You might think that you know the story of the dodo – that fat, flightless bird that
once roamed the mountainous, tropical forests of the island of Mauritius in the Indian Ocean.
It's long been a poster child for extinction and an example of an evolutionary mistake
– a species whose eventual demise at the hands of humans was pretty much inevitable.
Even the dodo’s name is rumored to have come from a Portuguese word for simpleton.
I've been called worse...
But it turns out that the things you might’ve heard about the dodo are just…not true.
And this is partially because, when it went extinct, nobody actually noticed.
No one was really worried about preserving any information about it, until it was too late.
It would take a new discovery in 2005 for
us to realize that almost all of our old assumptions
about it were just totally wrong.
It turns out, we didn’t know the dodo at all.
So what is the real story of the dodo?
How did such a unique bird even evolve in the first place?
And are we really responsible for its extinction?
Well, much like the dodo itself, the answers to these questions are not so simple.
As far as we can tell, people never spent much time on Mauritius until the early 16th
century, when sailors began stopping there on their travels.
The first written records of the dodo date to 1598.
Dutch sailors described it as fat, slow, and
so oblivious to threats that it could be caught and killed easily.
And even though they apparently weren’t especially tasty, a single chonky dodo could
feed so many sailors that they were hunted in large numbers.
Sixty years later, the dodo was gone.
The last widely accepted sighting dates to
around 1660, but no one is really sure exactly when
it disappeared because no one was really paying attention.
In fact, the concept of an entire species
being gone forever hadn’t really caught on in western science yet.
Extinction wouldn’t even be proposed until around a century later, in the late 1700s.
So it wasn’t until well after the dodo had
already vanished that scientists started paying attention.
See, when the British took over Mauritius
in 1810, a major boom in interest in natural history was unfolding.
And, by that point, tales of the dodo were so odd that, at first, British naturalists
wondered if it had ever been real at all, likening it to a mythical phoenix.
In 1816, they held a meeting to ask the island’s
oldest inhabitants if they remembered the dodo or any talk of it.
Now, over 150 years had passed since the last known sighting.
So, unsurprisingly, they did not.
All that was left were some Dutch illustrations and stories, many of which contradicted each
other, as well as a few bones and body parts scattered in museums throughout Europe.
The world had been left without even one complete dodo.
In 1848, two naturalists working at Oxford published the first scientific work on the animal.
They used what little evidence they’d been able to gather and study and drew from the
various Dutch accounts from centuries earlier.
They called it a “strange abnormal bird”
with a “grotesque appearance,” which seems needlessly mean, but they
were at least convinced that it had once existed.
They concluded that it was some odd form of
pigeon, an idea that they were widely ridiculed for at the time.
And, for a long time, that’s about as complete
a picture of the rise and fall of the dodo as we had.
But in 2005, all that began to change.
Excavations at a swamp on the island unearthed more than 200 dodo bones, giving
researchers a chance to study the animal in a new light.
The site allowed them to understand the broader ecosystem of the dodo and put the species
into its actual ecological context for the first time.
And what the researchers found was surprising.
The dodo’s supposed stupidity wasn’t a result of having evolved in a sheltered paradise
that left them fat, happy, and complacent.
The swamp and the dodos it preserved told a totally different story.
What the researchers saw was an ecosystem
characterized by significant environmental challenges.
Climatic instability and extreme weather events, like cyclones and droughts, were common.
For example, the site documented a drought 4200 years ago that caused animals to flock
to the area in search of fresh water.
The stress of this event even left a mark in the bones of the dodos themselves.
These marks came in the form of lines of arrested growth, which reveal periods where growth
slowed as the animal struggled to find resources.
So the fact that dodos, as a species, were able to survive and thrive under these kinds of
repeated challenges over evolutionary time meant that they must have actually been pretty
resilient and well-adapted to their unpredictable home.
And the more-complete skeletons from this swampy bone-bed even revealed that the birds had
a number of impressive adaptations for their environment.
For example, they had strong legs, which would
have helped them get around in their mountainous environment.
And they had big skulls that housed a pretty large brain with well-developed olfactory
regions, suggesting they had a good sense of smell.
