Javanese Homo erectus on the move in SE Asia circa 1.8 Ma

Abstract

The migration of Homo erectus in Southeast Asia during Early Pleistocene is cardinal to our comprehension of the evolution of the genus Homo. However, the limited consideration of the rapidly changing physical environment, together with controversial datings of hominin bearing sites, make it challenging to secure the robust timeline needed to unveil the behavior of early humans. Here, we reappraise the first appearance datum of Javanese H. erectus by adding the most reliable age constraints based on cosmogenic nuclides 10Be and 26Al produced in situ to a compilation of earlier estimates. We find that H. erectus reached Java and dwelled at Sangiran, Java, ca. 1.8 Ma. Using this age as a baseline, we develop a probabilistic approach to reconstruct their dispersal routes, coupling ecological movement simulations to landscape evolution models forced by reconstructed geodynamic and climatic histories. We demonstrate that the hospitable terra firma conditions of Sundaland facilitated the prior dispersal of hominins to the edge of Java, where they conversely could not settle until the Javanese archipelago emerged from the sea and connected to Sundaland. The dispersal of H. erectus across Sundaland occurred over at least tens to hundreds kyr, a time scale over which changes in their physical environment, whether climatic or physiographic, may have become primary forcings on their behavior. Our comprehensive reconstruction method to unravel the peopling timeline of SE Asia provides a novel framework to evaluate the evolution of early humans.

Full text

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Javanese Homo erectus
on the move in SE Asia circa 1.8 Ma
Laurent Husson1*, Tristan Salles2, Anne‑Elisabeth Lebatard3, Swann Zerathe1,
Régis Braucher3, Sofwan Noerwidi4, Sonny Aribowo1,5, Claire Mallard2, Julien Carcaillet1,
Danny H. Natawidjaja5, Didier Bourlès3 & ASTER team3*
The migration of Homo erectus in Southeast Asia during Early Pleistocene is cardinal to our
comprehension of the evolution of the genus Homo. However, the limited consideration of the rapidly
changing physical environment, together with controversial datings of hominin bearing sites, make
it challenging to secure the robust timeline needed to unveil the behavior of early humans. Here,
we reappraise the rst appearance datum of Javanese H. erectus by adding the most reliable age
constraints based on cosmogenic nuclides
10
Be and
26
Al produced in situ to a compilation of earlier
estimates. We nd that H. erectus reached Java and dwelled at Sangiran, Java, ca. 1.8 Ma. Using this
age as a baseline, we develop a probabilistic approach to reconstruct their dispersal routes, coupling
ecological movement simulations to landscape evolution models forced by reconstructed geodynamic
and climatic histories. We demonstrate that the hospitable terra rma conditions of Sundaland
facilitated the prior dispersal of hominins to the edge of Java, where they conversely could not settle
until the Javanese archipelago emerged from the sea and connected to Sundaland. The dispersal of H.
erectus across Sundaland occurred over at least tens to hundreds kyr, a time scale over which changes
in their physical environment, whether climatic or physiographic, may have become primary forcings
on their behavior. Our comprehensive reconstruction method to unravel the peopling timeline of SE
Asia provides a novel framework to evaluate the evolution of early humans.
When and how did Homo erectus disperse in SE Asia? e rst part of the question, when, has received great
attention since the early 20
th
century discovery of fossil remains in Java1,2. e second part, however, has mostly
been overlooked even though understanding how H. erectus dispersed holds clues not only on the climatic3,
ecological4, geological5, or physiographic6,7 environment suitable for the dispersal of hominins, but also on some
of the physical and behavioral characteristics of early humans. is question is all the more relevant given the
singular place that Javanese H. erectus occupy, not only as a historical landmark1, but also owing to their cardinal
position at the southeastern end of the realm of Early Pleistocene hominins. Here, we jointly tackle both parts of
the question: rst, we reappraise the age at which H. erectus colonized the region and second, we evaluate their
migration pathways using paleo-environmental and ecological modeling techniques.
In the very dynamic landscapes of Java and Sundaland (Fig.1), constantly reshaped by the joint action of
geodynamics and climate during the Quaternary7,8, a precise knowledge of the chronological framework is
requisite to reconstruct the physical environment. We therefore directly dated the earliest arrival of H. erectus
in Java, which denes the baseline that we then use to assess the past physiography and dispersal routes from
mainland Asia to Java. Javanese site Sangiran (Fig.1) is pivotal in that respect because it yields the largest number
of hominin nds, and also because it counts amongst the earliest H. erectus bearing sites in SE Asia. Recon-
structing the pathways and drivers of hominin dispersal across Eurasia oen relies on the purported age of rst
appearance of H. erectus in Sangiran9,10, which was commonly bracketed between 1.5 Ma and 1.7 Ma based on
40
Ar/
39
Ar and paleomagnetic dating11–14. However, a recent study opposed a younger age of
∼
1.3 Ma, based on
U-Pb radiometric dating and zircon ssion tracks15.
Dating in Java is notoriously dicult owing to the scarcity of datable material in the volcano-clastic sedi-
ments that would unambiguously determine the age of arrival of H. erectus with an unbiased method, but also
because of the geological setting of the Sangiran dome (Fig.1c). Despite its tectonic deformation providing good
OPEN
1ISTerre, CNRS, IRD, Univ. Grenoble Alpes, 38000 Grenoble, France. 2School of Geosciences, The University of
Sydney, Sydney, NSW 2006, Australia. 3CEREGE, Aix-Marseille Université CNRS-IRD-Collège de France-INRAE,
Technopôle de l’Environnement Arbois-Méditerrannée, 13545 Aix-en-Provence, France. 4Research Center for
Archaeometry, National Research and Innovation Agency (BRIN), Jakarta, Indonesia. 5Research Center for
Geological Disasters, National Research and Innovation Agency (BRIN), Bandung, Indonesia. *A list of authors and
their aliations appears at the end of the paper. *email: laurent.husson@univ-grenoble-alpes.fr
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exposure of fossiliferous layers, sedimentary deposits are oen inconveniently reworked. Yet, within the avail-
able dataset, only the latest dating15 is in fact dicult to reconcile with the others. While the large uncertainties
and the overdispersion of the data revealed by the mean square weighted deviation (Fig.3 in15) may explain this
outlier, their study indisputably revives the controversy. In addition, most previous dating methods suer from
large uncertainties arising from the poor constraints on the pre-burial history. Instead, Terrestrial Cosmogenic
Nuclide dating (TCN) is, to our knowledge, the only available method to focus on the burial time and thus to
minimize uncertainties associated to the pre-burial history. For that reason, this technique is increasingly applied
in archaeology and paleoanthropology, and sheds new lights on hominin dispersal16–21. Here, we date the rst
appearance of Javanese H. erectus using TCN relying on the concentration of two in-situ produced cosmogenic
nuclides (
10
Be and
26
Al) in quartz grains from the sedimentary layers of interest. ese isotopes accumulate in
the grains when they are exposed to cosmic radiations during exhumation and transport phases, and conversely
decay when the grains are shielded during burial periods. e burial duration in terrigenous sediments, and
exhumation history until sampling, is thus encoded in the sediments by the amount of each isotope they contain.
A rened knowledge of this time period is crucial to decipher the dispersal and behavior of Javanese H. erectus
for at least two reasons. First, depending on this age, it is unclear if Javanese H. erectus directly arrived along the
coastlines in a single out-of-Africa episode, or discontinuously stemmed from smaller size groups that expanded
earlier in China25,26; it implies that early humans could have entered Sundaland from dierent points in mainland
Asia (Fig.1a). Second, the subsequent trajectories of Javanese H. erectus across Sundaland were conditioned by
the extremely transient paleoenvironmental conditions. While it is at present-day largely ooded, Sundaland was
permanently continental during Early Pleistocene6; conversely, while Sundaland was slowly drowning, Java was
an upliing chain of volcanoes emerging from a shallow sea. e settlement of terrestrial faunas and hominins in
Java occurs soon aer the transition from marine to more terrestrial environments2,4,11,13,27,28. Within this broad
geographical framework, the direction and pace of movements of H. erectus were driven by the contingencies of
the local physical environment at the time of their migration, as dened by the river network, relief, and vegeta-
tion cover of Sundaland and Java.
