evolution of marathon running

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CO N F E R E N C E PAPER Sports M ed 2007; 37 (4.6): 20112-1642/07/00045km) using aerobic metabolism. Human ER capa-bilities derive from a suite of anatom ical, physio log-ical and behavioral features, many of which areuniquely evolved in humans, and which suggest thatER played an important role in human evolutionaryhistory.

In order to consider the evolutionary origins oflong distance running capabilities in humans, it isuseful to begin w ith a review of ER ability in mam -mals in general, including other primates. Primatesare not good runners, in part, because they havemany specialisations (e.g. large hands and feet, rela-tively short forelimbs) that improve perfonnance

the chimpanzee, is a typical example. Chimpanzcan sprint rapidly, but do so rarely and only for shdistances (


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al for hyperthermia. For exam ple, a

9 m/s for 10km can easily outrun hum ans,

l other mamm als and can sometimes outrunThe surprising ability of humans to run long

l of which are absent or tiny in othe r

to rapid pitching movements generated in runningbu t no t l J

Running also poses more challenges than walk-long-legged bipeds. Accordingly, humans have

runk and head during running, most of w hichle or no role during w alking. These featuresgluteus maximus, which

Finally, the biggest physiological challenges thatrunners face are thermoregulatory, because the vast-ly greater rate and number of muscle cross-bridgesneeded to power running generates as much as tentimes more heat than walking. Most mam mals ceasegalloping after short distances because they cannotcool core body temperatures fast enough to avoidhyperthermia.['1 Humans, uniquely, can run longdistances in hot, arid conditions that causehyperthermia in other mam mals, largely because wehave become specialised sw eaters. By losing almo stall our body fur and increasing the number anddensity of eccrine sweat glands, humans use evapo-transpiration to dissipate heat rapidly, but at theexpense of high water and salt demands.'"" In con-trast, other mammals cool the body by relying onpanting, which interferes with respiration, especiallyduring g alloping w hich requires 1 : 1 coupling ofbreathing and locomotion.'" '

The other questions that human ER capabilitiespose are when and why did humans become good atrunning long distances? These questions are harderto answer, but the fossil evidence suggests that ERcapabilities first evolved =2 million years ago (Ma).Importantly, this transition, unique among primates,occurred long after the evolution of bipedal walkingcapabilities, which first emerged when hominidsdiverged from chimpanzees =6Ma."^l Althoughthere is debate, it is probable that early hominids,such as the australopithecines, combined habitualbipedal walking with some degree of tree climb-ing.'^' However, features that would have improvedER capabilities, such as an expanded gluteus max-imus, spring-like feet, more sensitive semicirculaircanals and so on, do not appear until the genusHomo, mostly in H. erectus.^^^ Because of gaps inthe fossil record and because many soft tissues rele-vant to running do not fossilise, it is unclear whetherH. erectus was as good at ER as later hom inids suchas archaic Homo and/or modem humans. Futureresearch needs to address whether the transition tofully modem ER capabilities occurred before orafter the origin of H. erectus.


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290 Lieberman & Bra

early Homo a new ecological niche; that of a d iumalcarnivore. In particular, small teeth, larger bodiesand archaeological remains suggest that hominidsstarted to incorporate meat and other animal tissuesin the diet at least 2.5Ma, probably by hunting aswell as scavenging. To be a camivore, one mustcompete with other camivores, yet these hominidswere not only comparatively slow, but also lackedany weaponry more sophisticated and dangerousthan simple stone tools and possibly sharpened,untipped spears."^' In this context, ER might haveenabled hominids to scavenge carcasses from lionsafter they were abandoned but before hyenas ar-rived, as modem hunter-gatherers still do in EastAfrica.'' '' ' In addition, ER w ould have enabled hunt-er-gatherers in the hot, open habitats of Africa after1.9Ma to hunt animals before the invention of betterprojectile weapons such as stone-tipped spears,which first emerged 200 000 years ago, and the bowand arrow, which was invented within the last50 000 years."^! Before these inventions, hunterswould have had to kill animals by spearing them atshort range. Because one kick from a moderate-sized animal can be lethal, modem human huntersdo not hunt with spears without first trapping ordisabling an animal, using technologies not availa-ble for most of hominid evolutionary history. Yet, inhot weather, humans can effectively kill animalsusing persistence hunting, w here a runner follows ananimal, keeping it above its trot-gallop transition forseveral hours, driving the animal into hyperthermiaso that it can be killed safely at close range. Thiskind of persistence hunting has been documentedamong many recent hunter-gatherer groups, includ-ing the Bushmen.I'^l Since ER is typically 30-40%more costly than the most efficient walking speed,the caloric costs of persistence hunting would havebeen m inimal compared w ith the rewards of huntinga medium -to-large sized animal and would have putthe hunter at minimal risk.

In short, the human ability to mn long distances,such as a marathon, is neither a simple byprod uct ofthe ability to walk bipedally, nor a biologically

mn, the capacity and proclivity to mn marathonthe modem manifestation of a uniquely human that help make humans the way we are.

AcknowledgementsWe thank David Carder, David Raichlen and John for discussions and input, and the National Science Foution for funding. The authors have indicated that they havaffiliation or financial interest in any organisation(s) tha t have a direct interest in the subject matter of this article

References1. Hunt KD. Positional behavior of Pan troglodytes in the MMountains and Gombe Stream National Parks. Tanzania.Phys Anthropol 1992; 87: 83-1052. Alexander RM. The gaits of bipedal and quadrupedal aniInU J Robotics Res 1984; 3: 49-593. Heglund NC, Taylor CR. Speed, stride frequency and encost per stride: how do they change with body size and gaExp Biol 1988; 138: 301-184. Minetti AE. Physiology: efficiency of equine express psystems. Nature 2003; 426: 785-65. Aielio L, Dean MC. An introduction to human evolutioanatomy. London: Academic Press. 19906. Lieberman DE, Raichlen DA, Pontzer H, et al. The hugluteus maximus and its role in running. J Exp Biol 20062143-557. Bramble DM, Lieberman DE . Endurance running and the etion of Homo. Nature 2004; 432: 345-528. Spoor F, Wood B , Zonneveld F . Implications of early homlabyrinthine morphology for evolution of human bipedal motion. Nature 1994; 369: 645-89. Schmidt-Nielsen K. Animal physiology: adaptation and ronment. 4th ed. Cambridge: Cambridge University P199010. Carrier DR. The energetic paradox of human runninghominid evolution. Curr Anthropol 1984; 24: 483-9511. Bramble DM. Jenkins Jr FAJ. Mammalian locomotor-resp

ry integration: implications for diaphragmatic and pulmdesign. Science 1993; 262: 235-4012. Zollikofer CP, Ponce de Leon M, Lieberman D, et al. Vcranial reconstruction of Sahelanthropus tchadensis. N2005; 434: 755-913. Shea JJ. The origins of lithic projectile point technologydence from Africa, the Levant, and Europe. J Arch Sci 33: 823-4614. O JF, Hawkes K, Blurton-Jones NG. Hadza scavenging: ications for Plio-Pleistocene hominid subsistence. Currthrop 1988; 29: 356-6315. Liebenherg L. Persistence hunting by modem hunter-gathCurr Anthropol 2006; 47: 1017-25Correspondence: Daniel E. Lieberman, Departments thropology and Organismic and Evolutionary BioHarvard University, 11 Divinity A venue, Cambridge,


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