What came first, the chicken or the egg?

Swetasuria

I think it is the chicken. I can't understand why there is such confusion?

Why is it compared to the promblem over the first genetic material formed?

Is there any explanation on the basis evolution or mutation that supports the egg to be formed first?

onomatomanic

In the context of evolutionary biology, the standard answer is "egg", reasoning that if you trace the lineage of any chicken far enough back, you'll eventually end up with an ancestor that can't any longer be called a chicken - but the things it lays are nevertheless still eggs.

Reptillian

Wait...how can you have a chicken without an egg?...how can you have an egg without a chicken?...no chicken, no egg...no egg, no chicken...but one had to come first...chicken...egg...chicken...egg... BWAK BWAK BUKAWWW!!!! *head explodes*

(Lol, sorry I know I'm nutty. I agree with onomatomaniac)

Monique

Wrong! it's neither the chicken nor the egg.

Publication The evolution of early animal embryos: conservation or divergence?
From the author:Dilemma resolved..

Number Nine

It's a bit of a flawed question; categories like "chicken" are taxonomic conventions created for our convenience. There is no instant at which a "chickens" appeared where there were none before; we just look at the categories that exist today and decide that a group of animals are similar enough (in features and in ancestry) to be placed within a single category.

Dremmer

Which were we humans eating first, the chicken or the eggs?

onomatomanic

"The chicken (Gallus gallus domesticus) is a domesticated fowl", whereas eggs can be gathered from, inter alia, the nests of wild birds. Unlike domestication, gathering is as old as the human species. So the answer would again seem to be "egg".

Darwin123

Don't you mean ovamatermaniac?
The first chicken egg was laid by an animal that you wouldn't call a chicken. There was a an embryonic chicken in the egg, but the mother is considered a different type of bird.
I am not sure that you are quite serious, but I will expand on this anyway. It may be useful to quote this post when similar issues come up.
You made an error in logic. The "paradox" is based on a false hypothesis. The hypothesis is that a female animal has to lay an egg which is the same species as the mother. Obviously, if a dog could lay a chicken egg there would be no problem. However, we need not get so far. The line of discrimination between species can be somewhat arbitrary. A bird that is not a chicken, but very similar to a chicken, can lay an egg that hatches into a chicken.
Let me ask an analogous question. Which came first, the king or the prince?
A prince is the child of a king. However, the king had to grow up from a prince. So obviously, the theory of royal succession doesn't work.
At some point, there were no kings or princes. Far back, somebody was charismatic and aggressive enough to get everyone to declare not only him as boss, but all his children and his children's children. So he had himself declared as king. He did not grow up as a prince.
An example would be King Saul in the Bible. He was the first king. There was no prince and no king in Israel before him. So the king came first, in this example. In fact, the one that followed him was not a Prince. King David was not a prince. He replaced Saul as King.
In fact, that happened quite often in history. So the king always came first, not the prince.

onomatomanic

Yes, I've just been thinking along similar lines, partly in reference to this thread. I'd say it quickly becomes more an issue of semantics than anything else, if one takes this far enough. Let's try a thought experiment inspired by the basilisk legend:

"A [chicken/snake] lays [an avian/a reptilian] egg, from which hatches a [chicken/snake]."

("Avian" and "reptilian" is meant to refer only to the appearance and architecture of the egg.)

Consider each of the eight sentences which can be formed by selecting one word from each of the pairs, and decide whether you'd call the egg in question a "chicken egg" under those conditions.

jackmell

How about archaeopteryx:

http://en.wikipedia.org/wiki/Archaeoptryx

wouldn't that work? That's a (proposed) transition species between dinosaurs (which laid eggs) and birds and I assume archaeopteryx is also laying eggs and then by continued evolutionary change, its lineage includes a branch which gradually (or sometimes abruptly) evolved into the chicken lineage. So from that perspective one could argue the egg came before the chicken, i.e., archaeopteryx was laying eggs long before the chicken emerged. However, not quite sure the question is referring to just eggs or bonifide chicken eggs.

