 According to several authors (Machery 2008; 2018; Samuels 2012; Ramsey 2013), the expression “human nature” should be used to group properties that are the focus of much current behavioural, psychological and social science. However, as the cognitive and psychological sciences are generally interested in present-day humans, there is a mismatch between scientific focus and a grouping criterion that takes in all the properties generally or typically instantiated by specimens of the entire taxon. For this reason, the expression “human nature” is likely to refer to properties of an even more temporally restricted set of organisms belonging to the species. That restriction can be thought of in indexical terms, i.e., as a restriction to contemporary humans. However, some authors claim explicitly that their accounts entail that human nature can change (Ramsey 2013: 992; Machery 2018: 20). Human nature would then be the object of temporally indexed investigations, as is, for example, the weight of individual humans in everyday contexts. (Without temporal specification, there is no determinate answer to a question such as “How much did David Hume weigh?”) An example of Machery’s is dark skin colour. This characteristic, he claims, ceased to be a feature of human nature thus understood 7,000 years ago, if that was when skin pigmentation became polymorphic. The example indicates that the temporal range may be extremely narrow from an evolutionary point of view.