I don't think the question is whether any egg came before any chicken. That's obviously an egg, as you are implying. But the question is really, I think, what makes an egg a chicken egg? Is it an egg that is laid by a chicken or is it an egg from which a chicken hatches?

Also I think by definition a chicken is a bird that hatches from an egg (among other defining characteristics). So th egg must have come first, as a chicken-like creature that didn't come from an egg wouldn't be a chicken.

But where is the cutoff between reptile and chicken? Given how gradual it must've been, we can therefore posit that chicken's ancestors were themselves chicken. What came first, the reptile or the egg?

The koan implies chicken egg, though, not any old egg.

Did the proto-chicken lay a chicken egg which hatched the first chicken, or did the proto-chicken lay a proto-chicken egg which hatched the first chicken?

Is this just a mindless comment made without even skimming through the article or thinking about the actual meaning and intention behind the question? It's an intended correction I could attribute to a caricature of an autist, taking everything in absurdly literal terms. Typical of HN, in any case... The article talks about the actual origin of embryonic development mechanisms, pointing out that they could've preceded the existence of the animals that came out of them, not literally chickens and eggs (of course, its title uses those terms figuratively):

>"In fact, the study shows that either the principle of embryonic development existed before animals, or multicellular development mechanisms evolved separately in C. perkinsii."

It all boils down to the debate surrounding abiogenesis: the constant egg-chicken (or gamete-organism) loop does not explain how life came to be, emerging from, in principle, no life. It's paradoxical, just like trying to answer "the chicken" or "the egg". Or, as you seem to prefer, "the reptile" or "the egg".