ArticlePDF Available

Laetoli footprints preserve earliest direct evidence of human-like bipedal mechanics

Laetoli Footprints Preserve Earliest Direct Evidence of
Human-Like Bipedal Biomechanics
David A. Raichlen
*, Adam D. Gordon
, William E. H. Harcourt-Smith
, Adam D. Foster
, Wm. Randall
Haas, Jr.
1School of Anthropology, University of Arizona, Tucson, Arizona, United States of America, 2Department of Anthropology, University at Albany–SUNY, Albany, New York,
United States of America, 3Department of Anthropology, Lehman College, Bronx, New York, United States of America, 4Division of Vertebrate Paleontology, American
Museum of Natural History, New York, New York, United States of America
Debates over the evolution of hominin bipedalism, a defining human characteristic, revolve around whether
early bipeds walked more like humans, with energetically efficient extended hind limbs, or more like apes with flexed hind
limbs. The 3.6 million year old hominin footprints at Laetoli, Tanzania represent the earliest direct evidence of hominin
bipedalism. Determining the kinematics of Laetoli hominins will allow us to understand whether selection acted to decrease
energy costs of bipedalism by 3.6 Ma.
Methodology/Principal Findings:
Using an experimental design, we show that the Laetoli hominins walked with weight
transfer most similar to the economical extended limb bipedalism of humans. Humans walked through a sand trackway
using both extended limb bipedalism, and more flexed limb bipedalism. Footprint morphology from extended limb trials
matches weight distribution patterns found in the Laetoli footprints.
These results provide us with the earliest direct evidence of kinematically human-like bipedalism currently
known, and show that extended limb bipedalism evolved long before the appearance of the genus Homo. Since extended-
limb bipedalism is more energetically economical than ape-like bipedalism, energy expenditure was likely an important
selection pressure on hominin bipeds by 3.6 Ma.
Citation: Raichlen DA, Gordon AD, Harcourt-Smith WEH, Foster AD, Haas WR, Jr. (2010) Laetoli Footprints Preserve Earliest Direct Evidence of Human-Like Bipedal
Biomechanics. PLoS ONE 5(3): e9769. doi:10.1371/journal.pone.0009769
Editor: Karen Rosenberg, University of Delaware, United States of America
Received November 22, 2009; Accepted February 28, 2010; Published March 22, 2010
Copyright: ß2010 Raichlen et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: Funding was provided from the University of Arizona. The funders had no role in study design, data collection and analysis, decision to publish, or
preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail:
Ever since Darwin [1], bipedal walking has been considered the
defining feature of the human lineage. However, how and why this
unique form of locomotion evolved remains the subject of
considerable debate. In particular, debates over the origins and
evolution of bipedalism revolve around whether early bipeds
walked with energetically economical human-like extended limb
biomechanics, or with more costly ape-like bent-knee, bent-hip
(BKBH) kinematics [2]. If early hominins used a BKBH gait, then
we must account for the persistence of an energetically costly form
of bipedal walking until the evolution of the genus Homo. The
Laetoli footprints may help resolve this debate, since they record
the footsteps of at least two, and possibly three individuals who
walked bipedally across wet ashfall approximately 3.6 million years
ago [3,4]. These prints represent the earliest direct evidence of
bipedalism in the fossil record, yet no study to date has
demonstrated exactly how these hominins walked.
For decades, researchers have argued over whether the Laetoli
hominins walked with a modern human-like extended limb gait
[3,5–10], or a more ape-like form of bipedalism [11–14]. Most
recently, the discovery of 1.5 Ma footprints from Kenya provides
new evidence that the Laetoli prints were not completely modern
in weight transfer and morphology [15]. If true, then an
energetically costly form of bipedalism evolved and persisted in
early hominins until the evolution of the genus Homo [16].
Alternatively, if the Laetoli prints were made by extended-limb
bipeds, then, by 3.6 Ma, selection acted to reduce energy costs of
locomotion in hominins.
Most previous studies of the Laetoli prints, however, were
qualitative and did not test specific biomechanical hypotheses
about early hominin gait. Kullmer et al. [17] performed a
quantitative comparison of one Laetoli footprint (G1-36) with
three footprints made by a single human subject walking with
different postures. Their results suggest that Laetoli hominins did
not walk like modern humans, however their sample size was very
small (one human print for each posture studied) and there is not
enough kinematic information to generalize their results to the
Laetoli trackways. More recent quantitative work using geometric
morphometrics techniques [15,18] may conflate differences in foot
anatomy and shape with differences in locomotor biomechanics.
Without using experimental analyses, it is difficult to determine
which landmark differences between Laetoli and more recent fossil
footprints are due simply to differences in foot morphology, and
PLoS ONE | 1 March 2010 | Volume 5 | Issue 3 | e9769
which are, in fact, due to differences in kinematics. Thus, a
thorough experimental-based analysis of the Laetoli prints may
resolve the debate over hominin biomechanics, and therefore help
clarify the importance of selection for reduced energy costs of
locomotion prior to the evolution of the genus Homo.
Here, we present the results of the first experimental analysis of
footprints in a sample of humans walking with different gaits and
compare our results to the Laetoli prints. Eight human subjects
(mean body mass [SD] = 65.6 [6.1] kg) walked through a 5 m
trackway filled with 15 cm of fine grained sand (0.075 mm–
0.70 mm diameter). Although our subjects are likely heavier than
the earlier hominins that generated the Laetoli prints, body mass
does not appear to have an effect on footprint morphology [19].
