Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Arched footprints preserve the motions of fossil hominin feet

Nature Ecology & Evolution volume 7, pages 32–41 (2023)Cite this article

Subjects

Abstract

The longitudinal arch of the human foot is viewed as a pivotal adaptation for bipedal walking and running. Fossil footprints from Laetoli, Tanzania, and Ileret, Kenya, are believed to provide direct evidence of longitudinally arched feet in hominins from the Pliocene and Pleistocene, respectively. We studied the dynamics of track formation using biplanar X-ray, three-dimensional animation and discrete element particle simulation. Here, we demonstrate that longitudinally arched footprints are false indicators of foot anatomy; instead they are generated through a specific pattern of foot kinematics that is characteristic of human walking. Analyses of fossil hominin tracks from Laetoli show only partial evidence of this walking style, with a similar heel strike but a different pattern of propulsion. The earliest known evidence for fully modern human-like bipedal kinematics comes from the early Pleistocene Ileret tracks, which were presumably made by members of the genus Homo. This result signals important differences in the foot kinematics recorded at Laetoli and Ileret and underscores an emerging picture of locomotor diversity within the hominin clade.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Arched hominin tracks in soft substrates do not faithfully record the feet that made them.
Fig. 2: Discrete element method (DEM) simulations of arched track ontogeny.
Fig. 3: Arched tracks arise from human foot kinematics.
Fig. 4: Fossil RAV and implications for heel–sole–toe kinematic pattern.

Similar content being viewed by others

Data availability

Raw data from biplanar X-ray experiments are publicly available through the XMAPortal at the following link: https://xmaportal.org/webportal/larequest.php?request=CollectionView&StudyID=43&instit=BROWN&collectionID=20.

Code availability

Source data and code used to generate the figures in this manuscript are publicly available at the following address: https://doi.org/10.6084/m9.figshare.20736697.

References

  1. Darwin, C. The Descent of Man, and Selection in Relation to Sex (J. Murray, 1871).

  2. Morton, D. J. Evolution of the longitudinal arch of the human foot. J. Bone Jt Surg. 6, 56–90 (1924).

    Google Scholar 

  3. Holowka, N. B. & Lieberman, D. E. Rethinking the evolution of the human foot: insights from experimental research. J. Exp. Biol. 221, jeb174425 (2018).

    Article  Google Scholar 

  4. Bramble, D. M. & Lieberman, D. E. Endurance running and the evolution of Homo. Nature 432, 345–352 (2004).

    Article  CAS  Google Scholar 

  5. Leakey, M. D. & Hay, R. L. Pliocene footprints in the Laetolil Beds at Laetoli, northern Tanzania. Nature 278, 317–323 (1979).

    Article  Google Scholar 

  6. Day, M. H. & Wickens, E. H. Laetoli Pliocene hominid footprints and bipedalism. Nature 286, 385–387 (1980).

    Article  Google Scholar 

  7. White, T. D. & Suwa, G. Hominid footprints at Laetoli: facts and interpretations. Am. J. Phys. Anthropol. 72, 485–514 (1987).

    Article  CAS  Google Scholar 

  8. Raichlen, D. A., Gordon, A. D., Harcourt-Smith, W. E. H., Foster, A. D. & Haas, W. R. Laetoli footprints preserve earliest direct evidence of human-like bipedal biomechanics. PLoS ONE 5, e9769 (2010).

    Article  Google Scholar 

  9. Crompton, R. H. et al. Human-like external function of the foot, and fully upright gait, confirmed in the 3.66 million year old Laetoli hominin footprints by topographic statistics, experimental footprint-formation and computer simulation. J. R. Soc. Interface 9, 707–719 (2012).

    Article  Google Scholar 

  10. Hatala, K. G., Demes, B. & Richmond, B. G. Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees. Proc. R. Soc. B 283, 20160235 (2016).

    Article  Google Scholar 

  11. Bennett, M. R. et al. Early hominin foot morphology based on 1.5-million-year-old footprints from Ileret, Kenya. Science 323, 1197–1201 (2009).

