• Figure 1.
    Download figureOpen in new tabFigure 1. Geographical location and site map.

    (A) Location of the study area in northern Tanzania. (B) Location of Laetoli within the Ngorongoro Conservation Area, about 50 km south of Olduvai Gorge. (C) Plan view of the area of Laetoli Locality 8 (Sites G and S).

    DOI: http://dx.doi.org/10.7554/eLife.19568.003

    Figure 3.
    Download figureOpen in new tabFigure 3. Shaded 3D photogrammetric elevation model of the L8 trackway.

    Colour renders heights as in the colour bar. The empty circles indicate the position of the targets of the 3D-imaging control point system (see Materials and methods for details).

    DOI: http://dx.doi.org/10.7554/eLife.19568.008

    Figure 4.
    Download figureOpen in new tabFigure 4. Shaded 3D photogrammetric elevation model of test-pit L8 and close-up of the best-preserved tracks with contour lines.

    Colour renders heights as in the colour bar; distance between elevation contour lines is 2 mm. The empty circles indicate the position of the targets.

    DOI: http://dx.doi.org/10.7554/eLife.19568.009

    Figure 5.
    Download figureOpen in new tabFigure 5. Shaded 3D photogrammetric elevation model of the central portion of test-pit M9 and close-up of the best-preserved tracks with contour lines.

    Colour renders heights as in the colour bar; distance between elevation contour lines is 2 mm. The empty circles indicate the position of the targets

    DOI: http://dx.doi.org/10.7554/eLife.19568.010

    Figure 6.
    Download figureOpen in new tabFigure 6. Shaded 3D photogrammetric elevation model of test-pit TP2 and close-up of the three hominin tracks with contour lines.

    Colour renders heights as in the colour bar; distance between elevation contour lines is 2 mm. The empty circles indicate the position of the targets.

    DOI: http://dx.doi.org/10.7554/eLife.19568.011

    Figure 7.
    Download figureOpen in new tabFigure 7. Southern part of the hominin trackway in test-pit L8.

    Footprints L8/S1-1, L8/S1-2, L8/S1-3 and L8/S1-4 are visible from left to right. The heel drag mark is well visible posteriorly to L8/S1-3.

    DOI: http://dx.doi.org/10.7554/eLife.19568.012

    Figure 8.
    Download figureOpen in new tabFigure 8. Test-pit L8 at Laetoli Site S.

    In the northern part of the test-pit (at the top), the Footprint Tuff is particularly altered, damaged by plant roots and dislodged along natural fractures.

    DOI: http://dx.doi.org/10.7554/eLife.19568.013

    Figure 9.
    Download figureOpen in new tabFigure 9. Central part of the hominin trackway in test-pit M9.

    Tracks M9/S1-3 and M9/S1-2 are visible from left to right. The two tracks are crossed by some fractures filled by hard calcite veins, which were not removed. In M9, the Footprint Tuff is in almost pristine condition, and most of the tracks are still filled by compact sediment.

    DOI: http://dx.doi.org/10.7554/eLife.19568.014

    Figure 10.
    Download figureOpen in new tabFigure 10. Laetoli Site S geology.

    (A) Stratigraphic sketch of the sequence, as in test-pit M9. Numbers on the left (1–5) correspond to the lithologic units observed in the field: 1 — modern soil; 2 — grey augite-rich tuff; 3 — laminated grey tuff; 4 — finely layered grey and white tuff; 5 — light brown tuff. Unit two corresponds to the Augite Biotite Tuff (Hay, 1987); units 3 and 4 correspond respectively to the upper and lower horizons of the Footprint Tuff (Hay, 1987). Numbers on the right indicate the four and fourteen sublevels included, respectively, in the upper and lower part (Hay, 1987). Hominin tracks occur on the topmost sublevel of unit 4 (red line); a similar thick whitish footprint-bearing level can be observed in the same stratigraphic position at Localities 6 and 7. Oblique hatch: open cracks. White patches in unit 5 are burrower tunnels and disturbances. Green rectangle: location of panel B image. (B) Photomosaic showing the Footprint Tuff and part of the overlying unit.