We compared footprints made by subjects walking with a normal,
extended limb gait, and with a bent-knee, bent-hip (BKBH) ape-
like gait at their preferred speeds with sand water content of 6–8%
(see supplementary materials Text S1 for hind limb kinematic data
from these experiments). These substrate conditions match those
of Laetoli, which are described as similar to damp, fine to medium
grained sand [20]. We also examined the effects of increased speed
and increased substrate moisture (10–12% water) on footprint
morphology. We tested the hypothesis that a BKBH gait alters
body weight transfer and produces significantly different footprint
morphology than an extended limb gait. We predicted that Laetoli
footprint morphology would match humans walking with one of
these gaits. To test this prediction, we scanned each human print
using a 3D laser scanner (MicrosribeHMLX 6DOF digitizer with
attached Microscan laser sensor system), and compared the
maximum depths of the fore- (toe) and aft- (heel) sections of the
prints. These values were calculated after leveling each print, since
prints were made over a substrate that had a very small grade
(mean grade = 1.49%60.16%). We compared our experimental
data with Laetoli footprint depths calculated from contour maps of
the footprint trails [21] (Table S1). Additionally, we captured
kinematic and kinetic data to determine how walking biomechan-
ics influence footprint morphology (see supplementary materials
Text S1).
Results and Discussion
There is a significant difference in the relative depth of the toes
in BKBH compared to extended limb prints (Figs. 1 and 2;
Table 1). BKBH footprints from humans walking at preferred
speeds have toe depressions that are 76.69%68.35% lower than
the heel (calculated as toe depth as a percentage of heel depth;
Table 1). When walking with an extended hind limb at preferred
speeds, toe depressions are, on average, 22.36%64.28% below the
heel. Thus, BKBH gaits generate significantly greater toe relative
to heel depths compared to extended limb gaits. Speed influences
print morphology, with faster speeds leading to deeper toe
depressions in both gaits, however between-gait differences are
not significant (Table 1). Substrate moisture content also alters
footprint morphology (Table 1). Wetter substrates lead to greater
toe depths, regardless of gait, however, BKBH gaits have toe
depths that are significantly greater than extended limb postures
(Table 1).
The difference in print morphology is related to a fundamental
difference in body weight transfer between extended limb and
BKBH gaits. The center of pressure (COP) is the point of ground
reaction force application under the foot. As the COP travels from
the heel to the toe during stance phase, its path, and the
magnitude of ground force at any given moment, determines the
amount of substrate displacement at a given position under the
foot. During walking, as the COP shifts anterior to the metatarsal
heads, the metatarso-phalangeal joint flexes, and because of the
stiff longitudinal arch, the entire foot posterior to the metatarsal
heads lifts off the ground [22]. In a BKBH gait, the COP passes
the metatarsal heads significantly earlier in the step (i.e., closer to
heel-strike; Paired t-test p,0.001), and the ground reaction force
impulse after the COP passes the metatarsal heads is significantly
greater compared to extended limb gaits (Fig. 3; Paired t-test
p,0.001). The larger impulse when the body is supported by the
forefoot explains the increased toe-depth in BKBH footprints.
Since most researchers agree that the Laetoli prints exhibit
evidence of a longitudinal arch [5,6,8,10,23–26] (but see [13–15]
and supplementary materials Text S1; Figs. S1, S2), an analysis of
relative toe depths should provide unequivocal evidence of limb
posture in these early hominins.
The Laetoli prints have toe depths that are generally shallower
than heel depths, however, the trackways were made on a very
slight grade (3.12%60.94%; see supplementary materials Text
S1). After adjusting for this grade with the same procedures used
for the experimental footprints (see supplementary materials Text
S1 and above), mean toe depths for the G1 set of prints are
generally equal to mean heel depths (0.11%61.61% shallower
than heels [0.00 mm60.02 mm]), resembling weight transfer in a
modern human-like extended limb gait more than a BKBH gait
(Figs. 1 and 2; Supporting Table S1). In fact, while Laetoli
proportional toe depths fall within the range of normal human
patterns, Laetoli data fall outside of the range of human
proportional toe depths made during BKBH trials (Fig. 2). We
did not analyze the G2/3 set of footprints, since they were likely
made by two individuals walking one behind the other, rendering
their morphology less suitable for biomechanical determinations
[9,11,27]. There are two other caveats that must be considered in
this analysis. First, bioturbation is evident in some of the Laetoli
G1 prints [23], and could impact our results. However, much of
the bioturbation occurred on the rims of the prints and does not
greatly impact the internal morphology of most prints [23,24].
Second, the thickness of the substrate at Laetoli varies along the
print trail [28], which may have an effect on footprint depths [19].
However, the similarity of proportional depths across the G1 trail
(Table S1) suggests that differences in substrate thickness did not
impact our analysis. Finally, the Laetoli prints offer no evidence
that these individuals were walking at fast speeds, since high speed
walking also produces prints with much larger toe compared to
heel depths for both gaits (see Table 1). Therefore, we conclude
that the Laetoli hominins walked with an extended limb gait at
speeds consistent with previous predictions (i.e., preferred or slow
speeds) [8–10,26,29–32]. The relative toe depths of the Laetoli
prints show that, by 3.6 Ma, fully extended limb bipedal gait had
evolved. Thus, our results provide the earliest unequivocal
evidence of human-like bipedalism in the fossil record.
Hypotheses for the origins of bipedalism often focus on selection
for energy economy in early hominins [16,33]. Energetic
hypotheses are based on the reduced locomotor costs of humans
compared to apes walking with BKBH gaits, and therefore,
compared to ape-like pre-hominin ancestors [16]. Human walking
is inexpensive primarily because extended hind limb joints reduce
external moments acting at the joints, and therefore, reduce the
amount of muscle force required to support body weight [16,34].
