Hunt, G.R. & Gray, R.D. (2003).  Diversification and cumulative evolution in New Caledonian crow tool manufacture.  Proceedings of the Royal Society, London B., 270, 867-874.

Hurles, M. E., L. Matisoo-Smith, R.D. Gray, & D. Penny.  (2003).  Untangling Oceanic settlement: the edge of the knowable.  Trends in Ecology and Evolution. 18, 531-540.

 

Updated: November 18, 2008