roles in human evolution, including the evolution of cognitive capabilities. Its impact is probably because it is immediately apparent that humans possess an unusually potent capability to regulate, construct and destroy their environments, and that this is generating some pressing current problems (e.g. climate change, deforestation, urbanization). However, human scientists have been attracted to the niche construction perspective because it recognizes human activities as a directing process, rather than merely the consequence of natural selection. Cultural niche construction can also feed back to affect other cultural processes, even affecting genetics. Niche construction theory emphasizes how acquired characters play an evolutionary role, through transforming selective environments. This is particularly relevant to human evolution, where our species appears to have engaged in extensive environmental modification through cultural practices. Such cultural practices are typically not themselves biological adaptations (rather, they are the adaptive product of those much more general adaptations, such as the ability to learn, particularly from others, to teach, to use language, and so forth, that underlie human culture). Mathematical models have established that cultural niche construction can modify natural selection on human genes and drive evolutionary events. This interaction is known as gene-culture coevolution. There is now little doubt that human cultural niche construction has co-directed human evolution. Humans have modified selection, for instance, by dispersing into new environments with different climatic regimes, devising agricultural practices or domesticating livestock. A well-researched example is the finding that dairy farming created the selection pressure that led to the spread of alleles for adult lactase persistence. Analyses of the human genome have identified many hundreds of genes subject to recent selection, and human cultural activities are thought to be a major source of selection in many cases. The lactose persistence example may be representative of a very general pattern of gene-culture coevolution. Niche construction is also now central to several accounts of how language evolved. For instance, Derek Bickerton describes how our ancestors constructed scavenging niches that required them to communicate in order to recruit sufficient individuals to drive off predators away from megafauna corpses. He maintains that our use of language, in turn, created a new niche in which sophisticated cognition was beneficial. Current status While the fact that niche construction occurs is non-contentious, and its study goes back to Darwin's classic books on earthworms and corals, the evolutionary consequences of niche construction have not always been fully appreciated. Researchers differ over