In addition, extended-limb walking reduces joint reaction forces
[35] and reduces total body heat loads compared to BKBH
walking [36]. By 3.6 Ma, hominins at Laetoli, Tanzania walked
with modern human-like hind limb biomechanics, suggesting that
selection for energetically economical bipedalism occurred prior to
the evolution of the genus Homo. It is likely that reduced energy
costs associated with extended limb bipedalism allowed early
Laetoli Hominin Biomechanics
PLoS ONE | 2 March 2010 | Volume 5 | Issue 3 | e9769
hominins to increase ranging distances during times of forest
fragmentation [37] without enduring greatly increased energy
While our results show that Laetoli hominins walked with
human-like kinematics, we still cannot be sure of which hominin
taxon made the footprints. Many researchers suggest that
Australopithecus afarensis made the footprint trails [6,7,11], although
this hypothesis is disputed by others based on differences between
print morphology and fossilized foot remains [10,38]. If Au.
afarensis did make the Laetoli footprints, then our results support
the hypothesis that this species walked with relatively human-like
hip and knee extension [39,40], and that kinematically human-like
bipedalism is compatible with adaptations for arboreality found
throughout the australopith skeleton [2]. Thus, settling the dispute
over the taxonomic identification of the makers of the Laetoli
prints will clarify debates surrounding fossil hominin post-cranial
material and locomotor behavior [11,39].
Finally, although our results clearly demonstrate that human-
like bipedal kinematics had evolved by 3.6 Ma, the Laetoli prints
cannot provide detailed information regarding the locomotor
mechanics of earlier hominins. The recently published skeletal
material attributed to Ardipithecus ramidus raises the hypothesis that,
prior to 4.4 Ma, at least one lineage of hominins walked with
kinematics that differed greatly from those of modern humans and
other later hominins [41]. However, until further functional
morphological analyses are performed, it is difficult to assess the
Figure 1. Three dimensional scans of experimental footprints and a Laetoli footprint. Contours are 1 mm. A) Contour map of modern
human footprint (Subject 6) walking with a normal, extended limb gait and side view of normal, extended limb footprint. B) Contour map of modern
human footprint (Subject 6) walking with a BKBH gait and side view of BKBH print. C) Contour map of Laetoli footprint (G1-37) and side view of
Laetoli footprint (G1-37). Note the difference in heel and toe depths between modern humans walking with extended and BKBH gaits. Laetoli has
similar toe relative to heel depths as the modern human extended limb print.
Laetoli Hominin Biomechanics
PLoS ONE | 3 March 2010 | Volume 5 | Issue 3 | e9769
likely biomechanics of Ar. ramidus. Thus, based on the results of this
study, kinematically human-like bipedalism clearly evolved within
the first three to four million years of hominin evolution. However,
we are left with two possible scenarios for the origins and evolution
of bipedalism. First, if a detailed functional analysis supports the
hypothesis that Ar. ramidus was a habitual bipedal hominin that
walked with flexed lower limbs, then energetic selection pressures
likely became strongest after the origins of bipedalism, but prior to
3.6 Ma. This finding would not necessarily rule out the energy
hypothesis for the origins of bipedalism [34], but would suggest
that early bipeds were less energetically economical than modern
humans. Second, if Ar. ramidus was not a bipedal hominin, then the
earliest bipeds may have walked with extended limb joints,
suggesting that early bipedalism was as energetically economical as
that of later hominins, including those that made the Laetoli
footprints. Testing these hypotheses requires more detailed fossil
evidence from the earliest hominins. However, our analysis of the
Laetoli prints refines the timing of the evolution of human-like
bipedal mechanics in the fossil record. Future analyses of fossil
remains, and future fossil discoveries, will no doubt improve our
understanding of just how early human-like bipedal mechanics
evolved, and therefore, help us determine the importance of
selection for energy economy during the early evolution of bipedal
Eight subjects participated in this study (see Table S2). All
methods were approved by the University of Arizona Human
Subjects Committee and subjects gave their written informed
consent prior to participation.
All subjects were asked to walk at their preferred walking
speed through a sand trackway (see Table S3). After making two
passes down the walkway at their preferred speed, subjects were
asked to walk with a bent-knee, bent-hip (BKBH) gait at their
preferred speed. Subjects also repeated the BKBH trial twice.
The trackway was 15 cm deep and5mlong.Itwasfilledwith
mostly fine sand, with coarser grained sand confined to the
beginning and end of the trackway. Grain sizes ranged from
,0.074 mm to 0.7 mm in diameter. After walking at their
preferred speeds, a subset of the sample was asked to walk at a
fast speed using both gaits. A different subset of the sample was
asked to walk in both gaits at their preferred speeds after the
moisture content of the sand was increased by ,4%. Moisture
Scientific CD 620) soil moisture system. For low moisture trials,
moisture content was 6–8%. For high moisture trials, moisture
content was 10–12%. To determine moisture content, the
moisture probe was inserted into the footprint after each scan
was taken.
Prior to trackway trials, reflective markers were affixed to the
hip, knee, ankle, heel, hallux, 1
metatarsal head, and shoulder.
Subjects were filmed walking through the trackway using a six-
camera Vicon motion analysis system (200 Hz). Maximum,
minimum, and average joint angles were calculated for the hip
and knee during all trials (Table S4).
