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 benefits.
Now, what do you want to learn about?
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