Re: [asa] Re: Reading Genesis theologically NOT historicallyDennis:
As before, you have simply ignored most of my discussion, which disinclines me to continue. But thank you for answering at least one of my questions clearly. You wrote:
"There's no evidence to support the hypothesis that genus Homo arose more than once".
But what you won't further acknowledge is the implications of that, i.e., that is possible to imagine an event which would have prevented the rise of Homo sapiens, by wiping out the earliest members of the genus Homo, before the species Homo sapiens came into existence.
Yes *of course* we came from a population, in the sense that everyone's parents, grandparents, etc., came from a population. We carry genetic information that originated in more than two individuals. That is obvious, if we rule out (as Darwinists do) the special creation of a first human couple.
Your paragraph on population genetics is about *how the average of the population changes over time*. That is not what I am talking about. I am talking about *the origin of particular traits*. Unless you get new traits, it is pointless to talk about how the average of the population is going to change, because without new traits, there will be no evolution, just reshuffling of the same-old, same-old. Darwin presupposes a first ancestor *for particular traits*. Dawkins and Miller, both ultra-orthodox neo-Darwinians, follow Darwin in this. So it is not just the science of 1859 I was relying on. If you are going to say that Darwin was wrong to say that there is a first ancestor for particular traits, then make sure that you say that Miller and Dawkins are wrong, too. Also, of course, you will have to say that the hundreds of scientists and science writers who have used the okapi-giraffe example for the last 100 years are wrong, too. But that's OK; I support your academic right to disagree with the majority. (I wish the Darwinists would take that attitude towards ID people.)
You say, regarding our origin in one hominid: "For parts of our genetic makeup, yes."
Good, now think about that for a minute. Let's say, for example, that a larger cranium was essential to the genus homo. And let's say that the trend toward larger craniums, after, say, 300,000 years with a cranium of one size (please don't pick pedantically at the details; I'm making up an example to illustrate a point, and you can substitute any characteristic you like out of your specialist knowledge), began with a particular mutation in Grog the Ape-Man. That is, Grog was the first to have the gene (and yes, I know I am simplifying, because in most cases many genes control a feature, but we can change the details to suit your specialist needs; it doesn't matter for the logic of my argument) that made possible the sequence of larger craniums which led to modern man. So if Grog is trampled by a mammoth or killed by disease or by his arch-enemy Mog the Ape-Man, before he reproduces, that new gene will never enter the gene pool. The move to larger craniums is cut off at the root. Of course, it is possible that the gene (set of genes, whatever) will reappear in another primate, 10,000 or 100,000 or 1,000,000 years later. No one can say what might happen. But one thing that we can be sure of is that if Grog is killed before he reproduces, the particular sequence of descendants that he would have had will never come to be. That does not require a Ph.D. is population genetics to understand. Anyone who has had his dog neutered can see it.
So, in your language, a "part of the genetic makeup" of modern man could be located as *having a first occurrence* in a particular individual. With respect to that part of our genetic makeup, that first individual would be our ultimate parent.
Now if your point is that modern man has *many* characteristics, and that some of them may have come from *one* ultimate parent, and others may have come from *other* ultimate parents, e.g., our large skull may have come from Grog, whereas our opposable thumb may have come from Snog, a million years earlier, I have no disagreement. I am not suggesting that some crude primate being that was nothing like man gave birth to a "first human parent" who suddenly had thirty major human characteristics, as if some lemur or tarsier gave birth to Adam. I grant that the genus Homo itself owes features to earlier creatures, and those earlier creatures owe some features to still earlier creatures, etc. My point, however, is that, on premises you have now granted, we can imagine a first parent for individual features, a parent in whom a crucial mutation occurred upon which an opposable thumb or some other crucial structure was built. And in principle, by cutting off that mutation from entering the gene pool, we can progressively, in our thought-experiment, eliminate creatures with large skulls, creatures with opposable thumbs, mammals, reptiles, vertebrates, etc., going all the way back as far as we wish. There had to be a first parent in which each mutation occurred. I presume that evolutionary biologists still believe in mutations. (Even if, in your neck of the woods, and apparently only in your neck of the woods, they have dropped the okapi-giraffe argument.)
Yes, I have heard of a normal distribution. I took a two-semester course on Probability Theory at university. (The course was from the Math Department, not the Biology Department, so I got the real thing, not watered down for non-mathies. The textbook was by Freund, if you're interested.)
Cameron.
----- Original Message -----
From: Dennis Venema
To: Cameron Wybrow ; asa
Sent: Tuesday, October 06, 2009 3:41 PM
Subject: Re: [asa] Re: Reading Genesis theologically NOT historically
Cameron,
There is no evidence to support the hypothesis that genus Homo arose more than once. There is also no point where one could point at one hominid or a single pair of hominids and say they were the ancestors of us all. For parts of our genetic makeup, such as our mitochondrial DNA, yes. In toto, no. We come from a population, that came from a population, etc, etc.
Your ideas bear little similarity to those of Darwin, much less that of modern writers. Darwin understood that variation was continuous: you’re modeling variation in discontinuous categories with some sort of single-gene, Mendelian model. Your protests to the contrary, there is ample evidence that you do not understand even the basics of evolutionary biology.
“So instead of recommending me a dry technical article, why not tell me in plain language: how do you come up with an interbreeding population of a *thousand* okapis that are six inches taller before you have even *one* okapi that is six inches taller?”
Have you never heard of a normal distribution? Populations form normal distributions for traits that do not fall into discrete categories (such as height and weight). The average characteristics of a population can change over time under selection by incremental steps. There are many, many genes that contribute to continuous characteristics: variation within these genes within a population coupled with genetic segregation produces the variation we observe. If selection is acting on one side of the distribution then over time the allele frequencies will change in the population and the average will shift. I would recommend you pick up an introductory genetics text and look over the population genetics material therein.
That paper I linked to is not a “dry, technical paper.” It’s cutting-edge science that addresses your exact questions with the best techniques currently available. If you’re interested in these issues this is where to go: Darwin is all fine and well from a historical perspective, but he’s hardly current biology. If you want to ask questions as you read the paper, by all means, do so. If you’re not interested in reading the paper (or other, current science on this issue) then I’ll probably chalk up your approach as another datum point for the Dunning-Kruger effect and leave it at that. Vita brevis.
Dennis
On 06/10/09 12:09 AM, "Cameron Wybrow" <wybrowc@sympatico.ca> wrote:
Dennis, my ideas of speciation come from Charles Darwin -- whose works I have read with some care (unlike 90% of the biologists on the planet) -- and from a number of biologists who champion his writings, including Ken Miller and Richard Dawkins, not to mention a whole host of popular science writers, many of whom have Ph.D.s in paleontology etc. I've been reading about evolution for about 45 years now, so I have a pretty good idea what traditional neo-Darwinism says. My example of the okapi-like creature and the giraffe is classical; it's in just about every exposition of Darwinian evolution I've ever read, and if you don't recognize it, then I'm absolutely stumped. Perhaps you are much younger than I, and the way of teaching evolution in both schools and popular science books has completely changed in the past 20 years. But I doubt it, since Ken Miller and Dawkins still treat evolution in this manner, and they are still very much alive and kicking. I wouldn't be surprised if they both employ the giraffe example in one or more of their books.
But possibly you are not a neo-Darwinian. If not, please say so, so that we won't debate over a position that you don't hold.
One of the first requirements of any discussion between people of differing specializations is clarifying terms and concepts. I tried to offer some working distinctions within which you and I could hold a rational discussion. I made them jargon-free, and employed the technique of division by two which has been employed in Western logic and teaching since Aristotle, and which I assume that any person educated in any field can follow. I would gladly accept a modification of my divisions based on any defect in my logic (though I don't see how there can be a third option to the alternatives "one" and "more than one", when zero and all negative numbers are obviously ruled out). However, instead of addressing my divisions in the spirit of clarification in which they were offered, you play the "you don't understand enough biology, you need to read more articles" card, when nothing -- absolutely nothing -- that I said in my reply -- if you would read it carefully -- depends on any specialist knowledge of biology. My remarks require only the assumptions that: (1) Sexual reproduction happens; (2) Trees of ancestors can be drawn up; (3) Common ancestors exist. I believe that all evolutionary biologists accept these assumptions.
I know that mammals do not reproduce asexually. The very fact that, if I held such a view, I would be a complete ignoramus, should perhaps suggest to you (unless you think that I *am* a complete ignoramus, which I suppose is possible) that I might mean something more intelligent than that, and that you may not have read my words carefully enough before objecting to them. But just to clarify, and for the record: though of course two parents are necessary for reproduction, only *one* of the parents has to possess the mutation which gives the new trait to the offspring. Mendel's genetics explains why. If a long-necked okapi mates with a regular-necked okapi, and if the long neck of the one is a result a gene that it carries, then the gene, and hence long-neckedness, can find its way into the future population of okapis, as I am sure you must know.
Your criticism of my two-point distinction, followed by your point 3, shows either a misreading of my distinction, which could perhaps be my fault for being a poor expositor, or a failure in logic on your part, because you think that your answer #3 is different from my answer #2, when in fact it is merely *a special case* of my answer #2. Read again carefully. The words "The current crop of human beings on this planet is genetically descended from more than one pair of ultimate parents" are found in both your answer and mine. Your answer still falls entirely within my twofold division of "one" and "more than one". You have opted for "more than one", and therefore have not invalidated my distinction.
I think what may have thrown you is my word "unrelated". Obviously on evolutionary assumptions all life forms are ultimately related. By "unrelated" I meant, of course, "breaking off from the main stream of hominid (or possibly even primate) evolution at two completely different points". The larger question I was raising by the word "unrelated" was whether you supposed that human beings -- truly human beings, I mean, genus homo, not merely hominids generally -- in fact arose *more than once*, via *independent pathways*, with the two or more populations later being blended to produce modern homo sapiens, or whether you thought that human beings arose *only once*.
More important, you do not seem to see my point about the giraffe and the okapi. I will try one more time, briefly. You will agree that there was a time on earth when there were no mammals, correct? Then the *latest* common ancestor of man and the apes did not yet exist, correct? You will also agree that there was a time on earth when there were no primates, but there were other mammals, e.g., shrews, correct? Again, the latest common ancestor of man and the apes is not on the scene yet, correct? You will agree that there was a time when there were primates, but not yet the line of primates that was to lead to man and the apes, right? So we still aren't there. But now, there comes a time when the latest common ancestor of man and the apes exists, correct? Call it 4 million years ago, call it 7 million years ago, I don't care in the slightest when it was. I am making a logical point. After that ancestor, the various branches of higher primates go off in their various directions (I'm not getting into the details here of which of them is evolutionarily closer to which, because it's irrelevant to my point). But if I had a time machine, I could, in principle, go back in time, and kill off the genetic ancestor from which all of us evolved, thus preventing human beings from ever existing. And yes, of course, if on my first landing in the past, I find 1,000 interbreeding individuals, I would have to kill off 1,000 to prevent contemporary man from arising. But where did those 1,000 interbreeding individuals come from? Did they emerge spontaneously out of the earth? Did God call them into existence by fiat? No, I think you will say, they came from their parents, who were of course, sisters, brothers, and cousins of each other, and therefore sprang from earlier common ancestors. So then I could say, "I'm too lazy to kill 1,000 of these things", or "I don't have enough bullets for 1,000", and I could take my time machine back further, until I came to the being -- which you can classify any way you want in the technical jargon, proto-hominid or whatever is the latest label -- which was the common ancestor of them all, and if I kill that being, those 1,000 breeding individuals cannot ever be born.
If you have trouble accepting an argument, however logical and complete, that comes from a "non-biologist", just look at the diagram in The Origin of Species (it's the only diagram in Darwin's book), and look at Darwin's explanation in the first four chapters of how species are formed. He's clear that new species begin with a variation in an individual -- a longer neck or beak or better coloration for camouflage or an incipient new organ or behavioural trait -- which is then passed down to offspring. (For reasons later explained by Mendel; Darwin was fuzzy on the mechanics.) It is those offspring which become your "interbreeding population". No original daddy (or mommy) with the new trait in question, no subsequent interbreeding population with that trait. It requires no advanced biology to see that -- only the knowledge of the birds and the bees. If the first mutation doesn't occur, you can forget about breeding populations containing that mutation.
So instead of recommending me a dry technical article, why not tell me in plain language: how do you come up with an interbreeding population of a *thousand* okapis that are six inches taller before you have even *one* okapi that is six inches taller?
Cameron.
----- Original Message -----
From: Dennis Venema <mailto:Dennis.Venema@twu.ca>
To: Cameron Wybrow <mailto:wybrowc@sympatico.ca> ; asa <mailto:asa@calvin.edu>
Sent: Tuesday, October 06, 2009 12:32 AM
Subject: Re: [asa] Re: Reading Genesis theologically NOT historically
Hi Cameron,
“Obviously there must be a "first" in every biological line.”
Not so, if you mean “first individual” - as your response seems to indicate. The only thing obvious here is that you don’t understand how speciation works. I’m not trying to be harsh, just forthright. Your ideas of speciation are not like any I’ve seen before.
Populations change much more gradually. The change is in average characteristics, unless we are talking about rapid speciation due to chromosomal duplication, etc, when speciation is through a single pair or individual.
“And the five-foot-six ancestor was an individual, not a "population" -- though of course he or she eventually produced a population (of longer-necked okapi-like animals). “
And how, pray tell, did this poor creature do this all on its own? Mammals don’t reproduce asexually. The correct answer, even if your ideas were correct, would be that it would be through the existing population.
Your thoughts on human evolution are similarly muddled:
“1. All human beings are genetically descended from a single pair of ultimate parents (6,000 years ago, 30,000 years ago, 100,000 years ago, a million years ago, whenever).
2. The current crop of human beings on this planet is genetically descended from more than one pair of ultimate parents, parents who were themselves unrelated.”
These are not exhaustive.
The correct answer is:
3. The current crop of human beings on this planet is genetically descended from more than one pair of ultimate parents, parents who were members of an interbreeding population of at least 1000 individuals. This population shares a common ancestral population with a second population that went on to be the ancestors of modern chimpanzees. This speciation event is estimated to have occurred between 4-7 million years ago.”
It’s late, and I’m off to bed soon, but here’s a paper to read that might help. It discusses human population sizes since speciation with chimpanzees and gorillas.
Dennis
http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.0030007
------------------
On 05/10/09 5:56 PM, "Cameron Wybrow" <wybrowc@sympatico.ca> wrote:
Dennis:
Your remark below needs to be explained, because as it stands it obscures what you are saying, both in reference to biology and in reference to the notion of Adam and Eve.
Obviously there must be a "first" in every biological line. If we take the classic neo-Darwinian example of the hypothetical okapi-like animal which became the giraffe, presumably all modern giraffes can in theory be traced back to a *first* okapi-like animal which grew a neck significantly longer than the other members of its population, and survived food shortages (because it could reach higher leaves), thus leaving more offspring, etc. Neither biologically nor logically could there have been a "first population" of long-necked okapi-like animals until there was a "first individual" of this type. Supposing that the evolution of the giraffe began when an animal five feet tall produced a longer-necked offspring that was five foot six, the five-foot-six offspring is what is normally meant by the phrase "ancestor of the giraffe". The term "ancestor" is perfectly justified by common sense: if that five-foot-six animal had been eaten by a predator before reproducing, there would have been no giraffes -- or at the very least their evolution would have been delayed by however long it took to come up with another five-foot-six offspring, which would be by no means a certain thing. And the five-foot-six ancestor was an individual, not a "population" -- though of course he or she eventually produced a population (of longer-necked okapi-like animals). So your objection to a first ancestor does not make sense. You need to flesh out, in layman's language, what you mean by a "population" in this context. Why does a "first population" exclude a "first individual"?
Consider these two possibilities, which as far as I can tell exhaust the logical alternatives:
1. All human beings are genetically descended from a single pair of ultimate parents (6,000 years ago, 30,000 years ago, 100,000 years ago, a million years ago, whenever).
2. The current crop of human beings on this planet is genetically descended from more than one pair of ultimate parents, parents who were themselves unrelated.
Then there is a further distinction to be made between human and non-human, which when applied to the first distinction yields four possibilities:
1. a. The single pair of ultimate parents was fully human.
1. b. The single pair of ultimate parents were highly sophisticated primates, but not yet human.
2. a. The different pairs of unrelated ultimate parents were fully human.
2. b. The different pairs of unrelated ultimate parents were highly sophisticated primates, but not yet human.
Now:
If 1a is the case, there is no reason why you should object to the notion of a first human pair. I therefore presume that you reject 1a.
If 2a is the case, then the human species emerged *more than once* from the evolutionary process. This is most unlikely on neo-Darwinian premises. Therefore, I presume that you (whom I take to be a neo-Darwinian) reject 2a.
If 2b is the case, then either the descendants of the two (or more) unrelated primate lines mixed, or they did not. If they did not mix over thousands of generations, it was because they could not mix, and then the different types of modern human beings (e.g., Australian aborigine, Caucasian, Mongoloid, etc.) would not be able to mix, either. But all modern human beings can interbreed. Also, after thousands of generations, more like tens of thousands, of separation from two originally distinct primate species, we would expect at least species-level differences among human beings, not mere differences in pigment or hair curliness and so on. But no one thinks that different types of human beings today are of different species. So clearly the (hypothetical) distinct primate lines must have mixed to produce a common human race. But would the lines have been able to mix? That depends on how different the two unrelated primates were in the first place. If they were as different as, say, a baboon and a spider monkey, or a gorilla and an orangutan, or a human being and a gorilla, they would not be interbreedable, and then scenario 2b is impossible. On the other hand, if the two distinctive primate lines were close enough to be interbreedable, then they undoubtedly themselves sprang from a common ancestor, in which case 2b is just a slight variation on 1b.
Thus, by elimination, it looks as if you are plumping for 1b.
So, is your notion that the "first pair" from which all human beings have descended was *not yet human*, so that human beings did not come onto the scene until hundreds or thousands of generations later than the "first pair", by which time there would have been a population of them?
Or, to put it another way, are you granting that all human beings did indeed come genetically from a first pair, but not from a first *human* pair? Just as the present-day population of giraffes came genetically from a "first pair" (an okapi-like animal with a long neck crossed with an okapi-like animal with a normal neck), though that "first pair" was not itself a pair of giraffes? So that the Biblical story is inaccurate, not in postulating a first pair of genetic ancestors for all human beings, but in postulating that the first pair was *human*?
Cameron W.
----- Original Message -----
From: Dennis Venema <mailto:Dennis.Venema@twu.ca>
To: Gregory Arago <mailto:gregoryarago@yahoo.ca> ; George Murphy <mailto:GMURPHY10@neo.rr.com> ; Dick Fischer <mailto:dickfischer@verizon.net>
Cc: muzhogg@netspace.net.au ; asa@lists.calvin.edu
Sent: Monday, October 05, 2009 5:52 PM
Subject: Re: [asa] Re: Reading Genesis theologically NOT historically
Gregory,
The point (biologically) is that there is a first population, not a first individual. Your logic, if I understand it correctly, doesn’t hold. Speciation for humans was a population event, not via a single individual or pair, as far as we can tell.
Dennis
On 05/10/09 2:26 PM, "Gregory Arago" <gregoryarago@yahoo.ca> wrote:
George Murphy wrote: "Adam IS mankind."
If that is the case, George, and if you accept the logic *there must have been a first,* then do you accept that the 'first human' was ADAM, i.e. the first of 'mankind' or 'humanity'? If not, then why not? Are you a *degree, not kind* guy?
--------------------------------------------------------------------
From: George Murphy <GMURPHY10@neo.rr.com>
To: Dick Fischer <dickfischer@verizon.net>
Cc: dickfischer@verizon.net; muzhogg@netspace.net.au; asa@lists.calvin.edu
Sent: Tuesday, October 6, 2009 12:47:31 AM
Subject: Re: [asa] Re: Reading Genesis theologically NOT historically
When humankind (not just a single individual) is said to be created in the image & likeness of God in Gen.1:2, it's quite legitimate (IMO) to interpret the following words, "and let them [N.B.] have dominion over the fish of the sea, and over the birds of the air, and over all the wild animals of the earth, and over every creeping thin that creeps upon the earth" (NRSV). I.e., humans are to be God's representatives in ruling the other creatures of the world. The word "emissary" is really too weak for this. But more importantly, there is no suggestion that oen human being is commissioned to be an emissary to other human beings. So the point remains, there is no canonical texts that says - ot implies - "that Adam was God’s emissary to mankind." Adam IS mankind.
Shalom
George
http://home.roadrunner.com/~scitheologyglm
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