Re: "From Zarqawi To The Man On The Street, Sunni Arabs FearShiite Emancipation"


Vince Brannigan wrote:
> HawkCW4 wrote:
>
> >
> >
> > Does present a problem don't it? But has anyone yet been able to show
> > where, how one species evolved to become a new species. Simply, chimp
> > to man? Or any other such evolution as we are all supposed to come from
> > a single ball of slime. In all this time, why is no evidence of this
> > available.
>
> Mutaions take place on a molecular level. you mutate the gene, you
> change the next generation.
>
> Vince

http://www.hopkinsmedicine.org/press/2002/August/020815.htm

August 15, 2002
MEDIA CONTACT: Joanna Downer
PHONE: 410-614-5105
E-MAIL: jdowner1@xxxxxxxx

Study: "Jumping Genes" Create Ripples in the Genome- -and Perhaps
Species' Evolution

Laboratory experiments led by Hopkins scientists have revealed that
so-called "jumping genes" create dramatic rearrangement in the human
genome when they move from chromosome to chromosome. If the finding
holds true in living organisms, it may help explain the diversity of
life on Earth, the researchers report in the current (Aug. 9) issue of
Cell.

"Jumping genes," or retrotransposons, are sequences of DNA that are
easily and naturally copied from one location in the genome and
inserted elsewhere, particularly in developing eggs and sperm. There
are more than 500,000 copies in the human genome of the retrotransposon
the scientists studied, accumulated over the millions of years of human
evolution.

But the sheer quantity of these elements isn't as striking as what else
they might be doing as they jump around, says Jef Boeke, Ph.D.,
professor of molecular biology and genetics in the Institute for Basic
Biomedical Sciences at the Johns Hopkins School of Medicine.

"Textbooks always show these elements inserting themselves cleanly into
new places in the DNA," says Boeke, who headed the research team from
Hopkins, "but we saw that about 10 percent of the time, in addition to
inserting, it's taking out a big chunk of the chromosome. The
interesting thing isn't where these elements are going, but what
happens when they get there."

Jumping genes are tightly regulated, and the jumping process probably
doesn't happen as often in living organisms as in laboratory dishes,
notes Boeke. However, in cells that develop into egg and sperm, even in
adults, jumping genes are active. If retrotransposons cause as much
chaos in sperm as they do in the lab, they might allow new genetic
changes to begin in the next generation, Boeke speculates.

"Assuming that what we see in the laboratory is also happening in real
life, it suggests that these elements have been remodeling host genomes
more than previously realized, with deletions, insertions and
inversions," he says. "These changes were probably frequently
disastrous, but occasionally they might have benignly increased genetic
variation or even improved survivability or adaptability. Such
remodeling probably happened thousands of times during human
evolution."

<snip>
http://www.cell.com/cgi/content/full/110/3/327/

and

http://www.actionbioscience.org/evolution/ingman.html


Mitochondrial DNA Clarifies Human Evolution
By Max Ingman

"Where do we come from?" This has been one of the fundamental questions
asked by humans for thousands of years. Physical anthropologists have
been providing an answer for over a hundred years by studying
morphological characteristics, such as skull shape, of the fossilised
remains of our human and proto-human ancestors.

For the last 15 years or so, molecular anthropologists have been
comparing the DNA of living humans of diverse origins to build
evolutionary trees. Mutations occur in our DNA at a regular rate and
will often be passed along to our children. It is these differences
(polymorphisms) that, on a genotypic level, make us all unique and
analysis of these differences will show how closely we are related.
However, different approaches used by molecular and physical
anthropologists have led to opposing views on how modern humans evolved
from our archaic ancestors.


The two main hypotheses agree that Homo erectus evolved in Africa and
spread to the rest of the world around 1 - 2 million years ago; it is
regarding our more recent history where they disagree.

1) Multi-regional evolution

* suggests that modern humans evolved from archaic forms (such as
Neanderthal and Homo erectus) concurrently in different regions of the
world
* supported by physical evidence, such as the continuation of
morphological characteristics between archaic and modern humans
* now a minority standpoint

Out of Africa view: modern humans evolved in Africa before colonizing
the world.
2) Recent African origin

* proposes that modern humans evolved once in Africa between 100 -
200 thousand years ago
* modern humans subsequently colonised the rest of the world
without genetic mixing with archaic forms
* supported by the majority of genetic evidence

Mitochondrial DNA -- maternal DNA -- is used to construct evolutionary
trees.
Mitochondrial DNA

DNA is present inside the nucleus of every cell of our body but it is
the DNA of the cell's mitochondria that has been most commonly used to
construct evolutionary trees.

* Mitochondria have their own genome of about 16,500 bp that exists
outside of the cell nucleus. Each contains 13 protein coding genes, 22
tRNAs and 2 rRNAs.
* They are present in large numbers in each cell, so fewer samples
is required.
* They have a higher rate of substitution (mutations where one
nucleotide is replaced with another) than nuclear DNA making it easier
to resolve differences between closely related individuals.
* They are inherited only from the mother, which allows tracing of
a direct genetic line.
* They don't recombine. The process of recombination in nuclear DNA
(except the Y chromosome) mixes sections of DNA from the mother and the
father creating a garbled genetic history.

<more>

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