Adam, Eve and Population Genetics: A Reply to Dr. Richard Buggs (Part 1)

(T J Runyon) #711

Regarding Naledi being a “primitive” Erectus, I’m assuming you are referring to Tim White’s interpretation? The Erectus possibility has been shot down, most notably by John Hawks. Who as you know has a very close and intimate relationship with Naledi. Also for future reference Id be careful when you reference popular news sites. Reporting on human evolution is notoriously terrible.

(T J Runyon) #712

I dont think anyone would argue Erectus lacked all Modern behavior. This is the impression I have got from my studies, classes, lectures, meetings, etc. anyway. But I also think you won’t find anyone advocating Erectus had full behavioral modernity. Which seemed to arise around 50kya. Though I admit this is also controversial as is the whole behavioral modernity framework. See Shea for informstion on this:
So I defintely think Erectus had some modern behavior. To put it in cladistic terms Id say Erectus is on the stem when it comes to modern behavior. Some not all. So if you are comfortable with Adam being not fully modern then cool. More power to you. But there is a lot more to being modern than art, aesthetics and symbolic thought. It’s an interesting idea that needs to be explored. Though the probable lack of any real meaningful speech in Erectus is troubling for me. As are some biblical issues. But it should defintely be explored.

(Andrew M. Wolfe) #713

Fascinating abstract. Is this opinion fairly mainstream, or has there been pushback since 2011?

Paging both @aleo and @Jay313, whose interest I think may be piqued by this.

(T J Runyon) #714

Heres a good discussion of it :

Notice John Hawk’s comment at the bottom. He views it as incoherent

(Peaceful Science) #715

Thanks for the thoughtful comments.

I think, for @agauger, the key thing is genetic sole progenitorship, without interbreeding with other kinds. I’m not sure if the specific time of 2 mya is really the hill she is dying on here. If that is the case, she has available to her a stronger option…

She could take a model were Adam and Eve are about 700 kya, with the common ancestors of Neandertal, Homo sapiens, Denisovans, and others (possibly even H. nadeli too, if we take the recent dates). Right now there is quite a bit of anthropologists that seriously doubt the Neandertal-Homo sapiens distinction. And a secular anthropologist here at WUSTL scoffed with great vigor at any notion of Denisovans even being a distinct type (all we have is a mere knuckle, now reduced to dust). To take a view that this is “human” is solidly within the accepted range of views. Moreover, there are several anatomical features unique to Neanderthal and Sapiens. As I understand it the hyoid bone is specific to the two of them, and some have suggested it gave greater ability to vocalize.

Regarding “modernity” there is very little understanding of how much, if any, of the 50 kya “transition” was genetic vs. cultural. Given how long it would have taken for genetic mutations to fix during this time, there is good reason to think that culture is driving a large part of that transition. Frankly, there is not real way to disentangle intrinsic biological capability from cultural development endowed behavior. Our instinct is to tightly link them, but this instinct is likely flawed.

Regardless, if I’m understanding the specific concerns motivating @agauger’s model, this 700 kya Adam is much more defensible. It avoids the murky questions about H. erectus. It is actually closer to the mainstream consensus than @DennisVenema’s equivocation of H sapiens with “human” (which many anthropologists would say is wrong).

(T J Runyon) #716

Oh I agree if any non Sapiens could really vocalize it would be the Neanderthals. Their anatomy is right for it. But any other hominin, i strongly doubt

(T J Runyon) #717

Also, and take this with a grain of salt since my career is in its infancy, all anthropologists I’ve been been around would Define human as anyone belonging to the genus Homo. Homo Sapiens are broken down into Early Homo Sapiens, like the Jebel Irhoud specimens and anatomically modern humans. So Anne is arguing for an archaic Homo Sapiens (those that are morphologically and behaviorally between Erectus and Sapiens) Adam?

(Peaceful Science) #718

That’s the anthropologist I am around too. The’ve, once again, audibly scoff at the notion of “human” == Homo sapiens, as a totally backwards view, unless of course they are one of the few holdouts (or a BioLogos writer :wink: ). It is almost comical how large a swing this is from just a couple decades ago. In a lot of ways, it’s quite fascinating. There has been a convergence between YEC’s and secular anthropologists on how they understand “human” in the fossil record, though of course they totally disagree on the timeline. Both would usually say genus Homo is “human.” However, to call that a consensus is not quite correct either, because there is just a roiling debate about this in science. Even if we say “human” is Homo, we stil have to determine which bones are Homo or not. Which bones are sapiens or not. Etc.

@agauger is not really arguing for very much.

The way I read her (and please correct me Ann if I am wrong) is that sole genetic progeintorship is important.

The issue of God’s Image is, I would argue, a separable question. Because textually in Genesis 1 and 2, we can see that God’s Image is not actually part of the Adam narrative. We can propose a model where God first creates mankind in the image of God, and then later creates a man, Adam, and places him in a Garden. He is not the only one with God’s Image, so the problem she is concerned about is not there. Of course, perhaps we do not like this model, but its not wrong for the reason she puts forward here.

