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original human population size
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8/7/2012 at 12:20:28 AM GMT
Posts: 5

It is rather hard to say how many species fail to be fossilized because it depends on many factors: the species (soft body vs a shell or bones), how easily the organism is recycled into the environment and preservation of the rock formation (to name a few considerations).

 

One way or another, in order to have a fossil to look at, it needs to have been taken out of the recycling process for long enough. 

 

First, you need conditions where other animals don’t have any chance to carry off any edible parts; microorganisms don’t have a chance to break down whatever is there, and UV doesn’t eventually destroy the remains.  The easiest way for that to happen is that the remains are buried under an avalanche of fine sand and preserved in an anaerobic environment.   The ocean is more likely to provide ideal conditions compared to land.  So first of all, you need rare conditions that produce fossils.

 

Second, there may be many fossils "out there”, but most of them are unreachable because they are buried in unexposed rock formations.  You can only find fossils where you can reach them.  Moreover, these rock formations must be exposed enough that you can get at them without a lot of effort, but not so exposed that they come in contact with the elements for any significant length of time.    Eventually, even these rocks are eroded away, or melted away in subduction zones, or the fossil is distorted beyond recognition in metamorphic rocks, etc.   So second of all, you need to be lucky enough to find these things.

 

Consider how many people have artifacts from their family dating from 100 years ago.  How about 1000 years ago?   How many artifacts do we have that are 5000 years old in general?  How many documents and books were written in the ancient world that still exist today?  The materials we have the most data on are ones preserved on stone tablets.  Many of those were lost in wars, though sometimes, like in the case of Assyria, they were so hated, that, ironically, the library was preserved because it was flattened.   Without that, we would have very few records from that era.  If every decade after a person has passed away, 20% of his/her artifacts are lost each decade, after 100 years, only 10% of those items remain; a chest of drawers, some necklaces, etc.  After 1000 years, we’re talking parts per billion.  That means you need to leave a lot of stuff behind to have one artifact survive.  

 

Hence, it is rather hard to say what exactly is preserved or not when we really cannot say a lot about what was there and what was not.  Nevertheless, considering the odds of anything being preserved even a millennium (with willful human effort to boot), it seems like a reasonable claim to say that 90% of the species are never fossilized (a matter left entirely up to chance).

 

by Grace we proceed,

Wayne 



8/7/2012 at 9:07:01 PM GMT
Posts: 12

Wayne, I wonder if you intended your last comments to go to the Percent of extant species which have fossilized  discussion.


Keith, I agree with your comments. I may have mentioned that I wonder if it is possible that our humanness originated when our ancestors had little more than a chimp’s intelligence. The important thing was that we have some moral awareness and the intelligence to be able to relate to God. Well, just thinking about it, it does seem that we would need more than a rudimentary language. At any rate, I don’t think that it is necessary that humans have the full intelligence we have now. Nevertheless, the Upper Paleolithic Revolution (UPR) does mark a significant change in our ancestors’ behavior and apparent intelligence and it is a very possible origin point for the first humans in the biblical sense. There is a good possibility that this originated from a genetic change. The genetic change may have only produced the necessary conditions of humanness, such as a certain degree of intelligence (if the intelligence displayed at the UPR was necessary for humanness).

Back to the general discussion:

Dennis V., you made the following statement:

"More importantly, the scalability of this approach reveals that there was no significant change in human population size at the time modern humans appeared in the fossil record (~200,000 years ago), or at the time of significant cultural and religious development at ~50,000 years ago.

"Taken individually and collectively, population genomics studies strongly suggest that our lineage has not experienced an extreme population bottleneck in the last nine million years or more (and thus not in any hominid, nor even an australopithecine species), and that any bottlenecks our lineage did experience were a reduction only to a population of several thousand breeding individuals. As such, the hypothesis that humans are genetically derived from a single ancestral pair in the recent past has no support from a genomics perspective, and, indeed, is counter to a large body of evidence.” ("Genesis and the Genome,” Biologos foundation, (http://biologos.org/uploads/projects/venema_genesis_genome.pdf)

After having read most of the reference material several people have offered I still do not see any good reason for the denial that there was an original individual and then an original couple that began the human species we now have. I do not see that this possibility is at all incompatible with the evidence of large population sizes (several thousand at the smallest) of interbreeding individuals continuing from pre-humans to the current human population. The problem with your claim is that one individual has to have the mutation (or a recombination or similar event) that will bring about the change that will be either a sufficient condition for producing a human or merely the last genetic necessary condition (the sufficient non-genetic condition and/or other non-genetic necessary conditions being added by God and/or the environment). It could be the last of a number of genetic changes that produce this change but it is still a genetic change that occurs in only one individual. From this one individual (H1), this mutation or recombination can be easily passed on to produce a first human couple (one of which may or may not be the original first human, H1). They may live within a large population of non-humans in which their offspring can interbreed, with the number of the non-humans gradually diminishing with time. Thus the large interbreeding population will not be diminished though its non-human members will be gradually replaced by humans. The non-humans could also be isolated to become another species.

In Randy’s first response to this discussion, he said, "Perhaps it helps to think of a continuum of mutations and it is a composite set of many mutations that eventually leads to a recognition that the population now represents a new species.” I think this could be true but it must also be true that the composite of many mutations and continuum of mutations end in a particular individual who is sufficiently distinct from its predecessors to constitute a new kind. I do not say species because the first of this new kind must be able to breed with the unaltered population. So it is a new subspecies. Nevertheless, there must still be a first individual one of this kind. 

So, Dennis, would you be willing to now admit that, even if as recent as 50,000 y.a., humans could have "genetically derived from a single ancestral pair . . .” and that this possibility is compatible with the "genomic perspective” and is not "counter to a large body of evidence”?




9/24/2012 at 5:01:35 PM GMT
Posts: 2
original human population size

Sorry for the delay in this posting.  I have just come upon this forum topic.

 I hold that the biological species concept is most pertinent in this context in that it is functional in the dynamics of nature.  I also hold that the Genesis accounts (chapters one vs two) refer to separate events.  If one accepts the ekpyrotic universe model of Steirnhardt and Turok, (Google the topic if unfamiliar) then, I suggest, the Garden of Eden was and still exists in what I call the "heaven brane".  Note that in Genesis one, humans are "created" (I hold by God's natural process involving survival of the favored--see Psalm 104), but there is here no restriction to an original pair.  It is in the Genesis 2 account that Adam is designated and named.  God places him in the Garden of Eden.  I hold that this involves the transferal of "one" (Eve?) into the heaven brane.  Here the fall occurs.  Eve and Adam eat of the tree of the knowledge of good and evil.  Did this result in genetic mutations?  In any event, they have now achieved sufficient sentience to willfully dishonor God by disobedience so that God now must banish them back into the "earth brane" where their offspring interbreed with the earthly population of H. spapiens which subsequent population becomes fully human in sentience.  So we see that biologically our species always had a sizable population, but Adam and Eve were, as a single pair the original sentient (with understanding sufficient to allow willful obedience/disobedience to God's will) beings.

 Perhaps this is not the context to further expand on this perspective.  My book "Why the Universe Bothers to Exist, Theistic Determinism, Evidences and Implications" should be at press before the year is out.  Here this issue and several others such as "why is a new heaven (as well as earth") needed?  What is wrong with heaven as it now exists? are dealt with.

David V. McCorkle