But populations are made up of individuals. If any organism can be a different species from its ancestor, then there must be some point, even if it’s so murky as to be impossible to find, where an organism was a member of a different species than its parents.
A different species than it’s great-great-great (insert however many greats are needed) grandparents, perhaps, but not from it’s parents.
My understanding is that species are not formed or split in a generation. That’s why one answer to creationist’s question of “where are all the transitional species” is that all species are transitional, some are just transitioning faster than others. But I don’t think I’ve ever heard a definition of a different species being one that arose in a single generation.
If that is the case, any two successive generations are the same species. They may be a different species than many generations back or many generations forward, but any two parent/child generations will be classed as the same.
But I am for sure not an expert in this field. Anyone have a definitive answer on a child being classed as a different species as its parents?
If we use the definition that a species is “all the individual organisms of a natural population that generally interbreed at maturity in the wild and whose interbreeding produces fertile offspring”, then it’s not that conceptually difficult to discern what the first chicken was. Test all the creatures with a modern chicken and see if they get offspring. The first one that does is the first chicken. And since it’s the same genetically as its egg, the egg came first.
I believe the difficulty we are having is that we do not have an exact definition of a chicken. If we had a specific list of characteristics necessary to describe a chicken (and only a chicken) where if the subject that meets all those characteristics will be classified as a chicken.
Then we will have a certain population, ProtoChicken, which will almost but not quite meet all the characteristics associated with chickenhood. One or a few of these protochicken will produce the very first animal which would meet all the characteristics of a chicken. Since the animal would most likely not be birthed, but would hatch out of an egg (whether you define the egg as a protochicken egg or as a chicken egg,) that egg would be first, upon hatching from the egg, the chicken would be second. If you could prove that the first chicken was birthed, then you would have a case that the chicken came first.
Assuming we are talking about a fertilized egg, this question is tantamount to asking “Baby or Adult, Which came first?” and the short answer is the egg.
The process of speciation is more stuttering than sudden, on average, with recently emerging forms of near-chickens still able to reproduce viable offspring with their immediate predecessors. The question in its larger, cuter context represents a misunderstanding of speciation because its premise is that speciation is an abrupt break between a single set of parents and their offspring.
A nice idea, flawed if I may say, in several ways:
-We don’t have the ancestors anymore. They’re dead and gone
-Even in this case, I doubt the cutoff would be anything like as clean and distinct as you imply.
-And worst of all, lets suppose you hopped in your time machine and found an animal (Animal B) that could successfully reproduce with a modern chicken (animal A), but its parents (C and D) could not - you’ve identified that the C and D are a different species, right?
Except that even though the A can’t interbreed with the C and D, B almost certainly could - so you’re left with the contradictory situation that:
A is the same species as B
B is the same species as C and D
A is not the same species as C and D
On thinking about this more, I think that my argument is flawed, since it relies on the assumption that a species is an equivalence class. At any given moment of time, this is probably a good approximation for most cases, but when looking at ancestry, it fails. That is to say, “A is the same species as B” is not a transitive relation.
If the OP is asking which came first the ‘animal we now call a’ chicken or the egg, the answer is clearly the egg. If he is asking which came first egg-laying animals or eggs the answer can only be egg-laying animals.
Think of any textbook drawing of a line of an animal through evolution. Between every new species you could insert a completely new and different animal at that stage. It is these collections of changes that make a new species. There will be a murky point where you could define an offspring as a new species in relationship to it’s long distant relatives but not it’s parents.
Sorry Chronos, you posted while I was typing.
I said “conceptually”. I don’t need to actually find the first chicken, I just need an argument that it can be found. (Or actually just that it exists.)
How can it not be? Either the offspring is viable and fertile, or it isn’t. And yes, evolution can happen in jumps, such as the chromosome difference between man and apes.
Yeah, this is true. But I don’t think this is a problem. It’s just an intransitive class. And an animal can belong to several species at the same time. So B, C and D belong to the same species, which is not chicken, while B and A belong together to a different species, which is chicken.
Next: How many angels can dance on a pins head? I say 9.
Because speciation isn’t necessarily a distinct event, it’s a process - made fuzzy by all sorts of factors. It’s more likely that your population of protochickens would contain a shifting mixture of individuals capable of different statistical degrees of reproductive success with your modern one. I think it’s quite unlikely you’d ever find a distinct breakpoint - capacity to interbreed with your modern chicken is probably not boolean.
Allright. So I get some biologists to agree on what the reproductive success should be. Then I find the first creature that fullfills that. Notice that it doesnt matter who I choose to ask. I can ask other biologists, get a different success rate criteria, and we can still identify the first chicken. Which is all that is required.
Fair enough, but all you’re ending up with there is an academic ruling, rather than an actual discovery of the answer. However, I think that’s all that is possible, because the question itself is flawed and unanswerable.
An academic ruling of what a species is. And my conclusion is valid whatever academic ruling we choose. So this means that for any reasonable definition of what a chicken is, the egg came first.
How about in the East End of London?
This is a silly discussion. Mangetout nailed it in #4. Sure, you can draw an arbitrary line between chicken and non-chicken, and you can arbitrarily decide whether “chicken egg” means an egg laid by a chicken or an egg that will give rise to a chicken, but the answer to the “question” you’ll get will be, well, arbitrary.
A chicken egg is obviously an egg with DNA that qualifies as being of the species “chicken”. What if you manipulate the egg inside a chicken, so that it is identical to that of a pterodactyl egg, and the chicken lays it, will it be a chicken egg?
This is interesting. In the U.S. I’ve never seen any other kind of egg for sale than chicken’s. Yet you can easily find a goose or duck in the market.