Hunter-gatherer and the use of tools

Is it important to notice that the early hunter-gatherers are likely to have had greater levels of physical activity and mechanical stress on the skeleton [27]. Is it not clear whether Plio-Pleistocene hominins gained most of the meat that they ate from actively hunting animals or whether they scavenged from carcasses killed by other animals [28]but the physical activity was predominant in their lives.

Is it well known that all members of the genus Homo were tool makers and users [8]. Technology brought humans a major advantage over other primates helping them overcome some of the time limitations faced by foragers in patchy or seasonal environments. Technological advancements, such as the development of Oldowan industry, allowed easier processing of vertebrate carcasses and increased access to meat as well as energy-and nutrient-rich marrow and brains [29].

Increasingly sophisticated stone tools (Acheulean industry) emerged apporximately 1.6 to 1.4 mya, improving the ability of these hominins to process animal and plant materials [30]. These changes in diet and foraging behaviour would not have turned our hominin ancestors into carnivores; however, the addition of even modest amounts of meat to the diet (10% to 20% of dietary energy) combined with the sharing of resources -that is typical of hunter-gatherer groups- would have significantly increased the quality and stability of the diet of H. erectus [23]. Consumption of animal foods would have provided increased levels of fatty acids that would have been necessary for supporting the rapid hominin brain evolution. The increase in dietary quality and stability was likely achieved partly through changes in diet composition [31] and partly through social and behavioural changes like food sharing and perhaps division of foraging tasks [32]. This greater nutritional stability provided critical foundation for fuelling the energy demands of larger brain sizes.

So, the use of tools, possible mostly by brain development, and the social and behavioural changes provided the perfect scenario to eat more rich-diets and thus contribute to increasing nutrients in the body that lead to a better evolution of the Homo as specie.