Re: Incisions on ochre from a South African cave suggest modern human behavior emerged around 100,000 years ago

On Jun 13, 6:11 pm, Eric Stevens <eric.stev...@xxxxxxxxx> wrote:
On Sat, 13 Jun 2009 09:50:08 -0700 (PDT), "J.LyonLayden"



<JosephLay...@xxxxxxxxx> wrote:
On Jun 12, 4:25 pm, Jack Linthicum <jacklinthi...@xxxxxxxxxxxxx>
wrote:
Designs on pigment can be seen at the citation/cite.

 Engraved pigments point to ancient symbolic tradition
Incisions on ochre from a South African cave suggest modern human
behavior emerged around 100,000 years ago
By Bruce Bower
Web edition : 1:03 pm

Line designsGeometric patterns incised on pieces of ancient pigment,
such as these 100,000-year-old finds, may reveal the surprisingly
ancient origins of modern human behavior.Courtesy of C. Henshilwood
and F. d’Errico

Scientists excavating a Stone Age cave on South Africa’s southern
coast have followed a trail of engraved pigments to what they suspect
are the ancient roots of modern human behavior.

Analyses of 13 chunks of decorated red ochre (an iron oxide pigment)
from Blombos Cave indicate that a cultural tradition of creating
meaningful geometric designs stretched from around 100,000 to 75,000
years ago in southern Africa, say anthropologist Christopher
Henshilwood of the University of the Witwatersrand in Johannesburg and
his colleagues. Their report appears online and in an upcoming Journal
of Human Evolution.

Much debate surrounds the issue of when and where language, religion,
symbolic decorations and other facets of modern human behavior
originated. Researchers such as Henshilwood hypothesize that modern
human behavior developed gradually in Africa, beginning more than
100,000 years ago. Others posit that a brain-boosting genetic mutation
around 50,000 years ago fostered modern behavior in Africa. Some
researchers suspect that behavioral advances first appeared in Europe,
Asia and Africa at that later time.

Possible examples of symbolic behavior from around 100,000 years ago?—
such as proposed human burials in the Middle East and pigment use in
Africa?—?have been controversial.

“What makes the Blombos engravings different is that some of them
appear to represent a deliberate will to produce a complex abstract
design,” Henshilwood says. “We have not before seen well-dated and
unambiguous traces of this kind of behavior at 100,000 years ago.”

Further studies need to confirm that the ancient incisions were not
the result of, say, slicing into ochre with stone tools in order to
remove powder quickly, cautions anthropologist Curtis Marean of
Arizona State University in Tempe, who studies ancient human behavior
at another South African cave (SN: 10/20/07, p. 243).

Even if the Blombos pigments contain intentional designs, fully modern
human behavior?—?such as the use of figurative art (SN: 6/20/09, p.
11) ?—?didn’t emerge until tens of thousands of years later, contends
archaeologist Nicholas Conard of the University of Tuebingen, Germany.

Henshilwood and study coauthor Francesco d’Errico of the University of
Bordeaux I in Talence, France, disagree. In their view, the Blombos
pigments bear intentionally fashioned designs that held some sort of
meaning and were passed down the generations for 25,000 years. Thus,
the two researchers say, it’s likely that a 100,000-year-old society
already steeped in symbolic behavior originally produced the ochre
engravings.

In 2002, Henshilwood’s team described evidence of symbolic engravings
on two other ochre pieces from Blombos Cave. Those 77,000-year-old
finds were excavated in 1999 and 2000.

Engraved chunks of pigment in the new analysis were unearthed during
the same excavations. Specimens came from either of three sediment
levels with estimated ages of 72,000 years, 77,000 years and 100,000
years.

A microscopic analysis indicates that ochre designs were made by
holding a piece of pigment with one hand while impressing lines into
the pigment with the tip of a stone tool. On several pieces, patterns
covered areas that had first been ground down.

Geometric patterns on the ochre pieces include cross-hatched designs,
branching lines, parallel lines and right angles.

Pigment powder had also been removed from many of the recovered ochre
chunks. Incised patterns may have served as models for pigment designs
applied to animal skins or other material, the scientists speculate.

Excavations of Blombos Cave sediment from before 100,000 years ago
have begun. “The discovery of more, and perhaps even more striking,
engravings is very possible,” Henshilwood says.

http://www.sciencenews.org/view/generic/id/44668/title/Engraved_pigme....

Not only is the archaic idea of a 50,000 year old mutation in europe
stu[pid, a 75,000 year old to 100,000 year old one is stupid too.
Neanderthals had flutes and art and music, abstract thought is not an
HSS invention, and we most likely first learned religion from
Neanderthals.

So too is the idea of all of this having been caused by a single
mutation. Change arising from mutation is an ongoing process and it is
rarely possible to claim that any one mutation is responsible for
behavioural change. Just look at how many mutations are now known to
be related to improvements in what we call 'intelligence'.

Why a Paleolithic Revolution? Simple. Access to the Neanderthals and
homo erecti sparked cultural exchange between the ice sheets.
The only thing remarkable about HSS, as compared to other advanced
paleolithic hominids, is that whenever it gets warm between glaciers,
we *** and breed like rats and rabbits.

Eric Stevens

Single mutation gives us white men, genetic superiority concept, the
inability of a colored person to get a cab in Manhattan at night.

Scientists Find A DNA Change That Accounts For White Skin

By Rick Weiss
Washington Post Staff Writer
Friday, December 16, 2005; A01

Scientists said yesterday that they have discovered a tiny genetic
mutation that largely explains the first appearance of white skin in
humans tens of thousands of years ago, a finding that helps solve one
of biology's most enduring mysteries and illuminates one of humanity's
greatest sources of strife.

