The Origin of Bipedalism
It seems reasonable to suppose that, as the East African forests gave way to open woodland and grasslands several million years ago, our ancestors had to forage for food over increasing distances. In one area there would be fruits, in another roots, and elsewhere water. The simplest life would have been for these proto-humans to simply move from one food location to the next, eating as they went, and taking the shortest route from one location to the next.
If these proto-humans were not already formed into societies, then such an existence would have acted to form them into loose collections. For, in time, given the same need for the same food at the same time, they would tend to find themselves in the same place. A kind of society would form without any prior agreement or intention. Given a set of 6 food locations arranged on the points of a hexagon, the simplest route for all to take would have been to walk round the perimeter, from one location to the next, stopping to eat available food before moving on to the next location.
That proto-humans would have probably had to travel further to find food has led some authors to suggest that it was this which led to human bipedalism:
One very persuasive theory for the origin of bipedalism, the feature that established the human family, is that it was an adaptation for more efficient locomotion between widely distributed food sources.
But, assuming these proto-humans were essentially quadrupeds, it would seem more likely that, if locomotion was the main problem after they were driven from the forests, it would have been better to develop to become true quadrupeds, like most other mammals.
Idle Theory offers another theory for the origin of bipedalism, which is that humans had other uses for their already well-developed hands: they carried things around in them. With their hands full, they were not able to move as quadrupeds, and were forced into what was probably initially an uncertain, faltering bipedal motion. But what were they carrying?
The suggestion is that the proto-humans fairly soon gave up a nomadic existence in favour of a more settled existence, and that early humans spent most of their time at one place, a base camp, going out from time to time to collect food and bring it back. These camps would not have been permanent settlements, but stopovers where a human group would stay for a few weeks or months before moving on. The collection of food to bring back to the campsite meant that on the return journey, with their hands holding bundles of roots or fruits, the proto-humans would be forced to adopt a bipedal gait.
Settled existence of this sort reduced the amount of work that they had to do. Assuming that a nomadic society consisted of 6 individuals, and it took an hour to move from one food location to the next, then a complete circuit of the hexagon would take each individual 6 hours, not including the time spent eating at each food location. If, however, the 6 individuals were based at the centre of the hexagon, and each went out and collected enough of each food for six individuals, and brought it back to the base camp, then each individual would have to make one return journey of 2 hours to a food location. At one step, 4 hours of travel are saved, to produce the same amount of food. Much as a lioness returns with food for her cubs held in her jaws, a human mother would return with food for her infants, carried in her hands, or clutched in her arms.
Life at a base camp may not have been determined only by economy of effort, but by quite different considerations. Mothers with infants may have been unable to undertake the long journeys of the nomadic life. Equally, the threat from predators may have been such as to demand that the proto-humans spend as much time as possible in places where they were relatively safe - hilltops from which predators could be seen, trees, or other places inaccessible to predators.
If there was intense threat from predators, the use of a secure base camp from which to send out foraging parties would have resulted in:
The foragers would only have had to adopt a biped gait on the return journey from a food source. The rest of the time they could adopt whatever posture they chose. But if this was the principal way that food was gathered in early human society, natural selection would tend to favour those who could walk the most easily, the most rapidly, for the longest distances, carrying the most weight. The erect modern human posture may have come from the last of these, ensuring that the load was carried by the spinal column, with the minimum of muscular stress.
For once food could be carried back to the camp, then animal carcasses, defensive branches and stones, could also be carried back. A found object - a branch - could be used to increase the amount carried, if roots, fruits, and animals could be draped over it, or impaled by it.
The ability to carry food back to a base camp would often mean that a surfeit of roots, fruits, and other foods accumulated at the camp. The proto-human societies could then begin to store food for times when there was a scarcity.
In this approach, bipedalism is seen as the result of proto-humans using arms and hands to carry food back to a central campsite. The only other way to carry food without becoming biped, and without the use of tools, would be to carry far smaller amounts of food by mouth, or in one hand while adopting a triped gait. The bipedal form of locomotion would not have been particularly efficient, and if surprised by predators the proto-humans would probably have dropped what they were carrying and escaped on all fours.
The Individual and Society
The roving bands moving from feeding place to feeding place were collections of individuals rather than societies - because they did not depend on each other. But the more idle base camp society, which delegates individuals to collect food for everybody, is a society, because in it people depend upon others.
Since, in this example, roving-band aggregations are less idle than base-camp-excursion societies, increasing difficulty - longer time - in finding food would have resulted in the extinction of the roving bands, and the survival of nascent you-get-the-bananas-and-I'll-get-the-yams human society. Cooperative human society emerged out of necessity, when the individualistic alternative had become unworkable.
In such societies, individuals have to forego their individualistic inclination to fend for themselves alone, and take others into consideration. The yam-collector has to collect enough yams to feed everyone in the society, not just himself. And when he returns to the camp, he must share out the takings among them, rather than eat them all himself. Furthermore, anyone who behaves purely individualistically or selfishly, collecting no food for the group, but eating what others bring back, increases his own idleness at the expense of others, and is a menace to society. Such purely selfish individuals would have to have been ejected from society, and as outcasts rapidly died.
Once human societies formed, and provided the only means of human survival, humans were effectively locked into society, and confronted with the conflict of individual desire versus social requirement. For it always serves an individual better, short term, to act purely selfishly within society - but in so doing, the individual threatens the existence of society, the collapse of which leaves him in a far worse state than if had acted unselfishly.
Once human societies formed, the perennial problems of how they should be organized, and how wealth should be distributed within them, who should do (and not do) what, arose - and have remained with us ever since.
Author: Chris Davis
Last edited: 5 April 1998