It is reasonable to expect that the global dispersal of modern humans was influenced by habitat variation in space and time; but many simulation models average such variation into a single, homogeneous surface across which the dispersal process is modelled. We present a demographic simulation model in which rates of spatial range expansion can be modified by local habitat values. The broad‐scale vegetation cover of North America during the late last glacial is reconstructed and mapped at thousand‐year intervals, 13,000–10,000 radiocarbon years BP. Results of the simulation of human dispersal into North America during the late last glacial are presented; output appears to match observed variation in occupancy of habitats during this period (as assessed from discard rates of diagnostic artefacts), if we assume that intrinsic population growth rates were fairly high and that local population densities varied as a function of environmental carrying capacity. Finally, a number of issues are raised relating to present limitations and possible future extensions of the simulation model.

The orientational profile near a liquid-wall interface has been studied, concentrating, in the spirit of recent theories of wetting, on the existence of surface phase transitions. The Maier-Saupe theory has been used to investigate the behaviour of a nematic near a wall in the presence of both bulk and surface ordering fields. We find that the surface ordering transition predicted by Sheng is extremely sensitive to the form of the bulk nematic free energy. The surface transition is also dependent on the bulk ordering field, and terminates at a wetting temperature; it is symptomatic of prewetting behaviour and occurs near a wide variety of first order phase transitions. The surface adsorption, contact angle at a nematic-isotropic-solid contact line, and surface free energy as a function of bulk field and temperature are also studied.

A lattice model is used to investigate the surface behavior of smectic fluids close to the onset of smectic ordering. At the smectic-isotropic interface the nematic features of the smectic phase persist further into the bulk isotropic phase than the strictly smectic features. At the isotropic-vapor interface we find the possibility of a series of first-order layering transitions, each involving the addition of a smectic layer, in line with recent experimental results. However, at the nematic-vapor interface surface smectic order, if it exists, grows smoothly without layering transitions.

We develop both phenomenological and molecular-statistical theory of smectic-$A$–smectic-$C$ phase transition with anomalously weak smectic layer contraction. Using a general mean-field molecular model, we demonstrate that a relatively simple interaction potential suffices to describe the transition both in conventional and de Vries type smectics. The theoretical results are in excellent agreement with experimental data. The approach can be used to describe tilting transitions in other soft matter systems.