Over the past few months genetic data has been accumulating which will
seriously upset the preferred apologetical schemes. This data is clearly
indicating that humanity has genetically subdivided for over a million
years. By this I mean that to account for the polymorphism of some genes, we
must posit this length of time for the mutations to occur. For the old earth
creationist this means that the concept that Adam was a recent creation is
no longer tenable and for the young-earth creationist who believes in low
mutation rates, the genetic data provides an independent dating for a
history of human kind much longer than 6000 years. A commentary in the
Proc. Natl. Acad. Sci. USA, Jan 30, 2001 had some very interesting things to
say about the current status of genetics as it relates to human history.
“It has been an interesting decade in Human evolutionary genetics. We have
gone from hope to confidence and from confidence to despair. A series of
recent studies, two of which appear in this and a recent issue of PNAS,
gives new grounds for optimism.” Alan R. Rogers, “Order Emerging from Chaos
in Human Evolutionary Genetics,” PNAS, 93(2001):3:779-780, P. 779
Rogers then goes on to say:
“Various authors argued early on that the human population must have passed
through a bottleneck—a period of small population size—sometime during the
late Pleistocene.
“The next few years saw improvements both in the quality of mitochondrial
data available and in the statistical methods available for dealing with
those data. By the mid-1990s, we were able not only to reject the hypothesis
of stationary population size but also to place an upper bound on the
preexpansion population size, a lower bound on the postexpansion size, and
both bounds on the time of the expansion. The evidence indicated that,
sometime between 30,000 and 130,000 years ago, our ancestors expanded to
fill the globe from an initial population of roughly 10,000 breeding
individuals. Then just as this story seemed to be gaining momentum, the
bottom fell out from under it.
“In the late 1990s, as DNA sequencing got cheaper, people began assembling
large datasets from the human nuclear genome. The trouble was that each
genetic locus seemed to tell a different story. The mitochondrial story
received support from data from the Y chromosome and from extensive sets of
short tandem repeat (STR) loci distributed throughout the genome. But other
genes seemed to imply a long history of constant population size, and still
others suggested the action of balancing selection or of geographic
population structure. How can a single species have genes with such
disparate histories? Presumably because natural selection has affected
different loci in different ways. And if the pattern we see is telling us
mainly about the history of selection, then it is unlikely ever to tell us
much about the history of population size.
“This was not, of course, the first time that anyone had suggested a role
for natural selection in the evolution of human mitochondria. The problem is
that selection and population growth can be hard to tell apart. A favorable
mutation may sweep through the population under the influence of natural
selection. If we focus on the carriers of this favorable mutation, the
process looks just like population growth: the number of carriers is small
at first, then increases, and then levels off. For practical purposes, the
two processes have identical effects on genetic variation. There is still no
clean way of distinguishing them except by comparing DNA from different
genetic loci. Population growth should affect every locus in the same way,
whereas selection should affect different loci in different ways. The
disparate results that we see from different loci’ suggest that human
genetic variation is influenced strongly by natural selection. If this view
is correct, genetics may have little to tell us about population history.
“This view, however may be unnecessarily gloomy. There are two aspects of
the emerging pattern that are puzzling under the view that it is all a
product of natural selection: First, the genetic loci that show the
signature of a selective sweep are precisely the ones that, on a priori
grounds, seem most likely to be neutral—the sweeps all seem to have occurred
in DNA that does not code for protein. It is coding only regions that seem
clearly consistent with selective neutrality and constant population size.
This pattern is not as implausible as it may sound: Because of linkage, the
signature of a selective sweep may extend from the coding region on which
selection has acted into the noncoding regions that surround it.
Nonetheless, it is surprising that the effects of selection should be most
clearly visible in those portions of the genome that do not code for
protein. It is also hard to imagine that selection at linked loci was
responsible for the pattern seen in the STRs, because these are distributed
widely throughout the genome.” Alan R. Rogers, “Order Emerging from Chaos in
Human Evolutionary Genetics,” PNAS, 93(2001):3:779-780, P. 779
The article Rogers refers to says that the coalescence time for the gene
system they studied is quite long ago. The gene system was the ms205
minisatellite. They say of the variation seen among Basques, Japanese,
British and Africans:
“The coalescent adds a time dimension to the phylogenetic network (tree);
thus, assuming neutrality, panmixia, and constancy in population size, the
depth of the tree (the time to the most recent common ancestor) is estimated
as 0.72 coalescent units, or about 1.04 million years (…).” Santos Alonso
and John A. L. Armour, “A Highly Variable Segment of Human Subterminal 16p
Reveals a History of Population Growth for Modern Humans Outside Africa,”
Proc. Natl. Acad. Sci., USA, 98(2001):3:864-869, p. 868.
One million years ago, the only hominid on earth was H. erectus. We have his
genes, which means we interbred and are descended from him. Indeed, even
more important is the FACT now, that there were separate lineages over that
time span which are found in modern humans. We were not, as many Christian
apologists contend, the sudden creation de novo less than 120,000 years ago.
