Endurance running hypothesis: Difference between revisions

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"…one need not outrun a fast predator, but rather, merely not be the slowest individual trying to flee." [[Sprint (running)|Sprinting]] may be selected for because the potential benefit is so large.<ref name="glute-bartlett"/>
"…one need not outrun a fast predator, but rather, merely not be the slowest individual trying to flee." [[Sprint (running)|Sprinting]] may be selected for because the potential benefit is so large.<ref name="glute-bartlett"/>
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==="No horse or dog could possibly…"===

Comparison from long distance Man vs. Horse races shows that on hotter days, the race performance of horses worsens more than that-of humans. Yet even on hotter days, even while carrying a human rider, the horses typically run more quickly. As a matter of fact, there do seem to be examples of dogs running marathon distances in desert heat.<ref name="manvshorse">{{cite journal |last=Halsey |first=Lewis G. |author2=Bryce, Caleb M. |title=Are humans evolved specialists for running in the heat? Man vs. horse races provide empirical insights. |journal=Experimental Physiology |date=2021 |volume=106 |issue=1 |pages=258–268 |doi=10.1113/EP088502|pmid=32602586 |s2cid=220269476 |doi-access=free }}</ref>


==Academic discourse==
==Academic discourse==

Revision as of 21:27, 17 August 2023

The endurance running hypothesis is a series of conjectures which presume humans evolved anatomical and physiological adaptations to run long distances[1][2][3] and, more strongly, that "running is the only known behavior that would account for the different body plans in Homo as opposed to apes or australopithecines".[4]

The hypothesis posits a significant role of endurance running in facilitating early hominins' ability to obtain meat. Proponents of this hypothesis propose that endurance running served as a means for hominins to effectively engage in persistence hunting and carcass poaching, thus enhancing their competitive edge in acquiring prey. Consequently, these evolutionary pressures have led to the prominence of endurance running as a primary factor shaping many biomechanical characteristics of modern humans.

Endurance running hypothesis [1]

Premise

Australopithecus had structural adaptations for upright walking and running that are essentially those of modern humans.

Human running was thought to be less efficient than predicted for mammals of similar mass, and yet humans are capable distance runners, which seemed to be a paradox as some modern hunters apparently run prey animals to exhaustion. However, in more recent analyses, although 25% lower than predicted for human walking and 27% higher than predicted for human running, there was no statistically significant difference in cost compared to other mammals. [5] [6]

The efficiency of human running was thought not to change with running speed, so human hunters could chase at running speeds that were not optimal for the quadrupedal prey. However, more recent analysis shows that individual humans do have optimal running speeds; they are less efficient when running faster or slower than their optimal speed. [7] [8]

Hypothesis

That the efficiency constraint was overcome suggests that at some point in the evolution of hominins, there was strong selective pressure for "endurance running" — running many kilometers, running for hours, during the heat of the day — until faster prey could endure no more. (More recent analyses show no statistically significant difference in efficiency to overcome).

Something like persistence hunting by hominins created selective pressure for adaptations that improved "endurance running."

Endurance running hypothesis revisited [2]

Premise [9]

Australopithecus did not have structural adaptations for running. Selection for anatomical features that made "endurance running" possible radically transformed the hominin body.

Compared to Australopithecus fossil skeletons, selection for walking by itself would not develop some of these proposed "endurance running" derived traits —

  • evaporative heat dissipation from the scalp and face prevent hyperthermia
  • flatter face makes the head more balanced
  • Nuchal ligament helps counterbalance the head
  • shoulders and body can rotate without rotating the head
  • taller body has more skin surface for evaporative heat dissipation
  • torso can counter-rotate to balance the rotation of the hindlimbs
  • shorter forearms make it easier to counterbalance hindlimbs
  • shorter forearms cost less to keep flexed
  • backbones are wider, which will absorb more impact
  • stronger backbone pelvis connection will absorb more impact
  • compared to modern apes, human buttocks "are huge" and "critical for stabilization."
  • longer hindlimbs
  • Achilles tendon springs conserve energy
  • lighter tendons efficiently replace lower limb muscles
  • broader hindlimb joints will absorb more impact
  • foot bones create a stiff arch for efficient push off
  • broader heel bone will absorb more impact
  • shorter toes and an aligned big toe provide better push off

Hypotheses

There was strong selective pressure for "endurance running" — running many kilometers, running for hours — from persistence hunting until faster prey could endure no more.

