is reducible to another. Purist behaviorism John B. Watson in the 1920s and 1930s established the school of purist behaviorism that would become dominant over the following decades. Watson is often said to have been convinced of the complete dominance of cultural influence over anything that heredity might contribute. This is based on the following quote which is frequently repeated without context, as the last sentence is frequently omitted, leading to confusion about Watson's position:During the 1940s to 1960s, Ashley Montagu was a notable proponent of this purist form of behaviorism which allowed no contribution from heredity whatsoever: In 1951, Calvin Hall suggested that the dichotomy opposing nature to nurture is ultimately fruitless. In African Genesis (1961) and The Territorial Imperative (1966), Robert Ardrey argues for innate attributes of human nature, especially concerning territoriality. Desmond Morris in The Naked Ape (1967) expresses similar views. Organised opposition to Montagu's kind of purist "blank-slatism" began to pick up in the 1970s, notably led by E. O. Wilson (On Human Nature, 1979). The tool of twin studies was developed as a research design intended to exclude all confounders based on inherited behavioral traits. Such studies are designed to decompose the variability of a given trait in a given population into a genetic and an environmental component. Twin studies established that there was, in many cases, a significant heritable component. These results did not, in any way, point to overwhelming contribution of heritable factors, with heritability typically ranging around 40% to 50%, so that the controversy may not be cast in terms of purist behaviorism vs. purist nativism. Rather, it was purist behaviorism that was gradually replaced by the now-predominant view that both kinds of factors usually contribute to a given trait, anecdotally phrased by Donald Hebb as an answer to the question "which, nature or nurture, contributes more to personality?" by asking in response, "Which contributes more to the area of a rectangle, its length or its width?" In a comparable avenue of research, anthropologist Donald Brown in the 1980s surveyed hundreds of anthropological studies from around the world and collected a set of cultural universals. He identified approximately 150 such features, coming to the conclusion there is indeed a "universal human nature", and that these features point to what that universal human nature is. Determinism At the height of the controversy, during the 1970s to 1980s, the debate was highly ideologised. In