Data from: Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees

Bipedalism is a key adaptation that shaped human evolution, yet the timing
and nature of its evolution remain unclear. Here we use new experimentally
based approaches to investigate the locomotor mechanics preserved by the
famous Pliocene hominin footprints from Laetoli, Tanzania. We conducted
footprint formation experiments with habitually barefoot humans and with
chimpanzees to quantitatively compare their footprints to those preserved
at Laetoli. Our results show that the Laetoli footprints are
morphologically distinct from those of both chimpanzees and habitually
barefoot modern humans. By analysing biomechanical data that were
collected during the human experiments we, for the first time, directly
link differences between the Laetoli and modern human footprints to
specific biomechanical variables. We find that the Laetoli hominin
probably used a more flexed limb posture at foot strike than modern humans
when walking bipedally. The Laetoli footprints provide a clear snapshot of
an early hominin bipedal gait that probably involved a limb posture that
was slightly but significantly different from our own, and these data
support the hypothesis that important evolutionary changes to hominin
bipedalism occurred within the past 3.66 Myr.