Plus, as the field of ancient DNA has advanced over the last two decades, we’ve even been
able to study dodo genetics in increasing detail.
This has revealed that dodos are, indeed, most closely related to doves and pigeons,
confirming the idea proposed by Oxford researchers back in 1848.
Ok, but so how did they end up becoming so unusual compared to their closest living relatives?
Well, it seems that dodos emerged from a flying Asian pigeon ancestor that began
crossing the Indian Ocean around 43 million years ago.
As a chain of volcanic islands began to form in the Ocean around this time, the birds used
them as stepping stones on their travels.
Eventually, when Mauritius emerged from the waves around 7 million years ago, the dodos’
ancestors arrived by air, settled into their new home, and became flightless.
After all, evolution is about trade-offs, and in an environment without any predators,
the ability to fly simply wasn't worth the energy cost.
It’s a process we’ve seen happen time-and-time again with birds that arrive on islands without
animals they need to evade.
Flight becomes unnecessary, wings become vestigial,
and bodies become bulky - sometimes comically so.
Ok, so if the dodo was actually pretty well-adapted
to its environment, rather than being an evolutionary
mistake, then what happened to them?
Like, why did they go extinct?
Well, the classic story is that we simply ate them to extinction, because they were
too easy to catch.
But in reality, it seems that this was less a result of our appetite, and more our habit
of altering the delicate balance of ecosystems wherever we go.
You see, dodos had one key vulnerability that may have spelled their downfall - an Achilles
heel, if you will, that put them at risk even
before they were born…
They only laid one large egg at a time, and on the ground too, rather than hidden away
in some treetop nest.
And when people arrived on Mauritius, we brought a couple of very egg-hungry associates with us.
The associates I'm talking about are pigs and rats.
These creatures have devastated a range of island bird species across the world after
being introduced, regardless of whether those birds seem intelligent or agile or not.
So it wasn't exactly us humans that doomed the dodo – not directly at least.
Nor was it necessarily their supposed lack of smarts and speed.
Far from being the hopeless sitting duck that it may have seemed at first glance, the dodo
was for the most part, an evolutionary success.
It was a species superbly adapted to its specific ecological conditions.
Until, of course, we and other mammals that
we traveled with suddenly changed those conditions.
And its demise didn’t just prove to be a valuable case study in understanding the concept
of extinction back when that was a radical new idea…
But it also may end up being a case study
in an equally radical idea emerging today: de-extinction.
Armed with our new understanding of the dodo’s ecology, its DNA, and the recognition that
its extinction was not inevitable,
the possibility of bringing it back is seriously being explored.
So perhaps the dodos’ story has another
surprising chapter or two just waiting to be written.
Hey friends!
This episode was part of PBS's celebration of Earth Month,
and on that note I'm excited to tell you about a new series called "Women of the Earth".
It's a documentary series on PBS Terra about women
who are working to heal the earth from climate change.
In the first episode, you'll meet a shepherd pioneering sustainable grazing techniques.
There's a link to it in the description below.
We hope you check it out, along with the rest of PBS's Earth Month playlist. Thanks!
Ok, so hey, what do you want to know about the story of life on Earth?
Let us know in the comments!
And thanks to this month’s well adapted Eontologists!
Why...
are you making me say these things?
Gale Brown, Juan M, Jacksy Weiss, Melanie Lam Carnevale, Raphael Haase, Annie & Eric
Higgins, John Davison Ng, Jake Hart, and Colton.
Become an Eonite at patreon.com/eons and you
can get fun perks, like submitting a joke for me to read.
Like this one from The Kemp Family.
Why did archaeopteryx get the worm?
Because they were an ‘early bird’.
Yeah...
That, that works on two levels so I guess that counts as a joke.
[laughs]
[Faith, DIRECTOR OF THE SHOOT, OFFSCREEN] I loved it!
And as always thank you for joining me in the Adam Lowe studio.
Subscribe at youtube.com/eons for more primordial ordeals.
I like that!
...even revealed that the birds had a number of impressive adaptations for their environment.
For example, they had strong legs, which I do not...
[laughs]
Today's leg day so that's on my mind.
I'm already dreading it.
I'm up to 380 in the leg press. That's my PR.