Editing Walking (section)

=== Hominin ===
Data in the fossil record indicate that among hominin ancestors, bipedal walking was one of the first defining characteristics to emerge, predating other defining characteristics of ''[[Hominidae]]''.<ref name=":02">{{Cite journal |last1=Rodman |first1=Peter S. |last2=McHenry |first2=Henry M. |date=January 1980 |title=Bioenergetics and the origin of hominid bipedalism |url=https://onlinelibrary.wiley.com/doi/10.1002/ajpa.1330520113 |journal=American Journal of Physical Anthropology |language=en |volume=52 |issue=1 |pages=103–106 |doi=10.1002/ajpa.1330520113 |pmid=6768300 |issn=0002-9483}}</ref> Judging from footprints discovered on a former shore in Kenya, it is thought possible that ancestors of modern humans were walking in ways very similar to the present activity as long as 3 million years ago.<ref>{{cite news
 | url = https://www.reuters.com/article/scienceNews/idUSTRE51P82420090226
 | title = Footprints show human ancestor with modern stride
 | first = Will | last = Dunham | work = Reuters
 | date = February 26, 2009 | access-date = 
}}</ref><ref>{{cite magazine
 | url = http://www.sciam.com/article.cfm?id=15-million-footprints-uncover
 | title = Researchers Uncover 1.5 Million-Year-Old Footprints
 | first = Katherine | last = Harmon | magazine = Scientific American
 | date = February 26, 2009 | access-date = 
}}</ref>

Today, the walking gait of humans is unique and differs significantly from [[Bipedalism|bipedal]] or [[Quadrupedalism|quadrupedal]] walking gaits of other primates, like chimpanzees. It is believed to have been selectively advantageous in hominin ancestors in the [[Miocene]] due to metabolic [[Efficient energy use|energy efficiency]]. Human walking has been found to be slightly more energy efficient than travel for a quadrupedal [[mammal]] of a similar size, like chimpanzees.<ref name=":13">{{Cite journal |last1=Sockol |first1=M. D. |last2=Raichlen |first2=D. A. |last3=Pontzer |first3=H. |date=2007-07-16 |title=Chimpanzee locomotor energetics and the origin of human bipedalism |journal=Proceedings of the National Academy of Sciences |volume=104 |issue=30 |pages=12265–12269 |doi=10.1073/pnas.0703267104 |pmid=17636134 |pmc=1941460 |bibcode=2007PNAS..10412265S |issn=0027-8424|doi-access=free }}</ref> The energy efficiency of human locomotion can be accounted for by the reduced use of muscle in walking, due to an upright posture which places ground reaction forces at the hip and knee.<ref name=":13"/> When walking bipedally, chimpanzees take a crouched stance with bent knees and hips, forcing the [[quadriceps]] muscles to perform extra work, which costs more energy.<ref name=":23">{{Cite book |last=DeSilva |first=Jeremy |url=https://www.worldcat.org/oclc/1244114018 |title=First steps : how upright walking made us human |date=2021 |isbn=978-0-06-293849-7 |edition=1st |location=New York, NY |oclc=1244114018}}</ref> Comparing chimpanzee quadrupedal travel to that of true quadrupedal animals has indicated that chimpanzees expend one-hundred and fifty percent of the energy required for travel compared to true quadrupeds.

In 2007, a study further explored the origin of human [[bipedalism]], using chimpanzee and human energetic costs of locomotion.<ref name=":13"/> They found that the energy spent in moving the human body is less than what would be expected for an animal of similar size and approximately seventy-five percent less costly than that of chimpanzees. Chimpanzee quadrupedal and bipedal energy costs are found to be relatively equal, with chimpanzee bipedalism costing roughly ten percent more than quadrupedal. The same 2007 study found that among chimpanzee individuals, the energy costs for bipedal and quadrupedal walking varied significantly, and those that flexed their knees and hips to a greater degree and took a more upright posture, closer to that of humans, were able to save more energy than chimpanzees that did not take this stance. Further, compared to other apes, humans have longer legs and short dorsally oriented ischia (hipbone), which result in longer hamstring extensor moments, improving walking energy economy.<ref name=":3">{{Cite journal |last1=Kozma |first1=Elaine E. |last2=Webb |first2=Nicole M. |last3=Harcourt-Smith |first3=William E. H. |last4=Raichlen |first4=David A. |last5=D'Août |first5=Kristiaan |last6=Brown |first6=Mary H. |last7=Finestone |first7=Emma M. |last8=Ross |first8=Stephen R. |last9=Aerts |first9=Peter |last10=Pontzer |first10=Herman |date=2018-04-02 |title=Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins |journal=Proceedings of the National Academy of Sciences |volume=115 |issue=16 |pages=4134–4139 |doi=10.1073/pnas.1715120115 |pmid=29610309 |pmc=5910817 |bibcode=2018PNAS..115.4134K |issn=0027-8424|doi-access=free }}</ref><ref name=":13"/> Longer legs also support lengthened [[Achilles tendon]]s which are thought to increase energy efficiency in bipedal locomotor activities.<ref>{{Cite journal |last1=Blazevich |first1=Anthony J. |last2=Fletcher |first2=Jared R. |date=December 2023 |title=More than energy cost: multiple benefits of the long Achilles tendon in human walking and running |journal=Biological Reviews |language=en |volume=98 |issue=6 |pages=2210–2225 |doi=10.1111/brv.13002 |issn=1464-7931|doi-access=free |pmid=37525526 |arxiv=2205.13298 }}</ref> It was thought that hominins like ''[[Ardipithecus ramidus]],'' which had a variety of both terrestrial and arboreal adaptions would not be as efficient walkers, however, with a small body mass ''A. ramidus'' had developed an energy efficient means of bipedal walking while still maintaining arboreal adaptations.<ref name=":3" /> Humans have long [[femoral neck]]s, meaning that while walking, hip muscles do not require as much energy to flex while moving.<ref name=":23"/> These slight [[Kinematics|kinematic]] and [[Anatomy|anatomic]] differences demonstrate how bipedal walking may have developed as the dominant means of locomotion among early hominins because of the energy saved.<ref name=":13"/>