Dog domestication and the dual dispersal of people and dogs into the Americas

Abstract

Advances in the isolation and sequencing of ancient DNA have begun to reveal the population histories of both people and dogs. Over the last 10,000 y, the genetic signatures of ancient dog remains have been linked with known human dispersals in regions such as the Arctic and the remote Pacific. It is suspected, however, that this relationship has a much deeper antiquity, and that the tandem movement of people and dogs may have begun soon after the domestication of the dog from a gray wolf ancestor in the late Pleistocene. Here, by comparing population genetic results of humans and dogs from Siberia, Beringia, and North America, we show that there is a close correlation in the movement and divergences of their respective lineages. This evidence places constraints on when and where dog domestication took place. Most significantly, it suggests that dogs were domesticated in Siberia by ∼23,000 y ago, possibly while both people and wolves were isolated during the harsh climate of the Last Glacial Maximum. Dogs then accompanied the first people into the Americas and traveled with them as humans rapidly dispersed into the continent beginning ∼15,000 y ago. archaeology | genetics | domestication | dogs | peopling of the Americas

Full text

PERSPECTIVE
Dog domestication and the dual dispersal of people
and dogs into the Americas
Angela R. Perri
a,1
, Tatiana R. Feuerborn
b,c,d,e,f
, Laurent A. F. Frantz
g,h
, Greger Larson
i
, Ripan S. Malhi
j,k
, David J. Meltzer
l,m,1
, and Kelsey E. Witt
n,o,1

Edited by Theodore G. Schurr, University of Pennsylvania, Philadelphia, PA, and accepted by Editorial Board Member Dolores R.
Piperno December 8, 2020 (received for review June 4, 2020)
Advances in the isolation and sequencing of ancient DNA have begun to reveal the population histories of
both people and dogs. Over the last 10,000 y, the genetic signatures of ancient dog remains have been
linked with known human dispersals in regions such as the Arctic and the remote Pacific. It is suspected,
however, that this relationship has a much deeper antiquity, and that the tandem movement of people and
dogs may have begun soon after the domestication of the dog from a gray wolf ancestor in the late
Pleistocene. Here, by comparing population genetic results of humans and dogs from Siberia, Beringia,
and North America, we show that there is a close correlation in the movement and divergences of their
respective lineages. This evidence places constraints on when and where dog domestication took place.
Most significantly, it suggests that dogs were domesticated in Siberia by ∼23,000 y ago, possibly while
both people and wolves were isolated during the harsh climate of the Last Glacial Maximum. Dogs then
accompanied the first people into the Americas and traveled with them as humans rapidly dispersed into
the continent beginning ∼15,000 y ago.
archaeology
|
genetics
|
domestication
|
dogs
|
peopling of the Americas
Dogs were the first domesticated species and the only
animal known to enter into a domestic relationship
with people during the Pleistocene (1–4). Recent ge-
netic analyses of ancient dog remains and of the ar-
chaeological and genetic records of ancient people
have demonstrated that the spatiotemporal pattern-
ing of specific dog mitochondrial lineages are often
correlated with the known dispersal of human groups
at different times and places.
For instance, a study of mitochondrial signatures
derived from ancient Near Eastern and European
dogs has demonstrated that a specific haplogroup
arrived in Europe as dogs dispersed out of the Near
East along with farmers (5). The first dogs to arrive in
New Zealand did so with newly arriving Polynesians
(6). People and dogs also dispersed together in the
North American Arctic, where dogs carrying a specific
mitochondrial DNA (mtDNA) signature (haplogroup
A2a; refs. 7 and 8) accompanied Paleo-Inuit groups
as they moved into the region ∼5,000 y ago (5 ka).
Subsequently, the arrival of Inuit groups into the same
region ∼1 ka was accompanied by the introduction of
a dog population that carried novel mtDNA signatures
(A1a and A1b; ref. 7).