There was strong selective pressure for "endurance running" — running fewer kilometers, running less time — to reach nearby carcasses faster than other scavengers and hominins.

Evolutionary evidence

No primates other than humans are capable of endurance running, and in fact, Australopithecus did not have structural adaptations for running.[10][11] Instead, forensic anthropology suggests that anatomical features that directly contributed to endurance running capabilities were heavily selected for within the genus Homo dating back to 1.9Ma. Consequently, selecting anatomical features that made endurance running possible radically transformed the hominid body.[12] The general form of human locomotion is markedly distinct from all other animals observed in nature. ‘’From the Journal of Anatomy’’, author RM Alexander describes our unique form of bipedal motion:

"… no animal walks or runs as we do. We keep the trunk erect; in walking, our knees are almost straight at mid-stance; the forces our feet exert on the ground are very markedly two-peaked when we walk fast; and in walking and usually in running, we strike the ground initially with the heel alone. No animal walks or runs like that."[13]

From the perspective of natural selection, scientists acknowledge that specialization in endurance running would not have helped early humans avoid faster predators over short distances.[14] Instead, it could have allowed them to traverse shifting habitat zones more effectively in the African savannas during the Pliocene. Endurance running facilitated the timely scavenging of large animal carcasses and enabled the tracking and chasing prey over long distances. This tactic of exhausting prey was especially advantageous for capturing large quadrupedal mammals struggling to thermoregulate in hot weather and over extended distances. Conversely, humans possess efficient means to dissipate heat, primarily through sweating. Specifically, evaporative heat dissipation from the scalp and face prevents hyperthermia and heat-induced encephalitis by extreme cardiovascular loads.[15] Furthermore, as humans continued to develop, our posture became more upright and subsequently increased vertically with the elongation of limbs and torso, effectively increasing surface area for corporeal heat dissipation.[16]

In work exploring the evolution of the human head, paleontologist Daniel Lieberman suggests that certain adaptations to the Homo skull and neck are correlational evidence of traits selective to endurance running optimization. Specifically, he posits that adaptations such as a flattening face and the development of the nuchal ligament promote improved head balance for cranial stabilization during extended periods of running.[17]

Attracting publicity

Media reports in 2004 mostly reflected the official news release, plus thoroughly hyped "Humans were born to run, scientists say" sound bites from interviews. [9] [18] [19] [20] [21] The hype reached celebrity level in 2009 when the hypothesis was promoted in the book Born to Run.

Sound bites may not be as definitive as they sound —

"Your butt is a running muscle…"

“Your butt is a running muscle; you barely use it when you walk,” Dr. Lieberman said.[22]

"…walking won't do that, but running will…"

"There were 2.5 million to 3 million years of bipedal walking without ever looking like a human, so is walking going to be what suddenly transforms the hominid body?" said Bramble. "We're saying 'no, walking won't do that, but running will.' " [21]

Others say changes in body proportions between Australopithecus and Homo erectus can be explained as adaptations to load-carrying and long-distance walking. [23] In any case, many features proposed as derived traits in Homo are already seen in Australopithecus which diminishes the sudden transformation.[24]

"No Olympic sprinter could ever outrun a lion."

"No Olympic sprinter could ever outrun a lion. We humans gave up the ability to run fast by mammalian standards many millions of years ago when we became bipeds and lost the ability to gallop. " [25][26]

"…one need not outrun a fast predator, but rather, merely not be the slowest individual trying to flee." Sprinting may be selected for because the potential benefit is so large.[27] [28]

Academic discourse

The derived longer hindlimb was already present in Australopithecus along with evidence for foot bones with a stiff arch. Walking and running in Australopithecus may have been the same as early Homo. Small changes in joint morphology may indicate neutral evolutionary processes rather than selection.[24]

The methodology by which the proposed derived traits were chosen and evaluated does not seem to have been stated, and there were immediate highly technical arguments "dismissing their validity and terming them either trivial or incorrect."[28]

Most of those proposed traits have not been tested for their effect on walking and running efficiency. [24] The new trunk shape counter-rotations, which help control rotations induced by hip-joint motion, seem active during walking.[23][29] Elastic energy storage does occur in the plantar soft tissue of the foot during walking.[23] Relative lower-limb length has a slightly larger effect on the economy of walking than running.[29] The heel-down foot posture makes walking economical but does not benefit running.[30]