    DOI: http://dx.doi.org/10.7554/eLife.19568.015

    Figure 12.
    Download figureOpen in new tabFigure 12. Estimates of predicted stature of fossil hominin individuals by species over time for the interval 4–1 Ma.

    Solid symbols (or crosses in bold) refer to stature estimates based on actual femur length; open symbols refer to stature estimates based on estimated femur length, in turn based on femur head diameter. For Laetoli and Ileret, stature estimates are based on footprint length (see Materials and methods). For Laetoli, Ileret and Woranso-Mille, the average value and range of predicted stature are shown. Colours are associated to the geographical location of each fossil/footprint site on the map. See Supplementary file 5 for details.

    DOI: http://dx.doi.org/10.7554/eLife.19568.021

  • Table 1.

    Number of individual tracks (excluding hominins) at Laetoli Site S.

    DOI: http://dx.doi.org/10.7554/eLife.19568.016

    Taxon

    L8

    M9

    TP2

    M10

    Total

    Numididae (?Numida)

    -

    4

    -

    9

    13

    Bovidae, small size (?Madoqua)

    107

    39

    16

    211

    373

    Bovidae, medium size (?Gazella)

    39

    9

    -

    21

    79

    Equidae (?Hipparion)

    1

    2

    -

    -

    3

    Giraffidae

    -

    -

    -

    4

    4

    Lagomorpha (?Lepus)

    8

    -

    -

    4

    12

    Rhinocerotidae

    -

    1

    -

    -

    1

    Unidentified micromammals

    -

    27

    -

    17

    44

    Total

    155

    82

    26

    266

    529

  • Table 2.

    Dimensional parameters measured and derived from the Laetoli Site S tracks and stature and body mass estimates for S1 and S2.

    DOI: http://dx.doi.org/10.7554/eLife.19568.019

    Footprint

    Side

    Length (mm)

    Max width (mm)

    Foot index (%)

    Heel width (mm)

    Angle of gait (degrees)

    Estimated stature (cm)

    Estimated body mass (kg)

    H. sapiens§

    H. sapiens°

    Au. afarensis

    H. sapiens°

    Au. afarensis

    TP2/S1-1

    right

    271

    101

    37.2

    83

    6

    194–170

    175.4

    167–175

    53.8

    42.9–50.0

    TP2/S1-2

    left

    271

    99

    36.6

    81

    4

    193–169

    175.1

    167–175

    53.1

    42.8–49.8

    M9/S1-1

    left

    250

    102

    40.6

    73

    2

    179–156

    167.5

    154–161

    51.6

    39.6–46.0

    M9/S1-2

    right

    264

    105

    39.7

    80

    3

    189–165

    172.8

    163–171

    54.2

    41.8–48.7

    M9/S1-3

    left

    268

    111

    41.2

    91

    4

    192–168

    174.3

    166–173

    56.3

    42.5–49.4

    M9/S1-4

    right

    245

    101

    41.2

    71

    4

    175–153

    165.6

    151–158

    50.9

    38.8–45.1

    L8/S1-1

    right

    245

    104

    42.4

    78

    8

    175–153

    165.6

    151–158

    51.7

    38.8–45.1

    L8/S1-2

    left

    265

    106

    40.0

    82

    11

    189–166

    173.1

    164–171

    54.5

    41.9–48.8

    L8/S1-3

    right

    260

    103

    39.6

    77

    3

    186–163

    171.3

    161–168

    53.1

    41.2–47.9

    L8/S1-4

    left

    274

    106

    38.6

    81

    10

    196–171

    176.5

    169–177

    55.6

    43.4–50.5

    L8/S1-5

    right

    -

    -

    -

    -

    -

    -

    -

    -

    -

    -

    L8/S1-6

    left

    -

    -

    -

    86

    3

    -

    -

    -

    -

    -

    L8/S1-7

    right

    258

    110

    42.7

    90

    8

    184–161

    170.3

    159–166

    54.8

    40.7–47.4

    Average S1

    -

    261

    104

    40.0

    81

    6

    184–163

    171.6

    161–168

    53.6

    41.3–48.1

    TP2/S2-1

    right

    231

    120*

    51.9*

    86

    -

    165–144

    160

    142–149

    46.7

    36.5–42.4

    Step length

    Stride length

    Footprints

    Side

    Step length (mm)