Indeed, there is evidence that non-Africans have a genetic history going
back at least 600,000 years—much longer ago than the Out of Africa view
would allow. Consider a paper published last year which said:
"Human DNA sequence variation data are useful for studying the origin,
evolution, and demographic history of modern humans and the mechanisms of
maintenance of genetic variability in human populations, and for detecting
linkage association of disease. Here, we report worldwide variation data
from a 10-kilobase noncoding autosomal region. We identified 75 variant
sites in 64 humans (128 sequences) and 463 variant sites among the human,
chimpanzee, and orangutan sequences. Statistical tests suggested that the
region is selectively neutral. The average nucleotide diversity ( p [pi])
across the region was 0.088% among all of the human sequences obtained,
0.085% among African sequences, and 0.082% among non-African sequences,
supporting the view of a low nucleotide diversity (0.1%) in humans. The
comparable p [pi] value in non-Africans to that in Africans indicates no
severe bottleneck during the evolution of modern non-Africans; however, the
possibility of a mild bottleneck cannot be excluded because non-Africans
showed considerably fewer variants than Africans. The present and two
previous large data sets all show a strong excess of low frequency variants
in comparison to that expected from an equilibrium population, indicating a
relatively recent population expansion. The mutation rate was estimated to
be
1.15 × 10^9 per nucleotide per year. Estimates of the long-term effective
population size Ne by various statistical methods were similar to those in
other studies. The age of the most recent common ancestor was estimated to
be 1.29 million years ago among all of the sequences obtained and 634,000
years ago among the non-African sequences, providing the first evidence from
a noncoding autosomal region for ancient human histories, even among
non-Africans. Zhongming Zhao, et al, “Worldwide DNA sequence variation in a
10-kilobase noncoding region on human chromosome 22” Proc. Natl. Acad. Sci.
USA, Vol. 97, Issue 21, 11354-11358, October 10, 2000
http://www.pnas.org/cgi/content/abstract/97/21/11354
This article gives the time to the most recent common ancestors in Table 5
(reproduced below). Note that the 95% confidence interval on both sides of
the mean are ALL PRIOR TO THE TIME THAT ANATOMICALLY MODERN MAN WAS ON
EARTH. This data demonstrates the high likelihood of independent genetic
lineages stretching back long before the Out of Africa view would allow. And
it is the Out of Africa view that many Christian apologists like Ross,
Newman, Weister and Wilcox have incorporated into their apologetical
schemes. And they are wrong. Here is table 5 — (Ne is the effective
breeding population)
“Table 5. The age (T, 10^3 years) of the MRCA of human sequences
Sequences Ne Tmode Tmean 95% Interval
All samples 10,000 1,288 1,356 712~2,112
12,000 1,104 1,203 605~1,949
15,000 924 1,034 504~1,728
Africans 6,000 1,204 1,256 694~1,882
8,000 1,158 1,203 646~1,843
10,000 1,032 1,105 576~1,752
Non-Africans 6,000 747 806 384~1,330
7,000 678 756 353~1,277
8,000 634 713 333~1,229
The average mutation rate (2.28 × 10^4 per sequence per generation) was
used. “ source Zhongming Zhao, et al, “Worldwide DNA sequence variation in a
10-kilobase noncoding region on human chromosome 22” Proc. Natl. Acad. Sci.
USA, Vol. 97, Issue 21, 11354-11358, October 10, 2000
Note above that the upper limits of the 95% confidence interval incorporates
the earliest H. erecti.
The paper says:
“The TMRCA [The Most Recent Common Ancestor--grm] of Africans was about 0.4
Myr older than that of non-Africans (1,032,000 versus 634,000) (Table 5).
However, the TMRCA of non-Africans from our data are older than the fossils
for modern humans (see ref. 3) and is also older than those of non-Africans
estimated from PDHA1, the ß[beta]-globin gene, and mitochondrial DNA (1, 3,
8, 27). It indicates that even non-Africans have ancient genetic histories,
at least at some regions. Of course, a substantial or large part of the
genetic diversity in non-Africans at the region we studied might be due to
migration from Africa. However, the genealogical depths at this region and
the ß[beta]-globin gene region (1) in non-Africans and the long separation
time between African and non-African sequences at the PDHA1 region (3)
suggest that the transformation from archaic to modern humans might have
occurred in a subdivided population. This does not contradict the assumption
of the African origin of modern humans and also does not imply independent
evolution of modern characteristics in separate populations as implied by
the multiregional model, because the transformation could have occurred
through gene flow and natural selection (3). However, it does suggest that
the origin and evolution of modern humans is more complex than depicted by
the simple out of Africa model (1, 3), especially the assumption of a
complete replacement of all indigenous populations outside of Africa by the
African stock. “Zhongming Zhao, et al, “Worldwide DNA sequence variation in
a 10-kilobase noncoding region on human chromosome 22” Proc. Natl. Acad.
Sci. USA, Vol. 97, Issue 21, 11354-11358, October 10, 2000
A note that unfortunately must be said in this day of racial sensitivity.