To quantitatively unravel their migration pathways across this complex environment, we build upon two
recent advances in paleo-environmental and ecological modeling techniques. First, we reconstruct past physiog-
raphies over geological time, accounting for the joint eects of geodynamic deformations and climatic forcings,
by applying a Landscape Evolution Model (LEM). Concurrently, an array of mechanistic models have emerged
from conservationist studies29–31 to simulate contemporary species displacements across a given landscape, based
on a series of morphometric biases that prompt or hinder the motion of species,like relief and drainage, but also
climate or vegetation cover. Here, we reconstruct the past physiography using the LEM goSPL32 that simulates the
joint eects of erosion, sediment transport and deposition on the relief and drainage network with an adequate
resolution (
∼
500 m) to address biogeographical purposes7. e modelled landscape is sculpted at the time of
hominin migration by the interplay between geodynamics -which deforms the surface of the Sunda shelf6,7,33-
and climate evolution34 -which sets the amount of precipitation. e reconstructed landscape then denes the
environmental conditions for the mechanistic model of ecological displacement SiMRiv30, in which the random
trajectories of species are conditioned by landscape complexity, perceptual range, and partial memory of past
displacement (semi-correlated Lévy-ight)30. Applying this approach to the longterm dispersal of H. erectus
across Sundaland, we opt for a probabilistic assessment of a large set of simulations (3000 realizations with 5
Figure1. Geology of Sangiran. (a) Regional view. Black line delinates continental Sundaland (120 m isodepth).
Stars indicate possible northern entry points (thereaer set to Myanmar, ailand and Vietnam) for H. erectus.
(b) Java island and main biostratigraphic sites (hominin-bearing sites: Sangiran (s), Mojokerto (m), Trinil
(t), Ngandong (n); and faunal site Bumiayu (b). (c) 3D view of the Sangiran dome. Geological map redrawn
from15,22. Red star locates Bukuran creek outcrop; skull is Sangiran-1723. Maps on panels (a,b) were created using
GMT 5 (www. gener ic- mappi ng- tools. org)24; on panel (c). using ArcGIS (www. arcgis. com).
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millions iterations each), which we use to evaluate the travel distances and times, and the likelihood of the pres-
ence of hominins at any given location within the region. For reference, we additionally compute the least-cost
path end-member solution (upon the incongruous hypothesis that hominins had a destination and a roadmap).
Results
Dating Sangiran. We dated the earliest episode of continentalization of the Sangiran Dome (Fig.2a) in Java
island, that was colonized by hominins shortly aer13. e general lithostratigraphy spans more than 2 Ma36.
e marine Puren fm. forms the earliest layers. It is overlain by the Sangiran fm., wherein the earliest terrestrial
faunas are found in the Lower Lahar unit2. Hominin fossils appear in the uppermost part of the Sangiran fm.
where shallow marine environments gradually give space to more terrestrial settings. e conglomerates of the
Grenzbank unit, at the base of the Bapang fm. mark the onset of more permanent and hospitable conditions. e
overlying Bapang fm., predominantly uviatile, hosts the vast majority of H. erectus nds until the Upper Tu
unit. It is unconformably overlain by the Pohjajar fm., and ultimately by recent alluvium from the Solo river; to
date, no hominin fossil has been retrieved from these uppermost formations. Following their deposition, the
Bapang and Pohjajar formations have been eroded during the deformation of the Sangiran dome, exposing the
deeper fossil-bearing formations. In order to most comprehensively evaluate the chronology of the events, we
benet from available ages for the entire stratigraphic series that we complement by TCN dating of the critical
Grenzbank unit.
Samples were extracted in the Bukuran creek in the SE of the Sangiran dome (Fig.1c), less than 30 m north
of the nd spot of a maxilla27, at the exact location of a section that was previously dated with discordant ages
at
∼
1.5 Ma11 and
∼
0.9 Ma15. e local stratigraphy (Fig.2b,c) has been documented in great details15,27, and
corresponds to the base of the Bapang fm., the basal conglomerate being the Grenzbank unit, and the dark clay
the uppermost unit of Sangiran fm.
10
Be and
26
Al concentrations and ratios do not show signicant depth dependence (Fig.2d,e), while an
exponential depth decrease of cosmogenic isotope concentration could instead be expected a priori due to the
depth attenuation of the incoming cosmic ray particles (Methods). is uniformity results from the long-lasting
denudation of the
∼
100 m thick layers of the Bapang and Pohjajar formations: is episode, which necessarily
postdates the deposition of Pohjajar fm. at 0.15 to 0.25 Ma36, corresponds to mean denudation rates of 400 to 600
m/Ma. As it proceeds, this sustained yet recent exhumation advects and constantly trims the uppermost,
10
Be
and
26
Al enriched layers while they accumulate cosmogenic isotopes. Radioactive decay is modulated by post-
burial production during the nal stage of exhumation, which then has to be accounted for18,20. Inverting
10
Be
Figure2. Bukuran sampling site, stratigraphic setting, and analytical results. (a) General lithostratigraphy
of the Sangiran Dome15,22,35, depositional environment, and available datings
†
. Blue bars indicate proven
occurrence of H. erectus fossils remains, skull is Sangiran-1723. (b) Stratigraphic log of the sampling site. (c)
Sampling site, lithologies, and sample location (labeled by their sample name sux: 1 is SAN18-1). e Bukuran
stream ows at the bottom of the outcrop. (d,e):
10
Be and
26
Al concentrations and
26
Al/
10
Be ratios over depth.
Red and blue dots are
26
Al and
10
Be concentrations (S.I. Table1). L. Lahar: Lower Lahar; U. Tu: Upper Tu; al.:
alluvium; Gb.: Grenzbank unit.
†
Earlier datings: H11, paleomag35. L01,
40
Ar/
39
Ar11 ; M20a, U-Pb and ZFT15;
M20b, U-Pb15; M20c, U-Pb and ZFT15; S94,
40
Ar/
39
Ar12; S00,
40
Ar/
39
Ar, paleomag.13; B04,
40
Ar/
39
Ar14.
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and
26
Al concentrations yields a mean burial age of 1.78±0.20 Ma, pre-burial denudation rates ranging from 21
to 80 m/Ma, and post-deposition denudation rates from 334 to 608 m/Ma (Methods). ese mean denudation
rates are consistent with geological estimates of erosion rates following the deposition of the Pohjajar fm., and the
tenfold increase of pre-burial to post-burial rates is consistent with the respective lithologies of the source rocks
(volcanic rocks) and of the unconsolidated Pleistocene sediments. For reference, we also computed the minimal
burial age, given by the end-member case considering the (quasi-)instantaneous removal of tens of meters of
sediments over the outcrop, while ignoring the longer term erosion of the Bapang and Pohjajar formations. In
that case, only the time span since deposition sets the present-day ratios; this hypothesis yields a minimum
weighted mean burial duration of 1.45±0.10 Ma (Methods).
is TCN age (1.78±0.35 Ma) of the Grenzbank unit arguably belongs to the older end of the range of earlier
estimates (Fig.2a). e dated unit is bracketed by layers of compatible ages, from the base of the Sangiran fm. (
40
Ar/
39
Ar and paleomagnetic ages of
∼
1.914 and
∼
1.7 Ma12,13) and from its core (U-Pb ages of
∼
1.7 Ma15), to the
Upper Tu unit in the upper part of the Bapang fm. (paleomagnetic ages,
∼
0.8 Ma35). Although the new TCN
dating advocates for an older age, it remains compatible, within uncertainty, with the commonly used
∼
1.5 Ma
40
Ar/
39
Ar age obtained at the same site and stratigraphic position at the base of the Bapang fm.11. Conversely,
this TCN age contradicts recently estimated ages of
∼
0.9 to 1.0 Ma for the bottom part of the Bapang fm. and
Grenzbank unit (U-Pb and ZFT15) and earlier reported age estimates for the Bapang fm. of
∼
0.8 from the northern
Sangiran Ngebung site37. Besides these outliers, the overall contemporaneity of most ages below the lower Bapang
fm. can be explained by the rapid sedimentation in the shallow marine to swampy environments of the Sangiran
fm., which likely laid the sedimentary pile in less than 100 kyr. ese layers thus only represent a snapshot in the
history of Javanese H. erectus, for which the oldest age provides a conservative estimate of the rst appearance
datum, ca. 1.8 Ma. Conversely during the deposition of the more lacustrine and uviatile Bapang fm., which
may span up to 1 Ma until the last appearance of H. erectus in Sangiran ca. 0.78 Ma35, sedimentation rates are
much lower. It implies that, as a simple eect of sedimentation rates, hominin remains could be more diluted in
the fast sedimenting Sangiran fm. (likely above 1 mm/a) than in the slow-sedimenting Bapang fm. (possibly as
low as
∼
0.05 mm/a), consistent with the distribution and frequency of remains in these in the two formations.
