We have made progress on several central questions.
Agriculture in early societies
We adapted the CENTURY model to predict agricultural yield in Hawai’, using ecological data on plant growth, soil hydrology, nutrient inputs and climate (especially temperature and rainfall), . The model was calibrated using contemporary plant and soil data. Temporal and spatial variation in soil and environment interact with human food-sharing to determine the risk of going hungry:
Lee, C. and Tuljapurkar, S. 2006. Risky business: temporal and spatial variation in preindustrial Pacific dryland agriculture. Human Ecology 34(6): 739-763.
Kirch, Patrick V. , Chadwick, Oliver A., Tuljapurkar, Shripad , Ladefoged, Thegn , Graves, Michael, Hotchkiss, Sara and Vitousek, Peter, 2007. Human Ecodynamics in the Hawaiian Ecosystem, from 1200 to 200 YR BP. In: Model-Based Archaeology of Socionatural Systems (Chapter 6), T. Kohler and S. Van der Leuw, Eds., SAR Press, Santa Fe, NM.
Hunger and human demography
We used historical population estimates to obtain useful constraints on prehistoric mortality, fertility and growth rate:
Tuljapurkar, S., Lee, C. and Figgs, M. 2007. Demography and Food in Early Polynesia. In: The Growth and Collapse of Pacific Island Societies, P. V. Kirch and J. Rallu eds., University of Hawaii Press, pp. 35-51.
Climate, technology, social organization and human history
We used past studies of the response of pre-industrial populations to food supply to estimate the elasticity of mortality and fertility to per-capita food. We constructed a consistent model of historical population growth, given climate, agriculture and social food-sharing arrangements. This is the first such model of human prehistory and has many applications. Our model describes population expansion and also populations that are constrained by space and climate:
Lee, C., Tuljapurkar, S and Vitousek, P. 2008. Population and prehistory I: Food-dependent population growth in constant environments. Theoretical Population Biology 73:473–482
Puleston, C. and Tuljapurkar, S. 2008. Population and prehistory II: Space-limited human populations in constant environments. Theoretical Population Biology 74:147-160.
Lee, C. T., Puleston, C. and Tuljapurkar, S. 2009. Population and prehistory III: Space-limited human populations in constant environments. Theoretical Population Biology 76:179-188.
Immigration in Prehistoric Japan
There has been much debate about the importance of immigration into Japan in the distant past (covering crudely a range from “pure stock” to “mixture”). Stochastic demography suggests some constraints.
Aoki, K. and Tuljapurkar, S., 2000. Hanihara’s conundrum revisited: Theoretical estimates of the immigration into Japan from 300 BC to AD 700. Anthropological Science 108: 305-319.