 As we have seen, other presentations of cultural evolution begin in a more pragmatic, problem-driven fashion. In some cases they begin with explanatory puzzles similar to those that led Darwin to formulate his principle of natural selection in the first place. Darwin was concerned to explain how structures could arise which fit organisms so remarkably well to their conditions of existence. Cultural evolutionists frequently draw attention to a variety of adaptive cultural traits, whose origination seems inexplicable in terms of individual innovation alone. Henrich (2015, 97–100), for example, makes good use of the example of manioc processing. Manioc (also called cassava) is a good source of starch, but it needs to be processed to make it safe to eat. Without this processing it can release poisonous hydrogen cyanide. According to Henrich, while unprocessed manioc tastes bitter, the bitter taste is not a good indicator of its safety: bitterness disappears in the preparation process before it becomes safe to eat. Worse, while unprocessed manioc is poisonous, it is hard to discover that this is the case, because the symptoms of poisoning only appear well after eating unsafe manioc. Henrich argues that it is hard to see how any single insightful individual could have invented this processing technology. Instead, a more gradual process of cumulative cultural adaptation, spread across the population, must be invoked. In this kind of work, cultural analogues of organic selection processes are invoked because they promise a ‘hidden hand’ explanation for the appearance of adaptation, in contexts where explanations that rely on foresight seem unavailable. In other words, the rationale for turning to selection is the same in both the cultural and organic domains.