john hawks weblog

paleoanthropology, genetics and evolution

Chicken vs. egg: a timeless tale

Fri, 2006-05-26 19:49 -- John Hawks

Is this the definition (CNN) of a slow news day?

It's a question that has baffled scientists, academics and pub bores through the ages: What came first, the chicken or the egg?

Now a team made up of a geneticist, philosopher and chicken farmer claim to have found an answer. It was the egg.

Put simply, the reason is down to the fact that genetic material does not change during an animal's life.

Therefore the first bird that evolved into what we would call a chicken, probably in prehistoric times, must have first existed as an embryo inside an egg.

I'm ready to stand tall against this one.

  1. It ignores epigenetics -- are we to believe that just any egg can become a chicken without some rather important environmental influence -- starting with the fact that somebody has to sit on it?
  2. OK, even if epigenetics doesn't argue by itself for the chicken-first hypothesis, we still have the slight problem of how to define the species boundary between Gallus domesticus and its ancestor Gallus gallus. There certainly can't have been only a single egg that gave rise to the species -- that egg must have been part of a community of incipient chickens. What was the transformation rule between these? Was it the mere fact of egg-laying? Or was it...
  3. Domestication! Clearly, it was domestication that made the chicken. But is domestication something that humans do to eggs? No! It's something they did to red jungle fowl (Gallus gallus), transforming them to chickens. The first chicken was therefore a domesticated red jungle fowl, which had the desirable property of laying eggs around humans and not running away. So it was an epigenetic phenomenon: humans made chickens, which laid chicken eggs!
  4. Just to support all this, there is the suggestion that the domestication of red jungle fowl was really about making good cockfighters rather than tasty McNuggets. So maybe the first chicken was born a red jungle fowl until humans made it really, really MEAN!

I rest my case.

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