Regardless, given this high commitment to sole genetic progeintorship, she is willing to push Adam back as far as 2 mya, with the origin of the Homo genus. However, I do not sense that she is insisting it must be 2 mya. If there is a more plausible place to put Adam, consistent with the archaeological and genetic data, she would amenable. However, maybe she does feel H erectus is distinctly “human.”

That flexibility could be a strength, because she can chose the most defensible position as it arises, which I think might actually be at 700 kya, not 2 mya. So I am an the one suggesting something after H erectus and before H sapiens, not her. It just seems like a stronger option, that is still consistent with her motivations. Though, she is certainly entitled to her own view of what is most defensible. Most likely, most of this is being held very provisionally right now, as we work out the some more of the studies here.

(Dennis Venema) #719

This is how I see the data at present as well.

Edit: if anyone wants a primer on stem/crown groups, I discuss it at some length in the Evolution Basics series, starting with this post.

(T J Runyon) #720

I think an archaic H. sapiens Adam is much more defensible. A H. heidelbergensis Adam perhaps? If you prefer the interpretation of H. heidelbergensis being the common ancestor of us and neanderthals anyway. That’s something I could get behind. But I think i would need more than we can’t rule out a bottleneck between 400kya and 7mya before I really could consider it. Where the bottleneck actually took place is really really important. Is it closer to the 7mya mark? Or the 400K mark? And this leads me to ask is it even possible in theory to detect a bottleneck that far back? If so, what needs to be done to determine if such a bottleneck existed in that timeframe?

(Jon) #721

This shows she’s doing apologetics, not science. And that’s what this has been about all along.

(T J Runyon) #722

And another thing, when I read Dennis’ book and the part that dealt with the topic of this thread, I read it as though he was as certain that H. sapiens never started off as two people but were descedents of a larger population as he is heliocentrism. Not that a two person bottleneck never took place in the entire hominin evolutionary history. And it seems that is the conclusion that this thread reached. I owe a lot to Dennis. He had a huge part in bringing me back to Christianity. Helped show me I could be an intellectually fulfilled Christian evolutionary biologist. I owe him a lot. I just feel he has been read a little uncharitably here.

(Jon) #723

That’s how I see it. This discussion has been full of apologetics along the line of “Since there are lots of stories of floods around the world, there was clearly a worldwide flood like Genesis says”. Then you ask them when it happened, and they can’t answer, but claim it hasn’t been ruled out by science.

(T J Runyon) #724

This tells me we need more than a few beautiful handaxes to draw any real conclusions

(T J Runyon) #725

can you explain to this new Christian what the recent genealogical Adam view is?

(Jay Johnson) #726

I wish you hadn’t asked that question …

It’s all part of an ongoing discussion that mainly centers on two things: Was behavioral/cognitive modernity a “leap forward” (saltational), or was it the end of a long process? The other question involves what lies behind it all. The early answer from Tattersall and the archaeologists pointed either to language or Theory of Mind. The biologists and geneticists pushed back and sought an answer in biology. There was a lot of early enthusiasm for FOXP2, for example, until it was realized that there is no “language gene,” just as there is no “cancer gene.”

The consensus (there’s that bad word) leans toward the co-evolution of the brain and language, although there are still partisans on both sides. An example on the language side would be Charles Taylor’s The Language Animal: The Full Shape of the Human Linguistic Capacity. An example on the biological side would be Coolidge & Wynn’s The Rise of Homo Sapiens: The Evolution of Modern Thinking. Coolidge & Wynn do not reject cognitive modernity; they just seek to explain it by some other (non-Eurocentric?) standard besides symbolic behavior. As they put it, “the modern mind is not … simply an archaic mind augmented by symbolism and language.” In that, they’re certainly correct. But in the end, their theory of “Enhanced Working Memory” falls back upon some presently unknown mutation that allowed fully symbolic language, a change they believe occurred between 100,000 and 40,000 years ago, when cognitive modernity fully flowered.

Painting with a broad brush, of course, but that’s the general lay of the land. You can find a short example of how Coolidge & Wynn’s theory plays out in this 20-min talk at TedxVictoria by anthropologist Genevieve von Petzinger, The Roots of Religion

(T J Runyon) #727

I apologize haha

(Jay Johnson) #728

Right. Neanderthals are (so far) the only other hominin with a hyoid bone, which helps suspend the larynx in the neck. That bone is necessary to vocalize the full range of speech, mainly vowel sounds. Other than that, H. erectus/heidelbergensis around 500 Kya seems like a good candidate for the first speaker of “words,” although they probably wouldn’t be sounds that we would recognize as such.

(Dennis Venema) #729

Your story is easily one of the most encouraging ones I know of for me. Evolution is such a cool area of science, and it’s such a shame that so many Christians have such difficulties with it. I look forward to the day when there are just as many Christians in evolutionary biology (proportionately) as any other field. In my mind, you’re part of the beginning of that trend…

(Peaceful Science) #730