Editing Bipedalism (section)

===Multiple factors===
Napier (1963) argued that it is unlikely that a single factor drove the evolution of bipedalism. He stated "''It seems unlikely that any single factor was responsible for such a dramatic change in behaviour. In addition to the advantages of accruing from ability to carry objects – food or otherwise – the improvement of the visual range and the freeing of the hands for purposes of defence and offence may equally have played their part as catalysts."''<ref>{{Cite book |title=The evolution of bipedal walking in the hominids |last=Napier |first=JR|publisher=Archives de Biologie (Liege) |year=1964}}</ref> Sigmon (1971) demonstrated that chimpanzees exhibit bipedalism in different contexts, and one single factor should be used to explain bipedalism: preadaptation for human bipedalism.<ref>{{Cite journal |last=Sigmon |first=Becky |year=1971 |title=Bipedal behavior and the emergence of erect posture in man |journal=American Journal of Physical Anthropology |doi=10.1590/S1516-89132015060399 |volume=58 |issue=6 |pages=929–934 |pmid=4993117 |arxiv=1508.02739 |bibcode=2015arXiv150802739K |s2cid=761213}}</ref> Day (1986) emphasized three major pressures that drove evolution of bipedalism: food acquisition, predator avoidance, and reproductive success.<ref>{{Cite book |title=Bipedalism: Pressures, origins and modes. Major topics in human evolution |last=Day |first=MH |publisher=Cambridge University Press |year=1986 |location=Cambridge }}</ref> Ko (2015) stated that there are two main questions regarding bipedalism 1. Why were the earliest hominins partially bipedal? and 2. Why did hominins become more bipedal over time? He argued that these questions can be answered with combination of prominent theories such as Savanna-based, Postural feeding, and Provisioning.<ref>{{Cite journal |last=Kwang Hyun |first=Ko |date=2015 |title=Origins of Bipedalism |journal=Brazilian Archives of Biology and Technology |doi=10.1590/S1516-89132015060399 |volume=58 |issue=6 |pages=929–934 |bibcode=2015arXiv150802739K |arxiv=1508.02739 |s2cid=761213}}</ref>