Environmental Engineering Reference
In-Depth Information
faculties and less on instinct and emotion. Over millennia, this resulted in evolutionary
growthinthecorrespondingpartsofthebrain.However,alargerbrainalsoentails agreater
energetic cost. The human brain consumes about 400 kilocalories per day, three times that
of a chimpanzee. The larger, more energy-intensive brain paid its way by allowing us to
increase our energy budget, first and foremost through the ability to develop and use tools,
which in turn helped us to obtain more food, build shelter and make clothing. Our more
complex brains were therefore a success in evolutionary terms because they contributed to
a net energy gain (Isler and van Schaik
2009
).
While early humans displayed major differences of psychology and social organisation,
from a purely energetic point of view they lived much like other mammals: to obtain
food they relied exclusively on muscle strength and the elementary stratagems of hunting
and gathering. The energy requirements of the hunt provided a powerful incentive to
socialize. Sincealonehunter'schancesofkillinglargeanimalswerelow,groupsofhunters
cooperated to pursue, trap, kill and slaughter an animal, and to transport the meat back to
the settlement. As this was generally beyond the ability of a single family, hunter-gatherers
formed larger social groups and shared the fruits of collective effort.
Those prehistoric societies that evolved amidst a plentiful food supply naturally saw a
gradual increase in social complexity, up to the levels associated with the most advanced
agrariansocieties:permanentsettlements,highpopulationdensity,large-scalefoodstorage,
social stratification, elaborate rituals and early forms of cultivation.
Fire: The First External Energy Source
Tools allowed hominids to make the most of their muscle power by concentrating energy,
but it was only when they learned to use and control fire that they were able to harness and
manipulate an external source of energy. No other animal has done this. In this sense, the
discovery of fire was a watershed in the evolution of humanity, marking the birth of what
we might call
Homo energeticus
(Niele
2005
). With fire, humans were able to cook food,
warm their surroundings and keep dangerous predators and insects at bay. Firelight also
extended the productive day in winter.It is likely that hominids discovered fire byaccident,
as a result of lightning or wildfires, and for several hundred millennia were able to use but
unable to start it. This meant that fires had to be tended and maintained over generations.
From fire control to fire making.