Darwin123

It doesn't really matter. In both cases, the egg came first. So long as the species is defined in the adult form, the egg came first. Since the morphology of embryos doesn't evolve as fast as the morphology of the adult form, scientists will continue to define a species in terms of the adult form.
I assume that the species called chicken is defined in terms of the anatomy of the adult. The anatomy of embryos in the tail bud stage vary across class lines. However, I assume that the tail bud stage is conservative within any class of vertebrates. If so, one has to wait until the chick grows up to decide whether it is a chicken. By then, the egg has hatched.
If he meant any eggs whatsoever, then clearly the egg came before the chicken. Purported eggs presumably from some invertebrate have been found in rocks 700 million years old. Thus, "eggs in general" preceded the vertebrates.
If he meant the eggs of a "proper chicken", there is the question of how that egg is defined. When I look in any dictionary, the "chicken species" is defined in terms of its adult form. Thus, one would have to wait until the egg hatched before one decided that it was a chicken. Thus, the egg came first.
If the evolution of the embryo wasn't conservative, then we would have a harder time. However, the greatest taxonomic detail occurs in the adult stage. Know one can tell what the species is from a blastula.
Yes, I know that Haekel was wrong. Embryos even in the tail bud stage vary with taxon. You can tell the embryo of a fish from the embryo of a chicken in the tail bud stage. Haekel fudged his illustrations. However, I seriously doubt that you can tell the embryo of a chicken from the embryo of a duck at any embryonic stage. I suspect that it would be difficult to tell a newly hatched chicken from a newly hatched duck. Therefore, one has to wait for the corresponding chicks to grow up.
The "proper chicken egg" had to proceed the "proper adult chicken". However, I wonder about those rare cases where the embryo evolution is not so conservative.
It may be especially hard in the those animals that can reproduce both sexually and asexually. For instance, coral can reproduce by budding or by releasing eggs. Which came first, the coral adult or the coral egg?
Then there are the organisms that form embryo-like stages by fusing individuals. Such as fungi. Such as slime molds.
Which came first? The amoebic stage slime mold (asexual reproduction of protozoa-like cells), the slug stage slime mold (fusion of amoeboid individuals), or the spore (asexual reproduction of the multicellular slug)?
Please take into account that a typical slime mold species has five independent genders!

Darwin123

I read a theory that humans first started raising chickens for cock fighting. I think it was in a recent issue of Smithsonian Magazine. The popularity of chickens as a food came about only within the last four centuries, according to this article.

Swetasuria

"...evolution wasn't conservative...", What do you mean by that? Is it similar to the examples of fungi and coral you have given?

bobze

It would be good not to confuse people with this. Parents of 1 species don't give birth to offspring of different species. Organisms bequeath organisms so similar we consider them the "same species". Its important to remember here also that species in this context are arbitrary boundaries put upon the gradations of successive generations, for the ease of human convenience. Not natures.

There is also another very, very important point to make here that may confuse readers reading your post. Its that evolution happens to populations. There is no "first chicken" or "first person" or "first of any species". Evolution is the change in allele frequencies over time for a population. It is incorrect, both conceptually and in reality, to think of a not-quite chicken giving birth to a chicken. At no point did such a finite line exist where a species "pops up". What did happen is a population of organisms reproduced and their alleles over time were sufficiently altered for us to label them as a distinct species. That is an easily misunderstood point--even often by students of the biological sciences. Think about it like a color bar;



Its like asking where yellow becomes green. There is no finite point in the transition, only "populations of pixels" (think vertical lines) with changing RGB values (think of alleles). The "point" at which we consider 1 a "new" species in this case is going to be an artifact of human preference.

For chickens and the rest of real life, this distinction between "species" in context becomes even harder to detect. A domestic rooster;




A representative of that ancestral population, the red jungle fowl;



A population of, according to us, almost chickens---but not quite chickens.

I agree with the rest of your post though. I like the royal analogy--Just remember though that evolution is populations!

SW VandeCarr

Regardless of the changes in allele frequencies in populations over time, it's scientifically undisputed that birds evolved from reptiles and reptiles laid (and continue to lay) eggs. So, with respect to chickens (which are birds), the egg came before the chicken.

EDIT: My question is why mammals had to develop a new way. The avian egg is relatively simple and quite elegant IMO. The mammalian way is too complicated, messy and unnecessarily hard on the mother. Has a chicken ever died from the complications of pregnancy?

bobze

Having live young has its advantages. Ever seen a lowly raccoon raid a giant alligator nest, destroying all the young? Having your babies with you circumvents that problem.

SW VandeCarr

Well I've never seen a lowly raccoon raid a giant alligator nest, so I have to either take your word for it or demand a peer reviewed reference. Seriously, there are certain advantages to gestation and live birth, but our avian friends are doing just fine. They can fly south for winter without having to take a plane or get hotel reservations. And they can hang around the pool without feeling self-conscious because they're obviously pregnant. Besides we are talking about avian eggs, not reptile eggs. The birds perfected the egg IMO. They usually guard their eggs 24/7 until they hatch. I don't have a ready reference for it, but I've read that with many bird species, the female forms a monogamous relationship with the male to share egg minding duties. If you insist, I will find a reference for this. But you will then need to find a reference for the lowly raccoons (and not non-lowly raccoons) and giant alligator nests (it's not clear to me whether you mean giant alligators or giant nests, so you will need to cover both).