William Lane Craig CV

Transcript

Doctrine of Man (Part 11)

Transcript of William Lane Craig's Defenders 2 class.

In our lesson, we’ve been talking about the Doctrine of the Fall and we contrasted the traditional view of the Fall as a historical event involving Adam and Eve from a state of innocence into a state of corruption with all of the terrible results that that brought. We contrasted with that the modern view of the Fall which would interpret this story as purely mythological or symbolic; a story told in figurative language to describe the Fall that is universal among mankind. We all, in the course of our lives, fall into sin, and as a symbol of man’s fallenness and corruption before God.

Evaluation

Today we want to come to some evaluation of these competing views.

Now, on the one hand, Adam and Eve, as their very names indicate, do have a symbolic significance in the story. Adam just is the Hebrew word for “man.” So, in essence, Genesis 1 says that in the beginning God created man – Adam. This, I think, shows that he is a sort of general symbol of mankind. Similarly, Eve is referred to as “the mother of all living persons.” So, again, she has a kind of wider significance than just a historical person. Moreover, the narrative of the Fall is full of all sorts of symbolic or figurative elements like the tree of life, the tree of the knowledge of good and evil, the serpent in the garden who deceives the woman, and so forth.

Nevertheless, in spite of this obvious symbolic function of the narrative, it does seem to me that we also have good biblical grounds for thinking that Adam was an actual historical person. Let me mention four such factors.

1. There is no break in the narrative between Adam and indisputably historical figures. The story goes right on from Adam through Abraham and Moses and these are indisputably intended to be historical persons. There is no suggestion that the first part of the story is purely symbolic and then the later aspects are historical.

2. Adam is included in the genealogies that tell of the descent of historical persons. This is true both in the Old Testament and in the New Testament where the genealogy of Jesus is given in the Gospels. So Adam is included in the genealogies with the other historical figures just like a historical person.

3. Paul treats Adam as a historical figure in a number of places in the New Testament. For example, in his address on Mars Hill that is recorded in Acts 17:26 Paul says this, “. . . from one man he made every nation of men to inhabit the face of the whole earth, and he determined the exact times and places that they should live.” So here Paul, according to Luke’s account at least, says that all of the nations of men that inhabit the earth today are descended from one human ancestor – from one man. Paul refers to this man as Adam in various places in his epistles. For example, 1 Corinthians 15:45, “Thus it is written, ‘The first man Adam became a living being’; the last Adam became a life-giving spirit.” So here Paul refers to Adam as the first man and contrasts him with Christ who is the second Adam.[1] Also in 1 Timothy 2:13, Paul says, “For Adam was formed first, then Eve;” and then he says “Adam was not deceived, but the woman was deceived and became a transgressor,” referring to the Fall of man. So here again Paul refers to Adam as the first man who then fell into sin. Paul consistently treats Adam as a historical individual; someone who really lived, not simply as a symbolic figure.

4. As we’ve seen, Paul draws parallels between Adam and Jesus as historical individuals. Paul certainly believed that Jesus of Nazareth was a historical person. He parallels Christ with Adam as the second Adam. Remember we read last week that as through Adam – the first man – sin came into the world and spread to all men so through Christ life and forgiveness and redemption are made available to all men.[2] So there is a parallel drawn between Adam and Jesus as historical persons.

So it seems to me that, despite their symbolic function in the narrative, Adam and Eve are regarded by the biblical writers as genuine historical persons.

I think what we can say is that the Fall of man is a historical event that actually happened though it is told in a dramatic literary form involving figurative speech. The story of the Fall has been called, rightly I think, a historical drama. It is a dramatized, or figurative, story telling of an actual historical event, namely the fall of the parents of the human race into sin and separation from God.

Affirming the historicity of the Fall as I’ve done implies that the human race is descended from a single ancestral couple. It commits us to the monogenesis of the human race. Not merely that the human race originated in one place as opposed to multiple places around the globe, but monogenesis in a very peculiar sense, namely that there was an original ancestral human pair from which all of humanity is descended.

This traditional view of Adam and Eve has been vigorously challenged in recent years on the basis of the science of population genetics. Let me be the very first to say that this is a field about which I know little. Like most of you I am simply an interested student in these matters. But I want to lay out in a simple way something of the current controversy that arises from population genetics for the historicity of Adam and Eve. If you are like me you will be interested in reading more about this and trying to follow something of the debate.

