Which came first?

Last week I had a long debate on the classic question "Which came first the chicken or the egg?" with some people online.

The question sparked a debate in which some argued that according to evolution the chicken egg must have come first, since whatever we decide to call the "first real chicken" must have come from an egg. This argument is summed up in a Wikipedia article (http://en.wikipedia.org/wiki/Chicken_or_the_egg) that was referenced in the debate:

"A simple view is that at whatever point the threshold was crossed and the first chicken was hatched, it had to hatch from an egg. The type of bird that laid that egg, by definition, was on the other side of the threshold and therefore not technically a chicken -- it may be viewed as a proto-chicken or ancestral chicken of some sort, from which a genetic variation or mutation occurred that thus resulted in the egg being laid containing the embryo of the first chicken. In this light, de facto, that the argument is settled and the egg had to have come first."

However, does assuming a threshold line even make sense in the first place? Is it reasonable to determine a particular generation of chicken(s) as being the "first real chicken(s)"?

As opposed to the common conception the question "Is this creature a chicken or not?" is not a single question, it is a package of questions rolled up into one word for the sake of convenience and effective communication. I may as well be asking "Does this creature have two wings and walk on two legs and is covered in feathers and have a beak and eat worms..etc etc etc.?" We refer to chickens as being a group of creatures that all have a certain subset of features. When we compare the chickens of our time and place to the creatures they descend from, the further back you go it becomes clear that our label "chicken" couldn't (or rather shouldn't) apply to those creatures. So it seems like a simple enough approach to say, well then there must be some creature along the line whose children "jumps" to the species of what we would call chickens. The problem with this approach is that according to evolution these jumps don't exist. Even in that same Wikipedia article I referenced earlier this point is made:

"Not any mutation in one individual can be considered as constituting a new species. A speciation event involves the separation of one population from its parent population, so that interbreeding ceases; this is the process whereby domesticated animals are genetically separated from their wild forebears. The whole separated group can then be recognized as a new species."

Clearly then the "first real chicken" could not possibly be of a different species than its parent the "proto-chicken". Just as no single mutation could imply this child as being of a different species from its parent, it makes no sense for any such clear cut line to be drawn between parent and child generations to distinguish one as being chickens and the other being non chickens. It is only after multiple generations of mutations that any such distinction could be made.

So all in all this question has no single definitive answer. It would be similar to asking "Give me a single definitive answer to the question what is 4+6 and what is 54+12?". You could answer in parts saying the answers are 10 and 66 but not with any single number. So too you could call a range of chickens and eggs as belonging to the group of "among the first chickens and chicken eggs" but you would be unable to point to a single one and therefore answer the question definitively.

People may argue that "well fine you have a range now, but that upper limit of the range you set up has a chicken (the oldest of the range let's say) that was from an egg. Since the egg contains the same genetic information as the chicken itself it must be a chicken egg and thus an egg (this egg) came first." The problem with this approach is that by claiming there is a single creature that is the the "first real chicken" you must shift this range again since it can't be said that the parent of this "first real chicken egg" is itself a different species and thus not a chicken. So what do you do? You make another range. If you then pick out the oldest chicken from that range you again shift the range further out so on and so forth, ultimately having creatures in this range of "chickens" that hardly resemble what we refer to as chickens today at all. This approach would lead to dinosaurs being considered chicken, and sea creatures if you continue it long enough, it's a never ending cycle.

It is very similar to the question "How many grains of sand minimum do you need to make a "heap" of sand?" Again the best we can do is give some sort of range. If you say 1000 grains, what is to stop 999 grains of sand from being a heap? If you constantly shift the range to its lower bound and get a heap of say 3 grains of sand you have left the realistic range of what any normal person would consider a heap of sand, just as no normal person would consider a dinosaur a chicken.

Now... I am getting hungry.

Absence of Evidence

Is absence of evidence - evidence of absence?

I would say yes, if you are looking for a cat in a garage and after an hour long search fail to find either the cat or any evidence of the cat (no sounds of meows, no claw marks, no fur, no droppings, etc) then it stands to reason that this is evidence that the cat is not actually in the garage at all. Clearly it isn't proof that there is no cat in the garage, but it is still evidence that it isn't.