Unbiased Cultural Transmission in Time-Averaged Archaeological Assemblages
14 Pages Posted: 10 Apr 2012
Date Written: April 9, 2012
Unbiased models are foundational in the archaeological study of cultural transmission. Applications have assumed that archaeological data represent synchronic samples, despite the accretional nature of the archaeological record. I document the circumstances under which time-averaging alters the distribution of model predictions. Richness is inflated in long-duration assemblages, and evenness is “flattened” compared to unaveraged samples. Tests of neutrality, employed to differentiate biased and unbiased models, suffer serious problems with Type I error under time-averaging. Finally, the time-scale over which time-averaging alters predictions is determined by the mean trait lifetime, providing a way to evaluate the impact of these effects upon archaeological samples.
Keywords: cultural transmission, archaeology, Wright-Fisher model, time-averaging
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