Before There Were Sponges

I lifted the above image from an article in today’s issue of Science, which you probably can’t read unless you’re logged in from a subscribing institution. That’s okay: take a look at the Reuters article instead, although it doesn’t have any accompanying pictures.

Which is too bad, because however abstract, I think the above image (depicting results of x-ray tomography on the specimen) communicates its ideas fairly clearly.

The caption in the Science article reads as follows… “Aberrant embryos. (A) Reflected-light photomicrograph of a 3-cell embryo (specimen DOU-25). (B) Exterior isosurface model. (C) Volume rendered and extracted cell models, with the left cell rendered transparent to show the only subcellular structure (shaded green) in this embryo.” Admittedly, you might want to rewrite that before putting it in a press release: “(A) Here’s a photo. (B) We can reconstruct what’s inside. (C) We can even figure out its constituent parts—going so far as to see inside the fossilized cells to see their interior structure.” Something like that.

Of further interest is a punchline that appears in the scientific publication but not in the popular re-interpretation. The very last sentence reads, “the combined observations suggest that the Doushantuo embryos are probably stem-group metazoans.” Which, translated from biologiese, means that these cells are precursors to metazoans—i.e., further down the trunk of the family tree that led to us. Such humble beginnings…