Striding Bipedalism

Certainty Style Key
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True   Likely   Speculative
Human Uniqueness Compared to "Great Apes": 
Absolute Difference
MOCA Topic Authors: 

All apes are capable of bipedal locomotion, and some species walk bipedally on a fairly regular basis (although only in humans is bipedal walking the most common form of locomotion). However, human bipedalism differs from that of other apes in a number of ways, and only humans exhibit what is known as “full striding bipedalism.” Striding bipedalism involves: full extension of the hip and knee joints in the support leg during stance phase (apes maintain a degree of flexion at both of these joints during bipedal walking); movement of the hip joint over and in front of the knee and ankle joints in the support leg; and a longer stride length (both absolutely and relative to body size) than seen in ape bipedalism. In addition, the human femoral bicondylar angle (see Bicondylar Angle of the Femur) minimizes mediolateral shifts in the body’s center of gravity when alternating between support legs, while the arrangement of our gluteal abductors (see Pelvic Height and Iliac Flare) minimizes vertical displacements of the center of gravity as weight is shifted from limb to limb. In contrast, apes must usually shift their body weight over their support leg when walking bipedally (resulting in an exaggerated side-to-side swaying), and must tilt their pelvis upwards to counteract gravity operating on the nonsupport leg (while swinging the leg forward to reposition it for the next step), resulting in relatively great vertical displacements of the body’s center of gravity. Because vertical and mediolateral movement of the center of gravity is minimized in human bipedal walking, humans require less muscular effort in bipedal locomotion than do apes. It is generally held that full striding bipedalism evolved to increase energetic efficiency in the context of increased terrestrial mobility, perhaps in conjunction with an adaptive shift towards consumption of greater amounts of savannah resources (such as scavengable carcasses), in early members of the genus Homo.

Timing

Timing of appearance of the difference in the Hominin Lineage as a defined date or a lineage separation event. The point in time associated with lineage separation events may change in the future as the scientific community agrees upon better time estimates. Lineage separation events are defined in 2017 as:

  • the Last Common Ancestor (LCA) of humans and old world monkeys was 25,000 - 30,000 thousand (25 - 30 million) years ago
  • the Last Common Ancestor (LCA) of humans and chimpanzees was 6,000 - 8,000 thousand (6 - 8 million) years ago
  • the emergence of the genus Homo was 2,000 thousand (2 million) years ago
  • the Last Common Ancestor (LCA) of humans and neanderthals was 500 thousand years ago
  • the common ancestor of modern humans was 100 - 300 thousand years ago

Definite Appearance: 
2,000 thousand years ago
Background Information: 

Lovejoy, 1988. Evolution of human walking. Sci Amer Nov 1988:118-125.
Aiello & Dean, 1990. An introduction to human evolutionary anatomy. London: Academic Press.
Meldrum & Hilton (eds.), 2004. From Biped to Strider: The Emergence of Modern Human Walking, Running, and Resource Transport. New York: Academic/Plenum Publishers.
 

References

  1. Rethinking the evolution of the human foot: insights from experimental research, Holowka, Nicholas B., and Lieberman Daniel E. , The Journal of Experimental Biology, 2018/09/01, Volume 221, Issue 17, (2018)
  2. Acquisition of terrestrial life by human ancestors influenced by forest microclimate, Takemoto, Hiroyuki , Nature Scientific Reports, 2017/07/18, Volume 7, Issue 1, p.5741, (2017)
  3. Possible hominin footprints from the late Miocene (c. 5.7 Ma) of Crete?, Gierliński, Gerard D., Niedźwiedzki Grzegorz, Lockley Martin G., Athanassiou Athanassios, Fassoulas Charalampos, Dubicka Zofia, Boczarowski Andrzej, Bennett Matthew R., and Ahlberg Per Erik , Proceedings of the Geologists' Association, p. - , (2017)
  4. Bipedality and hair loss in human evolution revisited: The impact of altitude and activity scheduling., Dávid-Barrett, Tamás, and Dunbar Robin I. M. , J Hum Evol, 5/2016, Volume 94, p.72-82, (2016)
  5. Cliff-edge model of obstetric selection in humans, Mitteroecker, Philipp, Huttegger Simon M., Fischer Barbara, and Pavlicev Mihaela , PNAS, 2016/12/05, (2016)
  6. Footprints reveal direct evidence of group behavior and locomotion in Homo erectus, Hatala, Kevin G., Roach Neil T., Ostrofsky Kelly R., Wunderlich Roshna E., Dingwall Heather L., Villmoare Brian A., Green David J., Harris John W. K., Braun David R., and Richmond Brian G. , Scientific Reports, 2016/07/12, Volume 6, p.28766 - , (2016)
  7. New footprints from Laetoli (Tanzania) provide evidence for marked body size variation in early hominins, Masao, Fidelis T., Ichumbaki Elgidius B., Cherin Marco, Barili Angelo, Boschian Giovanni, Iurino Dawid A., Menconero Sofia, Moggi-Cecchi Jacopo, and Manzi Giorgio , eLife, 2016/12/14, Volume 5, p.e19568, (2016)
  8. The role of plantigrady and heel-strike in the mechanics and energetics of human walking with implications for the evolution of the human foot, Webber, James T., and Raichlen David A. , The Journal of Experimental Biology, 2016/11/30, Volume 219, Issue 23, p.3729, (2016)
  9. Surprising trunk rotational capabilities in chimpanzees and implications for bipedal walking proficiency in early hominins., Thompson, Nathan E., Demes Brigitte, O'Neill Matthew C., Holowka Nicholas B., and Larson Susan G. , Nat Commun, 2015, Volume 6, p.8416, (2015)
  10. The ancestral shape hypothesis: an evolutionary explanation for the occurrence of intervertebral disc herniation in humans., Plomp, Kimberly A., Viðarsdóttir Una Strand, Weston Darlene A., Dobney Keith, and Collard Mark , BMC Evol Biol, 2015, Volume 15, p.68, (2015)