Mcnugget or the omelette - a profound evolutionary dilemma (Jul/31/2007 )
This should probably be in chit chat but since I’m trying to compete with Fred for the top number of “counted” posts (2,956 to go for me) with a little bit of stretch, I will put this here. 
We’ve all been in either camp of the “chicken or egg, which came first” debate, and once we’ve looked beyond the semantics and the circular cause and consequence fallacy (and darn, they reported it resolved in the UK last year by a geneticist, a philosopher and a chicken farmer) I’m very curious to know how many random mutations, recombinations etc. in the germ line were needed and how long did it take for the animal which we now consider as chicken to be produced from its not-exactly-but-quite similar chicken parents? (Imagine it being a cross between a condor and a canary…ouch!!!) This evolution …did it happen gradually or by leaps and bounds…as in the punctuated equilibrium proposed by Stephen Jay Gould? Is there any rhyme and reason to speciation?
Down to 2,955 posts and counting,
casandra
Chicken or the egg - answer I got was ''whichever you order first''. About parents of present day chicken, I too wonder now; never thought of that.
I still need even posts more to get to 3000 (or well, let's try to be the first to get 5000 posts 
), so I gladly take this opportunity to raise my count. The porblem you raise is actually a problem of semantics. When is a chicken a chicken? Technically, the solution is quite simple. Only one mutation is required. If you define 'chicken' as 'the animal that has the genome of that bird that we breed for its eggs and meat' than its ancestor with a single mutation is no longer a chicken. Of course the chickens that exist today have multiple SNPs, but how can you define which is a chicken and which one is not? Or are they all chickens? Anyway, I am no expert on the evolution of chickens, so I won't claim that Gould is right with his punctuated equilibrum or whether it is because of gradual accumulation of mutations. (Although I must admit I would like to see what a cross between a canary and a condor would look like )
dpo hit the nail on the head but failed to answer the question
- egg came first
cos the very first chicken (chicken zero?) would start off as an egg ,its parents (pre-chicken) would not be part of the question (unless it was - which came first the pre-chicken or the egg (chicken egg or pre-chicken egg?))
dom
), so I gladly take this opportunity to raise my count.5000,eh? How about a race to a more realistic goal of 50?
) but I don't think that even technically one mutation is enough to diverge as a species. Besides how is the 'new' chicken gonna breed true if it will not encounter another 'new' chicken..what's the probability that this other chicken has the same mutation? But I could be wrong... )No, imagine first the canary to be the male!!!
4 more to go,
casandra
I wanted to be ambitious, so 5000 looked like a good number. As for 50, I have a weak feeling you'll be the first one to reach it.
I do have to stay with my suggestion for one mutation. I agree that the chances are slim that it would encounter another 'chicken' but one can always speculate about an immaculate conception ? On the other hand, philosophically, you can reason that it may breed with a pre-chicken. In the offspring, the chicken allele is dominant over the pre-chicken allele and from then on, you only have chickens. Of course, if you take the definition of species strict, two animals have to be of the same species in order to produce fertile offspring, but this would mean that both the chicken and the pre-chicken are chickens in that case. However, I don't think you can use the rule of speciation on this small level of single mutations. True species will only arise after enough time (and additional mutations). But the first one would be the most crucial one, i.e. conferring the selective advantage typical for true chickens and not for the pre-chickens. The other ones would then be the ones responsible for the separation of the species. Overall, you raised an interesting point of discussion, although I do agree with Dominic that the egg came first.
The canary-condor breed (is this a candor or a conary, or a canarydor?) will be in my mind for a long time when I see either of them I'm afraid 
I do have to stay with my suggestion for one mutation. I agree that the chances are slim that it would encounter another 'chicken' but one can always speculate about an immaculate conception ? On the other hand, philosophically, you can reason that it may breed with a pre-chicken. In the offspring, the chicken allele is dominant over the pre-chicken allele and from then on, you only have chickens. Of course, if you take the definition of species strict, two animals have to be of the same species in order to produce fertile offspring, but this would mean that both the chicken and the pre-chicken are chickens in that case. However, I don't think you can use the rule of speciation on this small level of single mutations. True species will only arise after enough time (and additional mutations). But the first one would be the most crucial one, i.e. conferring the selective advantage typical for true chickens and not for the pre-chickens. The other ones would then be the ones responsible for the separation of the species. Overall, you raised an interesting point of discussion, although I do agree with Dominic that the egg came first.
No one's arguing about the chicken egg (or is it the egg containing the new species chicken?) being first. I'm just not so convinced about the one mutation=new species speculation that you put forward...what kind of crucial mutation is this that would result in the emergence of a new species? Would it be enough to cause phenotypical modifications so as to produce the chicken we're eating right now?And you're right, the "new" chicken couldn't have mated with the pre-chicken if they were two distinct species because then they wouldn't have been able to produce fertile offsprings. How about.. there wasn't really any pre-chickens but has always been the "real" chicken from the start?(This is not so far-off from your immaculate conception hypothesis.)
So we're back to chasing tails....the chicken or the egg? Are you sure that it's not the mating act itself (with the canary as male, the phrase "lost in love" gets a whole new meaning)
which is gonna stay in your mind for a very long time?one down three more to go,
casandra
Suppose the pre-chicken has a mutation in one of its eggs in the promoter region of a hormone gene. Suppose this mutation increases the transcription of this gene and that this results in a higher frequency of egg laying once the 'chicken' has matured. In the course of time, the mutation that confers higher egg-laying capacities will grow in incidence in the population AND this 'chicken' is still able to mate with the pre-chicken. So this is a mutation that brings you the chicken, without compromising it's ability to breed with the pre-chicken. In reproduction, it is actually a continuous evolutionary struggle between the male and the female, so you cannot make a decisive timepoint where a new species arises. So although I have my second thoughts about the single mutation I offered in the beginning, I believe this is merely a question of semantics and the definition of a species. So actually I will stay with my hypothesis of one mutation.
I do like your assumption about the lack of pre-chicken, but this brings us to creationism, and that's not really my cup of tea.
I'm trying not to envision the poor male canary 
I do like your assumption about the lack of pre-chicken, but this brings us to creationism, and that's not really my cup of tea.
I'm trying not to envision the poor male canary
You are also making a lot of assumptions e.g., that several pre-chickens will have the same mutation in the same hormone gene which would've resulted in increased egg yield and all these mutant eggs will yield the "real" chickens (with the mutant gene) which were still able to miraculaously breed with the pre-chickens if they still couldn't find the other "real" chickens with the mutant gene and so on and on....and then it suddenly boils down to semantics and the definition of species
. Isn't it way past your bedtime there across the pond? Guess we have to continue this race tomorrow and maybe we could have some tea (your kind of cup) 
Poor canary...Cheers,
casandra
Actually there's only one pre-chicken that has to acquire the mutation that leads to a higher frequency of egg-laying. All of its offspring will inherit this mutation and hence make a lot of eggs also. This mutation does not induce more survival, but by supplying more progeny, the mutation will automatically increase in the population. So it starts from only one 'pre-chicken' that has the mutation, and this mutation then increases gradually in the population.
As the mutation only increases the number of progeny, there is nothing miraculous about mating with a pre-chicken. However, I do agree that you can barely call this a different species then (here I come with the semantics again ).
Just two more posts to go for you! I still need 20 