More generally, the highly variable sedimentation rates of the available archive might bias the interpretation of
the taphonomic, paleo-anthropological, paleo-environmental and paleo-ecological conditions at the time of
rst appearance of H. erectus.
Peopling Sundaland to Java. e slow drowning of the shallow Sunda shelf implies that the entire Sun-
daland was subaerial during most of the Pleistocene6. In order to reconstruct the landscape at the time when
H. erectus reached Java, we compiled and interpolated estimates of upli and subsidence rates7,33 over the entire
region (Methods). e backward integration of these rates over time allows to restore the paleo-elevation of
Sundaland at large spatial scales. In addition, in order to comprehensively retrodict the physiography at the local
scale and determine the migratory behavior of H. erectus, we model the surface processes overprint on this long-
wavelength relief using LEM goSPL32. We performed these reconstructions opting for a baseline age of 1.8 Ma,
which, based on the TCN age and existing earlier dating, is most representative of the period of dispersal, but
uncertainties in the ages and vertical land motions of course propagate into our physiographic reconstructions.
ese reconstructions primarily show that Sundaland was permanently continental ca. 1.8 Ma (Fig.3a),
regardless of glacio-eustatic sea level oscillations, while tectonic upli in the Indonesian arc completed the land
bridge from mainland Asia to the emerging relief of the Javanese archipelago. e elevation gently decreased
from more than 1000 m in the East towards the lowlands of what can be referred to as the “Mekong isthmus”
that separated the internally drained ailand sea (now Gulf of ailand) from the South China Sea to the
North, and towards the marginal seas and alluvial plains that border the inner margins of Sumatra and Java to
the Southwest. e drainage network nely dissected the surface of the continent, with a set of major rivers,
radially diverging from the core of Sundaland outwards, that incised the shelf; in the South in particular, N-S
trending rivers profoundly imprinted the landscape (Fig.3a and S.I. Fig.1B). Because of their sizes (the largest
computed discharge compares to that of the present-day Yangtze), these rivers might have acted as barrier to
migration and could have channelized terrestrial faunas and early humans38 towards the shallow marginal seas
that separated the shelf from the emerging landmasses of Java, where marine conditions prevailed until Early
Pleistocene (Fig.3). e protracted subsidence of Sundaland, stimulated by the slow deformation of the Earth
interior33 changed the landscape during mid-Pleistocene7. Lowlands gradually invaded most of the shelf, with
only a limited set of rivers draining towards the South China, Flores, and Andaman seas, followed by ever more
pervasive marine incursions over the latest interglacial stages.
Once the land bridges connecting Java to South Sundaland were opened during Early Pleistocene, H. erectus
reached Java, neither as seafarers nor islanders, but as continental walkers. e stratigraphic record in Java ubiq-
uitously indicates that terrestrial faunas and H. erectus dwelled as soon as the environment became continental
enough to support them13. Emersion was triggered by Plio-Pleistocene tectonic shortening and upli. It started
in East-Central Java -near Sangiran- and gradually propagated westward39,40 and northward, suggesting that
the Sangiran dome emerged and hosted hominins and terrestrial faunas earlier than the northern and western
counterparts, for instance near the more recently occupied site of Trinil41,42 (Fig.1b).
In order to develop a quantitative approach of the peopling of Sundaland and Java, we converted this con-
trasted physiography into a cost map of landscape complexity, that quanties the resistance of the physiography
to the displacement of species, integrating the eects of slope, distance to water bodies (rivers and shores), and
river size (Methods). Both least-cost paths and random (Markovian) walks eventually lead hominins from
mainland Asia to Java, but with extremely variable routes and travelled distances (Fig.3a). Depending on the
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entry point (Myanmar, ailand or Vietnam), least-cost paths show two preferential routes, either following the
western coastline of the epicontinental ailand sea or opting for an eastern path through the “Mekong isthmus”.
Markovian walks instead are more exploratory (see animated examples in Supplementary Information), and
show that the entire region was made available to hominins, albeit with a variable probability. e likelihood
that the species came across a given location (revealed by the kernel density estimation of all 3000 modeled
random walks, Fig.3b) unsurprisingly reaches the highest values in the northern part of the region, near their
entry points. En route to Sundaland, while the leasts cost paths includes a western trajectory through the Malay
peninsula, the probabilistic approach instead indicates that this western option is unlikely due to the rugged
topography of the Malay peninsula. Instead, the “Mekong isthmus” channelized them between the ailand and
South China seas. In these lowlands, landscape biases are low (absence of relief, favorable drainage network,
seeMethods), which further reinforces the likelihood of hominin occurence. Likewise, the likelihood is slightly
higher in the lowlands of eastern Sumatra than in more mountainous regions of Sundaland, and in the North,
in the at Chao Praya basin and Khorat plateau of ailand (Fig.3b). While these results indicate that peopling
Sundaland was ubiquitously possible, the likelihood that hominins joined the rims of Sundaland is however
relatively low. is result, seemingly at odds with the Javanese yield of fossil remains, could reveal that our
reconstructions and parametrizations are inadequate to the point of being misleading, and that better account-
ing for habitat suitability, using species distribution modeling in particular, would yield alternative and more
compatible solutions. Alternatively, this incongruence canbe simply explained by the inconvenient concealment
of fossil bearing sedimentary layers in subsiding, fast sedimenting basins (as in ailand) or below sea level (as
in the “Mekong isthmus”).
How long did the journey take? While least-cost paths are
∼
6,000 km long on average from mainland Asia to
Java (Fig.4a), the mean travelled distances are
∼
50 times longer for Markovian walks (327
×103
km), regardless
of the north entry point, and almost always in excess of 100
×103
km. e corresponding time span depends on
the migration speed. Estimates are available for more recent palaeolithic hominins, ranging from 1 to 10 km/
yr43–45. At similar speeds, the least-cost paths convert into an optimal travel time of 0.6 to 6 kyr, which is thus
the minimal time to cross Sundaland. Markovian walks imply much longer durations before hominins reached
Java, between 25-40 kyr at fast moving rates, and 250-400 kyr at slow moving rates (Fig.4b). ese relatively long
delays at average or slow moving rates are dicult to reconcile with the early arrival to Java ca. 1.8 Ma, following
departure from Georgia or China only a few 100 kyr before. We suggest that because these characteristic travel
times scale with the characteristic time scale of changes of the physical environment, external forcings impelled
hominins to migrate and boosted their displacement. Climatic variations notoriously impact the habitats of
hominins46,47, but here we suggest that the fast physiographic changes of geodynamic origin and environmental
stochasticity could have also prompted the dispersal of H. erectus.
Figure3. Migration pathways of H. erectus across Sundaland during Early Pleistocene. (a) Reconstructed
landscape ca. 1.8 Ma (model goSPL32). e underlying physiography, with overprinted modeled rivers, converts
into a map of resistance to displacement that serves to compute the migration pathways, either using a least-cost
path algorithm shown for the Myanmar entry point (purple), or a mechanistic movement model (SiMRiv30)
exemplied for the Vietnam entry point (orange). Blue star locates the ailand entry point. (b) Statistical
analysis of the pathways of H. erectus migration to Sangiran, from 3000 simulations (1000 per entry point). e
kernel density estimation (kde, normalized) indicates the likelihood that hominins came across a given region
(combined for the three entry points). Map on panel (a,b). were respectively made using Paraview (www. parav
iew. org) and GMT 5 (www. gener ic- mappi ng- tools. org)24.
