This book is primarily about the adipose tissue biology of humans in the context of their recent evolutionary history and contemporary ecological variability. Humans, however, are just one amongst a multitude of vertebrate species, in particular mammals, which benefit from adipose tissue as an adaptive trait and use it to mediate the match between energy capture from the environment and energy demand. To understand how adipose tissue has responded to specifically hominin selective pressures, it is helpful first to consider the longer-term evolution of the adipocyte, both as a type of cell, and in its larger form within adipose tissue, and how adipose tissue was shaped during early mammalian evolution.

The first part of this chapter draws extensively on the work of Caroline Pond, described in her 1998 monograph (Pond 1998) and further extended in subsequent papers (Pond 2003a; Mattacks, Sadler, and Pond 2004; Pond 2007). This work highlights the properties of adipocytes and indicates the likely selective pressures which favoured the emergence of this specific cell and its aggregation in discrete adipose tissue depots. The second part elucidates a number of concepts regarding the adaptive nature of energy stores, including a discussion of modelling the costs and benefits of adipose tissue and of the differential allocation of energy between storage and other functions. Such an approach is essential for generating clear hypotheses for empirical investigations in extant humans. These approaches are then exploited in the following two chapters, reconstructing possible hominin and early human profiles of adiposity.