Your Oldest Ancestor

“Not bloody likely.” That’s my first thought.

Scanning the Smithsonian email for signs of intelligent life in our solar system, I have spotted a rude headline.

Your Oldest Ancestor Was Probably Sponge Like

Now, my oldest known ancestor was a Bamford who was married in Plymouth in 1722, and there was nothing remotely sponge-like about him.  But to be fair, I read on.

A new study may settle a long-running debate
about which creature was the first to evolve
from a universal common animal ancestor.

Oh. That sort of ancestor.

But my forehead wrinkles again. What’s this about a long-running debate? A debate about what, exactly?

Researchers have split into two camps.
Some say it was a simple sponge-like creature that first formed,
while others believe it was the more complex creature like the comb jelly,
which has a nervous system, a gut and the ability to move.

Do these guys get out much? I can only imagine the heated debates at their conferences.

Sponge! Jelly! Was too! Was not!

Heated, and completely unnecessary, because I believe I can resolve this debate pretty quickly. Although I’ve never heard of them before, the way the debate has been framed in this article makes it clear that the first creature to evolve from a universal common animal ancestor must have been the comb jelly.

After all, I myself, now one of the oldest living descendants of the universal common animal ancestor, am a complex creature just like the comb jelly in my essentials. Nervous system? Check. Gut? Check. Occasional unhappy conflation of the two? Check. The ability to move? Check, albeit an ability not much exercised.

And, of course, comb jellies are beautiful hermaphrodites with “plates of giant fused cilia, known as combs, which run in eight rows up and down their bodies. The combs act like tiny oars, propelling the comb jelly through the water.”

Translucent, green jellyfish seen through aquarium window

Not a comb jelly, I admit, but at least a beautiful hermaphrodite.


OK, I admit we differ slightly there. Maybe I should check out the other option.

Sponges, it turns out, are covered with tiny pores, can be either encrusting (that’s the group that became extroverts in us descendants, I understand) or free-standing (leading to introverts, obviously), and sometimes grow into strange shapes. Check, check, and check.  Looking good.

They’re also beautiful hermaphrodites and effective filter feeders.


Hmm. You know, this is harder than it looks. But does it really matter?

The debate may seem pedantic, but . . .
identifying the first animals has big implications for biology . . .
knowing the correct branching order at the root of the animal tree
is fundamental to understanding our own evolution,
and the origin of key features of animal anatomy.


All right then. Carry on, guys. After all, who am I to get in the way of fundamental understandings? But given the long-running and, yes, heated debate about the whole notion of evolution, is the eventual resolution of the “Sponge! Jelly!” debate going to get much attention?

Not bloody likely. But that’s just my first thought.


Check out these beauties for yourself:

Sponges! (Were too!)

Comb Jellies! (Were not!)


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10 Responses to Your Oldest Ancestor

  1. Tom Watson says:

    Well, there you go. I’m some glad you resolved things, Isabel.

    Up to the point where you resolved it, I was starting to trying to figure out if I felt more like a sponge or a bit of comb jelly.

    In any event, I’m glad there are folks working on this.

  2. We’re watching a lot of “early man” documentaries these days on telly. For me, it matters not a whit who or what we came from, but then somebody’s gotta look into these things, I guess — and there always seems to be that one person, the expert, on exceeding arcane matters and endeavours. They have found their niche!

    • Isabel Gibson says:

      Barbara – Yeah, as a teenager I tried hard to be interested in archaeology and paleontology, but it was a non-starter. Others, of course, are baffled by how I spend my time . . .

  3. Jim Taylor says:

    I love academic debates, because they are so utterly unconnected to real life debates about whether I want a honey cruller or a Canadian maple donut at Tim Hortons today.
    In reality, though, I think the debate resolves itself. One of those “things,” whatever they look like, is described as “simple,” the other as “more complex.” The pattern of evolution says that the “simple” came first. The pattern is universal — evolution moves from the simple towards the more complex. Always. Each move itself makes the world more complex, which requires the next move, in turn, to be more complex to accommodate the more complex world it lives in.
    Jim T

  4. Eric says:

    Some (many) of my relatives are indeed sponges.

  5. I am horrified to find a shred of rationalization for one of the least inspiring of television characters for children, Sponge Bob Square Pants. When it pops up again in the grands artwork, I will try to summon a stepped-down version of this “In the Beginning” to raise their appreciation for Mr. Pants. Thank you, maybe!

    • Isabel Gibson says:

      Laurna – I’ve avoided Sponge Bob entirely so far, and hope to continue. Sorry to hear he’s not adding value, as they say.

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