Human Evolution

[Jose]

jcrawford and I have been having some interesting discussions in other threads, which have led to the notion that we really need a thread on human evolution. So, here it is.

The Rules
We want to work from data. Data that is discussed must be accessible in the scientific literature. Personally, I would prefer the peer-reviewed literature, because, as those of us in science know all too well, the peer reviewers are usually one's competitors. Thus, they are typically extremely critical of what we write.

Any other information that is brought to bear must also be accessible to everyone. Where requested, direct quotes from the sources will be important.

The questions for discussion

1. What is the current best understanding of human origins?

2. What "confounds" are there in the interpretation of data?

3. Given that there is always genetic diversity within populations, how easily can we assign hominid fossils to different groups? Here, the term "form-species" is probably most useful, referring to similar fossils with similar forms, but in the absence of information on the capacity for interbreeding. In many cases, different form-species are different species (fossil trees vs fossil insects), but sometimes they are not (fossil leaves vs fossil roots of the same tree).

4. Does information based on fossil data mesh with information based on genetic data? The true history must be genetically feasible. The fossils must have been left by individuals who were produced by normal genetic methods. To be valid, any explanation of origins must incorporate both fossil and genetic data.

5. What are the parts of human history that are most at odds with (some) Christian views, and what suggestions can we offer for reaching a reconciliation?

I will begin by posting the following genetic data, which is pictorial representation of the differences and similarities in mitochondrial DNA sequence of a whole bunch of people. Relative difference/similarity is proportional to the lengths of the vertical lines. Horizontal lines merely separate the vertical lines so we can see them.

How do we interpret these data?

[If appropriate, I will edit this post to ensure that the OP of this thread lists the important questions.

[jcrawford]

As for the assumptions upon which the interpretations are based, it might be good to evaluate them. You are particularly concerned, it sounds, about mitochondrial DNA. What are the assumptions that concern you?

The unfounded assumptions upon which mtDNA interpretations and conclusions are premised are:

1. That mtDNA is passed on only by the mother. - refuted by John Maynard Smith, Richard Hudson and Henry Harpending. (Lubenow)

I hasten to add Adam Eyre-Walker's contentions that "there's not one woman to whom we can trace our mitochondria," and that "recombination makes past events appear to be more recent than they really are and that Eve may actually be older than the mtDNA evidence now suggests." - Evelyn Strauss, "mtDNA Shows Signs of Paternal Influence," Science 286 (24 December 1999): 2436.

tbc:

[jcrawford]

As for the assumptions upon which the interpretations are based, it might be good to evaluate them. You are particularly concerned, it sounds, about mitochondrial DNA. What are the assumptions that concern you?

The unfounded assumptions upon which mtDNA interpretations and conclusions are premised are:

1. That mtDNA is passed on only by the mother. - refuted by John Maynard Smith, Richard Hudson, Henry Harpending and Adam Eyre-Walker. (Citations by Lubenow)

- "Games and theories," NewScientist (14 June 2003):50.

- Phillip Awadalla, Adam Eyre-Walker, and John Maynard Smith, "Linkage Disequilibrium and Recombination in Hominid Mitochodrial DNA," Science 286 (24 December 1999): 2524-25.

- In a commentary on the above paper in the same issue of Science, Hudson observes that this study "is pretty compelling and I can't think of good alternative explanations."

- Harpending adds that "There is a cottage industry of making gene trees in anthropology and then interpreting them. This paper will invalidate most of that." - Evelyn Strauss, "mtDNA Shows Signs of Paternal Influence," Science 286 (24 December 1999): 2436.

[Cathar1950]

Hey guy get with it. I don't have all day. Ok I do but SG1 is coming on.
I can tell this is going to be a lot of reading. It is a good thing I am not married or have a girl friend. She would dump me. I can just hear her now."Your always on the computer reading that stuff.""We never spend any time together", "You missed the kids being conceived", "are you going to eat or what" ?blah blah blah.
Any way I am looking forward to this venture. Sounds like fun.

[The Happy Humanist]

Any way I am looking forward to this venture. Sounds like fun.

Yes, this is exciting, could be the thread of the year. Jose vs. Jcrawford...is anyone selling popcorn?

[Jose]

Do you have any comments on Homo heidlebergensis as a candidate for modern European and Middle Eastern ancestry?

As you did, I'll provide a link to the Smithsonian's site. I agree happily that H. heidelbergensis is a fine candidate for modern European and Middle Eastern ancestry, along with being a fine candidate for the ancestry of everyone else.

The logic is: here's a group of H. heidelbergensis folks, among whom there appear one or more mutations that lead to their developing "modern" characteristics. Because they arent' interbreeding with other groups, these new characterisics don't spread throughout the heidelbergensis world. Instead, as these guys reproduce and their population increases, they fight with the others, generally winning. And here we are.

BTW, I just noticed that you are both a moderator and administrator on the forum. I was wondering how you managed to incorporate part of my thread into yours. Power to you.

It was easy. I followed the simple instructions that otseng wrote out. I wouldn't have had a clue what to do otherwise.

As far as providing "peer-reviewed" scientific citations provided by Lubenow, I guess I'll just have to spend the rest of my life typing up over 1000 scientific booknotes provided by Lubenow in his devastating critique of neo-Darwinst race theories as published by BakerBooks in 2004.

Oh, well, here go I but for the grace of God.

It's good thing you type well. If its any consolation, we all have the same requirement.

I hasten to add Adam Eyre-Walker's contentions that "there's not one woman to whom we can trace our mitochondria," and that "recombination makes past events appear to be more recent than they really are and that Eve may actually be older than the mtDNA evidence now suggests." - Evelyn Strauss, "mtDNA Shows Signs of Paternal Influence," Science 286 (24 December 1999): 2436.

