Marsupials are similar to placental mammals, but differ in how they reproduce. Most marsupials lack a placenta, so they are unable to feed their offspring in the womb. Instead, after only a few days of gestation, their young must crawl out of the womb to feed from a nipple inside the mother’s pouch. (Thank god we humans don’t give birth this way, I can’t imagine any woman would want baby fetuses crawling out of her nether regions. Creepy. Although… the current method isn’t much better.)
What’s also intriguing about marsupials is where they’re located. There are 334 known species of marsupials; 70% live in and around Australia, 28% live in South America, and 2% live in Central and North America.
Looking at the map below, we can see that marsupials make their homes about as far away as you can possibly get from the Middle East, where Noah’s Ark would’ve settled.
What’s also interesting is that there are no truly native placental mammals in Australia. How did all these marsupials manage to pull off such a long and segregated migration? Secular science and creationists offer two very different competing explanations, let’s take a look at both.
The Secular View
Fossil evidence suggests that the earliest marsupials originated in China and then became quite common in North America (even outnumbering placental mammals, for a time). As their numbers dwindled in North America, they began to thrive in South America. Most of the marsupials that remain in the Americas today are from the opossum family (didelphidae).
Scientists say that millions of years ago, our earth was a very different place. Back then, Australia was connected to South America by way of Antarctica. Scientists once theorized that a small number of marsupials must’ve found their way from South America to Australia by way of Antarctica. It was a pretty fantastic claim, but the discovery of marsupial bones in Antarctica have all but confirmed this suspicion.
For years and years people thought marsupials had to be there, this ties together all the suppositions made about Antarctica. The things we found are what you’d expect we would have.
— Dr. William J. Zinsmeister, Paleontologist at Ohio State University’s Institute of Polar Studies
More recent evidence from retroposon markers in DNA also suggests that all Australian marsupials descended from South American ancestry.
Other plant and animal fossils found in Antarctica match up with those found in Australia and South America, strongly suggesting that not only were these continents once connected, but that Antarctica once enjoyed a warmer climate before these lands split apart.
Roughly 35-50 million years ago, Antarctica wished Australia “bon voyage” and it slowly began drifting toward the equator. The Australian rain forests gave way to extensive grasslands, and the marsupial stowaways spent the next few million years in isolation, learning to survive in the new ecological niches that Australia offered.
Most palaeontologists agree that Metatheria originated in Asia, diversified throughout the northern continents, dispersed into Gondwana (the modern Southern Hemisphere) around the beginning of the Palaeocene epoch (65 million years ago), then moved through Antarctica to Australia before the Australian continent was isolated by the opening of Drake Passage between South America and Antarctica.
— Bennett, Verity. 2012. Fossil Focus: Marsupial evolution – A limited story? Palaeontology Online, Volume 2, Article 10, 1-9
Today there are far more species of marsupials in Australia than in South America, and it’s believed that this is due to Australia’s changing environment, and a lack of competition from other animals.
In other words, a handful of stranded marsupials evolved into all the marsupial species we find in Australia today. There are no native placental mammals there, because there were few, if any, on the continent when it set sail from Antarctica. Presumably, the route leading from South America to Australia was not a very heavily traveled one.
The Creationist View
Creationists have a largely different view; they believe a global flood wiped out all mammals except for those aboard Noah’s ark.
While creationists believe the landscape of the earth may have changed dramatically during the flood, most don’t believe that the earth has changed much since then. This means marsupials would’ve had to cross multiple bodies of water in order to reach Australia and South America. To bridge these gaps, creationists suggest an ice-age occurred soon after the flood.
Creationists theorize that this ice age lowered sea levels and created a land bridge between Asia and Australia. To the north, a snowy land bridge connected modern-day Russia to Alaska via the Bearing Strait, allowing for some marsupials to cross over the frozen landscape and make it down to South America (hopefully without becoming tiny, frozen, “marsupcicles” in the process).
To explain the absence of any placental mammals in Australia, creationists theorize that marsupials outpaced all placental mammals because they were able to carry their newborn in pouches as they continued their journey. The Australian marsupials then crossed the land bridge before rising waters (and possible earthquakes) caused the land bridge to disappear, preventing any placental mammals from passing.
When a marsupial has its young, they can hop into the mother’s pouch, and the mother can continue migrating. In other words, marsupials can travel farther faster than many placentals.
— Bodie Hodge, Answers in Genesis – June 8, 2012
So which explanation is correct?
Obviously, these explanations are very different. Let’s take a closer look at some of the more debatable points.
Both creationists and secular scientists believe in ice ages, and that there was once a land bridge across the Bearing Strait. But few (if any) scientists believe that water levels dropped low enough to create a land bridge between Asia and Australia during the “Last Glacial Period.”
Part of their reasoning is that there are deep trenches where subduction divides these continents. This tectonic border would likely prevent any land bridges from forming. Creationists counter this by suggesting that earthquakes may have since changed the landscape or made these trenches deeper, or that all the marsupials found other, more creative, ways to get across…
“In some cases, animals could have ridden on floating debris to make it to islands or other far-reaching places.”
— Bodie Hodge, Answers in Genesis – June 8, 2012
How did all the marsupials get their first?
Even assuming a land bridge existed, how did all marsupials arrive in Australia ahead of all placental mammals?
Marsupials can carry their young, which allows them to avoid having to stop to care for them, but some mammals are born with the ability to walk — and even run — while some marsupials would’ve surely made for extremely slow travelers.