In order to understand this controversy, it is important to understand that, according to the theory of evolution and contrary to popular impression perhaps, evolution does not proceed along an isolated individual line. It is not as though some sequence of individual reptiles evolved, for example, into the first bird. Rather, the idea is that whole populations evolve over time. So the ongoing front of evolution is not like a pointed spear, it is rather a broad front as a whole population of organisms evolves together over time. In this case, a whole population of reptiles would be evolving bird like characteristics. Similarly, in the case of human evolution, there is a whole population of hominids – man-like primates – which is gradually evolving characteristics of modern human beings. So, there weren’t originally two human persons – a couple – that were the ancestors of everybody else.[3] Rather, modern human beings evolved through a whole population of these hominids moving gradually toward more recognizable modern human forms.

Recent genetic studies have tried to determine the minimum size that that population of ancestral human beings could have had. How few of these ancestral human beings could there have been? One way to estimate the size of the ancestral population of humanity is by comparing the portion of the human genome, which is more similar to gorilla DNA (which we will symbolize here as G) then to chimpanzee DNA (that will be C). H then will be Homo sapiens – or human. [see Figure 1] According to the current evolutionary theory, human beings are more recently separated from a common ancestor to chimps and human beings than did this ancestor of chimps and humans from gorillas. The separation over time as you go vertically up the chart is that gorillas first separated off and then some time later chimps and humans separated off of the common ancestor from the common ancestor to gorillas and chimps and humans.


Figure
1 – Current Evolutionary Theory of Common Ancestry

The interesting thing is that a portion of the human genome, or genetic structure, is perhaps, contrary to expectation, actually more similar to gorilla DNA than it is to chimps even though humans and chimps are more recently separated and so you would expect them to be much more similar. In fact, I am told about 15% of the human genome actually resembles gorilla DNA more than it resembles chimp DNA. The idea of population studies is to explain how this could have happened. How is it that human DNA could be more similar in some respects to gorilla DNA than to chimpanzee DNA even though chimpanzees and humans evolved from a more recent common ancestor?

The theory is that the ancestral population for gorillas, chimps, and humans must have been sufficiently large that it could carry a variety of genetic traits. We can represent this by the red line – so the gorilla genome evolved from that common ancestor to all three of these groups. Another genetic line evolving off of that common ancestor then went into chimpanzees. Still yet another line of DNA went into human beings. As a result of this, human DNA structure shares some of the characteristics that went into the gorilla genome but did not go into the chimp genome. This requires a large enough population of this ancestral group in order for different genetic structures to go off on these different branches. So as a result human beings resemble in their genetic structures gorillas more than they resemble chimps. In order to carry this diversity of this genetic material that population has to be at least several thousand individuals, it is estimated. So on that basis, the claim is that you never get down to just two individuals. There has to be a fairly large population of at least several thousand individuals in order to be carrying this sort of genetic diversity.

Notice that this presupposes the doctrine of common ancestry that we talked about earlier. It presupposes, or assumes, that humans, chimps, and gorillas are all evolved from some common ancestor.[4] Someone who denies that humans and chimps evolved from a common ancestor actually might take the greater similarity of humans to gorillas than to chimps in some respects to be evidence that they did not evolve from a common ancestor. Rather, they are simply built on similar design plans and that the human design plan selectively reproduces parts of the chimp genome and parts of the gorilla genome and that is why they are alike in some respects even though on the theory chimps and humans are supposed to be more recently evolved from each other. So the special creationist, I think, would take this same evidence not to be evidence of a large ancestral population but rather evidence against common ancestry and say that what we have here are common design plans that incorporate elements of each other but don’t necessarily show ancestry.

Moreover, even given the assumption of the doctrine of common ancestry, what this data enables us to estimate, it seems to me, is the population of the organisms that were ancestral to chimps and humans. What it tells us is that this population of non-human, non-chimp ancestors (whatever it was) had to be sufficiently large to carry the genetic diversity to explain how we have chimps and humans today that differ from each other with regard to this gorilla DNA. But even if that population were fairly large, who is to say that the genetic line that goes to human beings wasn’t carried forward by just two individuals. I don’t see anything in this data that would say even though this population had to have several thousand persons in it that the population that carried forward this red line could not have been just two individuals – two persons. So it doesn’t seem to me that this data is compelling for showing that the human ancestral population, as opposed to the pre-human ancestral population, had to be more than two persons.