These correlations between the dispersals of peo-
ple and specific dog lineages may have begun much
a
Department of Archaeology, Durham University, Durham DH1 3LE, United Kingdom;
b
GLOBE Institute, University of Copenhagen, 1350
Copenhagen, Denmark;
c
The Qimmeq Project, University of Greenland, 3905 Nuussuaq, Greenland;
d
Archaeological Research Laboratory,
Department of Archaeology and Classical Studies, Stockholm University, 114 19 Stockholm, Sweden;
e
Department of Bioinformatics and Genetics,
Swedish Museum of Natural History, 114 18 Stockholm, Sweden;
f
Centre for Palaeogenetics, 114 18 Stockholm, Sweden;
g
Palaeogenomics Group,
Department of Veterinary Sciences, Ludwig Maximilian University, Munich D-80539, Germany;
h
School of Biological and Chemical Sciences, Queen
Mary University of London, London E1 4NS, United Kingdom;
i
The Palaeogenomics and Bio-Archaeology Research Network, Research Laboratory
for Archaeology and History of Art, University of Oxford, Oxford OX1 3QY, United Kingdom;
j
Department of Anthropology, University of Illinois at
Urbana–Champaign, Urbana, IL 61801;
k
Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana–Champaign, Urbana, IL 61801;
l
Department of Anthropology, Southern Methodist University, Dallas, TX 75205;
m
Lundbeck Foundation GeoGenetics Centre, GLOBE Institute,
University of Copenhagen, 1350 Copenhagen, Denmark;
n
Department of Ecology and Evolutionary Biology, Brown University, Providence, RI
02912; and
o
Center for Computational and Molecular Biology, Brown University, Providence, RI 02912
Author contributions: A.R.P., L.A.F.F., G.L., D.J.M., and K.E.W. designed research; A.R.P., T.R.F., L.A.F.F., G.L., R.S.M., D.J.M., and K.E.W. per-
formed research; A.R.P., T.R.F., L.A.F.F., G.L., R.S.M., D.J.M., and K.E.W. analyzed data; and A.R.P., T.R.F., L.A.F.F., G.L., R.S.M., D.J.M., and K.E.W.
wrote the paper.
The authors declare no competing interest.
This article is a PNAS Direct Submission. T.G.S. is a guest editor invited by the Editorial Board.
Published under the PNAS license.
1
To whom correspondence may be addressed. Email: angela.r.perri@durham.ac.uk, dmeltzer@smu.edu, or kelsey_witt_dillon@brown.edu.
This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2010083118/-/DCSupplemental.
Published January 25, 2021.
PNAS 2021 Vol. 118 No. 6 e2010083118 https://doi.org/10.1073/pnas.2010083118
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earlier, perhaps soon after dogs became domesticated from a
gray wolf ancestor in Eurasia, though precisely where and how
many times that process took place remains unknown. The
archaeologically documented presence of dogs in the Americas
by at least 10 ka (9) suggests that dogs accompanied the early
human groups who moved from northeast Asia across the Bering
Land Bridge (Beringia) into the Americas. On the basis of current
archaeological and genetic evidence, this movement likely took
place before 15 ka (10, 11). Here, we take advantage of this re-
cord and newly available evidence from humans and dogs in late
Pleistocene Siberia, Beringia, and North America to assess the
likelihood that the first peopletoreachanddisperseacross
the Americas did so in tandem with their dogs. This analysis al-
lows us to better understand that dispersal process and pre-
sent a hypothesis for the temporal and geographic origins of
domestic dogs.
The First Dogs
Numerous archaeometric approaches have been applied to
document the interaction between wolves, dogs, and people in
order to establish the time frame and geography of dog domes-
tication. These studies have shown, first, that dogs were the ear-
liest animal domesticated, and the only species that entered into a
domestic relationship with people during the Pleistocene (1, 2, 12,
13). Second, the specific wolf population from which dogs derived
appears to be extinct (1, 14, 15). Finally, genetic and archaeo-
logical evidence from modern and ancient dogs and wolves
demonstrates that dog domestication took place in Eurasia
(16–18). Many other aspects of dog domestication, including the
circumstances under which the relationship began, the time
frame, and the number and location(s) of potential independent
domestication regions, remain unresolved (19–21).
The shift in human–wolf interactions that led to domestication
has been addressed through a wide variety of approaches, and
there are ongoing debates over when the first recognizably do-
mestic dog appeared. The earliest generally accepted dog dates
to ∼15 ka (from the site of Bonn-Oberkassel, discussed below).
However, claims for the existence of domestic dogs as early as 40
ka (22–28) have been made on the basis of morphological (22,
24–27), isotopic (22, 29), genetic (22, 28, 30), and contextual as-
sessments (24, 31) of ancient canid remains. Yet, none of these
potential domestication markers is fail-safe, owing to the fact that
wolves and early domesticated dogs can be difficult to distinguish
from each other.
