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Our Earliest Example of an Animal Moving on Its Own

Here’s the footprint of an Earthling a long, long way from home.

picture of Neil Armstrong's boot print on the moon
Photograph Courtesy NASA

You know the one—it’s Neil Armstrong’s boot print on the surface of the moon. “A giant leap,” he called it. Well, here’s another leap—arguably just as “giant,” though a touch more obscure. It was discovered in a dark slab of rock that hangs on the edge of the North Atlantic in a remote corner of Newfoundland …

Photograph by Dr Alex Liu, University of Bristol
Photograph by Dr Alex Liu, University of Bristol

It’s an impression left by another Earthling, an odd-looking ocean dweller that lived roughly 565 million years ago and that was maybe the first creature—certainly the first we know of—to use its own muscles to move from where it was to someplace new.

We call them Ediacarans, or more properly, ‘ediacaran organisms’. They’re a weird family, some flowerlike, some like little plops of mud, this one a little like a palm leaf or maybe a ribbed pancake …

Picture of a fossil of an ediacaran organism
Photograph by O. Louis Mazzatenta, National Geographic Creative

But what a pancake! As described by Robert Moor in his new book, On Trails: An Exploration, one of these things

“… did something virtually unprecedented on this planet—it shivered, swelled, reached forth, scrunched up, and in doing so, at an imperceptibly slow pace, began to move across the sea floor, leaving a trail behind it.”

The path it carved that day in the ocean mud—now frozen and fossilized—is the oldest trail we’ve ever seen on Earth, laughably small compared to Neil Armstrong’s journey, but it’s The Beginning, our beginning, the very first evidence of animal-like locomotion.

A volcano must have poured lava on a patch of ocean millions of years ago, freezing every living creature in place, until slowly the earth shifted, and the rock layer surfaced, then got sculpted and exposed, so now if you go to Mistaken Point on the Newfoundland coast, you can see scores of them, fern-like, blob-like, pancake-like …

Photograph by Dr Alex Liu, University of Bristol
Photograph by Dr Alex Liu, University of Bristol

This is a famous site, well-known to fossil hunters. But, as sometimes happens, new eyes can find what everybody else missed, and when a young paleobiologist from Oxford, Alexander Liu, came by in 2008 and scrunched down to see what he could (this is him lying sideways on the rocks, shoes off, booties on to protect the fossils) …

 

Photograph by Jack Matthews
Photograph by Jack Matthews

 

… he noticed what first looked like a slime trail, a thumb-wide path that crossed the rock surface …

Photograph by Dr Alex Liu, University of Bristol
Photograph by Dr Alex Liu, University of Bristol

Moor visited more recently, and when he ran his fingers over this same fossil pathway (there were a bunch of them on those rocks) he wrote, “They bore the distinct texture of life. Their surface was patterned with a series of nesting arcs: ))))))”

You can see these clearly at the upper end, but they’re in the middle too …

Photograph by Dr Alex Liu, University of Bristol
Detail of Photograph by Dr Alex Liu, University of Bristol

Those may be the traces of a suction cup foot that these creatures probably used to fasten themselves to rocks or flat surfaces on the ocean bottom. Sea anemones behave that way today: They latch onto flat ground but occasionally pry themselves loose and take lumbering “steps” when it’s time to travel.

In 2009, Alexander Liu and colleagues wrote a paper suggesting that these ancient creatures were not floating or squirming or rolling or reaching. No, they were “crawling.” These were primitive proto-steps, and you can see each step as a series of nesting parentheses.

Critics said they could just as easily be tracks made by pebbles tossed by waves, but when the experts looked, most concluded Liu is right. Those aren’t pebble tracks. Those are trails—our earliest evidence of locomotion, of life on the move.

Why Go Anywhere?

The question is, Why bother? Why move?

Were they hunting food? Looking for sex? Fleeing a predator? Or—and here I get back to Neil Armstrong—were they just on a walkabout, wondering what lies beyond the next hump of sand?

There wasn’t a lot going on in the ocean 565 million years ago. The Earth was recovering from a deep chill that left the sea bottoms, Moor writes, “devoid of predators,” empty-ish. Same for the sea. There wasn’t much to look at: “Perhaps a primitive jellyfish would have passed overhead like a living cloud.”