More important direct evidence for the size of the ancestral human population comes from the genetic diversity of human beings today. Researchers have been able to sample the genetic diversity of present day human beings around the world and have been able to show that it exhibits a considerable degree of genetic diversity. The claim is that the evolution of this much genetic diversity among human beings today requires a minimal initial population of at least a couple thousand individuals and it could not have arisen from two people alone. If you originally just had two people evolving over time to the present day, you would not get the diversity in the human genome that we see in the present. Therefore, even if Adam and Eve were special creations of God – even if you deny common ancestry – still, from two persons you would not be able to generate the amount of observed genetic diversity today. This argument seems to me much more compelling. It doesn’t assume common ancestry. Even if Adam and Eve were special creations you still have the same problem. It doesn’t talk about the pre-human population. It is talking about the initial human population. How do you generate this much genetic diversity among living human beings from a single pair? It seems that you have to get down to no less than a couple thousand human persons.

What might one say in response to that? Notice that the argument assumes that the mutation rates among human beings were constant over time. In order to calculate whether this amount of genetic diversity could arise from an initial human pair, you have to assume a certain mutation rate that is constant over time. One might deny this conclusion by postulating accelerated rates of mutation in the early human population. One could see this as a result of divine intervention – that God accelerated the evolution of early humans so as to produce greater genetic diversity.[5] I don’t think that this would need to be an ad hoc or contrived move on the part of the defender of the historical Adam just to save the appearances. Rather, you will remember when we talked about the mechanisms that are behind the neo-Darwinian theory of evolution, namely random mutation and natural selection, we saw that those mechanisms operate far too slowly to plausibly explain the amount of biological complexity and diversity in the world today. Therefore, these mechanisms don’t seem to be adequate in and of themselves at the rate at which they operate to explain the observed biological complexity today. So the progressive creationist will postulate acts of divine intervention, either to cause mutation rates to accelerate that will drive evolution forward, or perhaps even acts of special creation in order to bring about the biological complexity that we see today to create new life forms. If you already believe that God is involved in producing accelerated rates of mutation in order to drive evolution forward then this really isn’t surprising if, in the case of human beings, he would have produced accelerated rates of mutation that would bring about the development of modern human beings. So I don’t think that this needs to be seen or criticized as a sort of ad hoc or contrived move. Rather, it fits in with what the progressive creationist would expect.

In any case, appeal to divine intervention to produce accelerated mutation rates may not even be necessary. Defenders of the historical Adam today note that these population estimates that we’ve been talking about are based upon highly idealized mathematical models which may not provide realistic population estimates. Fuz Rana, who is a scientist that works with the organization Reasons to Believe, has pointed out studies involving sheep and horses in which the original population size was known and yet the genetic diversity exhibited by present day populations is much greater than what the mathematical models predicted. He explains one such case involving sheep. I will quote from him here.[6] He says,

In 2007 a research team reported on the genetic diversity of wild mouflon sheep on one of the islands that are part of the Kerguelen sub-Antarctic archipelago. This group of sheep provided researchers with an unprecedented opportunity to study the effects of population dynamics on genetic diversity in small populations.

In 1957 a male and female yearling were placed onto Haute Island (an island in the Kerguelen Archipelago). . . . By the beginning of the 1970s, the number had grown to 100 individuals and peaked at 700 sheep in 1977. Since that time the population has fluctuated in a cyclical manner between 250 and 700 members.

Given that the population began with only two individuals, . . .has experienced cyclical changes in the population size, and was isolated on an island, the researchers expected very low genetic diversity (measured as heterozygosity).

. . .

What the researchers discovered, however, when they measured this quantity directly for the sheep on Haute Island was that it exceeded the predictions made by the models by up to a factor of 4.

So the genetic diversity was four times what the model had predicted.[7] He says,

In other words, the models underestimated the genetic diversity of the actual population.

The researchers explained this discrepancy by speculating that natural selection drives the increase in genetic diversity, since an increase in genetic variability increases the survivability of the population.

So natural selection actually accelerates the rise of genetic diversity because it has survival value in the struggle for survival.

Consequently, if these same models were used to estimate the effective sizes of the ancestral population from the measured genetic diversity at any point in time, they would have overestimated the original population size as much larger than two individuals.

In other words, had they not known that there were originally only two sheep placed on that island, looking at the genetic diversity exhibited by the present sheep using the mathematical models they would have over estimated the minimal size that that population would have had at any time in the past because the models did not take account of the accelerated rates of genetic mutation that were driven by natural selection.