After each pass through the trackway, footprints were digitized
using a 3-dimensional laser scanner (Microscribe MLX 6DOF
digitizer with attached Micorscan laser sensor system). At least two
prints (left and right) for each trial were scanned. For each scanned
print, four points were selected from the sand around the print:
two points medial and lateral to the toes, and two points medial
and lateral to the heel. A plane representing the sand substrate was
generated based on those four points using a least-squares fit in
Microscan Tools. The 3D coordinates of the print and plane were
then imported into R where the plane and print were reoriented
such that the plane was level. Finally, the depths of the deepest
point in the heel and in the toe were extracted from the leveled
print, and proportional toe depth was calculated as a fraction of
the depth of the heel.
A second sample of subjects (n = 6) were recruited to determine
the kinetics of BKBH walking. Subjects walked over a forceplate
(AMTI; 4000 Hz) and were simultaneously filmed with a six-
camera Vicon motion analysis system (200 Hz). Prior to walking
trials, reflective markers were affixed to the hip, knee, ankle, heel,
hallux, 1
metatarsal head and shoulder. Subjects walked at
preferred speeds using normal extended limb bipedalism as well as
two BKBH trials (one with light and one with deep knee and hip
flexion; Table S5).
Center of pressure data were collected from force plate
recordings for each trial. Combing kinematic and kinetic data,
we calculated the time of heel strike (touchdown) and the time
(relative to heel strike) that the COP passed anterior to the
metatarsal heads. We also calculated the total impulse of
metatarsal heads to toe-off. These values provide a biome-
chanical measure of how toe depths are generated. For
more information on methods see supplementary materials
Text S1.
Figure 2. Toe depths as a fraction of heel depth for BKBH,
normal walking and Laetoli prints. Laetoli values were calculated
using values from topographic maps. Note that the values for Laetoli
fall within the range of human normal prints but outside of the range of
human BKBH prints.
Table 1. Proportional toe depths of human footprints.
Side Speed Moisture Normal SEM BKBH SEM p-value
Right p d 0.27 0.04 0.77 0.12 ,0.001
Left p d 0.19 0.06 0.76 0.12 ,0.001
Both p w 0.48 0.11 0.81 0.12 ,0.05
Right f d 0.98 0.33 0.51 0.12 0.12
Left f d 0.38 0.08 0.67 0.16 0.07
p is preferred walk; f is fast walk; d is dry (6–8% water); w is wet (10–12% water).
Values are toe depths as a fraction of heel depth. P-values are for T-Tests
comparing BKBH and extended (normal) datasets.
Laetoli Hominin Biomechanics
PLoS ONE | 4 March 2010 | Volume 5 | Issue 3 | e9769
Supporting Information
Text S1 Supporting Text
Found at: doi:10.1371/journal.pone.0009769.s001 (0.02 MB
Table S1 Laetoli footprint data
Found at: doi:10.1371/journal.pone.0009769.s002 (0.03 MB
Table S2 Subject information
Found at: doi:10.1371/journal.pone.0009769.s003 (0.03 MB
Table S3 Sample size information for footprint analyses
Found at: doi:10.1371/journal.pone.0009769.s004 (0.03 MB
Table S4 Speed and joint angles for trackway trials. Values are
means (SEM) for all subjects.
Found at: doi:10.1371/journal.pone.0009769.s005 (0.03 MB
Table S5 Hip and knee angles for force plate trials.
Found at: doi:10.1371/journal.pone.0009769.s006 (0.03 MB
Figure S1 Proximal pressure ridge in a normal human footprint.
Found at: doi:10.1371/journal.pone.0009769.s007 (3.70 MB TIF)
Figure S2 Contour map of a footprint from a normal extended
limb step showing lack of discernable arch (compare with Fig. 1).
Found at: doi:10.1371/journal.pone.0009769.s008 (0.61 MB TIF)
We thank William Jungers, Daniel Lieberman, and Herman Pontzer for
helpful discussions of this project. Vija Garcia, Justin Higgins, Alicia Waltz,
Stephanie Reyes, and David Zahn provided assistance during data
collection. We thank Mitchell Pavao-Zuckerman for generously providing
us with equipment to measure soil moisture content. We are grateful to
Lars Fogelin for assistance in trackway construction. We also thank all of
our subjects for their time and effort.
Author Contributions
Conceived and designed the experiments: DR ADG WEHHS. Performed
the experiments: DR ADG. Analyzed the data: DR ADG. Contributed
reagents/materials/analysis tools: ADG WEHHS AF WRHJ. Wrote the
1. Darwin C (1871) The decent of man, and selection in relation to sex. London:
John Murray (Reprinted in 1981 by Princeton University).
2. Stern J (2000) Climbing to the top: a personal memoir of Australopithecus afarensis.
Evolutionary Anthropology 9: 113–133.
3. Leakey MD, Hay RL (1979) Pliocene footprints in the Laetoli beds at Laetoli,
northern Tanzania. Nature 278: 317–323.
4. Leakey MD (1981) Tracks and tools. Philisophical Transactions of the Royal
Society of London 292: 95–102.
5. Day MH, Wickens EH (1980) Laetoli pliocene hominid footprints an d
bipedalism. Nature 286: 385–387.
6. White TD (1980) Evolutionary implications of pliocene hominid footprints.
Science 208: 175–176.
7. White TD, Suwa G (1987) Hominid footprints at Laetoli: Facts and
Interpretations. Am J Phys Anthropol 72: 485–514.
8. Tuttle R (1985) Ape footrpints and Laetoli impressions: A response to the SUNY
claims. In: Tobias P, ed. Hominid evolution: Past, present, and future. New
York: Alan R. Liss. pp 129–133.