One can not use this data to say that the races were genetically distinct.
We aren't. The data accumulated by Alonso and Armour studied the DNA of 50
people, meaning that here were 100 individual strands of nuclear DNA
sequenced. The most popular allele (48) was shared by 13 Basques, 11
Japanese, 14 Brits, 8 Kenyans and 2 Pygmies (see p. 865 of Alonso and
Armour). Among other ethnically shared lineages are one each for the Basque
and Japanese; the Basques, Brits and Kenyans; the Basques and the Kenyans;
the Basques Japanese, Kenyans and Pygmies; and the Pygmies and Kenyans. That
being said, each of the populations sampled contained several unique
sequences. The pygmies had 8 unique lineages; the Japanese, 3; the Brits, 4;
the Basques, 1; and the Kenyans, 4. Clearly, while the unique genetic
lineages indicate a long time span back to the most recent common ancestor,
the lineages shared by various populations are widely enough shared to know
that we humans are clearly one interbreeding population and have been for
the past 1 million years.
These data fits well with other recent studies, such as the fact that
anatomically modern Mungo Man has an archaic form of mtDNA requiring
breeding with the archaics. [Proc. Natl. Acad. Sci. USA 98(2001):537-542]
These data fits well with the recent work by Wolpoff et al in which they
showed that early European anatomically modern people shared more traits
with Neanderthal than with the supposed African invaders [Milford H.
Wolpoff, John Hawks, David W. Frayer, and Keith Hunley, “Modern Human
Ancestry at the Peripheries: A Test of the Replacement Theory,” Science
291(2001):293-297]
It fits well with the discovery of a putative (but contested)
Neanderthal-human hybrid child at Lagar Velho [Cidália Duarte et al, "The
early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho
(Portugal) and Modern Human Emergence in Iberia " Proc. Natl. Acad.
Sciences, USA, Vol. 96, Issue 13, 7604-7609; Erik Trinkaus, and Cidalia
Duarte, “The Hybrid Child from Portugal,” Scientific American April 2000, p.
102]
It fits well with the data of Wallace et al in which the mutation that may
cause Alzheimer's disease was inserted into the human genome 770,000 years
ago. [Douglas C. Wallace, et al, “Ancient mtDNA sequences in the Human
Nuclear Genome: A Potential Source of Errors in Identifying Pathogenic
Mutations,” Proc. Natl. Acad. Sci., 94(1997):14900-14905, p. 14900]
In my opinion, Christians are tying themselves to a sinking ship by placing
such apologetical emphasis on the supposed recent (<120,000 year) creation
of man. There are two reasons for this belief. First, the new genetic
evidence is changing the landscape. It is changing the viability of the most
popular Christian view of human origins and it is providing a means of
dating the very creation of man which is also inconsistent with the other
popular view, the YEC view (already falsified many times over but what is
one more falsification between friends?). Secondly, Christians have tied
themselves with the epistemologically weakest view of human origins. It has
long been known that if the time to the most recent common mitochondrial
ancestor was around 200,000 years, then the time to the most recent nuclear
genomic ancestor would be 4-9 times that long. Christian apologists have
long ignored the warning about this that I have been giving for the past
several years (http://www.calvin.edu/archive/asa/199806/0083.html).
Templeton states:
"If the coalescence time of mtDNA is truly about 200,000 years ago, then the
expected coalescence time of almost all nuclear genes are going to be
commonly greater than one or two million years. This places the expected
coalescence times of much nuclear DNA into a period in which all humans
probably lived in Africa. Hence, studies on nuclear DNA are expected to
have an African root under all hypotheses of modern human evolution." ~ Alan
R. Templeton, "Testing the Out of Africa Replacement Hypothesis with
Mitochondrial DNA Data," in G. A. Clark and C. M. Willermet, ed., Conceptual
Issues in Modern Human Origins Research, (New York: Aldine de Gryuter,
1997), pp. 329-360, p. 353
In order for the recent origin of man, as envisioned by Christian
apologists, to be true, ALL GENETIC SYSTEMS MUST BE LESS THAN THAT AGE. That
means that no genes can have coalescence times of greater than 200,000
years. This clearly is falsified by the new data (and we should have seen it
coming). Christian apologists have tied themselves to the mitochondrial data
hoping that it would win the day for them. Unfortunately, to falsify this
position required only one genetic system be found with a coalescence
time longer than 200,000 years, which we now have. Obviously the concept of
a recent origin of man is less defendable than the ancient origin of man.
One further implication of this data must be noted. Either the Bible is
totally false in what it says about Adam or one must do what I am
doing--extend the Biblical chronology. To claim, in the face of this
evidence, that modern man was a de novo creation within the past 200,000
years is to do the same thing the young-earth creationists do--ignore the
data and believe what we want to believe regardless of the observational
data.
glenn
see http://www.glenn.morton.btinternet.co.uk/dmd.htm
for lots of creation/evolution information
anthropology/geology/paleontology/theology\
personal stories of struggle
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