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Discussion
Eugène Dubois1 wondered early on whether his revolutionary ndings in Java, as opposed to his unfruitful
attempts in Sumatra, were due to the habitats of early humans or to their preservation and outcrop. is ques-
tion is in fact a general one, on which our joint analysis of the chronology, physical environment, and dispersal
trajectories brings a new light on: Hominin nds in Java mark the onset of continental conditions there ca. 1.8
Ma rather than the timing of their migration across SE Asia. e high probability that earlier groups of hominins
thrived in the nearby Sundaland and were ready to disperse in Java, only waiting for more continental conditions
in the Javanese archipelago, suggests that the immediate ancestors of Javanese H. erectus could be abundantly bur-
ied in the sediments of the nearby Sunda shelf more than exposed in the Indonesian arc. During Early Pleistocene,
H. erectus likely clustered in lowlands during the peopling of Sundaland, in particular in the “Mekong isthmus”
that connected mainland Asia to the Sunda shelf, or in a few hotspots in mainland Asia. ese sites are currently
buried underneath sediments or seawater, or both, which explains that fossil nds are few elsewhere than Java.
is analysis is based on a large number of set of random walks across the region. While it advantageously
indicates the probability distribution of the trajectories, distances and tempos, a corollary limitation arises from
the unaccounted possibility that the peopling of SE Asia could have been the case of a limited number of groups
only. It would imply that a limited number of stochastic events, including the random selection of low cost paths,
could have been inuential on the nal peopling of the region.
While the impact of physiography on hominin evolution has been identied48, this case study of the iconic
Javanese H. erectus emphasizes the need to tie a quantied reconstruction of the past physiography to a robust
time frame before attempting to unravel the migration trajectories. is novel approach sheds new lights on the
dispersal of the genus Homo, by recasting hominins within their regional environmental framework. First, our
results emphasize the role of the physiography -lowlands, rivers, and reliefs in particular- in controlling hominin
habitats. Second, and perhaps more importantly, they highlight the impact of the transience of the environmen-
tal factors, by demonstrating that hominin dispersal operates at the same characteristic time scale than that of
physiographic changes, which could have spurred their displacement.
ese results open new perspectives to untangle the physical and behavioral capacities of H. erectus within
their changing physical environments. We nd that H. erectus migrated across Sundaland at remarkably fast rates
Figure4. Travelled distance and time of H. erectus migration to Sangiran, statistical analysis (3000 simulations,
1000 per entry point - Myanmar, ailand, and Vietnam). (a) Migration distance from the least-cost path (LCP)
analysis and successful mechanistic movement realizations (Markovian random walk) for the three entry points,
and all combined. (b) Travel times, for three dispersal speeds (slow: 1 km/yr43, medium: 5 km/year44, and fast:
10 km/yr45).
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(>10 km/yr) with respect to their prior journey across Eurasia, and to the displacement rates of other lineages of
the genus Homo. We suggest that the quickly changing physiography of Sundaland could have prompted their fast
migration, which implies that extrinsic (environmental) forcings prevailed over intrinsic factors (either cultural
or demographic)10. is proposition invites to go beyond the current study and comprehensively investigate the
joint evolution of the entire ecological and physical -climatic and physiographic- environments. Physiographic
changes in SE Asia triggered a chain of modications that impacted the behavior of H. erectus, including the
regional climate and its feedback relationships with the vegetation cover49, and ultimately on the foodchain on
which hunter-gatherers relied50. In order to more thoroughly address the impact of this changes on habitat suit-
ability, species distribution modeling would be a natural avenue to more precisely reconstruct the evolution of
early humans47,51.
At a more general scale, our TCN ages obtained for the rst appearance datum of H. erectus in Sangiran
advocate for an early peopling of Sundaland by H. erectus, contemporary with their Chinese26,52 and Georgian53,54
counterparts, whose endocranial capacity was much smaller54 than specimens from Sangiran55. ese results
reignite the long-standing controversy over the origin and dispersal pathways of archaic humans27,52,56 and invites
a reexamination of the out-of-Africa paradigm, which provides a global roadmap for the dispersal of the genus
Homo, but which one-way direction may be questioned12,57–60.
Methods
Terrestrial Cosmogenic Nuclide dating (TCN). e Bukuran creek outcrop (Fig. 1, red star,
110◦51′18′′E,7
◦27′58.3′′S, 99m.a.s.l.
) was sampled in July 2018. e 6 m high vertical section (Fig.2) is continu-
ously rejuvenated by lateral erosion by the Bukuran stream, thus oering ideal conditions for TCN application.
26
Al/
10
Be burial dating16,18–20 is based on the relative decay of
26
Al and
10
Be cosmogenic nuclides produced in situ
in quartz (SiO
2
) minerals upon exposure to cosmic rays. Given the half-lives of
10
Be (1.387±0.012 Ma61,62) and
26
Al (0.705±0.024 Ma63,64), it is applicable over a time frame of 200 ka to
∼
6 Ma16. During burial, the attenuation
of secondary cosmic ray particles with depth is marked by an exponential depth decay of cosmogenic isotope
concentration, while posterior erosion attens out the depth dependence.
e top of the sequence, down to
∼
1.5 m depth, is composed of a yellowish tu and quartz poor siltstone. A
light pink and yellowish tuaceous sand, also quartz poor, follows down to 3 m below. Between 3 m and 4.6 m, a
bedded sand and gravel layer yields a higher concentration of quartz grains. From 4.6 m to 5.6 m, an indurated
conglomerate with a higher concentration of quartz is observed, followed by a layer of dark clays, down to the
stream bed. 18 samples have been collected at 15 dierent depths from the surface (SAN18-1) down to the stream
bed (SAN18-18), the deepest samples (SAN-15 to SAN-18) being precisely extracted from the Grenzbank unit,
as identied in earlier studies15,27.
Measured
10
Be and
26
Al concentrations and ratios are depth independent and in agreement (see raw and
statistical values in S.I. Table1). is is explained by low and uniform inherited concentrations, and by long-
lasting denudation at a fast enough rate to dampen the depth dependent exposure of quartz grains to cosmic
rays. By modeling radioactive decay, we estimate the burial age, pre-burial and post-burial denudation rates18,65.
We assume that all samples were buried deep enough to be fully shielded from cosmic rays, but account for
post-burial production of nuclides since deposition (burial with post-production). We also model pre-burial
26
Al/
10
Be ratios (assuming that samples were at steady state before deposition). As all samples underwent the same
burial-exhumation history, we inverted for a common burial time and post-production for all samples at once,
while leaving individual inheritance independent for each sample. is yields a burial age of 1.78±0.20 Ma ( S.I.
Table1). Denudation rates of the source rocks range from 21 to 80 m/Ma, while post-deposition denudation rates
range from 334 to 608 m/Ma with a best t value of 436 m/Ma. Within the topmost meter of the sequence, the
fraction of post-burial
10
Be and
26
Al respectively ranges from 14 to 28% and from 26 to 47%, but then decreases
at greater depths to less than 10% for
10
Be and less than 20%, mostly, for
26
Al. Given the inferred high denudation
rates, the corresponding time span is on the order of 4000 years.
For reference, we also consider the end-member scenario, wherein the upper part of the prole has been
either quasi-instantaneously truncated by several tens of meters (burial without post-production), in order to
determine the minimal age. Individual minimum burial durations (i.e. treating each sample independently) range
from 0.58±0.20 Ma to 2.25±1.04 Ma, and pre-burial denudation rates range from 23 to 101 m/Ma (S.I. Table2).
χ2
test isolated three outliers (SAN18-2, SAN18-4 and SAN18-16). e remaining 13 samples yield a minimum
weighted mean burial duration of 1.45±0.10 Ma.