9. Tuttle R (1987) Kinesiological inferences and evolutionary implications from
Laetoli bipedal trails G-1, G-2/3, and A. In: Leakey MD, Harris J, eds. Laetoli A
Pliocene site in northern Tanzania. Oxford UK: Clarendon Press. pp 503–523.
10. Tuttle R, Webb D, Tuttle N (1991) Laetoli footprint trails and the evolution of
hominid bipedalism. In: Coppens Y, Senut B, eds. Origine(s) de la bipedie chez
les hominides. Paris: Cahiers de Paleioanthropologie, Editions du CNRS. pp
11. Stern JT, Susman RL (1983) The locomotor anatomy of Australopithecus afarensis.
Am J Phys Anthropol 60: 279–317.
12. Deloison Y (1992) Emprientes de pas a Laetoli (Tanzanie). CR Acad Sci Paris
315: 103–109.
Figure 3. Center of pressure (COP) position and ground reaction force impulse in humans walking with different limb postures. A)
COP movement during bipedal walking. Fraction from touchdown (TD) is the mean time as a fraction of stance phase when the COP passes anterior
to the metatarsal heads (error bars are SEMs). B) Late stance impulses during bipedal walking. Values are mean for the ground reaction force impulse
after the COP passes anterior to the metatarsal heads (error bars are SEMs). Normal is extended limb walking, BKBH 1 is walking with a slightly flexed
knee and hip, BKBH 2 is walking with a deeply flexed knee and hip.
Laetoli Hominin Biomechanics
PLoS ONE | 5 March 2010 | Volume 5 | Issue 3 | e9769
13. Meldrum D (2004) Midfoot flexibility, fossil footprints, and sasquatch steps: New
perspectives on the evolution of bipedalism. Journal of Scientific Exploration 18:
14. Meldrum D (2007) Renewed perspective on the Laetoli trackways: The earliest
hominid footprints. In: Lucas, Spielman, Lockley, eds. Cenozoic vertebrate
tracks and traces: New Mexico Museum of Natural History and Science Bulletin.
15. Bennett M, Harris J, Richmond B, Brain D, Mbua E, et al. (2009) Early hominin
foot morphology based on 1.5-million-year-old footprints from Ileret, Kenya.
Science 323: 1197–1201.
16. Sockol MD, Raichlen DA, Pontzer H (2007) Chimpanzee locomotor energetics
and the origin of human bipedalism. Proceeding of the National Academy of
Science 134: 12265–12269.
17. Kullmer O, Schrenk F, Dorrhoffer B (2003) High resolution 3D-image analysis
of ape, hominid and human footprints. Courier Forsch Senkenberg 243: 85–91.
18. Berge C, Penin X, Pelle E (2006) New interpretation of Laetoli footprints using
an experimental apprach and procrustes analysis: Preliminary results. CR
Palevol 5: 561–569.
19. D’Aout K, Meert L, Van Gheluwe B, De Clercq D, Aerts P (in press)
Experimentally generated footprints in sand: Analysis and consequences for the
interpretation of fossil and forensic footprints. Am J Phys Anthropol DOI:
20. Hay RL, Leakey MD (1982) The fossil footprints of Laetoli. Sci Am 246: 50–57.
21. Leakey MD, Harris JM (1987) Laetoli, A Pliocene Site in Northern Tanzania.
Oxford: Oxford University Press.
22. Imhauser C, Siegler S, Abidi N, Frankel D (2004) The effect of posterior tibialis
tendon dysfunction on the plantar pressure characteristics and the kinematics of
the arch and hindfoot. Clinical Biomechanics 19: 161–169.
23. Feibel CS, Agnew N, Latimer B, Demas M, Marshall F, et al. (2005) The Laetoli
hominid footprints - A preliminary report on the conservation and scientific
study. Evolutionary Anthropology 4: 149–154.
24. Schmid P (2004 ) Functional interpretation of the Laetoli footprints. In:
Meldrum DJ, Hilton C, eds. From biped to strider: The emergence of modern
human walking, running, and resource transport. New York: Kluwer Academic/
Plenum Publishing. pp 49–61.
25. Tuttle RH (1996) The Laetoli hominid G footprints. Where do they stand today?
Kaupia 6: 97–102.
26. Tuttle RH, Webb D, Weidl E, Baksh M (1990) Further progress on the Laetoli
trails. Journal of Archaeological Science 17: 347–362.
27. Robbins LM (1987) Hominid footprints from site G. In: Leakey MD, Harris JM,
eds. Laetoli: A pliocene site in northern Tanzania. Oxford: Clarendon Press. pp
28. Hay RL (1987) Geology of the Laetoli area. In: Leakey MD, Harris JM, eds.
Laetoli: A pliocene site in northern Tanzania. Oxford: Oxford University Press.
pp 23–47.
29. Charteris J, Wall JC, Nottrodt JW (1982) Pliocene homind gait: New
interpretations based on available footprint data from Laetoli. Am J Phys
Anthropol 58: 133–144.
30. Alexander RM (1984) Stride lengths and speed for adults, children, and fossil
hominids. Am J Phys Anthropol 63: 23–27.
31. Sellers W, Cain G, Wang W, Crompton RH (2005) Stride length, speed and
energy costs in walking of Australopithecus afarensis: Using evolutionary robotics to
predict locomotion of early human ancestors. Journal of the Royal Society
Interface 2: 431–441.
32. Raichlen D, Pontzer H, Sockol MD (2008) The Laetoli footprints and early
hominin locomotor kinematics. J Hum Evol 54: 112–117.
33. Rodman PS, McHenry HM (1980) Bioenergetics and the origin of hominid
bipedalism. Am J Phys Anthropol 52: 103–106.