Model-based analysis showing that scavengers would reach a carcass within 30 minutes of detection suggests that "endurance running" would not have given earlier access to carcasses and so not result in selection for "endurance running". Earlier access to carcasses may have been selected for running short distances of 5 km or less, with adaptations that generally improved running performance.[31]

The discovery of more fossil evidence resulted in additional detailed descriptions of hindlimb bones with measurable data reported in the literature. From a study of those reports, hindlimb proposed traits were already present in Australopithecus or early Homo. Those hindlimb characteristics most likely evolved to improve walking efficiency with improved running as a by-product.[32]

Gluteus maximus activity was substantially higher in maximal effort jumping and punching than sprinting, and substantially higher in sprinting than in running at speeds that can be sustained. The activity levels are not consistent with the suggestion that the muscle size is a result of selection for sustained endurance running.[33][8] Additionally, gluteus maximus activity was much greater in sprinting than in running, similar in climbing and running, and greater in running than walking. Increased muscle activity seems related to the speed and intensity of the movement rather than the gait itself. The data suggests that the large size of the gluteus maximus reflects multiple roles during rapid and powerful movements rather than a specific adaptation to submaximal endurance running.[27]

References

  1. ^ a b Carrier, David R. (August–October 1984). "The Energetic Paradox of Human Running and Hominid Evolution". Current Anthropology. 25 (4): 483–95. doi:10.1086/203165. JSTOR 2742907. S2CID 15432016..
  2. ^ a b Bramble, Dennis; Lieberman, Daniel (November 2004). "Endurance running and the evolution of Homo" (PDF). Nature. 432 (7015): 345–52. Bibcode:2004Natur.432..345B. doi:10.1038/nature03052. PMID 15549097. S2CID 2470602.
  3. ^ Krantz, Grover S. (1968). "Brain size and hunting ability in earliest man". Current Anthropology. 9 (5): 450–451. doi:10.1086/200927. S2CID 143267326.
  4. ^ Zimmer, Carl (17 November 2004). "The Evolution of Endurance: Physiologic adaptations may have made humans better runners". Science.
  5. ^ Halsey, Lewis G.; White, C.R. (2012). "Comparative energetics of mammalian locomotion: Humans are not different". Journal of Human Evolution. 63 (5): 718–722. doi:10.1016/j.jhevol.2012.07.008. PMID 22963931.
  6. ^ Rubenson, Jonas; Heliams, Denham B.; Maloney, Shane K.; Withers, Philip C.; Lloyd, David G.; Fournier, Paul A. (2007). "Reappraisal of the comparative cost of human locomotion using gait-specific allometric analyses". Journal of Experimental Biology. 210 (20): 3513–3524. doi:10.1242/jeb.000992. PMID 17921153. S2CID 46368362.
  7. ^ Steudel-Numbers, Karen L.; Wall-Scheffler, Cara M. (2009). "Optimal running speed and the evolution of hominin hunting strategies". Journal of Human Evolution. 56 (4): 355–360. doi:10.1016/j.jhevol.2008.11.002. PMID 19297009.
  8. ^ a b Carrier, David R.; Anders, Christoph; Schilling, Nadja (7 November 2011). "The musculoskeletal system of humans is not tuned to maximize the economy of locomotion". PNAS. 108 (46): 18631–18636. doi:10.1073/pnas.1105277108. PMC 3219105. PMID 22065766.
  9. ^ a b "How Running Made Us Human". The University of Utah. 17 November 2004.
  10. ^ Hunt, Kevin (1 December 1991). "Mechanical implications of chimpanzee positional behavior". American Journal of Biological Anthropology. 86 (4): 521–536. doi:10.1002/ajpa.1330860408. PMID 1776659.
  11. ^ Stern, Jack; Susman, Randall (1983). "The locomotor anatomy of Australopithecus afarensis". American Journal of Biological Anthropology. 60 (3): 279–317. doi:10.1002/ajpa.1330600302. PMID 6405621.
  12. ^ Lieberman, Daniel (2007). "Lieberman, Daniel E., et al. "The evolution of endurance running and the tyranny of ethnography: A reply to". Journal of Human Evolution. 53 (4): 439–442. doi:10.1016/j.jhevol.2007.07.002. PMID 17767947. S2CID 14996543.
