History and Theoretical Framework of Human Bipedalism and Stone Tool Evolution

Introduction
Walking upright on two legs is the unique characteristics that separate human beings
from all other known primates. The unique attribute of the adaptation of skeleton to the
bipedalism is utilized to recognize human hominid ancestors. However, due to the lack of the
fossil record as evidences, the fragmentary of the remains of fossils as well as the challenges
from inferring particular behaviour from such fossils, many vital questions have been
remained unanswered which are related to the evolution of human bipedalism
(Friedman,2006). Nonetheless, over the last few decades, various researches and studies are
being conducted in order to enhance the knowledge regarding human locomotion mechanics
to have deeper insights into the bipedalism of human beings. This paper is going to critically
analyse and evaluate the history and background of human bipedalism. During the discussion
the development of stone-tool technology will be considered in the paper. It is also focussed
to discuss all the theoretical aspects of human bipedalism in brief.
History and background of human bipedalism
Human bipedalism was driven by the principle of natural selection by Darwin.
Hominines did not become bipedal for any specific reason but time allowed the evolution of
bipedalism in humans as it was a favourable trait (Thorpe, McClymont & Crompton, 2014).
It was beneficial for the efficient survival of both the units itself as well as its offspring. Out
of all the great apes, hominines are the only species to have features of bipedalism.
According to some modern anthropologists, the enlarged as well as complex brain structure
of human being also contributes to the evolution of bipedalism among them.
Paleoanthropologists, who study the evolution of human beings, provided a variety of ideas
regarding the association between human evolution and the environmental factor. The
environmental conditions stimulated many important developments of human origin. Human

evolution coincided with multiple environmental factors that include environmental change
such as cooling, drying, climate fluctuations and many others. Hominines experienced a large
scale shifts in the temperature and precipitation that caused vast changes in the vegetation
which shifted grasslands and shrub lands into woodlands and forests and as a consequence
various changes in the climate had also been experienced (Foley & Gamble, 2009).
There is diversion as well as variation in the locomotive behaviours of primates.
Apes, including chimpanzees, gorillas, gibbons and others show some particular loco motor
habits arm swinging, fist walking, quadrumanous wlking and others (Schmitt, 2003). The
most common mode of locomotion among the primates is the quadrupedalism. The walking
gaits of primates widely differ from the other mammals. First of all, most of the primates use
the diagonal sequence footfall pattern. Secondly, according to some researchers, primates
have humerus which is relatively protracted at the forelimb touchdown. Thirdly, some other
literatures indicated that most of the primates have relatively greater peak vertical forces on
the hindlimd. Even, some studies by the researchers also revealed that quadrupedal primates
used walking gaits that involved substantial increases in elbow flexion (Winder, King, Deves
& Bailey, 2014). This kind of walking style has been documented in a wide range of primates
which includes large-boiled quadrupedal apes. Various different features have been acquired
naturally due to the human bipedalism. In this different and new mechanism of the body, the
skull is balanced directly on the top of the spine. These features support the vertical trunk of
the body and at the same time, it efficiently transfers the weight through the legs during
standing, walking as well as running. Apart from that, various other features of human
bipedalism have been achieved by the hominines. The closest living relatives of human being
such as chimpanzees can spend very little time being bipedal due to the absence of such
special features.

Many researches and studies have been conducted to find out the actual reason behind
the transformation of human being into bipedalism traits, but no satisfactory result or
evidences have been found in this regard (Winder, King, Deves & Bailey, 2014). Darwin
linked this feature to tool use especially for defence as well as hunting. The theories of
twentieth century proposed another range of factors that has driven the evolution of hominine
bipedalism. Furthermore, as an environmental factor, scientists indicated that bipeds were
regularly exposed to direct sunlight and standing upright would be benefited in many ways
such as less body surface would be exposed to direct harmful sunlight and it would help them
in finding relief in the cooler air.
Stone tools and its contribution towards evolution
Paralleling to biological evolution among the human beings, development of many
new technologies and cultures allowed them to become successful and the main origin of
evidence behind the success can be seen as the innovation and creation of stone tools and use
of them for different survival purpose (Proffitt et al., 2016). According to some
anthropological evidences, the first unquestionable stone tools were used by the human
beings of East Africa almost 2.5 million years ago (Lewis & Harmand, 2016). They were
named as Oldowan tools after the location and it consisted of different categories (Harcourt-
Smith, 2010). The species of such stone tools have been found by the anthropologists at
various sites in association with animal bones that displays the characteristics of those tools
in the use of butchery or hunting any animals and this discovery of anthropologists provided
indirect evidence of tool use. Even, some of the experts suspect that by 2.6 million years ago
hominids had been making several kinds of stone tools for thousands of years and they were
using it for different survival purpose (Diez-Martín et al., 2015). The origins of stone tools
might have started more before according to some experts and it was considered as the first
stage of human evolution (Harmand et al., 2015).