It is not an unreasonable hypothesis that Homo Habilis was the predecessor of early Homo Erectus, possibly via Homo Ergaster, who lived from about 2 million years ago, and that a descendant of later Homo Erectus was the predecessor of Homo Sapiens or Modern Man. Homo Erectus was the first species to include hunting as a significant way of obtaining meat (rather than scavenging), to use fire (well over one million years ago), to make stone tools accurately shaped on both sides for hand axes, and they were the first to leave the African continent. This last achievement may have been linked to the greater reliance on meat, as the hunting of animals removes most geographic hurdles of food availability.

One of the major breakthroughs in technology was the control of fire. Homo Erectus would have been familiar with fire, seeing lightning strikes cause bush fires and their usefulness in killing trapped animals. The first controlled use may well have been to expand such fires for their own benefit. Once he understood fire, it allowed the burning of areas of grassland to drive and trap animals for food, to ward off predators, to keep warm - allowing migration to cooler areas, and to cook food (from over 1 million years ago in Africa). This last development killed bacteria and parasites, deactivated toxins in vegetation and made food easier to digest, which caused the evolution of smaller teeth and jaws and flatter faces, and also permitted the evolution of a smaller stomach to contain the richer food.

Prior to Homo Erectus, our predecessors, although upright, were still quite ape-like in appearance and still had relatively small brains. In early Homo Erectus the brain size increased again to about 900cc and they were more athletic in build so they could run very much as we do.  Brain size is probably the second most important evolutionary characteristic after bi-pedalism. Perhaps a key to our development was the ability of man to increase the use of his brain to think his way through more stressful environments, such as avoiding and outwitting predators and other dilemmas that might otherwise have led to his demise. There was also the need to develop organisational, social and behavioural skills, as these would be essential in the group endeavours of hunting, defence and child rearing.

The survival of any Hominid species was always extremely precarious, depending so much on chance in the evolutionary process. A whole branch of hominids became extinct about one million years ago, possibly because they were too specialised in their way of life and could not compete for food as well as the more adaptable Homo Erectus. As an example, one, called Robustus, was large and heavy with large teeth and jaws, who fed almost entirely on tough vegetation. With the climate changing, total dependence on this narrow food range might have contributed to Robustus becoming extinct.