  The following manuscript reviews various theories of bipedalism and provides
a holistic answer to human evolution. There are two questions regarding
bipedalism: i) why were the earliest hominins partially bipedal? and ii) why
did hominins become increasingly bipedal over time and replace their less
bipedal ancestors? To answer these questions, the prominent theories in the
field, such as the savanna-based theory, the postural feeding hypotheses, and
the provisioning model, are collectively examined. Because biological evolution
is an example of trial and error and not a simple causation, there may be
multiple answers to the evolution of bipedalism. The postural feeding
hypothesis (reaching for food/balancing) provides an explanation for the
partial bipedalism of the earliest hominins. The savannah-based theory
describes how the largely bipedal hominins that started to settle on the ground
became increasingly bipedal. The provisioning model (food-gathering/monogamy)
explains questions arising after the postural feeding hypothesis and before the
savannah theory in an evolutionary timeline. Indeed, there are no straight
lines between the theories, and multiple forces could have pushed the evolution
of bipedalism at different points. Finally, this manuscript states that the
arboreal hominins that possessed ambiguous traits of bipedalism were eliminated
through choice and selection. Using the biological analogy of the okapi and
giraffe, I explain how one of the branches (Homo) became increasingly bipedal
while the other (Pan) adapted to locomotion for forest life by narrowing the
anatomical/biological focus in evolution.
