Footprint evidence of early hominin locomotor diversity at Laetoli, Tanzania.

Bipedal trackways discovered in 1978 at Laetoli site G, Tanzania and dated to 3.66 million years ago are widely accepted as the oldest unequivocal evidence of obligate bipedalism in the human lineage1-3. Another trackway discovered two years earlier at nearby site A was partially excavated and attributed to a hominin, but curious affinities with bears (ursids) marginalized its importance to the paleoanthropological community, and the location of these footprints fell into obscurity3-5. In 2019, we located, excavated and cleaned the site A trackway, producing a digital archive using 3D photogrammetry and laser scanning. Here we compare the footprints at this site with those of American black bears, chimpanzees and humans, and we show that they resemble those of hominins more than ursids. In fact, the narrow step width corroborates the original interpretation of a small, cross-stepping bipedal hominin. However, the inferred foot proportions, gait parameters and 3D morphologies of footprints at site A are readily distinguished from those at site G, indicating that a minimum of two hominin taxa with different feet and gaits coexisted at Laetoli.

The skull of Homo naledi.

The species Homo naledi was recently named from specimens recovered from the Dinaledi Chamber of the Rising Star cave system in South Africa. This large skeletal sample lacks associated faunal material and currently does not have a known chronological context. In this paper, we present comprehensive descriptions and metric comparisons of the recovered cranial and mandibular material. We describe 41 elements attributed to Dinaledi Hominin (DH1-DH5) individuals and paratype U.W. 101-377, and 32 additional cranial fragments. The H. naledi material was compared to Plio-Pleistocene fossil hominins using qualitative and quantitative analyses including over 100 linear measurements and ratios. We find that the Dinaledi cranial sample represents an anatomically homogeneous population that expands the range of morphological variation attributable to the genus Homo. Despite a relatively small cranial capacity that is within the range of australopiths and a few specimens of early Homo, H. naledi shares cranial characters with species across the genus Homo, including Homo habilis, Homo rudolfensis, Homo erectus, and Middle Pleistocene Homo. These include aspects of cranial form, facial morphology, and mandibular anatomy. However, the skull of H. naledi is readily distinguishable from existing species of Homo in both qualitative and quantitative assessments. Since H. naledi is currently undated, we discuss the evolutionary implications of its cranial morphology in a range of chronological frameworks. Finally, we designate a sixth Dinaledi Hominin (DH6) individual based on a juvenile mandible.

Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa.

We describe the physical context of the Dinaledi Chamber within the Rising Star cave, South Africa, which contains the fossils of Homo naledi. Approximately 1550 specimens of hominin remains have been recovered from at least 15 individuals, representing a small portion of the total fossil content. Macro-vertebrate fossils are exclusively H. naledi, and occur within clay-rich sediments derived from in situ weathering, and exogenous clay and silt, which entered the chamber through fractures that prevented passage of coarser-grained material. The chamber was always in the dark zone, and not accessible to non-hominins. Bone taphonomy indicates that hominin individuals reached the chamber complete, with disarticulation occurring during/after deposition. Hominins accumulated over time as older laminated mudstone units and sediment along the cave floor were eroded. Preliminary evidence is consistent with deliberate body disposal in a single location, by a hominin species other than Homo sapiens, at an as-yet unknown date.

Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa.

Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.

Swift and sure-footed on the Savanna: A study of Hadzabe gaits and feet in Northern Tanzania.

Data on footprints and gait of 54 Hadzabe, 6-70 years of age expand understanding of pedal morphology of unshod people and assist the development of ideas about the evolution of hominid bipedality and upright posture. Contrary to published data on gaits and pedal morphology of unshod populations, Hadzabe (also known as Hadza) from northern Tanzania exhibit values of stride length, relative stride length, and walking speeds that exceed those of rural and small-town populations. In all observable plantar features, including foot indices, an interdigital space between the hallux and second toe, fanning of the foot anteriorly, and foot angles (in-toeing and out-toeing), Hadzabe feet are comparable with those of never-shod Machiguengas in Perú. On average, Hadzabe hallucal gaps and ball widths are narrower than those of Machiguengas and other unshod short people. Hadzabe feet are also characterized by valgus halluces versus the varus halluces of never-shod Machiguengas and certain West Africans. Although characterized by a valgus toe, Hadzabe hallucal angles, which do not exceed 20°, are lower than those of Northern Hemispheric urbanites and shod rural populations of the Southern and Northern Hemispheres. Hadzabe also exhibit less medial and lateral rotation of the hip joint than Machiguengas do. The heel and the longitudinal arch impressions of the Hadzabe footprints closely resemble those of the Laetoli bipeds in the manner of weight distribution during locomotion. The striking similarity of footprint impressions, especially the heel and the longitudinal arch, between Hadzabe and Laetoli hominid footprints clearly imply that the pedal features of the Laetoli printmakers are remarkably humanoid. Am. J. Hum. Biol. 9:303-321, 1997. © 1997 Wiley-Liss, Inc.