    Article  CAS  Google Scholar 

  12. Ward, C. V., Kimbel, W. H. & Johanson, D. C. Complete fourth metatarsal and arches in the foot of Australopithecus afarensis. Science 331, 750–753 (2011).

    Article  CAS  Google Scholar 

  13. Pontzer, H. et al. Locomotor anatomy and biomechanics of the Dmanisi hominins. J. Hum. Evol. 58, 492–504 (2010).

    Article  Google Scholar 

  14. Falkingham, P. L. & Gatesy, S. M. The birth of a dinosaur footprint: subsurface 3D motion reconstruction and discrete element simulation reveal track ontogeny. Proc. Natl Acad. Sci. USA 111, 18279–18284 (2014).

    Article  CAS  Google Scholar 

  15. Falkingham, P. L., Turner, M. L. & Gatesy, S. M. Constructing and testing hypotheses of dinosaur foot motions from fossil tracks using digitization and simulation. Palaeontology 63, 865–880 (2020).

    Article  Google Scholar 

  16. Hatala, K. G., Gatesy, S. M. & Falkingham, P. L. Integration of biplanar X-ray, three-dimensional animation and particle simulation reveals details of human ‘track ontogeny’. Interface Focus 11, 20200075 (2021).

    Article  Google Scholar 

  17. Hatala, K. G. et al. Footprints reveal direct evidence of group behavior and locomotion in Homo erectus. Sci. Rep. 6, 28766 (2016).

    Article  CAS  Google Scholar 

  18. Usherwood, J. R., Channon, A. J., Myatt, J. P., Rankin, J. W. & Hubel, T. Y. The human foot and heel–sole–toe walking strategy: a mechanism enabling an inverted pendular gait with low isometric muscle force? J. R. Soc. Interface 9, 2396–2402 (2012).

    Article  CAS  Google Scholar 

  19. Webber, J. T. & Raichlen, D. A. The role of plantigrady and heel-strike in the mechanics and energetics of human walking with implications for the evolution of the human foot. J. Exp. Biol. 219, 3729–3737 (2016).

    Article  Google Scholar 

  20. Masao, F. T. et al. New footprints from Laetoli (Tanzania) provide evidence for marked body size variation in early hominins. eLife 5, e19568 (2016).

    Article  Google Scholar 

  21. Hatala, K. G. et al. Hominin track assemblages from Okote Member deposits near Ileret, Kenya, and their implications for understanding fossil hominin paleobiology at 1.5 Ma. J. Hum. Evol. 112, 93–104 (2017).

    Article  Google Scholar 

  22. Morse, S. A. et al. Holocene footprints in Namibia: the influence of substrate on footprint variability. Am. J. Phys. Anthropol. 151, 265–279 (2013).

    Article  Google Scholar 

  23. McNutt, E. J. et al. Footprint evidence of early hominin locomotor diversity at Laetoli, Tanzania. Nature 600, 468–471 (2021).

    Article  CAS  Google Scholar 

  24. Zeininger, A., Schmitt, D. & Wunderlich, R. E. Mechanics of heel-strike plantigrady in African apes. J. Hum. Evol. 145, 102840 (2020).

    Article  Google Scholar 

  25. Elftman, H. & Manter, J. Chimpanzee and human feet in bipedal walking. Am. J. Phys. Anthropol. 20, 69–79 (1935).

    Article  Google Scholar 

  26. Latimer, B. & Lovejoy, C. O. The calcaneus of Australopithecus afarensis and its implications for the evolution of bipedality. Am. J. Phys. Anthropol. 78, 369–386 (1989).

    Article  CAS  Google Scholar 

  27. Prang, T. C. Calcaneal robusticity in Plio-Pleistocene hominins: implications for locomotor diversity and phylogeny. J. Hum. Evol. 80, 135–146 (2015).

    Article  Google Scholar 

  28. Fernández, P. J. et al. Evolution and function of the hominin forefoot. Proc. Natl Acad. Sci. USA 115, 8746–8751 (2018).

