In 19th century Australia, English settlers
set out to explore the continent’s vast interior. But the hot, dry climate of the Outback was
too harsh even for the most resilient horses. So, settlers and traders enlisted the help
of another domesticated animal that was up to the task: the camel. Thousands of camels were imported to Australia
to work as pack animals on expeditions and trade routes. They continued to cross the continent until
the early 20th century, when they were effectively put out of business by the arrival of the
combustion engine. Their services no longer needed, the camels
were set loose in millions of square miles of arid desert where few animals could survive. And those camels didn’t just survive, they
thrived. Today, that feral population numbers over
one million! With their wide feet, to help them walk on
shifting sands, and their fatty humps to store energy, camels are famous for the adaptations
that allowed them to flourish where most other large mammals would perish. But the fact is, camels didn’t originally
evolve in the desert at all. They didn’t even evolve in Africa or Asia,
where they live today. The story of the camel begins over 40 million
years ago in North America, and in an environment you’d never expect: a rainforest. The very first known possible member of the
camel family is Protylopus which appears in the fossil record about 45 million years ago,
in what were once the rainforests of southwestern North America. Today the Southwest makes us think of red
rocks and cactus, but during the Eocene Epoch, it was lush, balmy, and very rainy. Protylopus was well suited to this environment
because it was an artiodactyl, an even-toed, hoofed mammal whose members today include
antelope, deer, and pigs. So you might say Protylopus looked more like
a tiny deer than a camel because, unlike today’s camels, it walked on four toes, all capped
with hooves. And its toes are what took scientists by surprise
when the first Protylopus fossil was found in Utah in 1898. At the time, the flat-footed stance of the
camel was assumed to be a primitive condition that other artiodactyls lost as they adapted
to living in more open environments. In fact, the suborder Tylopoda, which includes
camels and their extinct relatives, was named for the wide “cushion feet” that scientists
thought all camels always had. But it turned out that the splayed toes that
make modern camels so good at traversing the desert weren’t a feature that camels started
off with. They were a later adaptation. And Protylopus also didn’t have a lot of
the other traits that we associate with members of the camel family, like long limbs and long,
flexible necks. In fact, Protylopus is so strange that it’s
sometimes put in a family with other, kinda bizarre, not-quite-camel creatures, called
the Oromeryicidae So, you’d be forgiven for not seeing the
family resemblance. But, Protylopus is still considered one of
the earliest known Tylopods, because it had many of that group’s more subtle but defining
traits, like having incisor teeth in the upper jaw, and sharp, tusk-like teeth in the lower
jaw. And speaking of its teeth, there’s one more
weird thing about this very tiny camel. A closely-related group of artiodactyls called
ruminants have four-chambered stomachs that help them digest grasses. But Protylopus and its descendents have had
to make do with less efficient three-chambered stomachs. So, Protylopus was more of a browser, preferring
a diet of soft leaves and fruit over grass -- a preference that will play a big role
in its evolutionary story. Now, little Protylopus didn’t make it out
of the Eocene. But it had a cousin with whom it shared an
ancestor, and it was better suited to the mosaic of forests and grasslands that was
starting to transform North America. That cousin was the slightly larger Poebrotherium,
which showed up about 37 million years ago. Poebrotherium had long, slender limbs, good
for running on more open terrain, but like Protylopus, it still walked on hooves rather
than toe pads. And this camel did very well for itself indeed. Fossils of Poebrotherium have been found across
western North America, and in a greater range of habitats, from wooded grasslands to shortgrass
prairies. But we can tell by its teeth -- specifically,
its shorter molars -- that it still relied on leaves as its main food source, rather
than grass. Now, Poebrotherium disappears from the fossil
record about 33 million years ago, and like Protylopus, that marked the end of its lineage. But other lineages continued to thrive as
the shrubs and trees of the Oligocene turned into the grassy, open Miocene. This was the time of what you might call the
Camelid Explosion! In the Miocene, camels reached their peak
of diversity, when nearly 30 genera roamed all over North America. In fact, camels at this time were so successful
and abundant that they’re one of the most common herbivores found in Miocene fossil
beds. This explosion in diversity saw the development
of four different subfamilies, including the one that led to all modern camels: Camelinae. And while these families had a lot of differences,
they also had one major thing in common - they didn’t walk on tip-toes anymore. For instance, fossils of the long-necked Aepycamelus
have been found in deposits from this time, from California to Florida. And in addition to its kinda giraffe-like
features and impressive height, this camel was notable because it’s one of the first
to have feet like those of modern camels. While early camelids walked on the tips of
their hooved toes, Aepycamelus walked on the padded bottoms of its feet. It had relatively short toes, with ankle bones
that splayed out at the base, suggesting that its toes spread apart and were supported by
large pads. And these new feet were a great adaptation
for its new environment. Because, Aepycamelus browsed on the open savanna,
a lot like a modern giraffe does, where trees were fewer and farther between, so it had
a lot of ground to cover in its search for food. But the way this camel looked and lived also
brought about another innovation: It gave rise to a whole new way of walking. Aepycamelus was probably the first animal
to develop the “pacing gait” seen in modern camels. In a pacing gait, the front and back legs
on the same side move at the same time, rather than the front and back legs on opposite sides. This keeps those long legs from knocking into