The work suggests that the skin-whitening mutation occurred by chance
in a single individual after the first human exodus from Africa, when
all people were brown-skinned. That person's offspring apparently
thrived as humans moved northward into what is now Europe, helping to
give rise to the lightest of the world's races.

Leaders of the study, at Penn State University, warned against
interpreting the finding as a discovery of "the race gene." Race is a
vaguely defined biological, social and political concept, they noted,
and skin color is only part of what race is -- and is not.

In fact, several scientists said, the new work shows just how small a
biological difference is reflected by skin color. The newly found
mutation involves a change of just one letter of DNA code out of the
3.1 billion letters in the human genome -- the complete instructions
for making a human being.

"It's a major finding in a very sensitive area," said Stephen
Oppenheimer, an expert in anthropological genetics at Oxford
University, who was not involved in the work. "Almost all the
differences used to differentiate populations from around the world
really are skin deep."

The work raises a raft of new questions -- not least of which is why
white skin caught on so thoroughly in northern climes once it arose.
Some scientists suggest that lighter skin offered a strong survival
advantage for people who migrated out of Africa by boosting their
levels of bone-strengthening vitamin D; others have posited that its
novelty and showiness simply made it more attractive to those seeking
mates.

The work also reveals for the first time that Asians owe their
relatively light skin to different mutations. That means that light
skin arose independently at least twice in human evolution, in each
case affecting populations with the facial and other traits that today
are commonly regarded as the hallmarks of Caucasian and Asian races.

Several sociologists and others said they feared that such revelations
might wrongly overshadow the prevailing finding of genetics over the
past 10 years: that the number of DNA differences between races is
tiny compared with the range of genetic diversity found within any
single racial group.

Even study leader Keith Cheng said he was at first uncomfortable
talking about the new work, fearing that the finding of such a clear
genetic difference between people of African and European ancestries
might reawaken discredited assertions of other purported inborn
differences between races -- the most long-standing and inflammatory
of those being intelligence.

"I think human beings are extremely insecure and look to visual cues
of sameness to feel better, and people will do bad things to people
who look different," Cheng said.

The discovery, described in today's issue of the journal Science, was
an unexpected outgrowth of studies Cheng and his colleagues were
conducting on inch-long zebra fish, which are popular research tools
for geneticists and developmental biologists. Having identified a gene
that, when mutated, interferes with its ability to make its
characteristic black stripes, the team scanned human DNA databases to
see if a similar gene resides in people.

To their surprise, they found virtually identical pigment-building
genes in humans, chickens, dogs, cows and many others species, an
indication of its biological value.

They got a bigger surprise when they looked in a new database
comparing the genomes of four of the world's major racial groups. That
showed that whites with northern and western European ancestry have a
mutated version of the gene.

Skin color is a reflection of the amount and distribution of the
pigment melanin, which in humans protects against damaging ultraviolet
rays but in other species is also used for camouflage or other
purposes. The mutation that deprives zebra fish of their stripes
blocks the creation of a protein whose job is to move charged atoms
across cell membranes, an obscure process that is crucial to the
accumulation of melanin inside cells.

Humans of European descent, Cheng's team found, bear a slightly
different mutation that hobbles the same protein with similar effect.
The defect does not affect melanin deposition in other parts of the
body, including the hair and eyes, whose tints are under the control
of other genes.

A few genes have previously been associated with human pigment
disorders -- most notably those that, when mutated, lead to albinism,
an extreme form of pigment loss. But the newly found glitch is the
first found to play a role in the formation of "normal" white skin.
The Penn State team calculates that the gene, known as slc24a5, is
responsible for about one-third of the pigment loss that made black
skin white. A few other as-yet-unidentified mutated genes apparently
account for the rest.

Although precise dating is impossible, several scientists speculated
on the basis of its spread and variation that the mutation arose
between 20,000 and 50,000 years ago. That would be consistent with
research showing that a wave of ancestral humans migrated northward
and eastward out of Africa about 50,000 years ago.

Unlike most mutations, this one quickly overwhelmed its ancestral
version, at least in Europe, suggesting it had a real benefit. Many
scientists suspect that benefit has to do with vitamin D, made in the
body with the help of sunlight and critical to proper bone
development.

Sun intensity is great enough in equatorial regions that the vitamin
can still be made in dark-skinned people despite the ultraviolet
shielding effects of melanin. In the north, where sunlight is less
intense and cold weather demands that more clothing be worn, melanin's
ultraviolet shielding became a liability, the thinking goes.

Today that solar requirement is largely irrelevant because many foods
are supplemented with vitamin D.

Some scientists said they suspect that white skin's rapid rise to
genetic dominance may also be the product of "sexual selection," a
phenomenon of evolutionary biology in which almost any new and showy
trait in a healthy individual can become highly prized by those
seeking mates, perhaps because it provides evidence of genetic
innovativeness.

Cheng and co-worker Victor A. Canfield said their discovery could have
practical spinoffs. A gene so crucial to the buildup of melanin in the
skin might be a good target for new drugs against melanoma, for
example, a cancer of melanin cells in which slc24a5 works overtime.

But they and others agreed that, for better or worse, the finding's
most immediate impact may be an escalating debate about the meaning of
race.

Recent revelations that all people are more than 99.9 percent
genetically identical has proved that race has almost no biological
validity. Yet geneticists' claims that race is a phony construct have
not rung true to many nonscientists -- and understandably so, said
Vivian Ota Wang of the National Human Genome Research Institute in
Bethesda.

"You may tell people that race isn't real and doesn't matter, but they
can't catch a cab," Ota Wang said. "So unless we take that into
account it makes us sound crazy."
.

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