  13. ^ Alexander, R M. (2004). "Bipedal animals, and their differences from humans". Journal of Anatomy. 204 (5): 321–330. doi:10.1111/j.0021-8782.2004.00289.x. PMC 1571302. PMID 15198697. S2CID 46335255.
  14. ^ Lieberman, Daniel. "Britannica Biography: Daniel Lieberman". {{cite journal}}: Cite journal requires |journal= (help)
  15. ^ Rasch, W.; Samson, P. (August 1991). "Heat loss from the human head during exercise". Journal of Applied Physiology. 71 (2): 590–595. doi:10.1152/jappl.1991.71.2.590. PMID 1938732.
  16. ^ Wheeler, P.E. (1993). "Wheeler, P. E. "The influence of stature and body form on hominid energy and water budgets; a comparison of Australopithecus and early Homo physiques". Journal of Human Evolution. 24 (1): 13–28. doi:10.1006/jhev.1993.1003.
  17. ^ Leiberman, Daniel (1 April 2011). "The Evolution of the Human Head". Harvard University Press. doi:10.4159/9780674059443. ISBN 9780674059443.
  18. ^ Zimmer, Carl (19 November 2004). "Faster Than A Hyena? Running May Make Humans Special". Science. 306 (5700): 1283. doi:10.1126/science.306.5700.1283. PMID 15550638. S2CID 39101965.
  19. ^ "Research: Humans Are Born to Run". ABC News. 17 November 2004.
  20. ^ "Running 'key to human evolution'". BBC News. 18 November 2004.
  21. ^ a b "Humans were born to run, scientists say". NBC News. 17 November 2004.
  22. ^ Parker-Pope, Tara (26 October 2009). "The Human Body Is Built for Distance". The New York Times.
  23. ^ a b c Crompton, R. H.; Vereecke, E. E.; Thorpe, S. K. S. (2008). "Locomotion and posture from the common hominoid ancestor to fully modern hominins, with special reference to the last common panin/hominin ancestor". Journal of Anatomy. 212 (4): 501–543. doi:10.1111/j.1469-7580.2008.00870.x. PMC 2409101. PMID 18380868.
  24. ^ a b c Pontzer, Herman (2012). "Ecological Energetics in Early Homo". Current Anthropology. 53 (S6): S346–S358. doi:10.1086/667402. S2CID 31461168.
  25. ^ Klosterman, Chuck (16 July 2011). "Is the Fastest Human Ever Already Alive?". Grantland. #3.
  26. ^ "Brains plus Brawn: A conversation with Daniel Lieberman". Edge Foundation, Inc. 17 October 2012.
  27. ^ a b Bartlett, Jamie L.; Sumner, Bonnie; Ellis, Richard G.; Kram, Rodger (2014). "Activity and Functions of the Human Gluteal Muscles in Walking, Running, Sprinting, and Climbing". American Journal of Physical Anthropology. 153 (1): 124–131. doi:10.1002/ajpa.22419. PMID 24218079. S2CID 29957031.
  28. ^ a b "Unlike apes, humans were born to run, study says / Finding could help date human evolution -- but other scientists say the theory is bunk". SFGATE. 18 November 2004.
  29. ^ a b Steudel-Numbers, Karen L.; Weaver, Timothy D.; Wall-Scheffler, Cara M. (2010). "The evolution of human running: Effects of changes in lower-limb length on locomotor economy". Journal of Human Evolution. 143 (4): 601–611. doi:10.1002/ajpa.21356. PMC 3011859. PMID 20623603.
  30. ^ Cunningham, C.B.; Schilling, N.; Anders, C.; Carrier, D.R. (1 March 2010). "The influence of foot posture on the cost of transport in humans". The Journal of Experimental Biology. 213 (5): 790–797. doi:10.1242/jeb.038984. PMID 20154195. S2CID 14834170.
  31. ^ Ruxton, Graeme D.; Wilkinson, David M. (2012). "Endurance running and its relevance to scavenging by early hominins". Evolution. 67 (3): 861–867. doi:10.1111/j.1558-5646.2012.01815.x. PMID 23461334. S2CID 41162625.
  32. ^ Deckers, K.P. (15 July 2017). "These bones were made for jogging: an analysis of the lower limb skeletal evidence for the endurance running hypothesis". Inter-Section. 3: 7–13. hdl:1887/3210949.
  33. ^ Carrier, David R.; Schilling, Nadja; Anders, Christoph (2015). "Muscle activation during maximal effort tasks: evidence of the selective forces that shaped the musculoskeletal system of humans". Biology Open. 4 (12): 1635–1642. doi:10.1242/bio.014381. PMC 4736035. PMID 26538637.
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