Question about evolution, genetic bottlenecks, and inbreeding

This thread reminds me of high school biology. Back then, I was a hardcore creationist who would argue for hours with the biology teacher. I remember one of the things I and many other students struggled with was this very thing you guys are talking about, that the common ancestor is a species and not an individual and that individuals don't evolve. I think part of the problem for me was I had this preconceived notion about evolution that stuff evolve by morphing. This preconceived notion of evolution is closer to what happens to Marcus Corvinus in Underworld Evolution than reality.I think at this point I'm suppose to say god rules evolution sux.

Let's take this the simple way.Common ancestor refers to a whole species or at least a population.Most recent common ancestor refers to a whole species, population, or individual.Don't get caught up with the idea that a whole species is derived from one single individual! While an individual may be responsible for a specific genetic trait for the entire human race, there were billions of others who contributed parts and pieces of other genetic traits.Here is a simple analogy (don't get caught up too much in the analogy!). My great great grandfather gave my great grandfather some genes. The number of genes that my great great grandfather contributed to my great father was smaller. The number of genes my father inherited from my great great grandfather was even smaller. I got from my great great grandfather an even smaller number of genes.My great great grandfather also had a daughter, Catherine. Catherine's daughter Julie inherited some genes from my great great grandfather. Julie's daughter Anne inherited an even less number of genes from my great great grandfather. Anne gave birth to June.Is it inbreeding if June and I got married and have kids? Did we both get all our genes from our great great grandfather? Answer that question and I think you should have a good understanding of what's going on here.

I knew this was going to happen. I knew you'd take the analogy too seriously and treat it like the real thing. *sigh*Let me start this again. The most recent common ancestor can refer to either a population or individual, depending on what we are talking about. If we're talking about two distinct species, say chimp and human, the most recent common ancestor couldn't have possibly be one single individual. This is a ridiculous statement to make. Why? (1) individuals can't evolve. The smallest unit that can evolve is a population. (2) The combination of traits from many individuals contributed to the emergence of both species.On the other hand, it is also an obviously true statement that at some point in the past there was an individual that had at least 1 genetic trait that now exists in both species.One could even argue that this is all semantics. I know I am correct. I think I'll play dumb for a little bit. First, you disagreed with me. Then you said I was correct. I think you have an integrity issue here. I think you are caught in a web of lies that you've resorted to contradicting yourself. Do you lie often?

The answer to this question is bleedingly obvious. Say that chimp and human share a common gene A, there was a common individual ancestor for the particular gene A. Say there was another gene B that we both share. There was another common individual ancestor for the particular gene B. Surely, gene A alone does not define a human or a chimp. Neither is gene B alone.

This has everything to do with the diagram. Just like "macroevolution" is just "microevolution" taken over long periods of time, tracing lineages to the MRCA of an entire species is just tracing lineages of individual family trees over long periods of time. The diagram proves that no matter how far back you go, you always have a group of contemporaries all individual common ancestors of the population generations later.Yes, there was a single individual who was the common ancestor of individuals A and B many generations later. But the same thing can be said of many other individuals who contributed to the myriads of other genes inherited by A and B. By your approach, MRCA as an individual is meaningless because there were a kazillion MRCA's.

Different lines? How else would you trace the MCRA?I hate to break this to you, but your genetic makeup is not entirely made up of genes contributed from your father. The MCRA of you and your sister (if you have one) include both your father and mother. Already, I've just proven that just taken one generation back you have multiple MCRA. If you want to take another generation back, the MCRA consisted of 4 individuals. No matter how far back you go, you're never going to find JUST ONE individual who was the sole MCRA.Now, if you want to take another route and say your MCRA for your Y chromosome, then yes the MCRA of your and your brother's Y chromosome is your father. Is this what you're trying to say?

And how exactly do you propose this population started out? Are we talking about a male figure with 20 wives isolated on an island?

You're absolutely correct. That was my mistake there. I was thinking of common ancestors, not most recent.Edited by Taz, : No reason given.

And I've been saying since the beginning that I'm not denying there could have been only 1 MRCA. I've been trying to point out to you 2 problems with assuming 1 individual MRCA. (1) Having 1 individual MRCA drastically limits the genetic variation in the gene pool. A single disease could potentially wipe out the african cheetah population because of this. (2) On a species scale (such as human and chimp), 1 individual MRCA that connects the two species is a pointless concept. This is not the movie Underworld where lycans and vampires had a common ancestor name Alexander Corvinus.

For now, ignore everything I said in this thread. Thanks for confusing the hell out of me now. I'll come back to this once my mind is untangled! That or I don't die first of concussion.Edited by Taz, : No reason given.

What, I can't have doubts about my own understanding of things?Added by edit.Don't get me wrong, I still say it's kinda pointless to look for a single individual most recent common ancestor that connects chimps and humans. To me, this is like trying to find that one specific footprint of yours when you put your foot down the wrong way somewhere in Nevada after you've spent 2 years walking from California to New York.I've become confused about another part of our conversation.Edited by Taz, : No reason given.

Haha, I just noticed this post. From your message 26.

quote:

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Look at it this way (say we are looking for male). If I ask you to tell me your most recent common ancestor with your brother/sister, there is no way that is going to be a group, it is your father, end of story.

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I take it you think women are insignificant enough that they don't need a mention?Haha, ok that was a joke. But you should know what I mean. It takes 2 to tango. I don't know why you keep insisting on 1 organism being the Abraham figure.