Chemical sample preparation and
10
Be and
26
Al measurements were carried out at the French Accelerator
Mass Spectrometry national facility, ASTER (CEREGE, Aix-en-Provence) following the standard procedure19. A
challenging aspect for TCN application at the Bukuran creek site is the low quartz content of the uvio-volcanic
sediments. As the amount of quartz mineral is notoriously poor, a mass of 0.5 to 2 kg of sediment per sample
was collected, depending on the lithology (S.I. Table3). Acid attacks were repeated until the maximum amount
of pure SiO
2
was retrieved, within the availability limit of materials. All samples (besides SAN18-7 to SAN18-9)
yielded enough quartz to perform suitable measurements. Aer purication, the quartz content was dissolved in
HF 48% aer addition of 150
µl
of a 3025±9 ppm
9
Be solution. Natural Al content was determined by ICP-OES
using an ICAP6500 from ermo. BeO and Al
2
O
3
were respectively mixed with niobium and silver powders prior
to measurements. Beryllium data were directly calibrated against the STD11 standard66 with a
10
Be/
9
Be ratio of
(1.191±0.013) x 10
−11
. Aluminum measurements were performed against in-house standard SM-Al-11, with a
26
Al/
27
Al ratio of (7.401±0.064) x 10
−12
, previously cross-calibrated against the primary standards certied by
a round-robin exercise67,68. e successive measurement batches are characterized by stable, high level
9
Be and
27
Al currents during AMS measurements (S.I. Table3) that attest for their high reliability (despite low
10
Be and
26
Al counts at the AMS receptors). Analytical uncertainties (reported as 1
σ
) include uncertainties associated
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with AMS counting statistics, AMS external error (0.5% for
10
Be), chemical blank measurement, and
26
Al,
27
Al
measurements. Measurements of chemically processed blank yield ratios on the order of (2.0±0.75) x 10
−15
for
10
Be and (2.0±2.0) x 10
−15
for
26
Al. A sea level high latitude spallation production rate of 4.02±0.32
at.g−1.a−1
69
was used and scaled using Stone’s polynomials70. e
26
Al/
10
Be production ratio induced by the standardization
used at ASTER is 6.61±0.50.
Sundaland physical landscape reconstruction ca. 1.8 Ma. In order to reconstruct the landscape
at 1.8 Ma, we rst compiled rates of vertical land motions inferred from geomorphological indicators, strati-
graphic, and seismic data (S.I. Fig.1a adapted from6,7,33). is dataset provides discrete informations that we
interpolated in order to obtain a continuous map of upli rates over the region, which backward integration in
time provides a paleo-elevation map. To reconstruct a realistic landscape at 1.8 Ma, we ran the Landscape Evolu-
tion Model (LEM) goSPL32 over a 10,000 years period starting from an adjusted paleo-elevation surface (1 km
resolution) derived from the upli map and past absolute sea level, set to -30 m during Early Pleistocene sea level
highstands71. Continuity of mass is the main equation of the model, and is expressed by:
where z is surface elevation (m), t is time (yr), U is vertical land motion (
m/yr
) and
κ
the diusion coecient
for soil creep (set to
5×10−3
m
2
/yr). e last term in the right-hand side of Eq. (1) represents uvial processes
based on a stream power law with erodibility
ǫ
(set to
4×10−6
m
−1
yr
−1
), dimensionless constants m and n
(empirically set to 0.5 and 1) and water ux PA combining upstream watershed area A and precipitation P. e
stream power law here incorporates the eect of local mean annual precipitation rate (obtained from paleoclimate
model HadCM3BL-M2.1aD34), d being a positive exponent (set to 0.42), ngerprinted in the paleo-landscape
and paleo-drainage maps (see resulting landscape aer 10 kyr of concurrent action of riverine and hillslope
processes in S.I. Fig.1b). Both processes erode, transport and deposit sediments with maximum erosion (>500
m) along the Barisan Mountains in Sumatra and deposition (up to 400 m) in several endhoreic lakes and basins
across Borneo and East Malay Peninsula (S.I. Fig.2a).
Resistance to species displacement from regional physiography. To compute the dispersal of H.
erectus in Sundaland and its migration to Sangiran, we extracted from the landscape evolution model three phys-
iographic features known to inuence early human dispersal72–75. ese features (S.I. Fig.2) are then converted
into cost values at a
∼
1 km
2
resolution, with high costs corresponding to resistant regions impeding movement.
First, we consider endorheic lakes and oceans as absolute dispersal barriers (normalized cost set to 1.0) and
assume that major rivers (> 5.5
×
10
3
m
3
/s - approximately the Niger river ow rates) represent strong barriers
to crossing72. From our simulation, the largest river ow rate reaches 30.5
×
10
3
m
3
/s, one sixth of the current
discharge of the Amazon river, comparable to the discharge of the Yangtze river. As opposed to earlier studies72,
we do not deem these major rivers as fully impermeable in the cost calculation, and let their normalized values
to vary linearly with ow rates from 0.7 to 0.95. Second, we estimate a riparian buer zone by computing the
distance to rivers over the entire region. In addition to rivers, we also set maritime and lacustrine coastlines as
preferential pathways38 and add these distances in our cost calculation. Computed distances are then converted
into an exponential series75, to account for the exponentially increasing diculty of travel as H. erectus moves
away from freshwaters72. Finally, we account for topographic complexity by calculating the local slope Slopes
below 0.5
◦
are considered costless, and the normalized cost increases linearly between 0.1 and 0.6 from 0.5
◦
to
5
◦
and set to 0.8 above 5
◦
. Combining individual cost from each variable, we obtain a nal normalized cost map
(S.I. Fig.1c) that favour routes along riparian areas and coastal plains and avoid hilly and mountainous regions.
Assuming foraging time and energy expenditure minimization, this cost map is then used to compute the dis-
persal of H. erectus across South East Asia and colonization of Sundaland.
We then dened three entry points, corresponding to western, central and eastern routes, at places with low
resistance to displacement (riparian areas with low topographic complexity). First, from its migration out of
Africa via the Levantine corridor, traces of a western route can be found in Riwat, Pakistan76, which could lead to
the Himalayan foreland, Ganges-Brahmaputra rivers, down to the North of the Irrawaddy delta in Myanmar. Sec-
ond, hominin fossil remains in south China near Yuanmou77, that we found contemporaneous to H. erectus from
Sangiran, set an eastern route, hypothesizing that the Mekong and Red rivers acted as barriers and channelized
early humans to the coast south of the Red river in Vietnam. Last, an intermediate northern route upstream of
the Chao Phraya plain in ailand, hypothesizes that H. erectus either crossed the Shan plateau in Myanmar
or the Yunnan-Guizhou plateau, bounded by the Salween and Mekong rivers on its western and eastern sides.
Assuming H. erectus omniscience: least‑cost paths. A convenient theoretical approach to predict
movement of species through a landscape relies on a least-cost path (LCP) analysis75,78. Here, LCP are calculated
using the Dijkstra’s algorithm accounting for diagonal connectivity between cells and implemented using the
scikit-image library79. LCPs not only require the positions of the entry points but also the location of the end-
ing point (here set to Sangiran). Both the traveled distance and landscape resistance (S.I. Fig.1c) determine the
most parsimonious route connecting these endpoints. While stochasticity imposes to consider this route as a
possible option, LCP otherwise implicitly rests on the unrealistic assumption that the species had a destination,
a compass and a roadmap. LCPs thus give a reference for the minimum travelled distance across Sundaland. Esti-
mated walked distances for all 3 cases are comparable (5545, 5620, and 7050 km, respectively for the Myanmar,
ailand, and Vietnam entry points). e western and central routes merge aer
∼
1500 km downstream of their
(1)
∂z
∂t
=U+κ∇2z+ǫPd(PA)m∇z
n
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entry points (S.I. Fig.3), while the eastern route merges with them South of the endorheic ailand sea, between
the Malay peninsula and the “Mekong isthmus” that connected South Vietnam to the Sunda shelf. As expected
from the cost surface, LCP follows preferentially alluvial plains and coastal regions. LCP occasionally signicant
detours from the shortest distance path, specically where large rivers hamper dispersal and force migration
across upstream smaller tributaries of lower discharge.