For example, common morphological markers used to identify
domestication such as tooth crowding, skull size, and reduced
snout length often fail to clearly distinguish dogs from wolves
(32–36). Isotopic signatures, and their dietary inferences, have
been used to identify early dogs, though these have also been
questioned given that the isotopic variation is often consistent
with wolf diets (3). In addition, genetic analyses of these proposed
early dogs have demonstrated that they do not belong to the
same lineages as ancient or modern dogs (30, 37). While genomic
estimates from multiple studies place the split time within wolf
lineages, including the one that ultimately gave rise to dogs, to
between ∼40 and 27 ka (14, 38), this timing is unlikely to reflect
the initiation of the domestication process (1, 39). Finally, sites
with purported domestic dogs have been questioned based on an
absence of carnivore gnawing (40) or pups (41), features taken to
indicate the presence of a living, breeding dog population.
Accordingly, claims for domestic dogs at the Belgian site of
Goyet (22, 42, 43) have been disputed since their cranial and
dental morphologies do not exclude the possibility that they are
wolves (3, 32–36, 44, 45). mtDNA analyses of these canids also
showed that they belong to an ancient European wolf lineage that
is genetically highly divergent from any dog haplogroup (30).
Similarly, genetic analyses of proposed Paleolithic dogs from the
sites of Ulakhan Sular (23), Tumat (46), Razboinichya (27), Berelekh
(23), Kostenki 8 (23), and Eliseevichi (25) have shown these canids
to be more closely related to ancient and modern wolves than
they are to dogs (30, 37, 47).
At least one of the purported dogs from the Czech site of
P
redmost´
ı(24, 48) has also shown a genetic affinity to wolves
over dogs (37). The domestic designation of these canids has
likewise been questioned based on analyses of their dental
and cranial morphologies (12, 32–36, 44, 45). Isotopic (29)
and dental microwear (31) analyses of the diet of the pro-
posed dogs at the site may also fallwithintherangeofvaria-
tion of the local wolf populations (12). Additionally, P
redmost´
ı
lacks evidence for carnivore gnawing or pups (40, 41), raising
further questions about the presence of a dog population at
the site.
The challenge for all claims of late Pleistocene dogs has been
to show conclusively, across several lines of evidence, that
the specimen(s) in question can be clearly distinguished from
contemporaneous wolves (3). Here, we take a conservative ap-
proach and only include those canids whose taxonomic status is
unambiguously domestic.
The earliest generally accepted remains of a domestic dog,
based on a convergence of morphological, genetic, isotopic, and
contextual evidence, comes from the site of Bonn-Oberkassel in
Germany, dated to ∼15 ka (4, 30) (Fig. 1). The morphology and
genetics of this young dog clearly distinguish it from local wolves.
Its coburial with humans and the evidence for its care after suf-
fering an illness also suggest it was a dog. Claims for contempo-
raneous domestic dogs have also been made at sites in France
(49), Germany (50), Israel (51), Italy (52), and Switzerland (53).
Based on their morphology and context, additional poten-
tial dogs may be present at Pleistocene Siberian sites such as
Afontova Gora, Diuktai Cave, and Verkholenskaia Gora (9, 23),
although their status has yet to be established. In the Americas,
the earliest confirmed archaeological dog remains, based on
combined morphological, genetic, isotopic, and contextual evi-
dence, are from the Koster and Stilwell II sites, which have been
dated to ∼10 ka (9, 16).
From a genetic perspective, hundreds of ancient and modern
canid mitochondrial and nuclear genomes have been sequenced.
Analyses of the nuclear data indicate that all dogs represent a
genetically homogeneous group that possesses varying degrees
of ancestry from three major ancestral lineages: a western Eur-
asian lineage (mostly found in European, Indian, and African
dogs); an east Asian lineage (e.g., dingoes); and an Arctic lineage
(e.g., huskies and ancient American dogs) (16). A recent study of
dozens of ancient dog genomes suggests that these lineages
were all established by at least 11 ka (54).
mtDNA data indicate that the vast majority of modern dogs fall
into one of four monophyletic haplogroups (A, B, C, or D), with the
majority belonging to haplogroup A (SI Appendix, Fig. S1). Recent
ancient DNA studies demonstrated that all precontact dogs in the
Americas south of the Arctic possess a unique mitochondrial
haplogroup (A2b) that is nested within mitochondrial haplogroup
A and which has since virtually disappeared (∼0.5%; ref. 16) in
modern dogs inside and outside of the Americas (16–18, 55).
