Introduction

In our discussion of developmental evolution we concluded that the physiology of the mature organism merits separate attention from the physiology of the developing organism. Particularly important for the evolution of humans, and indeed for all mammals, is the fact that exploratory behaviour, and hence exposure to new environmental conditions, and all the evolutionary consequences of such activities, depends upon a reliable, stable physiological state. You cannot live in an extreme climate unless you are physiologically capable of keeping your internal environment within safe limits.

In this section we intend to establish how most aspects of human physiology are fundamentally similar to that of the placental mammals, and how that basic physiology enhanced the evolvability of the placental mammals, including humans. We also go further back in time to show how environmental changes have had very significant links with physiological evolution. All of this evolution had already happened by the time humans emerged, but it is best to know the foundations if the upper storeys are to be understood. This should not however divert our attention from our emergent physiological and psychological characteristics, such as mind, memory, language and arts. Nor should that uniqueness divert our attention from our ability to abuse our talents.

Before proceeding we wish to re-emphasize the distinction that we made in ‘Evolutionary theory’ (Appendix A), regarding adaptation and adaptability.