34. Pontzer H, Raichlen D, Sockol MD (2009) The metabolic cost of walking in
humans, chimpanzees and early hominins. J Hum Evol 56: 43–54.
35. Carey TS, Crompton RH (2005) The metabolic costs of ‘bent-hip, bent-knee’
walking in humans. J Hum Evol 48: 25–44.
36. Crompton RH, Li Y, Wang W, Gunther M, Savage R (1998) The mechanical
effectiveness of erect and ‘bent-knee, bent-hip’ bipedal walking in Australopithecus
afarensis. J Hum Evol 35: 55–74.
37. Cerling T, Harris JM, MacFadden B (1997) Global vegetation change through
the Miocene/Pliocene boundart. Nature 389: 153–158.
38. Harcourt-Smith WEH (2005) Did Australopithecus afarensis make the Laetoli
footprint trail? New insights into an old problem. American Journal of Physical
Anthropology Supplement S40: 116.
39. Latimer B, Lovejoy CO (1989) The calcaneus of Australopithecus afarensis and its
implications for the evolution of bipedality. Am J Phys Anthropol 78: 369–386.
40. Ward CV (2002) Interpreting the posture and locomotion of Australopithecus
afarensis: Where do we stand? Yearbook of Physical Anthropology 45: 185–215.
41. Lovejoy CO, Suwa G, Spurlock L, Asfaw B, White TD (2009) The pelvis and
femur of Ardipithecus ramidus: The emergence of upright walking. Science 326:
Laetoli Hominin Biomechanics
PLoS ONE | 6 March 2010 | Volume 5 | Issue 3 | e9769
... Therefore, they offer hope for understanding the mechanics of Pliocene hominin locomotion and whether a human-like bipedal gait may have emerged by 3.66 Ma. However, past analyses of the Laetoli tracks have also reached conflicting conclusions [6,[9][10][11][12][13][14][15][16][17]. Some of these disagreements stem from differences in qualitative interpretations [6,9,10,12,16], yet differing results have also been obtained from quantitative approaches [11,13 -15,17]. ...
... Some of these disagreements stem from differences in qualitative interpretations [6,9,10,12,16], yet differing results have also been obtained from quantitative approaches [11,13 -15,17]. It is notable that most previous quantitative analyses of the Laetoli footprints have entirely lacked data on chimpanzee footprints (or the footprints of any other non-human ape) and thus they have lacked direct evidence to support arguments that the Laetoli tracks could [13] or could not [11,14,15] reflect a bipedal gait that in some ways resembled that of modern African great apes. A study by Kullmer et al. [17] compared a single Laetoli hominin foot- print with three modern human tracks and one Gorilla gorilla footprint, and they found that the Laetoli track was distinct from the one formed during normal human bipedal walking and also from the track that the gorilla formed when walking bipedally. ...
... Even more important than the absence of relevant comparative footprint samples though has been the limited knowledge of how specific biomechanical vari- ables are expressed in, and can be inferred from, footprint morphologies. One previous analysis [14] used biomechani- cal experiments that focused on how one biomechanical variable-lower limb flexion-influences footprint shape. This was accomplished by having humans make tracks under two conditions-when walking normally and when walking with flexed hips and knees. ...
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 homi-nin 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.
... Extant great apes are often used as models to help reconstruct the origin and evolution of bipedality, and to help interpret the variable hindlimb morphology that is preserved in the hominin fossil record. The morphology of the knee in particular has played a central role in palaeoanthropological studies about the form of bipedality our ancestors adopted (Stern & Susman, 1983;Susman, Stern & Jungers, 1984;Crompton et al., 1998;Carey & Crompton, 2005;Lovejoy & McCollum, 2010;Raichlen et al., 2010). Some researchers propose that early hominins, such as australopiths, used bent-hip, bent-knee locomotion, similar to African ape bipedal locomotion (Stern & Susman, 1983;Susman, Stern & Jungers, 1984), while others propose extended-hip and knee locomotion, similar to that of modern humans (Carey & Crompton, 2005;Lovejoy & McCollum, 2010;Raichlen et al., 2010). ...
... The morphology of the knee in particular has played a central role in palaeoanthropological studies about the form of bipedality our ancestors adopted (Stern & Susman, 1983;Susman, Stern & Jungers, 1984;Crompton et al., 1998;Carey & Crompton, 2005;Lovejoy & McCollum, 2010;Raichlen et al., 2010). Some researchers propose that early hominins, such as australopiths, used bent-hip, bent-knee locomotion, similar to African ape bipedal locomotion (Stern & Susman, 1983;Susman, Stern & Jungers, 1984), while others propose extended-hip and knee locomotion, similar to that of modern humans (Carey & Crompton, 2005;Lovejoy & McCollum, 2010;Raichlen et al., 2010). Studying the morphology of the knee joint and its links to locomotion in extant apes can help reconstruct how early hominins (e.g. ...