Within A2b are four additional and well-supported monophyletic
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subhaplogroups, A2b1 through A2b4 (16), which are only found in
the Americas. Of those four haplogroups, A2b1 is pan-American
(possessed by dogs from California’s Channel Islands to Argen-
tina), while the other three haplogroups are more geographically
restricted, given current data (Fig. 2).
Molecular clock analyses have revealed the timing associated
with splits within haplogroup A (SI Appendix, Fig. S1). First, the
split between lineages A1b and A2 at the base of the haplogroup
is estimated to date to ∼22.8 ka (95% CI 26 to 19.7 ka; ref. 7). This
timing, which represents the oldest known coalescence between
Fig. 1. Lineages and estimated population divergence times (hexagons) for dogs (Top, in red), and humans (Bottom, in blue), for the period from
∼24,000 to 10,000 y ago. Divergence times are shown as point estimates. Confidence intervals for the respective point estimates are shown in
the horizontal red bars (dogs) and bluebars (humans) in the center of the figure, which shows as well the span of the LGM, ∼23,000 to 19,000 y ago.
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two dog mitochondrial lineages, suggests that dogs were do-
mesticated several thousand years prior to their first appearance
in the archaeological record. This estimate may have been af-
fected by later gene flow between wolves and dogs, though this
possibility is less likely since these haplogroups have not been
found in any ancient or modern wolves, and because wolf–dog
admixture appears to have been uncommon (54). Regardless, this
suggested early time frame indicates that dogs were likely do-
mesticated by the time humans crossed into the Americas.
The First People in the Americas
Our understanding of the origins and antiquity of the first people
to reach the Americas has advanced significantly over the past
decade through the identification of new archaeological sites and
the generation of ancient human genomes from individuals in the
Americas and northeast Asia.
Genomic evidence indicates that Native American ancestry
can be traced to a population that is currently estimated to have
diverged from an East Asian ancestor ∼30 ka (95% CI 36.4 to 26.8
ka; ref. 56) (all age estimates in this section are based on nuclear
DNA, except where noted). Around 24 ka (95% CI 27.9 to 20.9 ka
based on nuclear data and 24.9 to 18.4 ka based on mitochondrial
data; ref. 57), that population then split into at least two groups.
One group identified as Ancient Paleosiberians (APS) appears to
have remained in far northeast Asia, while the other group be-
came the basal branch of Native Americans (56). Both groups
subsequently, and separately, received gene flow (∼24 ka; Fig. 1)
from Ancient North Siberians (ANS), a population whose ances-
tors are detected archaeologically at the Yana RHS site in far
northern Siberia (∼31.6 ka; Fig. 2) and the Mal’ta site near Lake
Baikal (∼24 ka; Fig. 2; ref. 56).
From the time of the Last Glacial Maximum (LGM, ∼23 to 19
ka), the basal branch of Native Americans appears to have been
isolated in northeast Asia, where they remained before departing
for the Americas. There is currently no evidence of subsequent
gene flow with other populations in the region, though this does
not preclude the possibility of interaction with other groups that is
not visible genetically. This period of isolation, by virtue of where
it is suspected to have occurred, is known as the Beringian
Standstill (58). Estimates of its duration based on nuclear DNA, Y
chromosome, and mtDNA vary, but overall they indicate this
episode may have lasted as little as 2,400 y to as long as 9,000 y
(10, 57–59).
During this period of isolation, current evidence indicates that
perhaps ∼21 ka (95% CI 21.9 to 18.1 ka) this basal branch split into
at least two distinctive populations: Ancient Beringians (AB) and
Ancestral Native Americans (ANA) (60). Both the AB and ANA
populations crossed into eastern Beringia (present-day Alaska)
after their split, though the timing of their dispersal(s), whether
they moved simultaneously, and how long they may have main-
tained a degree of gene flow once they diverged from one an-
other remain unclear (60, 61). Although both populations reached
Alaska, to date no genomic evidence of the AB has been found
south of Alaska, or in any Alaskan populations after ∼9 ka (the
radiocarbon age of the AB individual from the Trail Creek Cave
site, Alaska; Fig. 2; ref. 10).
