It was the summer of 2018 in Siberia, and
a patch of permafrost near the Indigirka River had melted enough to uncover the body of a
two-month-old puppy.. After its almost perfectly preserved remains
were discovered, scientists determined that the puppy was an astonishing 18,000 years
old The frozen animal was nicknamed “Dogor”
- not only the word for ‘friend’ in the local language, but also a clever play on
words: is it a dog, or…? Something else? And, despite its age, it still had most of
its fur, teeth, and even a cute little nose preserved. But while Dogor was in really good condition
for a nearly 20,000 year old pup, scientists were unable to confirm what species it belonged
to. Was it a dog or was it a wolf? Or was it something in between? Dogor comes from the period of time when scientists
think wolves were becoming domesticated, so knowing whether it was a wolf or a dog could
help us better understand the specific time, and maybe even the place, that domestication
occurred. Because, there’s still a lot we don’t
know about how wolves went from fairy tale villains to our canine companions. Like, when did they first become domesticated? Where did this happen? And what did the process look like, in terms
of genetics and anatomy? We’re still figuring out the details, but
most scientists agree that it took thousands of years of interactions to develop our deep
bond with these good boys and girls. Modern dogs….like my good friend Abby here…. belong to the subspecies known as Canis lupus
familiaris And we can trace their origins back to a now-extinct
species of wolf from the Pleistocene, an ancestor they share with the modern grey wolf, called
Canis lupus. But the exact species of this ancestor is
still unknown. While some potential ancestral wolf species
- like the extinct species from which the Taimyr wolf, a specimen discovered in Northern
Siberia, is from - have been identified, genetic analysis has shown that they’re not direct
ancestors to what would become Canis lupus familiaris. What we can say from studies of dog and wolf
genomes is that wolves and dogs began to genetically diverge from each other sometime between about
40,000 and 27,000 years ago. And figuring out the exact timing is tough,
because it looks like the split happened over a very short period of time, and there was
probably interbreeding between domestic dogs and wild wolves along human migration routes. So dogs still looked pretty wolf-like at the
start of domestication. It’s also complicated because these two
species diverging genetically isn’t necessarily the same thing as domestication; one’s just
a split in the gene pool, while the other’s the whole behavioral and genetic process that
humans were involved in. But one of the key genetic traits wolves and
modern dogs share, that has been really strongly selected for in modern dogs, seems to be hypersociability,
which is the tendency for adult animals to initiate social contact even with members
of other species. And for some wolves, this tendency, along
with other behaviors, like scavenging for food, could’ve made them a better fit for
eventual domestication. These traits also would’ve been useful as
human settlements became more widespread, with resources that these canines definitely
would have wanted. This is known as the commensal pathway to
domestication, where an animal benefits from a relationship with humans, but there’s
little to no benefit for the humans themselves... well you know at least at first In this case, proto-dogs were drawn to the
discarded human food, which also likely attracted other animals that they could’ve preyed
on, too. And there seems to be some evidence that this was
probably happening around 28,500 years ago. A new paper published in 2020 was able to
distinguish between two different types of canids from a site in the Czech Republic based
on the microscopic wear on their teeth. One group had wear that better matched a diet
with more meat in it, while the other group had wear that suggested they’d been chomping
on harder, more brittle foods - things like bone. And the researchers think the difference means
that the bone-chewing group was hanging around this human settlement more and eating their
scraps. Eventually, humans realized that wolves - once
domesticated - could be useful: they could be guards, work with hunters, and even help
with domesticating other livestock species. And after that, wherever humans went, their
canine companions followed. In fact, we can actually track the spread
of agriculture through a particular genetic adaptation in dogs! In 2013, scientists were able to isolate the
gene associated with the change from the carnivorous diet of wolves to a more starchy diet
in dogs. Domestic dogs have more copies of the gene
known as AMY2B than wolves do. AMY2B codes for an enzyme that’s secreted
by the pancreas that breaks down starch. An increase in starch consumption in people