The southern marsupial mole, for example, spends most if its life underground… and has no eyes. Did it blindly burrow its way to Australia?
The koala bear is another example. It sleeps or rests 22 hours a day and is completely arboreal (lives in trees). When it’s not resting, it’s busy filling up on yummy eucalyptus leaves (which are indigenous to Indonesia and Australia, but that’s another problem).
It’s hard to imagine that all these blind, sleepy, and slow marsupials could’ve managed such a migration, let alone beat every single placental mammal to boot! (Especially when you consider that placentals outnumber marsupials 15 to 1!). What’s also amazing is that not a single marsupial stayed behind to make its home elsewhere along the way — they all migrated to the furthest ends of the earth before making their home.
How did this migration happen?
It’s almost as if all marsupials traveled together in one large group, one that outpaced all the placental mammals. Perhaps one marsupial, I imagine it would’ve been the kangaroo (because they’re obvious natural leaders), stood up after the flood and said, “Alright mates, listen up! I want everyone with a pouch to line up over here. God wants us to go on a walkabout to the ends of the earth, so that means there will be no settling anywhere in Africa, Europe or Asia. Got that? Also, some of us are much slower than others… or completely blind… so we may need to carry these guys on our backs or in our pouches.”
Perhaps, when they’d traveled as far as Mongolia, the kangaroo announced, “The God of Abraham has sent an ice age so that we may finish our journey. Some of the opossums will head north, across the Bearing Strait, and down through Canada, and into the Americas.” (Of course, these places didn’t actually go by these names back then, but I’m not sure what a kangaroo would’ve called them).
The kangaroo continued: “It’s going to be a long, cold, arduous journey with weather like you’ve never seen, so make sure you opossums dress warm and have a snow buddy. The rest of us will be heading south to Australia ahead of all the placental mammals. We will never see each other again, so ladies and gentlemarsupials, I want to say what an honor it’s been making this long journey with you all.”
It may sound crazy, but if we can have talking snakes and donkeys, this trip may have required a talking kangaroo.
The Fossil Record
Unfortunately, there is no fossil evidence for a migration of modern marsupials across Europe and Asia. Creationists reason that just because we don’t find these fossilized remains, it doesn’t mean it never happened. They acknowledge that it’s rare for fossils to form, and insist that an absence of fossil evidence does not disprove their theory. (Wait… why is this all sounding so familiar?)
When we think with a Biblical perspective, we realize that all kinds of land animals must’ve once lived in the Middle East, because they came with Noah’s ark.
— Ken Ham, President Answers in Genesis, USA
Meanwhile, scientists had made an almost equally absurd claim about marsupials once journeying across Antarctica… and the fossil evidence proved them right!
Evolution can sometimes seem like a leap of faith, because we can’t see it happening. How does something like an opossum morph into something as different as a koala bear, a wallaby, or a kangaroo?
While scientists might rely on things like fossils and genetic evidence, this evidence cannot be readily observed by the layman like myself. I’m more comfortable with evidence I can actually see.
In the case of marsupials, some of that observable evidence comes from similarities in features, like the trademark pouch. Another thing that’s observable is that all these similar animals live in an isolated neighborhood.
While many marsupial transitional forms may be long gone (even creationists admit fossils are difficult to find), when I look at the marsupials that exist today, I can see the family resemblance. The brown dorcopsis looks like a small wallaby, and the wallaby looks like a small kangaroo, and the tree kangaroo, with its long tail, looks like the lovechild of a kangaroo and a koala.
Considering their isolation and similarities, I feel I can safely conclude that these animals must be somehow closely related. While it’s reassuring that other lines of scientific evidence confirm this relationship, we don’t need this evidence to make this initial observation.
If we wanted to press the matter, we could suggest that God performed some form of miracle — perhaps magically transporting all these mammals. But if that’s true, why transport only marsupials, and not placental mammals? Why deceive us with the impression that these similar animals must’ve evolved on this island?
The natural evidence suggests one history, and the Bible another. While I’m willing to accept the flood account, I must insist that it be accompanied by respectable evidence. If we didn’t have the Bible, there’s just no way we’d conclude that all Australian marsupials emerged from the Middle East after a great flood and an ice age.
Because we only find these uniquely similar marsupials in Australia, I’d have to conclude that the most logical explanation is that this is where they originated.
Think what the geographical distribution of animals should look like if they’d all dispersed from Noah’s Ark. Shouldn’t there be some sort of law of decreasing species diversity as we move away from an epicentre — perhaps Mount Ararat? … Why would all those marsupials – ranging from tiny pouched mice through koalas and bilbys to giant kangaroos and Diprotodonts — why would all those marsupials, but no placentals at all, have migrated en masse from Mount Ararat to Australia? Which route did they take? And why did not a single member of their straggling caravan pause on the way, and settle — in India, perhaps, or China, or some haven along the Great Silk Road? … Why would an all-powerful creator decide to plant his carefully crafted species on islands and continents in exactly the appropriate pattern to suggest, irresistibly, that they had evolved and dispersed from the site of their evolution?
— Richard Dawkins, The Greatest Show on Earth: The Evidence for Evolution, 2009, pp. 268-270
While the prospect of marsupial evolution may be difficult to believe, is it really any less absurd than believing that an ancient man built a ginormous boat and filled it with two of every animal on earth? And that all marsupials (including the slow and the blind) hiked their way from the Middle East to Australia, across a non-existent land-bridge, together, ahead of all placental mammals, after a global flood?