Full-text available
Background In addition to external bone shape and cortical bone thickness and distribution, the distribution and orientation of internal trabecular bone across individuals and species has yielded important functional information on how bone adapts in response to load. In particular, trabecular bone analysis has played a key role in studies of human and nonhuman primate locomotion and has shown that species with different locomotor repertoires display distinct trabecular architecture in various regions of the skeleton. In this study, we analyse trabecular structure throughout the distal femur of extant hominoids and test for differences due to locomotor loading regime. Methods Micro-computed tomography scans of Homo sapiens ( n = 11), Pan troglodytes ( n = 18), Gorilla gorilla ( n = 14) and Pongo sp. ( n = 7) were used to investigate trabecular structure throughout the distal epiphysis of the femur. We predicted that bone volume fraction (BV/TV) in the medial and lateral condyles in Homo would be distally concentrated and more anisotropic due to a habitual extended knee posture at the point of peak ground reaction force during bipedal locomotion, whereas great apes would show more posteriorly concentrated BV/TV and greater isotropy due to a flexed knee posture and more variable hindlimb use during locomotion. Results Results indicate some significant differences between taxa, with the most prominent being higher BV/TV in the posterosuperior region of the condyles in Pan and higher BV/TV and anisotropy in the posteroinferior region in Homo . Furthermore, trabecular number, spacing and thickness differ significantly, mainly separating Gorilla from the other apes. Discussion The trabecular architecture of the distal femur holds a functional signal linked to habitual behaviour; however, there was more similarity across taxa and greater intraspecific variability than expected. Specifically, there was a large degree of overlap in trabecular structure across the sample, and Homo was not as distinct as predicted. Nonetheless, this study offers a comparative sample of trabecular structure in the hominoid distal femur and can contribute to future studies of locomotion in extinct taxa.
... In the image, three-dimensional scans of the Laetoli hominid footprints, compared to modern human footprints. source:Raichlen et al. (2010) : coutline of a modern human footprint with bent knees and hip C: outline of Laetoli footprint G1 ...
Human communities have settled very diverse geographical and climatic environments on a more or less permanent basis. Much of the archaeological evidence left by humans shows the strategies they adopted in terms of mobility, the structure of exchange networks, and the evidence of their inhabiting an environment that they quickly learned to manage and appropriate. This article provides an overall assessment of the archaeological reality and analytical potential of this record. It is based on cases of recent prehistory and evidence of mobility and nomadism, both from a global perspective and by using specific examples from the Near East.
... The oldest direct evidence of a leather moccasin-type shoe was found in the cave of Areni-1 (Armenia) and dates only to the Chalcolithic (3627-3377 cal BC) 8 . This question is rarely discussed in ichnology, probably because the great majority of recent studies are focused on barefoot tracks at Pleistocene African and European open-air sites [9][10][11][12][13][14][15][16][17][18][19][20] . Palaeolithic caves have also long been studied from this perspective due to the presence of barefoot prints in several of them [21][22][23][24][25][26][27][28] (SI Table S1). ...
Full-text available
Humans appear to have regularly worn footwear since at least the Early Upper Palaeolithic. However, due to the perishable nature of footwear, the archaeological record of its presence during the Pleistocene is poor. While footwear would have played an essential role in protecting the foot, it could also have been used as ornamentation and/or as a social marker. Footprints may provide the most relevant insight regarding the origin and function of footwear. Here we report the discovery of footprints in Cussac Cave (southwest France) at 28–31 ka cal BP and the results of a multi-focal approach, including experimentation, that demonstrate that Gravettian people most likely wore footwear while moving through the cave. These singular footprints would constitute one of the oldest cases of indirect evidence for this unusual practice in decorated Palaeolithic caves and reinforce the exceptional nature of Cussac already attested by the presence of monumental engravings and funerary deposits.
... Some studies show that neither the foot structure of Homo habilis (Robinson 1965) nor fossil footprints have signs of flat foot (Bennett et al. 2009;Raichlen et al. 2010;Crompton et al. 2012). However, it was reported that Homo naledi's foot arch was a flat one (Berger et al. 2015;Dirks et al. 2017). ...
The collection of 1550 Homo naledi fossil remains includes six tarsal and five metatarsal bones from the right foot, forming a nearly complete humanlike flat foot arch. The missing right medial cuneiform, however, raises our interest to explore the true structure of Homo naledi's foot arch. We hypothesize that Homo naledi does not have flat foot. To verify our hypothesis, the left medial cuneiform of Homo naledi was mirrored using three-dimensional reconstruction and virtual model analysis. Then, we defined quantities of Euler, standardized the body coordinate system of foot bone and developed a new foot arch reconstruction method based on discrete bones. The reconstructed transverse foot arch corroborated our hypothesis, thus providing biomechanical evidence for interpreting the evolution of human locomotion and bringing novel ideas to the research of the biomechanical mechanism of ankle stability.
... Such a morphological condition would also be incompatible with the 3.6 Ma Au. afarensis set of hominin footprints at Laetoli, Tanzania, which are markedly human-like (e.g. Raichlen et al., 2010). Although the consensus view remains that the prints were made by that taxon (e.g. ...
Bipedalism is a defining trait of hominins, as all members of the clade are argued to possess at least some characters indicative of this unusual form of locomotion. Traditionally the evolution of bipedalism has been treated in a somewhat linear way. This has been challenged in the last decade or so, and in this paper I consider this view in light of the considerable new fossil hominin discoveries of the last few years. It is now apparent that there was even more locomotor diversity and experimentation across hominins than previously thought, and with the discovery of taxa such as H. floresiensis and H. naledi, that diversity continues well into the genus Homo. Based on these findings,we need to reevaluate how we define members of the genus Homo, at least when considering postcranial morphology, and accept that the evolution of hominin bipedalism was a complex and messy affair. It is within that context that the modern human form of bipedal locomotion emerged.
... The pitfalls that exist when trying to address experiential or sensory ele ments in the deep past are clearly evident in the context of Laetoli in Tanzania. c o p y r i g h t e d m a t e r i a l Discovered in 1976, the footprints left by three early humans as they walked away from the Sadiman volcano over 3.5 million years ago continue to provide impor tant data regarding hominid morphology and bipedalism (e.g., Raichlen et al. 2010). While a general search on the Internet for Laetoli produces many in situ pho tographs or casts of the footprints, at the time of this writing roughly half of the images retrieved were artists' renditions of the early humans walking through volcanic ash during the eruption. ...