The ANA lineage, on the other hand, reached North America
south of the continental ice sheets, after diversifying ∼15.7 ka
(95% CI 17.5 to 14.6 ka; ref. 60) into northern (NNA) and southern
(SNA) branches (62). The NNA/SNA split must have taken place
well after ANA had physically separated from the population
represented by the AB lineage (57, 60), since NNA and SNA
groups are genetically equidistant to AB (otherwise, one or the
other of the groups would have been closer to AB). It is inferred
that this split took place as the ANA were moving south
from Alaska.
The estimated time of the split, and the archaeological evi-
dence for people in the Americas ∼15 ka (e.g., refs. 11 and 61),
implies that the route to the Americas south of the continental ice
sheets must have been along the Pacific coast. The alternative—an
interior route between the ice sheets (the “ice-free corridor”)—had
yet to open and did not yet support the plant and animal re-
sources necessary for human foragers (11, 63, 64). How much
earlier people may have arrived in the Americas is unclear:
Archaeological evidence provides only a minimum age, since the
oldest sites that have been found are not the oldest on the conti-
nent (61). Genetic estimates provide a maximum value, since
the peopling process must postdate the basal split of Native
Zhokhov
Bonn-Oberkassel
Afontova Gora
Mal'ta
Yana RHS
Trail Creek Cave Dog Haplogroup
A2a
A2b1
A2b2
A2b3
A2b4
C
Unknown canid
Dog
Species
Human
Human Ancestry
A1b
Ancient North Siberian (ANS)
Ancient Beringian (AB)
Koster
Fig. 2. A map depicting the sites and lineages mentioned in the text. Human and dog lineages are denoted (see references in the text).
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Americans, which could have been as early as 27.9 ka. It is note-
worthy, however, that there are no archaeological sites in the
Americas that can be shown to securely predate or were occu-
pied during the LGM.
Once people arrived south of the ice sheets, the NNA branch
appears to have had a relatively limited geographic spread. The
SNA branch, however, radiated throughout the hemisphere, and
as they dispersed they diverged genetically, starting ∼14.1 ka
(95% CI 14.9 to 13.2 ka; refs. 10, 62, and 65).
Reconciling Lineage Branching in Late-Pleistocene Humans
and Dogs
The Americas were one of the last regions of the world to be
settled by people, and based on the antiquity of dogs in North
America it is possible that the first people had canine companions
with them when entering this new landscape (9, 66). Dogs were
part of a larger cultural repertoire that may have assisted humans
in rapidly dispersing into and throughout the Northern Hemi-
sphere (67). Though people could have come to the Americas
without them, dogs must have entered along with people. It is
also reasonable to assume that, when human populations split
from one another, they took their dogs with them. Thus, by
aligning their respective population splits (Fig. 1), we can identify
the timing of their tandem late-Pleistocene movements.
Perhaps not surprisingly, there are challenges in comparing
divergence estimates obtained for dogs and humans. The dates
relevant to the introduction of dogs in the Americas were derived
from mitochondrial data and represent ancestral coalescence
events that predate population splits, especially if the ancestral
population was large. All ancient American dogs outside of the
Arctic, however, belong to the same lineage (A2b) which coa-
lesces with an ancient Siberian dog lineage ∼16.4 ka (95% CI 18.6
to 14.3 ka; refs. 7 and 16) (SI Appendix, Fig. S1). Although this
time provides an upper bound for the introduction of dogs in the
Americas, evidence for a population bottleneck associated with
the founding of the ancient American dog lineage (18) suggests
that this age may, in fact, be close to the population split between
ancient Siberian and American dogs. The deepest coalescence
event among A2b lineages dates back to ∼15 ka (95% CI 16.9 to
13.4 ka; ref. 7). Given that the A2b haplogroup is virtually absent
from outside of the Americas, it is likely that its deepest coales-
cence took place in the ancestral population of American dogs.
This time can, thus, be interpreted as a lower bound for diver-
gence between American and Siberian dogs.