Mechanistic movements conditioned by landscape heterogeneity: Markovian walks. Migra-
tion models assuming a destination (e.g., LCP) would rarely reect the actual movements of species across a
heterogeneous landscape, which impairs their predictive capacity. In reality, most species progress without a
planned destination during their lifespan80 and have no memory of longterm prior displacements: their move-
ments are only determined from local information81 and immediate prior displacement. To li the aforemen-
tioned LCP limitations, we adapted the recently developed mechanistic model SiMRiv30 that simulates spatially
explicit stochastic movements (multi-state Markov model82) accounting for landscape heterogeneity and per-
ceptual range (i.e., the radius up to which an individual perceives its surroundings) (S.I. Fig.4a). Here again, the
normalized resistance map (S.I. Fig 1c) denes the underlying environmental complexity of the region and H.
erectus movement is simulated with a two-state movement (Lévy-like walker83) that alternates between random
and correlated random walks84, where the incremental azimuthal direction is correlated with the prior direction
(turning angle concentration parameter of the wrapped normal distribution is set to 0.99 in our simulations)
(S.I. Fig.4b). To inform the mechanistic model on the probabilities of changing between the two states, SiMRiv
provides a transition matrix (which values are here set to 0.01 and 0.002). We also set the step length (unit of
movement) for both states to 100 m in order to avoid unrealistic jumps over high cost cells. Finally, we set the
perceptual range to 5 km for both states: the movement decisions at each step accounts for the resistance that the
walker sees in a 5 km radius around its current location (i.e., it attempts to bypass high-resistance areas within
this range, see S.I. Fig.4b, which illustrates the two-state mechanistic movement for a given realization with
multiple phases of acceleration and deceleration as H. erectus moves over the heterogeneous landscape). To have
statistically signicant results, we run 1000 realizations over 5 million steps each for the three routes (Myanmar,
ailand, and Vietnam entry points). One third of the 3000 realizations reaches Sangiran (respectively 29%, 34%
and 38%). As expected, Markovian walks to Sangiran are much longer than LCP (LCP lengths amount to 7-9%
of the shortest mechanistic realizations - Myanmar: 83,000 km, ailand: 66,000 km, and Vietnam: 76,000 km -
S.I. Fig.5a). We then compute the likelihood of H. erectus occupation at any given location, when combining all
realizations successfully passing through Sangiran. We use a kernel density estimate analysis (KDE, S.I. Fig.5b)
weighted by the inverse normalized cost surface, which not only allows to illuminate the most favourable physi-
ographic settings (e.g., riparian areas, lowlands and coastal plains) but also to account for the slower progression
(and proportional number of steps) in complex landscapes (S.I. Fig.4b).
H. erectus migration speed range. Estimating the dispersal velocity across Sundaland remains challeng-
ing for H. erectus, and we rely on available estimates for better documented, more recent hunter-gatherers homi-
nins. In light of the limited available data on their diet and anatomy, H. erectus are also commonly thought to
be hunter-gatherers85,86, although controversy persists87. Recolonization speed estimates for late glacial hunter-
gatherers of northern Europe, deduced from reproduction and mobility parameters, occurred at rates of 0.7 to
1.4 km/yr43. e distribution of the Clovis-age occupations across North America suggests a speed of 5-8 km/
yr44. e rst peopling of the Americas, and the Neolithic transition in Europe, occurred at rates between 6 and
10 km/yr, based on archaeological boundary conditions45. mtDNA variation in isolated populations in southeast
Asia shows a migration speed of 4 km/yr for the dispersal of modern humans from Eurasia to Australasia88.
Based on these estimates, we conservatively assume plausible migration speeds ranging from 1 to 10 km/yr for
Southeast Asian H. erectus, and use this range to compute the travel time for each of the routes obtained from
both LCP and Markovian walks.
Data availability
All necessary data are available in the text and tables.
Code availability
goSPL32, is available from https:// github. com/ Geode ls/ goSPL and the soware documentation can be found at
https:// goSPL. readt hedocs. io. SiMRiv30 is available at https:// github. com/ miguel- porto/ SiMRiv.
Received: 2 July 2022; Accepted: 26 October 2022
References
1. Dubois, E. On Pithecanthropus Erectus: a transitional form between man and the apes. J. Anthropol. Inst. G. B. Irel. 25, 240–255
(1896).
2. von Koenigswald, G. H.R. Neue Pithecanthropus-funde, 1936-1938 : ein beitrag zur Kenntnis der Praehominiden Wetenschappelijke
Mededeelingen ; no. 28 (Landsdrukkerij, Batavia, 1940).
3. Janssen, R. et al. Tooth enamel stable isotopes of Holocene and Pleistocene fossil fauna reveal glacial and interglacial paleoenviron-
ments of hominins in Indonesia. Quatern. Sci. Rev. 144, 145–154 (2016).
4. Bettis, E. A. et al. Way out of Africa: Early Pleistocene paleoenvironments inhabited by Homo erectus in Sangiran, Java. J. Hum.
Evol. 56(1), 11–24 (2009).
5. Human, O. Geologic context and age of the Perning/Mojokerto Homo erectus, East Java. J. Hum. Evol. 40(4), 353–362 (2001).
6. Sarr, A.-C. et al. Subsiding Sundaland. Geology (Boulder) 47(2), 119–122 (2019).
Content courtesy of Springer Nature, terms of use apply. Rights reserved

10
Vol:.(1234567890)
Scientic Reports | (2022) 12:19012 | https://doi.org/10.1038/s41598-022-23206-9
www.nature.com/scientificreports/
7. Salles, T. et al. Quaternary landscape dynamics boosted species dispersal across Southeast Asia. Commun. Earth Environ. 2(1),
1–12 (2021).
8. Husson, L., Boucher, F. C., Sarr, A., Sepulchre, P. & Cahyarini, S. Y. Evidence of Sundaland’s subsidence requires revisiting its
biogeography. J. Biogeogr. 47(4), 843–853 (2020).
9. Winder, I. C. et al. Evolution and dispersal of the genus Homo: A landscape approach. J. Hum. Evol. 87, 48–65 (2015).
10. Carotenuto, F. et al. Venturing out safely: e biogeography of Homo erectus dispersal out of Africa. J. Hum. Evol. 95, 1–12 (2016).
11. Larick, R. et al. Early Pleistocene 40Ar/39Ar ages for Bapang Formation hominins, Central Jawa, Indonesia. Proc. Natl. Acad. Sci.
PNAS 98(9), 4866–4871 (2001).
12. Swisher, C. C., Curtis, G. H., Jacob, T., Getty, A. G. & Suprijo, A. Age of the earliest known hominids in Java, Indonesia. Science
263(5150), 1118–1121 (1994).
13. Sémah, F., Saleki, H., Falguŕes, C., Féraud, G. & Djubiantono, T. Did early man reach Java during the Late Pliocene?. J. Archaeol.
Sci. 27(9), 763–769 (2000).
14. Bettis, E. et al. Landscape development preceding Homo erectus immigration into Central Java, Indonesia: e Sangiran Forma-
tion Lower Lahar. Palaeogeogr. Palaeoclimatol. Palaeoecol. 206(1), 115–131 (2004).
15. Matsu’ura, S. et al. Age control of the rst appearance datum for Javanese Homo erectus in the Sangiran area. Science 367(6474),
210–214 (2020).
16. Granger, D. E. & Muzikar, P. F. Dating sediment burial with insitu-produced cosmogenic nuclides: eory, techniques, and limita-
tions. Earth Planet. Sci. Lett. 188(1), 269–281 (2001).
17. Shen, G., Gao, X., Gao, B. & Granger, D. E. Age of Zhoukoudian Homo erectus determined with 26Al/10Be burial dating. Nature
458(7235), 198–200 (2009).
18. Pappu, S. et al. Early Pleistocene presence of Acheulian Hominins in South India. Science 331(6024), 1596–1599 (2011).
19. Lebatard, A.-E. etal. Dating the Homo erectus bearing travertine from Kocabaş (Denizli, Turkey) at at least 1.1 Ma. Earth Planet.
Sci. Lett.390, 8–18 (2014).
20. Lebatard, A.-E., Bourlès, D. L. & Braucher, R. Absolute dating of an Early Paleolithic site in Western Africa based on the radioactive
decay of insitu-produced 10Be and 26Al. Nucl. Instrum. Methods Phys. Res. Sect. B 456, 169–179 (2019).
21. Braucher, R., Oslisly, R., Mesn, I., NtoutoumeMba, P.P. & Team, A. Insitu-produced 10 Be and 26 Al indirect dating of Elarmé-
kora Earlier Stone Age artifacts: First attempt in a savannah forest mosaic in the middle Ogooué valley, Gabon. Philos. Trans. Biol.
Sci. (2021) .
