We thank Professor Fitzgerald for his interest in our editorial.^{Reference Abed, Ayton, St John-Smith, Swanepoel and Tracy1} He raises two objections. The first is a challenge to the appropriateness of the application of evolution to psychology in general and the second is questioning the value of attachment theory to psychiatry.

Fitzgerald quotes Plotkin^{Reference Plotkin2} in his contention that the reliance of evolutionary hypotheses on past environments and past selection pressures renders evolutionary approaches untestable and removes them from the realm of science. However, on reading Plotkin's book it is clear that in the quote given (p. 151) the author was specifically critiquing the concept of the environment of evolutionary adaptiveness (EEA) and not the application of evolution to psychology. Furthermore, Plotkin's support for the application of evolution to psychology is made abundantly clear in the final chapter of the book (pp. 158–161), which is fully dedicated to discussing the reasons why he predicts that the role of evolution in psychology is likely to expand in the future; something that Plotkin clearly wholeheartedly welcomes.

It is important to understand that the modern use of EEA is a statistical composite for a population for a given time; it is not one simple single hypothetical entity. An analogy in physics would be the use of dark matter to explain observations, which does not render physics ‘out of the realm of science and imprisons it within speculative narrative’. We now know vastly more about any particular EEA, from archaeology, anthropology and modern comparative DNA studies, than in 2004 when Plotkin wrote his comments. Nevertheless, we consider Plotkin's views on the value of the EEA as a concept worthy of further discussion, but either way, evolutionary psychology can continue with or without it.

Professor Fitzgerald's second objection concerns the role of attachment theory and he quotes the philosopher Christian Perring in support of this position.^{Reference Perring, Perring and Wells3} Perring correctly criticises Wakefield's mistaken view that only a ‘secure attachment’ style is considered ‘normal’. We fully agree with Perring that Wakefield's position did not make sense from an evolutionary point of view as those with other attachment styles may also be able to function well. However, once that misunderstanding is cleared up, evolutionary thinking actually confirms the importance of attachment theory and is not in conflict with it. We would suggest that Professor Fitzgerald read a previous publication by one of the present authors ‘How evolution can help us understand child development and behaviour’, which states that: ‘the traditional disease model, still dominant in psychiatry, is less than ideal for making sense of psychological issues such as the effects of early childhood experiences on development. We argue that a model based on evolutionary thinking can deepen understanding and aid clinical practice by showing how behaviours, bodily responses and psychological beliefs tend to develop for “adaptive” reasons, even when these ways of being might on first appearance seem pathological.’ The paper goes on to explain that ‘It is now clear that humans are particularly good at adapting to different environments. We survive in a wide range of physical environments, from the Arctic to rainforest to the Sahara. We can also survive in a wide range of emotional environments, from loving to neglectful to violent ones’.^{Reference Swanepoel, Sieff, Music, Launer, Reiss and Wren4} As soon as we understand that attachment theory is distinct from the unfortunately similarly named ‘attachment disorders’ and that attachment theory by no means states that only secure attachments are ‘normal’, it should become clear that our position is very different from what Professor Fitzgerald initially assumed. We would also like to reassure him that we recognise the importance of neurodevelopmental disorders and have published a further paper that he may find interesting which integrates opposing views by using the concept of ‘evolutionary mismatch’.^{Reference Swanepoel, Music, Launer and Reiss5}