This time frame is remarkably consistent with that of the first
peopling of the Americas (Fig. 1) and there are several key di-
vergence nodes in common. First, the deepest coalescence event
among dogs at ∼26 to 19.7 ka (16) is contemporaneous with the
split between APS and ANA/AB at ∼27.9 to 20.9 ka (56). This
correspondence suggests that dogs were already domesticated
around the time ANA ancestry was established. Second, the co-
alescence of the A2b (American dog) and A2a (Siberian and
American Arctic dog) lineages, at ∼18.6 to 14.3 ka (7, 16), and the
deepest coalescence event within A2b, at ∼16.9 to 13.4 ka (7),
overlap with the split time between the two major Native Ameri-
can lineages (NNA/SNA), at ∼17.5 to 14.6 ka (60). This indicates
that the radiation of the major human and dog lineages in the
Americas was contemporaneous, suggesting that they diverged
in tandem. This evidence, combined with the antiquity of dog
remains in North America (∼10 ka; ref. 9), and the lack of later
human migration into the Americas until the early to middle Ho-
locene (between 9 and 5 ka; ref. 68), indicates that dogs crossed
Beringia during the Pleistocene and were present south of the
continental ice sheets by the time the A2b lineage radiated at ∼15
ka, coincident with the widespread and rapid dispersal of the
SNA lineage.
Either ANA or AB could have brought dogs into the Americas
since there is archaeological evidence supporting the notion that
both groups crossed the land bridge. However, they may not have
crossed at the same time. AB are associated with a distinctive
microblade/microcore stone tool technology (69, 70) seen at the
eastern Siberian site of Diuktai Cave dated to ∼16.8 ka, from
which it spread northeastward into western Beringia, ultimately
reaching Alaska by ∼14.2 ka (site of Swan Point; ref. 71). Yet, by
that time people using a very different technology had already
been in the Americas south of the continental ice sheets for more
than a millennium and had begun to disperse throughout the
hemisphere (10). Although caution is always appropriate when
drawing links between stone tool traditions across space and time
(similar tools readily occur as a result of convergence), or between
stone tools and human populations, this evidence suggests that,
by the time AB arrived in Alaska ANA and dogs had already
passed through that region. This, in turn, implies that ANA were
the people who first brought dogs into the Americas.
Dog Domestication in Siberia
These parallels in the population divergences of humans and
dogs place constraints that allow us to reevaluate previously
proposed narratives for the origins of dogs and suggest a hy-
pothesis for the timing and geographic location of dog domes-
tication. On one hand, the split time estimated between wolf
lineages, including the one that gave rise to dogs, provides an
upper bound for domestication at ∼40 ka (14, 38). On the other
hand, since we established that dogs likely crossed Beringia with
the initial human arrivals, the archaeological evidence of people in
the Americas by ∼15 ka (11, 72, 73) provides a lower bound for
dog domestication. Combined with evidence that indicates that
dogs were not domesticated in the Americas (16), this points to
dogs having been present in Siberia prior to 15 ka.
Ancient human genome studies have identified multiple ge-
netically divergent groups that were in Siberia/western Beringia
within that time frame. This includes the ANS, APS, and the basal
branch of Native Americans, which, after ∼21 ka, split into ANA
and AB (Fig. 1). Ancient genomic data indicates that there was no
significant gene flow among these Siberian groups after ∼23 ka,
or with groups from outside Siberia from ∼39 ka (56). During this
same period there is also a paucity of archaeological sites in arctic
and subarctic Siberia and Beringia (71, 74, 75). Together, this
evidence suggests that human populations in the region must
have been small and living in relative isolation. They appear to
have remained so up to the time when ANA and AB (separately)
crossed into the Americas.
This evidence for little to no interaction with communities
outside of Siberia raises the question of how ANA acquired the
dogs that accompanied them into the Americas. One possible
explanation is that dogs were domesticated from a wolf pop-
ulation somewhere in Siberia or western Beringia during the late
Pleistocene, and before ANA crossed into the Americas. Previous
studies have suggested on the basis of genetic evidence that
dogs became domesticated in either East Asia (76), Europe (30),
Central Asia (77), or in more than one of these locations inde-
pendently (39). If dogs were domesticated in western Eurasia,
then their spread eastward into Siberia would have required a
far-ranging movement of people. Although possible, this seems
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unlikely given that western and eastern Eurasian human populations
had already diverged ∼39 ka (95% CI 45.8 to 32.2 ka) (56, 75, 78).
Any of the groups known to have been in Siberia during the
LGM (ANA, AB, APS, ANS, and their ancestral lineages; Fig. 1)
may have domesticated dogs. Dogs associated with ANA, how-
ever, do not represent a basal lineage but instead cluster with
Arctic dogs (7, 16, 67), suggesting they were not the initial do-
mesticated population. Likewise, although APS could have
domesticated dogs, there is no genomic evidence of their inter-
action with ANA (though meetings could have taken place and not
been recorded either archaeologically or genetically). Similarly,
dogs may have been domesticated by AB, but there is currently
no genetic evidence of their interacting with ANA. Nevertheless,
dogs could have been domesticated by their shared ancestral
lineage prior to its split at ∼21 ka.