    Article  Google Scholar 

  29. Venkadesan, M. et al. Stiffness of the human foot and evolution of the transverse arch. Nature 579, 97–100 (2020).

    Article  CAS  Google Scholar 

  30. Latimer, B. & Lovejoy, C. O. Hallucal tarsometatarsal joint in Australopithecus afarensis. Am. J. Phys. Anthropol. 82, 125–133 (1990).

    Article  CAS  Google Scholar 

  31. DeSilva, J. M., Gill, C. M., Prang, T. C., Bredella, M. A. & Alemseged, Z. A nearly complete foot from Dikika, Ethiopia and its implications for the ontogeny and function of Australopithecus afarensis. Sci. Adv. 4, eaar7723 (2018).

    Article  Google Scholar 

  32. DeSilva, J. M. et al. Midtarsal break variation in modern humans: functional causes, skeletal correlates, and paleontological implications. Am. J. Phys. Anthropol. 156, 543–552 (2015).

    Article  CAS  Google Scholar 

  33. Kelly, L. A., Cresswell, A. G., Racinais, S., Whiteley, R. & Lichtwark, G. Intrinsic foot muscles have the capacity to control deformation of the longitudinal arch. J. R. Soc. Interface 11, 20131188 (2014).

    Article  Google Scholar 

  34. Kelly, L. A., Lichtwark, G. & Cresswell, A. G. Active regulation of longitudinal arch compression and recoil during walking and running. J. R. Soc. Interface 12, 20141076 (2015).

    Article  Google Scholar 

  35. Holowka, N. B., Richards, A., Sibson, B. E. & Lieberman, D. E. The human foot functions like a spring of adjustable stiffness during running. J. Exp. Biol. 224, jeb219667 (2021).

    Google Scholar 

  36. Wood, B. & Collard, M. The human genus. Science 284, 65–71 (1999).

    Article  CAS  Google Scholar 

  37. Brainerd, E. L. et al. X-ray reconstruction of moving morphology (XROMM): precision, accuracy and applications in comparative biomechanics research. J. Exp. Zool. 313A, 262–279 (2010).

    Google Scholar 

  38. Knörlein, B. J., Baier, D. B., Gatesy, S. M., Laurence-Chasen, J. D. & Brainerd, E. L. Validation of XMALab software for marker-based XROMM. J. Exp. Biol. 219, 3701–3711 (2016).

    Google Scholar 

  39. Kloss, C. & Goniva, C. in Supplemental Proceedings: Materials Fabrication, Properties, Characterization, and Modeling Vol. 2 (ed. TMS) 781–788 (John Wiley & Sons, 2011).

  40. Stukowski, A. Visualization and analysis of atomistic simulation data with OVITO—the Open Visualization Tool. Model. Simul. Mater. Sci. Eng. 18, 015012 (2010).

    Article  Google Scholar 

  41. R Core Team. R: A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, 2019).

  42. Wickham, H., François, R., Henry, L. & Müller, K. dplyr: A grammar of data manipulation. R package version 1.0.7 (2019).

  43. Wickham, H. ggplot2: Elegant Graphics for Data Analysis (Springer-Verlag, 2016).

Download references

Acknowledgements

We thank D. Baier, B. Brainerd, S. Cheleden, F. Drury, K. Fiske, K. Huffman, B. Knörlein, D. Laidlaw, K. Tani Little, S. Megherhi, J. Novotny, D. North, M. Turner and the students of CS137 for assistance directly related to the design and implementation of this project. We thank the anonymous volunteers who participated in biplanar X-ray experiments. We are grateful to A. Manafzadeh for feedback at many stages of analysis. Discrete element simulations were made possible through a PRACE allocation of supercomputer resources (project 2021250007, Irene-Rome). This study received funding support from the National Science Foundation (BCS-1825403 to K.G.H. and P.L.F.; BCS-1824821 to S.M.G.) and from the Chatham University Research & Sabbatical Committee (to K.G.H.).