22. Grimaud-Hervé, D. et al. Position of the posterior skullcap fragment from Sendang Klampok (Sangiran Dome, Java, Indonesia)
among the Javanese Homo erectus record. Quatern. Int. 416, 193–209 (2016).
23. Sartono, S. Observations on a new skull of Pithecanthropus erectus (Pithecanthropus VIII), from Sangiran, Central Java. Koninklijke
Akademie Wetenschappen te Amsterdam 74, 185–194 (1971).
24. Wessel, P., Smith, W. H. F., Scharroo, R., Luis, J. & Wobbe, F. Generic mapping tools: Improved version released. EOS Trans. Am.
Geophys. Union 94(45), 409–410. https:// doi. org/ 10. 1002/ 2013E O4500 01 (2013).
25. Antón, S., Potts, R. & Aiello, L. Evolution of Early Homo: An integrated biological perspective. Science (New York, N.Y.)345 (2014).
https:// doi. org/ 10. 1126/ scien ce. 12368 28.
26. Luo, L. et al. e rst radiometric age by isochron 26Al/10Be burial dating for the Early Pleistocene Yuanmou hominin site,
southern China. Quat. Geochronol. 55, 101022. https:// doi. org/ 10. 1016/j. quageo. 2019. 101022 (2019).
27. Zaim, Y. etal. New 1.5 million-year-old Homo erectus maxilla from Sangiran (Central Java, Indonesia). J. Hum. Evol.61(4), 363–376
(2011).
28. Rizal, Y. et al. Last appearance of Homo erectus at Ngandong, Java, 117,000–108,000 years ago. Nature 577(7790), 381–385 (2020).
29. McRae, B. & Beier, P. Circuit theory predicts gene ow in plant and animal populations. Proc. Natl. Acad. Sci. USA 104, 19885–90.
https:// doi. org/ 10. 1073/ pnas. 07065 68104 (2008).
30. Quaglietta, L. & Porto, M. SiMRiv: An R package for mechanistic simulation of individual, spatially-explicit multistate movements
in rivers, heterogeneous and homogeneous spaces incorporating landscape bias. Mov. Ecol. https:// doi. org/ 10. 1186/ s40462- 019-
0154-8 (2019).
31. Landau, V.A., Shah, V.B., Anantharaman, R. & Hall, K.R. Omniscape.jl: Soware to compute omnidirectional landscape con-
nectivity. J. Open Source Sow.6(57), 2829 (2021). https:// doi. org/ 10. 21105/ joss. 02829.
32. Salles, T., Mallard, C. & Zahirovic, S. gospl: Global Scalable Paleo Landscape Evolution. J. Open Source Sow.5(56), 2804 (2020).
https:// doi. org/ 10. 21105/ joss. 02804.
33. Husson, L. etal. Slow geodynamics and fast morphotectonics in the far East Tethys. Geochem. Geophys. Geosyst. 23(1), n/a (2022).
34. Valdes, P., Scotese, C. & Lunt, D. Deep ocean temperatures through time. Climate Past 17, 1483–1506. https:// doi. org/ 10. 5194/
cp- 17- 1483- 2021 (2021).
35. Hyodo, M. et al. High-resolution record of the Matuyama–Brunhes transition constrains the age of Javanese Homo erectus in the
Sangiran dome, Indonesia. Proc. Natl. Acad. Sci. PNAS 108(49), 19563–19568 (2011).
36. Brasseur, B., Sémah, F., Sémah, A.-M. & Djubiantono, T. Pedo-sedimentary dynamics of the Sangiran dome hominid bearing
layers (Early to Middle Pleistocene, central Java, Indonesia): A palaeopedological approach for reconstructing ‘Pithecanthropus’
(Javanese Homo erectus) palaeoenvironment. Quatern. Int. 376, 84–100 (2015).
37. Falguéres, C. et al. Geochronology of early human settlements in Java: What is at stake?. Quatern. Int. 416, 5–11 (2016).
38. Roach, N. etal. Pleistocene footprints show intensive use of lake margin habitats by Homo erectus groups. Sci. Rep. 121 (2016).
https:// doi. org/ 10. 1038/ srep2 6374.
39. Simandjuntak, T. O. & Barber, A. J. Contrasting tectonic styles in the Neogene orogenic belts of Indonesia. Geol. Soc. Spec. Pub.
106(1), 185–201 (1996).
40. Clements, B., Hall, R., Smyth, H. R. & Cottam, M. A. rusting of a volcanic arc; a new structural model for Java. Pet. Geosci. 15(2),
159–174 (2009).
41. Joordens, J., Wesselingh, F., de Vos, J., Vonhof, H. & Kroon, D. Relevance of aquatic environments for hominins: A case study from
Trinil (Java, Indonesia). J. Hum. Evol. 57(6), 656–671 (2009).
42. Berghuis, H. et al. Hominin homelands of East Java: Revised stratigraphy and landscape reconstructions for Plio-Pleistocene Tr inil.
Quatern. Sci. Rev. 260, 106912 (2021).
43. Fort, J., Pujol, T. & Cavalli-Sforza, L. Palaeolithic populations and waves of advance. Camb. Archaeol. J. 14, 53–61. https: // d oi. org/
10. 1017/ S0959 77430 40000 46 (2004).
44. Hamilton, M. & Buchanan, B. Spatial gradients in Clovis-age radiocarbon dates across North America suggest rapid colonization
from the north. Proc. Natl. Acad. Sci. USA 104, 15625–30. https:// doi. org/ 10. 1073/ pnas. 07042 15104 (2007).
45. Hazelwood, L. & Steele, J. Spatial dynamics of human dispersals: Constraints on modelling and archaeological validation. J.
Archaeol. Sci. 31, 669–679. https:// doi. org/ 10. 1016/j. jas. 2003. 11. 009 (2004).
46. Bae, C., Li, F., Liuling, C., Wang, W. & Hanlie, H. Hominin distribution and density patterns in pleistocene China: Climatic inu-
ences. Palaeogeogr. Palaeoclimatol. Palaeoecol. 512 (2018). https:// doi. org/ 10. 1016/j. palaeo. 2018. 03. 015.
47. Timmermann, A. et al. Climate eects on archaic human habitats and species successions. Nature 604, 1–7. https:// doi. org/ 10.
1038/ s41586- 022- 04600-9 (2022).
48. Bailey, G. N., Reynolds, S. C. & King, G. C. Landscapes of human evolution: Models and methods of tectonic geomorphology and
the reconstruction of hominin landscapes. J. Hum. Evol. 60(3), 257–280 (2011).
Content courtesy of Springer Nature, terms of use apply. Rights reserved

11
Vol.:(0123456789)
Scientic Reports | (2022) 12:19012 | https://doi.org/10.1038/s41598-022-23206-9
www.nature.com/scientificreports/
49. Sarr, A., Sepulchre, P. & Husson, L. Impact of the Sunda Shelf on the Climate of the Maritime Continent. J. Geophys. Res. Atmos.
124(5), 2574–2588 (2019).
50. Louys, J. & Roberts, P. Environmental drivers of megafauna and hominin extinction in Southeast Asia. Nature 586(7829), 402–406
(2020).
51. Raia, P. et al. Past extinctions of homo species coincided with increased vulnerability to climatic change. One Earth 3(4), 480–490
(2020).
52. Zhu, Z. etal. Hominin occupation of the Chinese Loess Plateau since about 2.1 million years ago. Nature 559(7715), 608–612
(2018).
53. Gabunia, L. et al. Earliest Pleistocene hominid cranial remains from Dmanisi, Republic of Georgia: Taxonomy, geological setting,
and age. Science 288, 1019–1025. https:// doi. org/ 10. 1126/ scien ce. 288. 5468. 1019 (2000).
54. Lordkipanidze, D. et al. A complete skull from Dmanisi, Georgia, and the evolutionary biology of early homo. Science 342(6156),
326–331 (2013).
55. Baba, H. etal. Homo erectus calvarium from the pleistocene of java. Sci. (Am. Assoc. Adv. Sci.) 299(5611), 1384–1388 (2003) .
56. Ciochon, R. L. & Bettis, E. A. III. Asian Homo erectus converges in time. Nature 458(7235), 153–154 (2009).
57. Dennell, R. & Roebroeks, W. An Asian perspective on early human dispersal from Africa. Nature 438(7071), 1099–1104 (2005).