    Footprints

    Side

    Stride length (mm)

    TP2/S1-1 → 2

    right → left

    553

    M9/S1-1 → 3

    left

    1044

    M9/S1-1 → 2

    left → right

    548

    M9/S1-2 → 4

    right

    1069

    M9/S1-2 → 3

    right → left

    505

    L8/S1-1 → 3

    right

    1140

    M9/S1-3 → 4

    left → right

    571

    L8/S1-2 → 4

    left

    1159

    L8/S1-1 → 2

    right → left

    552

    L8/S1-4 → 6

    left

    1284

    L8/S1-2 → 3

    left → right

    587

    Average right

    1105

    L8/S1-3 → 4

    right → left

    573

    Average left

    1162

    L8/S1-6 → 7

    left → right

    660

    Average

    1139

    Average right → left

    545

    Average left → right

    591

    Average

    568

    • *Values overestimated because of the enlarged morphology of the only preserved track of S2. §Estimation based on the relationship between foot length and stature in Homo sapiens (Tuttle, 1987). °Estimation based on the relationship between footprint length and stature/body mass in H. sapiens (Dingwall et al., 2013). Estimation based on the relationship between foot length and stature/body mass in Au. afarensis (Dingwall et al., 2013). See Materials and methods for details.

  • Table 3.

    Data and estimates for the five Laetoli track-makers from Sites S and G. Limited to S1, mean values, standard deviation and range are provided.

    DOI: http://dx.doi.org/10.7554/eLife.19568.020

    Trackway

    S1

    S2

    G1

    G2

    G3

    Number of measurable footprints

    11

    1

    9

    2

    8

    Average footprint length (mm)

    261 ± 10.5 (245–273)

    231

    180

    225

    209

    Average footprint max width (mm)

    104 ± 3.7 (99–111)

    120*

    79

    117

    85

    Average foot index (%)

    40.0 ± 1.9 (36.6–42.7)

    51.9*

    43.8

    48.0

    41.5

    Average step length (mm)

    568 ± 44.3 (505–660)

    -

    416

    453

    433

    Average stride length (mm)

    1139 ± 94.0 (1044–1284)

    -

    829

    880

    876

    Estimated stature (cm)

    H. sapiens§

    163–186

    144–165

    113–129

    141–161

    130–149

    H. sapiens°

    171.6 ± 5.4

    160 ± 5.4

    141.4 ± 5.4

    158.2 ± 5.4

    152.2 ± 5.4

    Au. afarensis

    161–168

    142–149

    111–116

    139–145

    129–135

    Estimated body mass (kg)

    H. sapiens°

    53.6 ± 3.7

    46.7 ± 3.8

    39.3 ± 3.7

    52.6 ± 3.7

    43.2 ± 3.7

    Au. afarensis

    41.3–48.1

    36.5–42.4

    28.5–33.1

    35.6–41.4

    33.1–38.5

    Walking speed (m/s)

    0.47–0.55 (0.93)

    0.43–0.50 (1.00)

    0.36–0.42 (0.79)

    0.39–0.46 (0.88)

    Relative speed (s−1)

    0.25–0.34 (0.54)

    0.33–0.44 (0.71)

    0.23–0.30 (0.50)

    0.26–0.35 (0.58)

    • *Values overestimated because of the enlarged morphology of the only preserved track of S2. §As in Table 2. °As in Table 2. As in Table 2. For walking speed and relative speed, values outside the brackets are based on the method of Alexander (1976), those inside the brackets are based on the method of Dingwall et al. (2013). See Materials and methods for details.