Full-text available
In this chapter I use Michel Serres’s The Five Senses and The Natural Contract as conduits through which to enter a discussion of the role of bodily experience in scientific interpretation and the framing of natural phenomena as a form of “violence.” I consider bodily perception and its relation to the phenomena of radically changing environments, for which I use the volcano in eruption as an exemplar. In so doing, I purposefully conflate the categories of “cultural” and “natural” forms of violence. Nature and culture are messily combined and not viewable as easily separated entities; through perception, a humanized or cultured nature exists. Drawing on Hegel’s views of the roles of art and science and Kant’s framing of the volcano as a perceptual object, I propose that violently changing environments are in many ways supersensible: They lie beyond what we are able to mentally grasp through our senses and reason. We can only attempt to understand them based on our prior experience and knowledge. How we interpret the material and immaterial correlates of others’ human experience is entirely dependent on our own sensoria, or sum of perceptions, which provide a map of the objective world. It is, I propose, incumbent on archaeologists to attempt to evaluate sensory correlates of human experience, despite the difficulty of the endeavor, in order to provide more complete and more accurate conceptions of the past. © 2013 by the Board of Trustees, Southern Illinois University. All rights reserved.
What can, and perhaps more importantly cannot, be inferred from a series of human tracks? In this chapter we explore this question by first looking at the relationships that exist between various foot dimensions and such things as stature and body mass. We explore the population specific nature of these empirical relationships and demonstrate their limitations with respect to the interpretation of tracks in the geological record. In the latter part of the chapter we explore what can deduced about the speed of a track-maker and the way in which variations in that speed may be reflected in the topology of the tracks themselves.
Human footprints provide some of the most emotive and tangible evidence of our ancestors. They provide evidence of stature, presence, behaviour and in the case of early hominin footprints, evidence with respect to the evolution of human gait and foot anatomy. While human footprint sites are rare in the geological record the number of sites around the World has increased in recent years, along with the analytical tools available for their study. The aim of this book is to provide a definitive review of these recent developments with specific reference to the increased availability of three-dimensional digital elevation models of human tracks at many key sites. The book is divided into eight chapters. Following an introduction the second chapter reviews modern field methods in human ichnology focusing on the development of new analytical tools. The third chapter then reviews the major footprint sites around the World including details on several unpublished examples. Chapters then follow on the role of geology in the formation and preservation of tracks, on the inferences that can be made from human tracks and the final chapter explores the application of this work to forensic science. Audience: This volume will be of interest to researchers and students across a wide range of disciplines - sedimentology, archaeology, forensics and palaeoanthropology.
We introduce a morphometric method, based on high resolution 3D-topometry, for the purpose of quantifying and comparing footprints. Prints of modern Homo sapiens, Gorilla gorilla and early hominid feet from Laetoli (Tanzania) are measured. The pattern of impression depth and the calculation of actual surface area in defined zones supplies information about pressure distribution and shape of the foot sole.
The chimpanzee foot is flexible near its middle, it can bend about the axis of the transverse tarsal joint, whereas the human foot is a comparatively rigid arched platform. Flexion at the transverse tarsal joint—the ''midtarsal break''—uncouples the functions of a grasping, or prehensile, forefoot and a propulsive hindfoot during grasp-climbing on vertical or inclined supports. At some point after the transition to habitual bipedalism, these grasp-climbing adaptations were compromised by the evolution of the longitudinal arch, which permits increased mechanical advantage of the flexors of the ankle and im- proved endurance for long-distance walking and running. Ape, human, and Plio-Pleistocene hominid footprints were examined for the effects of a midtarsal break. The human footprint reflects arched-foot architecture, combined with a stiff-legged striding gait. Pressure releases occur at particular locations behind the ball and the great toe, or hallux. Early (ca. 3.5 million years ago) hominid footprints from the Laetoli excavation confirm midfoot flexibility, including repeated suggestion of an associated pressure ridge. The Terra Amata footprint (ca. 400,000 years ago), yet to be fully pub- lished, exhibits evidence of midfoot flexibility. Several footprints attributed to an alleged North American ape, commonly known as sasquatch, exhibit a distinctive midtarsal pressure ridge and other indications of midfoot flexibility. In the Patterson-Gimlin film, the feet of the film subject correlate with the kinematics inferred from the footprints, in that a midtarsal break is present. Additional independent examples corroborate the consistent presence of this feature, including examples of half-tracks that record contact beneath the foot only anterior to the midtarsus. These data provide a fresh perspective from which to consider the pattern and timing of the emer- gence of the distinctive features of modern human bipedalism and bear on the credibility of the possible existence of sasquatch. The observed and inferred sas- quatch locomotor anatomy parallels the stable adaptations that marked the greater span of early hominid bipedalism.
Animal tracks and hominid footprints have been discovered in the Laetolil Beds of Tanzania. The volcanic-ash deposits were formed between 3.5 and 3.8 million years ago by the eruption of the volcano sadiman. The Laetolil Beds are north of Lake Eyasi and southeast of Lake Victoria. Early hominid remains have been found near the area. The footprint tuff lies near the top of the fossil-bearing strata. Thousands of animal tracks have been discovered in the ash deposits. The savanna supported an abundant and diverse animal population. The ash buried animal bones, teeth, eggs and dung. Fossilized twigs, shrubs, thorns and leaves provide information on the plants of the savanna. The hominid tracks are proof that they walked fully upright. No stone tools have been found in the Laetolil Beds.-F.McElhoe Jr