This may be true, but addresses only two issues, both of which have been overblown. The first is the romantic notion of "mitochondrial eve." Biologically and genetically, it makes no sense that there would be just one person from whom all of humanity sprang. There would be a population that acquired modern characteristics. It's a nice image, given the Biblical reference, but requires romanticising beyond the validity of the data.

Second, this suggests that we can't accurately determine ages from mtDNA lineages. Well, we already know that. There's a temptation to estimate ages from trees like this, but since there are several confounding issues, such estimates are pretty loose.

That's OK, though. The actual question concerns the relationships among the people in the sample. We aren't concerned about how many ancestors are represented in the first line, or how long ago that ancestor lived, because the data don't really speak to that.

[jcrawford]

Hey guy get with it. I don't have all day. Ok I do but SG1 is coming on.

Would you stop cracking the whip like you're some master of fantasy on a science fiction show?

Any way I am looking forward to this venture. Sounds like fun.

Fun? We are dealing with life and death issues here, sir! Matters of our very survival or extinction! As amateur scientists, anyway.

[jcrawford]

Yes, this is exciting, could be the thread of the year. Jose vs. Jcrawford...is anyone selling popcorn?

Not yet. Jose and I still haven't decided who should get the concession.

Interested?

[The Happy Humanist]

Yes, this is exciting, could be the thread of the year. Jose vs. Jcrawford...is anyone selling popcorn?

Not yet. Jose and I still haven't decided who should get the concession.

Interested?

If it includes an exclusive merchandising contract with the winner...sure!

[jcrawford]

Do you have any comments on Homo heidlebergensis as a candidate for modern European and Middle Eastern ancestry?

As you did, I'll provide a link to the Smithsonian's site. I agree happily that H. heidelbergensis is a fine candidate for modern European and Middle Eastern ancestry, along with being a fine candidate for the ancestry of everyone else.

The logic is: here's a group of H. heidelbergensis folks, among whom there appear one or more mutations that lead to their developing "modern" characteristics. Because they arent' interbreeding with other groups, these new characterisics don't spread throughout the heidelbergensis world. Instead, as these guys reproduce and their population increases, they fight with the others, generally winning. And here we are.

Thanks for the fine phylogeny of human evolution presented by the Smithsonian, Jose. Hopefully, we may make extensive references to it in our ensuing discussions on signs of common ancestry in the human fossil record.

I wouldn't go so far as to theorize that H. heidlebergensis is ancestral to everyone in the world, because such early/archaic H. sapiens fossils are dated to have been living contemporaneously in Asia, Africa and Europe, and, using neo-Darwinist logic about one or more mutations leading to their developing "modern" characteristics, their inter-sterility with other racial groups, and these new characterisics not spreading throughout the rest of the heidelbergensis racial groups, we inevitably end up with these guys reproducing and their population increasing to the point of fighting for survival with other racial groups in the world for world domination.

As I see it, H. heidlebergensis was contemporaneous with other racial groups within H. erectus in China, H. ergaster in Africa, H. antecessor in Spain, H. neandertalensis and other H. sapiens throughout Eurasia, the Middle East, Africa and the rest of the world, and no human evolution from one species to another ever occurred.

[jcrawford]

The chimp DNA doesn't tell us anything other than the "root" of the tree. We could have used cauliflower DNA (except we probably couldn't, since it's probably too different). It merely tells us "start here."

Similarly, we could make a tree of everyone in my immediate family, and use jcrawford as the outgroup, or we could make a tree of jcrawford's immediate family, and use me as the outgroup.

In these cases we would be using members of the same species (Crawford and Jose) as outgroups, so it's not similar to using a chimp at all. Using a chimp as the outcrop influences the genetic data in the diagram.

The important information is derived from the pattern of similarities and differences among the humans.

Yes, but the information derived from the pattern of similarities and differences among the humans is influenced by a chimp.

I redrew the figure from Freeman and Herron's Evolutionary Analysis, 2nd edition, published by Prentice-Hall. Their rendition of it is a somewhat simplified version of the tree shown by Penny et al., Mol. Biol. Evol. 12(5):863-882. 1995, Improved Analyses of Human mtDNA Sequences Support a Recent African Origin for Homo sapiens.

How do we know that you "redrew the figure" accurately?

according to Lubenow's scientific research and citations, Svante Paabo, in criticizing Bertorelle and Barbujani, claims that "Cro-Magnon DNA is so similar to modern human DNA that there is no way to say that what has been seen is real." - Alison Abbott, "Anthropologists cast doubt on human DNA evidence," Nature 423 (29 May 2003):468

Paabo is very good, so this is a valuable statement. What it says, in essence, is that finding the same sequence as modern humans is uninformative, because it may well be contamination. Conversely, finding a different sequence is more meaningful, because modern DNA would not produce that sequence.

How do we know that 'similar' sequences to humans in fossils are not overlooked and rejected because they are thought to be the result of contamination by modern humans doing the fossil examination?

Thus, we can infer that the differences seen in neanderthal DNA are likely to be real, while the lack of difference in presumed Cro-Magnon DNA may not be real. Cro-Magnon could be like modern humans, or, perhaps, we just don't know because the investigators got contamination.

"It's tough to distinguish DNA intrinsic to an ancient sample from the modern DNA that contaminates it - the source of many false claims in the past. Ancient human samples are especially tricky, because their sequences might not differ much from that of contaminating modern human DNA, so it's hard to get a believable result." - Patricia Kahn and Ann Gibbons, "DNA From an Extinct Human," Science 277 (11 July 1997):176-77.