Sunday, May 28, 2006

The "chicken or the egg" question is over.

The egg came first. That's it. There's the answer.

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.

In all honesty, I figured that out years ago without significant knowledge of science, and I've never understood why this wasn't immediately apparent to everyone.


Blogger Sanjay said...

But their result seems backward to me. I mean, look, in a certain sense the egg always came first: there were eggs long before there were birds. So when we ask, which came first? we mean, which came first, the chicken or the _chicken egg_? And the chicken egg can't have come before the chicken.

Those scientists are answering, aha! don't you see, by the time it's in the egg, it's already, genetically, a chicken. But that seems to require that the chicken, not the egg, is first (see, this is a chicken --- therefore this other thing it's in is a chicken egg. The chicken comes logically first.) And in fact, I'd even say it's still wrong. Let's say the first chicken evolves from brachiosaurii. So one daym a chicken hatches, amazingly, out of what we would have called until that moment a brachiosaurus egg. So again, the chicken appears first. Only when _it_ produces an egg do we speak of a chicken egg. No?

4:48 PM  
Blogger Sanjay said...

Oh, man, the word verification right now is "luggg."

4:50 PM  
Blogger Meade said...

Good gracious, the sky really IS falling!

But what I want to know is this: How did that first so-called chicken egg ever become fertilized? How did the first ovum inherit its second set of DNA, its W chromosome? Whence cometh it's male gametic contribution?

Oh, and one more thing: Who put the ram in the rama-lama-ding-dong?

Who the heck was that man? I'd like to shake his comb.

9:50 AM  
Blogger Daryl Herbert said...

in re: Sanjay's statement:

I would not call an unhatched egg with chicken DNA in it a "brachiosaurus egg." At least, not on purpose. That we would be mistaken about its genetic identity simply because we lacked knowledge would not make it a brachiosaurus egg. We might say it was, but we would be mistaken.

in re: John's statement: "must have first existed as an embryo inside an egg"

If your question is, which came first, the chicken or the chicken embryo, that might appear to be a facile question. You have defined victory for yourself in advance, no? What could grow up to become a chicken but a chicken embryo? But I do not believe it is so easy.

A question of origin:

The DNA of the bird itself cannot change, but what about the DNA in its testicles? What if that changes?

If a single sperm were to change, and that lucky fellow found its way to an ovum, I would agree that the egg still came first (the sperm being an element of the egg, and being unique from all other sperm issued by the father chicken, thus it would not make sense to declare the father chicken as a whole to be part of the new species).

But what if the first stem cell making up the testicle as a whole underwent mutation, such that all sperm manufactured in that chicken would, upon fertilization of a normal egg, give rise to a mutant beast-cock?

There is a definitional problem regarding speciation:

Technically the new beast might not be a completely new species, different species being incapable of producing fertile offspring with one another, by the very definition of the term "species." But if it was sufficiently different it could be the metaphorical piece of sand around which the pearl of a new subspecies formed, which would eventually drift apart from the original species until cross-breeding for fertile offspring was no longer a possibility.

No First Members:

There may never have been a "first" member of the species, if during the split between subspecies, it was possible from members of the breaking-away-group to produce fertile offspring with some but not all of the original group. So really, you would have three groups: A (originals), B (first mutation), C (more mutations)

You start with all belonging to A. Then some mutation occurs and a B is born. B is still technically part of the same species as A because B is mating with As and making fertile babies, some of whom are Bs and some of whom are As. Eventually, the size of group B might grow if it possessed genetic advantage. Then at some point a mutant child of B would be born (i.e.: C). Let us further stipulate that C would be compatible with B but not A. So you could say A and B are part of the same species, B and C are part of the same species, but not A and C? It doesn't make sense from the traditional definition, but it happens often enough in the real world.

But if, over time, B died out completely such that all that was left was either A or C, then it is easy to say that there is a new species, because As and Cs are incompatible. It's not so easy to say who was "first."

Further stretching of the testicles hypothetical:

The hypothetical as desrcribed above is merely one possibility for describing an animal that is not the same species as its 1-cell embryo. For instance: if just one of the two testicles was corrupted, then one cock would be capable of producing fertile offspring with both species (even if other members of the 2nd species did not exist at the time the cock was first able to issue two flavors of semen). Then that bird would be the first and only member of Group B, and upon its death all members of Group C (its descendants from the mutant nut) would instantly become the "first" members of a new species. If you allow for multiple "firsts," this works.

Chickens and Eggs jointly achieve firsthood:

It is further possible that some members of group C would at the time of the original mutant's death be eggs. So those eggs would be among the "first" members of the species.

It is unlikely, but certainly possible (especially depending on the life-cycle of the creatures), that all members of group C would be eggs upon the death of the original mutant. In that event, the eggs could be said to come first.

12:52 AM  

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