each other as the camel speeds up, which in turn allows for a longer stride that conserves
energy. And this is great when you have a lot of ground
to cover. But the pacing gait also makes the animal
a lot less stable, which is why most four-legged mammals don’t use it. It causes an awkward rocking motion as all
the animal’s weight moves from one side to the other. And this is where those wide, flat, toe pads
came in handy. They helped stabilize the big, heavy camelids
as they swayed from side to side in search of their next meal. And as the Miocene went on, camels were definitely
getting bigger, and heavier. Megatylopus was one of the biggest camels
ever, at 3.5 meters tall - which is a meter and a half taller than most camels today. And Megatylopus is also one of the first camels
that we’re pretty sure had that other famous camel feature: a hump. It had spines on the vertebrae just below
its neck that were incredibly long — perfect for supporting a fatty, muscular lump of tissue. Those fat stores probably helped Megatylopus
as it paced across the ever-expanding grasslands of North America, acting like a snack pack
in areas where food was scarce. But while Megatylopus wandered far and wide
within North America, a close relative would be the first camel to leave the continent. Sometime in the Miocene, Paracamelus crossed
the Bering land bridge into Asia, changing the course of camel history. The earliest fossils of this camel have been
found in Nevada, dating back about 12 million years. But by 7 million years ago, this intrepid
explorer had already made it as far as Spain. Its fossils have been found throughout Europe
and Asia, in places like China, Russia, Turkey, and Romania. But perhaps the strangest place it’s been
found is on Ellesmere Island in northern Canada, where a 3.4 million year old fossil was reported
in 2013. Needless to say, that’s a strange place
to find camel fossils, because it’s...very, very far north. So far north that, at 78.5 degrees latitude,
it’s in the Arctic Circle. Now, the Arctic was warmer 3 million years
ago than it is today. And if Paracamelus stayed in this environment
year-round, it would still have lived in boreal forests with deep snow, experienced average
annual temperatures below freezing, and endured 6-month-long winters with little sunlight. And yet! The very same adaptations that allowed Paracamelus
to survive the unforgiving conditions of deserts and grasslands may also have been what allowed
it, and other camels, to possibly survive in the Arctic. For instance, their humps would have served
them well during those long winters. Their large furry bodies would have retained
heat longer. And their broad, padded feet that worked so
well on sand could have functioned like snow shoes. And it was this lineage of hardy pioneers
that eventually brought us the camels we know today. Camelus, the genus of modern camels, was the
first camelid to evolve outside of North America. And it and its descendants are what are now
known as the Old World Camels. But they had to wait a few million years before
their favorite travel companion hit the scene. By which I mean, us. Once humans and camels found each other, both
animals would be changed forever. Because, we domesticated them. But, only some of them! About 5,000 years ago, humans in Asia managed
to domesticate some members of the species Camelus bactrianus, the bactrian camel. These are the double-humped camels that originated
on the steppes of Central Asia. But there was a whole population of bactrians
that were never domesticated! And DNA evidence has revealed that, by 700,000
years ago, the wild and domesticated bactrians had diverged enough that they had actually
become two completely distinct species. Today, only about 1400 wild bactrians are
still alive, the only truly wild members of the camelus genus. And at the same time that Bactrians were becoming
domesticated in Asia, another species, the Dromedaries, were starting to be used by humans
around the Arabian Peninsula and the Horn of Africa. Those dromedary camels are the species that
was sent to Australia in the 1800s. But old world camels aren’t the only members
of the camelid family, and they’re not the only ones that we domesticated. While ancient old world camel relatives were
roaming the Arctic 3 million years ago, another one was traveling in a different direction. Members of a genus known as Hemiauchenia left
North America to go check out South America, which had recently become connected by a land
bridge. And Hemiauchenia likely became the direct
ancestor of all of South America’s camelids. This includes the wild guanacos, which eventually
gave rise to the llama. And the wild vicugna, from which alpacas are
descended. So today, all modern members of the camelid
family around the world are either domesticated or have a domesticated descendant. And that’s because all the features that
made camels so good at adapting to harsh ecosystems - their size, their pacing gait, their splayed
toes, and for some, their humps - also made them useful companions to humans throughout
the ages. So, why do camels no longer roam their native
turf of North America? Well, in the second half of the Miocene, grasslands
continued to expand, causing camels’ preferred leafy foods to become less common, while animals
that were better adapted to feed on grass - like horses - flourished. One North American camel, called Camelops,
lived just long enough to cross paths with humans when we arrived in North America. Its remains have been found at a human hunting
site dated to about 13,000 years ago. Soon after, though, Camelops vanished, and
the time of camels in North America came to a close. But camels survived in their new homes on
other continents, and once again began to spread to new frontiers with the help of human
companions. So, camels have made an incredible journey,
a journey that began in North America. And from there, they’ve adapted to some
of the world’s most extreme environments -- from the deserts of northern Africa to
the Australian Outback -- and have often taken humans along with them, for the bumpy ride. Thanks for joining me for today. And BIG thanks to our Eontologists: Jake Hart,
Jon Ivy, John Davison Ng and of course, everybody’s pal, STEVE! If you’d like to join them in supporting
this channel, head over to patreon.com/eons and make your pledge for some neat n nerdy
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Aepycamelus looks like something I would come up with in Spore