is often associated with agriculture - like growing wheat and rice. And domesticated dogs living in human settlements
would’ve been fed the kinds of things that people were eating, too. Along with the difficulties in figuring out
when dogs were domesticated, there’s also been some debate about whether it happened
once or more than once. Like cats, dogs were once thought to have
been domesticated twice, because in 2016 researchers showed that the genetic divergence between
European and Asian dogs seemed to happen after dogs were found in these areas, suggesting
domestication happened in both Europe and Asia. However, another study from 2017 suggests
that dogs may only have been domesticated once. This research on the genomes of two really
old dog specimens from Germany shows that this might’ve happened as far back as 20,000
to 40,000 years ago! One set of dog remains was 7,200 years old
and the other 4,700 years old. And by comparing them to modern wolves and
dogs, scientists were able to find that they both had between 70-80% of European ancestry
within their genetic make-up. And this study found a much older date for
the genetic divergence between European and Asian dogs than the 2016 study did - old enough
to suggest that domestication happened just the one time. So it seems there was one continuous lineage
of domesticated dogs, instead of two separate domestication events. While we’re still figuring out when all
of this took place and how it happened, it didn’t seem to take that long before people
were deeply attached to their pups. And we can see this bond in the archaeological
record with burials. Across Europe, Asia, Africa, and North America,
dog burials can be found spanning the Late Pleistocene to the Mid-Holocene Epoch. What makes these dog burials special is that
many of them were treated and deposited in ways that are really similar to how humans
are buried. This implies that these dogs were seen as
very close companions, even in death. For example, the remains of a male dog were
recovered by archaeologists at the 9,000 or so years old cemetery in Siberia
alongside other artifacts, like a spoon made from a large antler. This dog was an older adult, with evidence
of wounds that were partially healed by the time he died, showing that he had been cared
for during his life. An analysis of the chemistry of one of
his vertebra showed that his diet included both terrestrial and aquatic resources, similar
to the diets of the people at the site. This might mean that these dogs and humans
lived in close proximity, even sharing food. We also see mixed burials in some cultures,
where both dogs and humans are laid to rest together. In fact, the earliest known burial of a dog
-- a puppy that was buried around 16,000 years ago in Germany -- was actually found alongside
two human bodies! Dogs were also buried alongside their humans
in Egypt, where dogs were often used in hunting and guarding. This may have been the case for a mummified
dog found in a tomb at Valley of the Kings, which may have been a
favourite hunting dog of one of the rulers buried nearby. Over thousands of years, domestication created
both physical and genetic changes in dogs. While many early dogs looked pretty similar
to each other, new breeds were developed to meet a variety of human needs, and coat colors
and textures became more diverse. Many of these changes can be traced to the
cross-breeding and hybridization of individual dog populations, as humans moved around the
planet with their canine companions and came across new groups of canids. Today, there are hundreds of dog breeds, and
most of them aren’t actually that old. They came about because of the introduction
of dog shows during the Victorian era in Britain. So dogs were originally drawn to our ancestors
for food, but they eventually bonded with us, working and living alongside us for thousands
of years. And this bond continued even after death,
based on the archaeological record of human and dog burials. But the origins of this relationship are still
more complicated than scientists originally thought, with new discoveries changing the
history of dog domestication all the time. And we’re still waiting to find out the
DNA results of Dogor, that 18,000 year old puppy from Siberia. The hope is that it can shed some light on
the early days of domestication. But, at the very least, we can say that dogs
have been our species’ best friend, for a very, very long time. Gotta give a quick shoutout to David Howe,
the ethnocynology guru, for making sure what had our “pups” in a row. Big high fives to this month’s Paws-itively
awesome Eontologists: Patrick Seifert, Jake Hart, Jon Davison Ng, Sean Dennis, Konstantin
Haase, and Steve! All pledge levels have access to our Discord,
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Dogs are still nature