58. Martinon-Torres, M. et al. Dental evidence on the hominin dispersals during the Pleistocene. Proc. Natl. Acad. Sci. PNAS 104(33),
13279–13282 (2007).
59. Wood, B. Did early Homo migrate “out of’’ or “in to’’ Africa?. Proc. Natl. Acad. Sci. PNAS 108(26), 10375–10376 (2011).
60. Shen, G. et al. Isochron 26Al/10Be burial dating of Xihoudu: Evidence for the earliest human settlement in northern China.
Anthropologie 124, 102790. https:// doi. org/ 10. 1016/j. anthro. 2020. 102790 (2020).
61. Chmele, J., von Blanckenburg, F., Kossert, K. & Jakob, D. Determination of the 10Be half-life by multicollector ICP-MS and liquid
scintillation counting. Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. Atoms268(2), 192–199 (2010).
62. Korschinek, G. etal. A new value for the half-life of 10Be by Heavy-Ion Elastic Recoil Detection and liquid scintillation counting.
Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. Atoms 268(2), 187–191 (2010) .
63. Nishiizumi, K. Preparation of 26Al AMS standards. Nucl. Inst. and Meth. in Phys. Res. 223-224, 388–392 (2004).
64. Norris, T. L., Gancarz, A. J., Rokop, D. J. & omas, K. W. Half-life of 26Al. J. Geophys. Res. Solid Earth 88(S01), B331–B333 (1983).
65. Braucher, R., Merchel, S., Borgomano, J. & Bourlès, D. Production of cosmogenic radionuclides at great depth: A multi element
approach. Earth Planet. Sci. Lett. 309(1), 1–9 (2011).
66. Braucher, R. etal. Preparation of ASTER in-house 10Be/9Be standard solutions. Nucl. Instrum. Methods Phys. Res. Sect. B Beam
Interact. Mater. Atoms361, 335–340 (2015) .
67. Merchel, S. & Bremser, W. First international 26Al interlaboratory comparison—Part I. Nucl. Instrum. Methods Phys. Res. 223–224,
393–400 (2004).
68. Arnold, M. et al. e French accelerator mass spectrometry facility ASTER: Improved performance and developments. Nucl.
Instrum. Methods Phys. Res. 268(11), 1954–1959 (2010).
69. Borchers, B. et al. Geological calibration of spallation production rates in the CRONUS-Earth project. Quat. Geochronol. 31,
188–198 (2016).
70. Stone, J. O. Air pressure and cosmogenic isotope production. J. Geophys. Res. Solid Earth 105(B10), 23753–23759 (2000).
71. Bintanja, R. & van de Wal, R. S. W. North American ice-sheet dynamics and the onset of 100,000-year glacial cycles. Nature 454,
869–872. https:// doi. org/ 10. 1038/ natur e07158 (2008).
72. Field, J. & MirazonLahr, M. Assessment of the Southern Dispersal: GIS-Based Analyses of Potential Routes at Oxygen Isotopic
Stage 4. J. World Prehist. 19, 1–45 (2005). https:// doi. org/ 10. 1007/ s10963- 005- 9000-6.
73. Howey, M. Multiple pathways across past landscapes: Circuit theory as a complementary geospatial method to least cost path for
modeling past movement. J. Archaeol. Sci. 38, 2523–2535. https:// doi. org/ 10. 1016/j. jas. 2011. 03. 024 (2011).
74. Tassi, F. et al. Early modern human dispersal from Africa: Genomic evidence for multiple waves of migration. Investig. Genet. 6,
13. https:// doi. org/ 10. 1186/ s13323- 015- 0030-2 (2015).
75. Kealy, S., Louys, J. & O’Connor, S. Least-cost pathway models indicate northern human dispersal from Sunda to Sahul. J. Hum.
Evol. 125, 59–70. https:// doi. org/ 10. 1016/j. jhevol. 2018. 10. 003 (2018).
76. Dennell, R. W., Rendell, H. M. & Hailwood, E. Late pliocene artefacts from northern Pakistan. Curr. Anthropol. 29(3), 495–498
(1988).
77. Zhu, R. et al. Early evidence of the genus homo in east asia. J. Hum. Evol. 55(6), 1075–1085 (2008).
78. Gowen, K. M. & de Smet, T. S. Testing least cost path (LCP) models for travel time and kilocalorie expenditure: Implications for
landscape genomics. PLoS ONE 15(9), 1–20. https:// doi. org/ 10. 1371/ journ al. pone. 02393 87 (2020).
79. Walt, S. et al. scikit-image: Image processing in Python. PeerJ 2, e453. https:// doi. org/ 10. 7287/ peerj. prepr ints. 336v2 (2014).
80. Mueller, T. & Fagan, W. Search and navigation in dynamic environments—From individual behaviors to population distributions.
Oikos 117, 654–664. https:// doi. org/ 10. 1111/j. 0030- 1299. 2008. 16291.x (2008).
81. Bastil le-Rousseau, G., Douglas-Hamilton, I., Blake, S., Northrup, J. & Wittemyer, G. Applying network theory to animal movements
to identify properties of landscape space use. Ecol. Appl. 28 (2018). https:// doi. org/ 10. 1002/ eap. 1697.
82. Michelot, T., Langrock, R. & Patterson, T. moveHMM: An R package for the statistical modelling of animal movement data using
hidden Markov models. Methods Ecol. Evol. 7 (2016). https:// doi. org/ 10. 1111/ 2041- 210X. 12578 .
83. Benhamou, S. How many animals really do the Lévy Walk. Ecology 88, 1962–9. https:// doi. org/ 10. 1890/ 06- 1769.1 (2007).
84. Turchin, P. Quantitative Analysis of Movement: Measuring and Modeling Population Redistribution of Plants and Animals (Sinauer
Associates, Sunderland, 1998).
85. Lieberman, D. E. e Story of the Human Body: Evolution, Health, and Disease (Pantheon Books, New York, 2013).
86. Braun, D. etal. Early hominin diet included diverse terrestrial and aquatic animals 1.95 Ma in East Turkana, Kenya. Proc. Natl.
Acad. Sci. USA 107, 10002–7 (2010). https:// doi. org/ 10. 1073/ pnas. 10021 81107.
87. O’Connor, S., Louys, J., Kealy, S. & SamperCarro, S.C. Hominin dispersal and settlement east of huxley’s line: e role of sea level
changes, island size, and subsistence behavior. Curr. Anthropol. 58(S17), S567–S582 (2017).
88. Macaulay, V. etal. Single, rapid coastal settlement of asia revealed by analysis of complete mitochondrial genomes. Science (New
York, N.Y.)308, 1034–6 (2005). https:// doi. org/ 10. 1126/ scien ce. 11097 92.
Acknowledgements
Authors are grateful to Nandang from LIPI Geotek for his continued involvement in the eld, to the people of
Sangiran for their assistance, andto the Museum Situs Manusia Purba Sangiran and Tanto for their guidance.
e authors thank J. Arief for his help in the eld, F. Semah and C. Falguères for discussions, L. Léanni for her
valuable assistance during chemical treatments and ICP-OES measurements, and D. Daddi-Addoun for her sup-
port. J. Louys and two anonymous reviewers greatly help improving the manuscript. Our colleague and friend
Didier L. Bourlès, who passed away in 2021, instigated this study.
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Authors’ contributions
L.H., T.S., A.-E.L., D.B. designed the study, T.S., A.-E.L., L.H., and ASTER team conducted the experiments, L.H.,
T.S., A.-E.L., S.Z., R.B., S.N., S.A., C.M., J.C., D.H.N. analyzed the results. All authors reviewed the manuscript.
Funding
ASTER AMS national facility (CEREGE) is supported by INSU/CNRS, ANR “Projets thématiques d’excellence”,
and IRD. National Geographic Society and CNRS-INSU provided nancial support.
Competing interests
e authors declare no competing interests.
Additional information
Supplementary Information e online version contains supplementary material available at https:// doi. org/
10. 1038/ s41598- 022- 23206-9.
Correspondence and requests for materials should be addressed to L.H.
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© e Author(s) 2022
ASTER team
Georges Aumaitre3, Didier Bourlès3 & Karim Keddadouche3
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