By process of elimination and for several other reasons, ANS
therefore represents the more likely population to have initiated
the domestication process. For example, genomic analyses of
ANS individuals at the Siberian sites of Mal’ta (∼24 ka) and
Afontova Gora (∼17 ka) show evidence for late Pleistocene gene
flow from these populations into both ancient Native American
(Fig. 1) and western Eurasian lineages (79). This provides a
mechanism for the transfer of dogs into different groups and thus
their movement both east and west following their domestication.
Potential late Paleolithic dogs have also been identified at Afon-
tova Gora (80, 81), possibly representing the basal lineage,
though the genomes of these canids have yet to be analyzed. This
scenario also fits with a recent study supporting a single origin for
domestic dogs (54) and reconciles the presence of dogs in
western Eurasia, the Near East, and the Americas by ∼15 ka.
Dog domestication in Siberia during the LGM provides a
plausible context for the process. Climatic conditions may have
brought human and wolf populations (37) into close proximity
within refugial areas, given their attraction to the same prey
species. Increasing interactions between the two, perhaps
resulting from the mutual scavenging of kills, or from wolves
drawn to the detritus of human campsites (82, 83), may have ini-
tiated a shift in the relationship between the species, eventually
leading to dog domestication. A number of recently identified
potential late-Pleistocene dogs from the region, including those
from Afontova Gora (80) and Diuktai Cave (9, 23), offer an op-
portunity to test this hypothesis.
Conclusions
The archaeological evidence for both early humans and dogs in
Siberia and the Americas is sparse. The ability to isolate and se-
quence ancient DNA from the few individuals that have been
recovered is gradually providing new insights into the populations
that initially moved east over the Bering Land Bridge and into the
Americas. Dog mitochondrial sequences reflect the history of just
a single locus, and genomic sequences are necessary to recon-
struct their population history. Nonetheless, the coalescence time
estimates of their mtDNA lineages suggest that dogs and humans
share a correlated history of population divergences and migra-
tion from Siberia into the Americas. More specifically, we suggest
that the first people to enter the Americas likely did so with their
dogs. The subsequent geographic dispersal and genetic diver-
gences within each population suggest that where people went,
dogs went.
The convergence of the early genetic histories of people and
dogs in Siberia and Beringia suggests that this may be the region
where humans and wolves first entered into a domestic relation-
ship. The oldest time to most recent common ancestor of the A
haplogroup suggests that this process had already begun by
26–19.7 ka, which precedes the first unequivocal dogs in the
Eurasian archaeological record by ∼11,000 to 4,000 y. The vast
expanse of the region, combined with limited excavation, may
explain the absence of earlier dog remains in Siberia. Future anal-
yses of the handful of existing putative dogs, such as those from
the site of Afontova Gora (80), are necessary to test this hypothesis.
Since their emergence from wolves, dogs have played a wide
variety of roles within human societies, many of which are spe-
cifically tied to the lifeways of cultures worldwide. Future ar-
chaeological research, combined with numerous scientific
techniques, will no doubt reveal how the emerging mutual rela-
tionship between people and dogs led to their successful
dispersal across the globe.
Data Availability. All study data are included in the article and/or
SI Appendix.
Acknowledgments
A.R.P. was funded by the European Union’s Seventh Framework Programme for
research, technological development and demonstration under grant agree-
ment 609412. T.R.F. was funded by the European Union’s EU Framework Pro-
gramme for research and innovation Horizon 2020 under grant agreement
676154, and funding for the Qimmeq project came from the Velux Foundations
and the Aage og Johanne Louis-Hansens Fond. L.A.F.F. and G.L. were sup-
ported by a European Research Council grants (ERC-2013-StG-337574-UN-
DEAD and ERC-2019-StG-853272-PALAEOFARM) and Natural Environmental
Research Council grants (NE/K005243/1 and NE/K003259/1). D.J.M. is sup-
ported by the Quest Archaeological Research Fund. K.E.W. was supported by
a Wenner Gren Foundation grant and with R.S.M. an NSF (BCS-1540336) grant
and is currently supported by NIH grant awarded to Dr. Emilia Huerta-Sanchez
(1R35GM128946-01). The authors thank Victor Moreno-Mayar, Yun S. Song, and
the editor and the reviewers for helpful advice.
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