From Astrand to Gromit: Professor Astrand often finishes his eloquent lectures with the
statement ‘you should always take your dog for a walk even if you don’t have one!’
Blair (1988), for example, suggests that four evolutionary periods are important in under-standing the relationship between physical activity and health. The preagricultural period (up until about 10,000 years ago) was characterised by hunting and gathering activities. Exercise levels were high and diet was low in fat. The agricultural period (from 10,000 years ago until about the beginning of the nineteenth century) was characterised again by reasonably high physical activity levels and relatively low fat diets, although the fat content
probably increased during this time