Drawing by Robert Krulwich
Drawing by Robert Krulwich

With no pressing reason to move about, I’m thinking that maybe what pushed these pioneers to travel was (how to put this?) a touch of restlessness, a behavior that would be passed down the great chain of life as animals moved in greater arcs, butterflying their way to Mexico, flying from Canada to the tip of Argentina, circumnavigating the globe, lifting off the planet, and, ultimately, landing on the moon.

That’s why we move, I like to think: to see, to stretch, to have more choices.

But when Moor asks this same question (“Why do we, as animals, uproot ourselves and go somewhere else?”) he doesn’t go to restlessness. The creatures that invented locomotion, paleobiologist Liu tells him, probably wanted security—a clean, flat surface to cling to. Surfaces crack, shift. When life becomes too hard where you are, you go to where it’s easier.

They didn’t want adventure, they wanted comfort.
The two explanations sound opposite, but they’re not. No place stays safe forever, not even our little blue planet. At some point, out of restlessness or desperation, it doesn’t matter which, you have to do that thing that the pancakes invented 565 million years ago—you don’t have a choice. Nature knew that early. So Earthlings learned it early.

You either move—or you die.

So we moved. And we never stopped.


Robert Moor’s new book On Trails: An Exploration (it will be out in a few weeks) is a meditation on paths—not just the paths that ancient creatures made, but also ant paths, elephant paths, footpaths, the paths in our brains and in our machines. Moor, a guy who likes to walk, does the full Appalachian Trail from Georgia to Maine, walks along highways, loses a trail full of sheep, messes with ants, befriends all sorts of fellow walkers, and as he wanders, he wonders how paths form, change and last. Hanging with him you meet a host of different byways, get in (and out) of trouble and the experience is not just enlightening, it’s sweaty, hot, cold and … well, to say it plainly … fun.

8 thoughts on “Our Earliest Example of an Animal Moving on Its Own

  1. All these pictures are from Mistaken Point, Newfoundland.
    On You Tube exist some very beautiful videos of these fossils an Google presents excellent pictures.
    If you are really interested, you can spend hours with studying all those documents.
    Notice, that the Edicarian is the period (system) from 635 to 541 Million years BP (before present).
    You may check this with the International Chronostratigraphic Chart v2015/01 from the International Commission on Stratigraphy.
    Another giant step is clearly visible at Green Point, Newfoundland, where life got on land. Here we are in the Ordovician period (485.4-419.2 Million years BP)

  2. The mind boggles at the human time scale involved since that “animal” or “animals” left their prints in sea mud. How small we are, how little we know!

    1. We already know a lot !
      Jack Szostack explains with “The Origin of Cellular Life on Earth” the ABIGENESIS.
      Craig Venter created the first synthetic life. It does not exist in nature, but only in the lab. It is the life form of minimal genomes. There are only 473 of them !

  3. “You either move—or you die.” While poetic, this theme of the piece is kinda silly. Far more life on earth is sessile, or has no ability to move deliberately: plants, fungus, algae, corals sponges…those taxa represent most eukaryotic life on earth, and they are doing just fine without locomotion.

    1. Jason says my piece is “kinda silly”. I say, maybe, if you’re a tree, a bush, a fungus, an algae; as Jason says, they do just fine being where they are. But the reason this tale caught my eye is because I’m an animal. Animals move. And need to. Plants (for the most part) don’t. The trail I describe here may be the first evidence of animal life on earth. Or at least very, very early evidence. Complex (eukaryotic) life has kingdoms. A long, long time ago, plants and animals branched from one another. This little guy, having muscles, and muscle fiber, is maybe the earliest example we have of animal life on earth. Rather than being “silly”, I think this is — in its slow to evolve but remarkable way — a huge and important change in our history, “our” being we animals. If Jason were a tomato plant, or an elm tree, I think he’d have a better case.

      1. Robert, thanks for your reply. To be clear, I don’t think the entire piece is silly–it was actually a really good read, and I think the fossil evidence you highlighted is fascinating. I just objected to the more poetic suggestion that life started to move because of some necessary, inherent wanderlust. It’s just not true that “you either move or you die”, plenty of life does just fine rooted in one spot, including, I’m fairly sure, the majority of eukaryotic life (both by taxa and biomass), and the longest lived organisms we know of.

        For the record, I’m a plant biologist, so I just have a bit of chip on my shoulder about animal-centric notions of evolutionary history. Sorry if I was a bit harsh.

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