Author information

Authors and Affiliations

  1. Department of Biology, Chatham University, Pittsburgh, PA, USA

    Kevin G. Hatala

  2. Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, RI, USA

    Stephen M. Gatesy

  3. School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK

    Peter L. Falkingham

Authors
  1. Kevin G. Hatala
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Stephen M. Gatesy
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Peter L. Falkingham
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

All authors participated in the conceptualization, planning and administration of this project. K.G.H. and S.M.G. carried out biplanar X-ray experiments with input from P.L.F. P.L.F. carried out discrete element simulations with input from K.G.H. and S.M.G. All authors participated in analysing the data and in writing and editing the manuscript.

Corresponding author

Correspondence to Kevin G. Hatala.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Ecology & Evolution thanks the anonymous reviewers for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Track RAV and navicular height.

Within this previously published experimental data set17 (Supplementary Note 1), we observed no statistically significant relationship between track RAV and relative navicular height (navicular height/foot length).

Extended Data Fig. 2 Origins of kinematic hypotheses.

(a) Maya visualization of the foot at midstance directly above the track that this foot produced during a walking trial. (b) An ‘animation snapshot’ positioned at the same height as the foot in A, directly above the 3-D model of the track that this foot and its motion produced. The foot at midstance is relatively flat compared with the longitudinally arched track. However, the animation snapshot and the track are similarly arched. A sequence of similar observations led us to hypothesize that track arch morphology was a product of foot kinematics and not foot anatomy.

Extended Data Fig. 3 RAVs and morphologies of human and chimpanzee tracks.

(a) As an example we focus on one Laetoli track, one Walvis Bay track and one experimental chimpanzee track, with similar RAV and relative depth measurements (red circle). (b) The morphologies of the two hominin tracks and their respective arch models are similar to each other and readily distinguished from those of the bipedal chimpanzee (all models from right feet). The arch volume of hominin tracks is concentrated beneath the medial midfoot, while that of the bipedal chimpanzee track is concentrated distally, in between the first and second rays. Thus, the hominin tracks are arched longitudinally, while the bipedal chimpanzee track is not. Two different colour scales are applied to map relative heights, one for tracks and one for arch models, to optimize visualization of each set. Scale bar at right is 10 cm.

Extended Data Fig. 4 Photograph of trackway setup used for biplanar X-ray experiments.

Two X-ray emitters (foreground) project overlapping collimated X-rays that are received by two circular image intensifiers (background) equipped with video cameras. At the intersection of the biplanar X-ray beams is a container that is filled with mud (‘wet 5’ variety pictured here). Atop the remainder of the trackway is a deformable foam whose thickness matches the depth of mud within the container, which therefore allows subjects to sink to a similar extent with each step.

Extended Data Fig. 5 Interobserver variation in RAV measurements from track and foot 3-D models.

Paired observations and line of identity are plotted. Average interobserver difference was 0.42 (95% confidence interval of −1.00 to 0.15). RAV measurements were more consistent between observers for deeper tracks.

Supplementary information

Supplementary Information

Supplementary Notes 1–3.

Reporting Summary

Supplementary Video 1

Oblique isometric view of an animated foot (animated using biplanar X-ray experimental data) moving through a DEM-simulated mud. The foot is semitransparent, allowing for observation of foot–substrate interactions. Playback of simulation allows for visualization of continuous track arch formation throughout stance phase.

Supplementary Video 2

Cross-sectional view of simulated track formation. Same animation and simulation as presented in Supplementary Video 1 but with an opaque foot and with the simulated mud sectioned from heel-to-hallux, as in Fig. 2. This provides a more direct perspective for visualizing track arch formation over time. The track’s arch begins to form soon after heel strike and is continually shaped through push-off.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Hatala, K.G., Gatesy, S.M. & Falkingham, P.L. Arched footprints preserve the motions of fossil hominin feet. Nat Ecol Evol 7, 32–41 (2023). https://doi.org/10.1038/s41559-022-01929-2

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41559-022-01929-2

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing