For some time I’ve puzzled over how mutations arose essentially simultaneously (i.e. within a short time span) to generate new hominid species, especially homo sapiens. (Please, dear reader, don’t refer me to elementary texts or courses on evolution–they don’t answer this question satisfactorily. In this I’m not alone–better minds than mine–Stuart Kauffman, Thomas Nagel, Ilya Prigogine–to name just a few, are not satisfied with the conventional neo-Darwinian model for evolution
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Greg Bear, the author of "Darwin Radio", gives a plausible (if unproven) answer to this question. Human ERV (Endogenous RetroVirus) cause an epidemic: the HERV is transmitted by men to women with whom they have a “steady” sexual relation; the virus causes spontaneous abortions, but the aborted fetus carries an egg that produces a second pregnancy. The child born in this second pregnancy has unusual and different capabilities, including parallel processing in the brain, pherenomes and facial pigmentation changes to convey subtleties in communication–in short a new species.
That such an evolutionary change has occured before is shown in the novel by the discovery of a prehistoric couple preserved in a glacial cave; the male and female are some 15000 years old, and apparently Neanderthals–but there is also a baby, which is apparently Homo Sapiens. The discovery in this prehistoric couple of the HERV that occurs in the modern epidemic suggests that this was the cause of change to Homo Sapiens from early forms. (In this Bear make a paleontological error; Neanderthals and Homo Sapiens were both present over a fairly long time period, and various human races contain up to 3% of Neanderthal genes.)
So, Bear’s suggestion is that somehow, a concerted epidemic carried by ERV, is the mechanism by which jumps to new species occurs. An important question (not answered in the novel) is “who sends the signal for Darwin’s Radio to sound?”, i.e. what causes this epidemic to occur over a limited time span?
How would one criticize Bear’s speculative mechanism? What might be alternative mechanisms for simultaneous mutation in many individuals over a short time period?
And I’ll be the first to admit my scientific expertise is not in molecular biology.
*Molecular biology terms will be explained with links to appropriate websites.
Ah, good question! Here’s how Greg Bear does this: the first fetus produces an egg (mutated) which then implants as per usual in the mother’s womb. Another change: the father and the mother undergo physical changes so that they resemble the mutated child. But there’s an inconsistency here, since the Neanderthals that gave rise to humans did not show such a change. If you think this device is strained, please complain to Greg Bear
I’m confused. Are you saying that the egg of the fetus gets implanted in the mother’s uterus? If so, how does that happen? A female fetus would have a supply of immature eggs.
[quote=“Bob_Kurland, post:1, topic:3694”]
The child born in this second pregnancy has unusual and different capabilities, including parallel processing in the brain,
[/quote]@Bob_Kurland
HI Bob
I think that one need not resort to such a highly speculative mechanism (as ‘second pregnancy’) to explain the relatively sudden appearance of humans, and this is the matter of primary importance to the BioLogos audience. Contributors to this Forum have made good arguments for there being over-emphasis placed on Natural Selection in the origin of species, but no biologist of note (including Prigogine) doubts that new species are produced through evolution. What seems to have been overlooked is the evidence that the rapid increase in size of the primate brain over the past three million years was an exaptation–useful for survival but very greatly ‘over-designed’. You can see the evidence for this if you enter ‘Adult Hydrocephalus’ in Wikipedia. There you will see a recent brain scan of a Frenchman who was living a normal life in modern society with less brain matter than utilized by Lucy, the famous Australopithicus africanus. He was evidently born with a normal sized brain, and so he was able to learn language and the other skills needed to blend into 20th century society, but while progressive hydrocephalus shrunk his active brain (and increased the amount of fluid between lobes) his continued experiences and learning re-programmed the remainder so that he could remain functional.
Since ancient Egyptian times people have wondered: if you deprived a new born baby of any human contact (beyond that needed to keep him clean and fed), how would he behave as an adult, and what language would he speak? The answer? He wouldn’t survive. The nearest thing to that ‘experiment’ was the life of Helen Keller. At the age of 19 months, when her brain had developed enough for baby talk and a few experiences, she lost both sight and hearing. So there was no effective way of reaching her conscious brain to explain the meaning of symbols. It is a very moving story of how Anne Sullivan broke through that barrier by running water over Helen’s hands, while making the Braille symbols on her skin. As soon as Helen grasped the idea of symbols standing for objects, she rapidly ‘programmed’ her brain and joined the human race–even to graduating from college with honors.
So when did Homo sapiens become human? Genetically human, about 200,000 yrs BP–but behaviorally human, only about 40,000 yrs. BP. For 150,000 yrs. they lived side-by-side with the Neanderthals and probably behaved like them. Richard Dawkins observed that, with no evident genetic change, they made a Great Leap Forward. It was as if “their brains were suddenly programmed.”
Is there any known biological mechanism that would accomplish this? Not yet. But if I were running the NIH (Thank the Lord that Collins is, and not me) I would look favorably on a grant application that examined how DNA methylation operates differently in the brain than in other tissues, affecting the maturation of neurons.
So, Bob, I think the speculation I have presented is a little easier to swallow than your ‘second pregnancy.’ What do you think?
Al Leo
Thanks for a very interesting comment AL; I’ll have to chew on it a while. It is Greg Bear, in his novel, who posits a HERV that causes sudden jumps in evolution, and the “second pregnancy”. My problem with the neo-Darwinian model is that i don’t see how genetic changes can occur within a population in a short time interval that cause major phenotypical and physiological changes—in other words changes that cause a new species to occur. If someone can point to a mathematical model that shows how that might occur, I would be most grateful.
I believe what you propose in exaption might be what Gould and Lewontin have proposed as “spandrels”: a change occuring as a byproduct of other changes that do enhance survival–but again, with respect to those primary changes that enhance survival, how do they occur together within a relatively short time period. In other words I don’t believe you find a continuous change in skull (and therefore brain) sizes–rather you find a small range in austrolopithecus (sp?), a greater mean, but still small range in homo erectus, etc.; and even if skull sizes overlap, for example between neanderthals and homo sapiens, there are distinct differences in skull morphology, not continuous changes going from one species to another. Continuous differences are what one would observe I think if new mutations occurred over a long period of time.
Also, Al, you might be interested in reading/ listening to “The Rise of Humans–Great Scientific Debates” by John Hawks; this is where I’m getting most of my information from. I’m a physicist, not a molecular biologist, and models to impress me very much unless they can be set up mathematically so that predictions from the model can be verified quantitatively (or falsified).
LATER Al, I’ve thought some more about your comment; the notion of homo sapiens being “behaviorally human” 160,000 years after they were genetically human is in accord with Kenneth Kemp’s notion of ensoulment and with my beliefs as a Catholic in monogenesis, in this case theological monogenesis. See Kenneth Kemp’s article “Science, Theology and Monogenesis”.
Well, dcscccc (did I get the number of c’s ok?), it isn’t my notion that an epidemic was required to do the ERV modification but Greg Bear’s. However, as a mechanism for sudden change, it fits the bill. With respect to “Irreducible Complexity”, that is part of the original “design”, and so you have to ask is the design set for ERV’s to infect on a regular schedule or does the Designer send out a signal to cause the ERV’s to infect. You tell me!
How could an IMMATURE egg from a fetus make its way to its mother’s fallopian tubes to be fertilized presumably by its grandfather? Note that the fetus wouldn’t be having menstrual cycles, right? Sounds very–um-- FSHy to me.
That is precisely my point. It seems that most people assume that the transition from pre-human to human had to be genetic–essentially a new species, and, via sexual reproduction, that takes millennia under favorable conditions. But the Great Leap Forward was evidently not made genetically–via normal evolution. Dawkins deals with this in “The Ancestor’s Tales”(p. 35) but the clearest exposition is by Ian Tattersall in either “Becoming Human” or, more recently “The Masters of the Planet”.
Thanks for the tip on “The Rise of Humans…” by John Hawks.
Al Leo
The question isn’t really so much how it COULD happen…but how it can’t be avoided.
As we know, even in the human population, some mating pairs do not produce offspring. But on average, human generations are able to produce enough offspring to make a replacement generation. This is possible because there is a constant movement and exchange of genetic material throughout the population.
However, imagine if a group of mating pairs moves to a distant canyon … or the other side of a river … or Australia … any boundary or geography that reduces the free exchange of genetic material between the TWO groups. This in effect makes TWO groups of mating pairs. And there is no longer a UNIFIED average of fertile pairs creating a replacement generation.
What we have are essentially two different populations. And as one population experiences its own unique pattern of genetic changes … there is virtually no way the 2nd population can experience exactly the same pattern. Over time, the average mating pairs of one group has become different enough that pairs formed by individuals from both population groups have become virtually incompatible.
Once the two populations have arrived at this point of divergency … there is virtually no way for the two groups to be considered anything but two separate species. And over time, they will become increasingly different … both in physical appearance and in genetic configuration.
the egg was presumably already fertilized and from the first fetus which produced–as I said, if you find this improbable, complain to Greg Bear, the author!
Beagle Lady, to answer your second question first, I’ll repeat what I said in the original post:
“For some time I’ve puzzled over how mutations arose essentially simultaneously (i.e. within a short time span) to generate new hominid species, especially homo sapiens. (Please, dear reader, don’t refer me to elementary texts or courses on evolution–they don’t answer this question satisfactorily. In this I’m not alone–better minds than mine–Stuart Kauffman, Thomas Nagel, Ilya Prigogine–to name just a few, are not satisfied with the conventional neo-Darwinian model for evolution Greg Bear, the author of ‘Darwin Radio’, gives a plausible (if unproven) answer to this question.”
And, as I said in a previous reply,
“if someone can point to a mathematical model that shows how that [sudden
speciation change] might occur, I would be most grateful.”
To reply to your first question, I’ll quote from the book (pp 96-97) describing the first fetus:
“it’s not much more than an ovary with a blood supply…the eggs were mature…and one follicle has already ruptured…”
Bear does not explain why the second egg is already fertilized, but I’m sure one could, in the context of science-fiction, find a mechanism for that. I can think of several.
Finally, let me say that If you’d like a fuller description, please go to a public library; I’m sure “Darwin’s Radio” would be available (it was on the NY Times best seller list for some time).
George Brooks, thanks for your comment. I understand how geographic isolation leads to speciation. However, I don’t know that such isolation has been shown to exist for homo sapiens and other hominid subspecies (but see below). Moreover, I think Ayala has shown that the vatiation in the DRB1 gene is too large for any such bottleneck to have occurred (cited in Kemp’s Science, Theology and Monogenesis I discuss this in a post “Did Neanderthals have a soul” (Department of shameless self-promotion ) There is, however, evidence for geographic isolation in the case of Denisovan and Neanderthal species, according to John Hawks (The Rise of Humans–Great Scientific Debates)
Mutations don’t have to arise simultaneously. There is genetic variation within almost all populations (except perhaps in severely inbred animals in a laboratory setting).
@Bob_Kurland… Ahhh… As you can see, I thought your concern was over the very basic idea of speciation.
Well, we supporters of BioLogos have God as part of our answer. If a particular issue looms so large in your mind that it is an obstacle in your acceptance of Evolution - - how does God not enter in as part of the resoluton?
) There is, however, evidence for geographic isolation in the case of Denisovan and Neanderthal species, according to John Hawks