If it is the case that natural selection can drive the increase in genetic diversity then that calls into question the assumption that the mutation rates have been constant over time for humanity, and hence it calls into question the population estimates based on that assumption.

Discussion

Question: I was just wondering how this might apply to Noah and the ark?

Answer: I haven’t even thought of that! I am struggling enough with the historical Adam! You are raising the point that there you also had a very tiny bottleneck of human beings as to where you put Noah and would this be evidence, maybe, for a local flood instead of a universal flood. Those issues all arise again. But right now we are trying to deal with Adam. So I’ll beg off that.

Question: Do biologists understand what determines genetic diversity? Is it directly correlated to, say, the number of people in a population? How do we even begin to determine this?

Answer: I will say a little bit more about that in a second. But, yes, they look at the amount of variability in the genetic structure and then you calculate how this could have arisen based upon mutation rates and the amount of time available. That will then give you these population estimates. But there are quite a number of assumptions that go into this kind of modeling that the defender of the historical Adam, I think, could challenge.

Question: If I am not mistaken, one of the questions you have always had or one of the problems you always had with the typical neo-Darwinian model is the mechanism for getting the diversity we have now. You always sort of questioned that, right? It sounds like now you are saying that maybe the mechanism is adequate to create the diversity that exists today. Is that right?

Answer: That is a fair point. What we are suggesting here is that some evidence shows that perhaps natural selection can drive an increase in genetic diversity because it has survivability value. But I think that is a long, long way from saying that genetic diversity among, for example, human beings today would be sufficient to explain how a bat and a sponge could evolve from a common ancestor. That is a lot, lot different. Here we are just talking about the sort of genetic diversity that is exhibited by Africans and Asians, for example. That is a far cry from the kind of biological complexity that exists in the world. So I think that the evidence that I shared in the lectures on creation-evolution would not be substantially affected by the claim here that the mutation rates that affect genetic diversity may not have been constant over time. When you think about it, it is really quite remarkable, it seems to me, that with these models they are able to get the minimum human population size down to a couple thousand people.[8] I mean, that in itself is astonishing. It wouldn’t take a great error to go from two thousand to two, I think. So, really, it is quite remarkable, I think, that these estimates do allow you to have such a small original human population.

Question: When I read Fuz Rana’s work and what he had said about how the generally accepted population is down to, like you say, a thousand and there were different humanoids that died off and then one branch went up. Then when they did the sheep on the island, does the scientific community embrace that as an indication that perhaps there were a pair rather than a population?

Answer: I don’t know the answer to that. As I said, this is an area in which I have only a surface knowledge. So I am sharing with you some of this information to just give you a familiarity with the issue. But you can bet that obviously evolutionary biologists who study population genetics will not be persuaded by the example of the sheep on Haute Island.

Followup: Because they don’t want to be.

Answer: What I think we can say is that given this data the traditional view is defensible. But I am not suggesting that this proves it. It is just that we are looking here as to whether it is defensible in light of the data.

Question: It also assumes that the only change in genetic diversity comes from mutations. Mutations are generally destructive and destroy genetic information. It seems like just the opposite. So the original pair could have more associated genetics that are available perhaps than what they are looking at right now.

Answer: Well, apparently the human genome can only carry so much diversity. In order to get the amount of genetic traits you need more than just two people. I will say something more about that in a minute. Hang on to that. But I doubt that you can say that two persons could have carried the sort of genetic diversity that is being imagined to have existed at that early time. You are going to have to get something that would accelerate the growth of genetic diversity in order to defend the view that the minimum population could have been as small as two.

Question: I have heard Fuz Rana talk about on some of the Reasons to Believe podcasts that there is evidence for human Neanderthal interbreeding. I was wondering what that would do for the genetic diversity.

