R. Firth in the UK and Louis Hjelmslev in Denmark developed their own versions of structural and functional linguistics. In anthropology According to structural theory in anthropology and social anthropology, meaning is produced and reproduced within a culture through various practices, phenomena, and activities that serve as systems of signification. A structuralist approach may study activities as diverse as food-preparation and serving rituals, religious rites, games, literary and non-literary texts, and other forms of entertainment to discover the deep structures by which meaning is produced and reproduced within the culture. For example, Lévi-Strauss analysed in the 1950s cultural phenomena including mythology, kinship (the alliance theory and the incest taboo), and food preparation. In addition to these studies, he produced more linguistically-focused writings in which he applied Saussure's distinction between langue and parole in his search for the fundamental structures of the human mind, arguing that the structures that form the "deep grammar" of society originate in the mind and operate in people unconsciously. Lévi-Strauss took inspiration from mathematics. Another concept used in structural anthropology came from the Prague school of linguistics, where Roman Jakobson and others analysed sounds based on the presence or absence of certain features (e.g., voiceless vs. voiced). Lévi-Strauss included this in his conceptualization of the universal structures of the mind, which he held to operate based on pairs of binary oppositions such as hot-cold, male-female, culture-nature, cooked-raw, or marriageable vs. tabooed women. A third influence came from Marcel Mauss (1872–1950), who had written on gift-exchange systems. Based on Mauss, for instance, Lévi-Strauss argued an alliance theory—that kinship systems are based on the exchange of women between groups—as opposed to the 'descent'-based theory described by Edward Evans-Pritchard and Meyer Fortes. While replacing Mauss at his Ecole Pratique des Hautes Etudes chair, the writings of Lévi-Strauss became widely popular in the 1960s and 1970s and gave rise to the term "structuralism" itself. In Britain, authors such as Rodney Needham and Edmund Leach were highly influenced by structuralism. Authors such as Maurice Godelier and Emmanuel Terray combined Marxism with structural anthropology in France. In the United States, authors such as Marshall Sahlins and James Boon built on structuralism to provide their own analysis of human society. Structural anthropology fell out of favour in the early 1980s for a number of reasons. D'Andrade suggests that this was because it made unverifiable assumptions about the universal structures of the human mind.