the 1930s and extensively developed in the period following the Second World War and was incorporated into both anthropology and sociology in the 1960s. It bases its theories on empirical evidence from areas of archaeology, palaeontology, and historiography and tries to eliminate any references to systems of values, be it moral or cultural, instead trying to remain objective and simply descriptive. While 19th-century evolutionism explained how culture develops by giving general principles of its evolutionary process, it was dismissed by the Historical Particularists as unscientific in the early 20th century. It was the neo-evolutionary thinkers who brought back evolutionary thought and developed it to be acceptable to contemporary anthropology. Neo-evolutionism discards many ideas of classical social evolutionism, namely that of social progress, so dominant in previous sociology evolution-related theories. Then neo-evolutionism discards the determinism argument and introduces probability, arguing that accidents and free will greatly affect the process of social evolution. It also supports counterfactual history—asking "what if" and considering different possible paths that social evolution may take or might have taken, and thus allows for the fact that various cultures may develop in different ways, some skipping entire stages others have passed through. Neo-evolutionism stresses the importance of empirical evidence. While 19th-century evolutionism used value judgments and assumptions for interpreting data, neo-evolutionism relies on measurable information for analysing the process of sociocultural evolution. Leslie White, author of The Evolution of Culture: The Development of Civilization to the Fall of Rome (1959), attempted to create a theory explaining the entire history of humanity. The most important factor in his theory is technology. Social systems are determined by technological systems, wrote White in his book, echoing the earlier theory of Lewis Henry Morgan. He proposes a society's energy consumption as a measure of its advancement. He differentiates between five stages of human development. In the first, people use the energy of their own muscles. In the second, they use the energy of domesticated animals. In the third, they use the energy of plants (so White refers to agricultural revolution here). In the fourth, they learn to use the energy of natural resources: coal, oil, gas. In the fifth, they harness nuclear energy. White introduced a formula, P=E·T, where E is a measure of energy consumed, and T is the measure of efficiency of technical factors utilising the energy. This theory is similar to Russian astronomer Nikolai Kardashev's later theory of the