Answer: I wasn’t going to talk about that but that is a very, very unsettling question. When we talk about this human lineage, this includes not just modern human beings but that includes these other – I am hesitant to call them humans – but it includes these other organisms like Neanderthal man, there is this other group called Denisovans, and then of course earlier forms like Homo erectus and Homo habilis. These are all in the human line as well. So the question is: where do you want to insert Adam and Eve? Were they before Neanderthal? Or were they after the Neanderthals branched off because the Neanderthals seem to be a different species. If they were afterward, then it would seem that Neanderthals really weren’t human beings. They were highly evolved primates but they really weren’t human if you say the human race is descended from Adam and Eve. But apparently modern human beings interbred with Neanderthals as you say. I remember being taken aback when one of these population geneticists said to me when I was in Canada earlier this year that you, yourself, carry Neanderthal DNA. In my own genetic profile, I carry the DNA of these Neanderthals who interbred with human beings. Now, if they weren’t humans that meant that the descendants of Adam were literally committing bestiality, right? They were interbreeding with animals. Well, maybe that is possible. Maybe that is part of the fall of man into sin – that they engaged in behavior like that. On the other hand, maybe you want to say Neanderthals were human but then you are going to face the question of where do you put Adam and Eve in there?[9] The bottleneck that seems to exist of the minimal size of about two thousand people is around 150,000 years ago or so which is after Neanderthals separated from modern Homo sapiens. So on that view if you put Adam and Eve in there where it seems to fit the best, these Neanderthals were not fully human. They were highly evolved primates but they weren’t fully human. That would seem the natural place to put Adam and Eve in there. But again, as I responded to your question, I find this very unsettling and I am not sure exactly what to do about them.

Question: A few years ago there was a cover story in National Geographic and a story about how all of humanity was genetically related to one woman that was designated as mitochondrial Eve. It seems like there is a lot of stuff on the web. That seems to be the case. Is that not the current thinking anymore?

Answer: That is the current thinking. The mitochondrial DNA that we all carry today is ultimately traceable back to a single woman, which is astonishing that there would be this person who is the mother of all mankind who actually lived and we all carry the imprint of her DNA. But among these evolutionary biologists and population geneticists, that doesn’t mean that she was the unique person who was the only human female at that time. There were lots of other human females, too, but their descendants died out and everyone who exists today is descended from this one woman. But there were other women, too, whose descendants eventually died off and so they are not in the population today. Although that evidence is consistent with the idea of a historical Eve, it doesn’t require it.

Question: Just like the Bible records Abraham and his descendants, we don’t know about evolution’s situation but if Adam has the Spirit of God which is the eternal Spirit, wouldn’t natural selection just kind of work other species out and only the Spirit in people gets passed down as Noah’s situation indicated?

Answer: Let me interpret this question in a way to raise another difficult issue that is related to this. That is, suppose there was a minimum population of around two thousand of these creatures, or individuals let’s call them. We won’t call them humans, we’ll just call them individuals and there were around two thousand of them. And God picked out two of them to place his Spirit in and breathe into them a human soul so that they became the true human parents. In that case, there could have been others that looked like them and acted like them but they weren’t fully human because God had selected just these two to be Adam and Eve. Well, that is possible and I know some Christians who hold to that view. They would say this answers questions like “Where did Cain find his wife?” “Who was Cain afraid of that was going to kill him?” There were these others around but they are just not mentioned because the text focuses on this special pair that God had picked out. This is going to have impact, though, on your view of original sin because if you think that all of humanity is implicated in Adam’s fall then what about all the descendants of these other people that were around that weren’t descendants of Adam? They wouldn’t be implicated in original sin. So this is going to cause really interesting reverberations in your doctrine of original sin. We are going to talk about that a little bit later, too. I am not closing the door on that by any means but I am just saying that realize that all of these alternatives have really interesting and unsettling theological reverberations that we need to be aware of. So that is an alternative that some people have suggested.[10] What I am arguing right now is I am not sure we are forced to that alternative because I am not convinced that the evidence is inconsistent with there being an original historical human pair. The bottleneck got so small that it was just two people – Adam and Eve – and if you then imagine accelerated rates of mutation which would be either by divine intervention or just naturally, like the sheep on Haute Island, then that is entirely consistent with the evidence that we have today.

With that we will conclude. Next time I want to talk about some specific DNA studies that have been done that call into question the variability of the genetic lines that were present in this early human population, and it suggests indeed they could have been born by only two individuals. That is reserved for next time.[11]



[1] 5:02

[2] cf. Romans 5:12-21

[3] 10:07

[4] 14:59

[5] 20:11

[6] Fazale Rana, “Were They Real? The Scientific Case for Adam and Eve,” Reasons To Believe, October 1, 2010. See http://www.reasons.org/articles/were-they-real-the-scientific-case-for-adam-and-eve (accessed September 15, 2013).

[7] 24:57

[8] 30:09

[9] 35:10

[10] 40:03

[11] Total Running Time: 41:18 (Copyright © 2013 William Lane Craig)