PLEASE NOTE:
*
CCNet, 2 November 1999
----------------------
QUOTE OF THE DAY
"The transition from early humans
to modern humans apparently
occurred during the period from 50,000
to 10,000 years ago
(Middle-Upper Paleolithic transition). A
central question is
whether the transition occurred abruptly
or gradually."
--Science Week, 1 November 1999
(1) INTERACTIVE IMPACT CRATERING
Jay Melosh <jmelosh@LPL.Arizona.EDU>
(2) AIR FORCE FEARS SATELLITE DAMAGE DURING UPCOMING
METEOR
SHOWER
Ron Baalke <baalke@ssd.jpl.nasa.gov>
(3) LEONIDS LIVE! BALLOON FLIGHT SCHEDULED FOR NOVEMBER 18, 1999
NASA Science News <expressnews@sslab.msfc.nasa.gov>
(4) CREATING THE MODEL COMET
Ron Baalke <baalke@ssd.jpl.nasa.gov>
(5) SURVIVAL OF LIFE ON ASTEROIDS, COMETS & OTHER SMALL
BODIES
B.C. Clark et al., LOCKHEED MARTIN
(6) HOW TO FIND AN IMPACT ORBIT FOR THE EARTH-ASTEROID COLLISION
G. Sitarski: UNIVERSITY OF BIALYSTOK
(7) COORBITAL DYNAMICS AT LARGE ECCENTRICITY & INCLINATION
F. Namouni et al., UNIVERSITY OF LONDON
(8) MAGNETIZATION OF ASTEROIDS
R. Bingham and M. Dawson, RUTHERFORD APPLETON
LAB
(9) DAMAGE FROM COMET-ASTEROID IMPACTS WITH EARTH
J.G. Hills & M.P. Goda, LOS ALAMOS NATL
LAB
(10) PEER REVIEWED SCIENCE FICTION
Benny J Peiser <b.j.peiser@livjm.ac.uk>
(11) THE CCNET AS A SELF-CORRECTING FORUM
William B. McKinnon <mckinnon@levee.wustl.edu>
(12) SCIENCE & SCIENCE FICTION ON CCNET
Michael Paine <mpaine@tpgi.com.au>
(13) THE ORIGIN OF MODERN HUMANS - GRADUAL OR SUDDEN?
ScienceWeek <prismx@scienceweek.com>
==============
(1) INTERACTIVE IMPACT CRATERING
From Jay Melosh <jmelosh@LPL.Arizona.EDU>
Dear Benny:
I remain an interested, although usually silent, reader of your
net.
However, you and your readers might be interested in a feature
that I
just added to my web site. Using the scaling relations published
in my
book "Impact Cratering" my webmaster, Ross Beyer, and I
have created an
interactive program to compute crater sizes from projectile
diameters or,
inversely, projectile diameters from crater size. I created
the site
mainly in response to a reader question to Astronomy magazine
(the site
will be advertised in the January issue and we will keep it
stable for a
least a few years). Since I have had many people writing to
request
this kind of information I thought it useful to put it out on the
web
so anyone can sign on and put in their own impact
parameters. I have
also included a complete downloadable FORTRAN program that makes
the
same computations for those users who have the appropriate
compiler.
The site to visit is: http://www.lpl.arizona.edu/tekton/crater.html
Sincerely, Jay Melosh
Jay
Melosh
Tel: (520) 621-2806
Professor of Planetary
Science
Fax: (520) 621-4933
Lunar and Planetary
Lab
email: jmelosh@lpl.arizona.edu
University of Arizona
Tucson AZ 85721-0092
==============
(2) AIR FORCE FEARS SATELLITE DAMAGE DURING UPCOMING
METEOR
SHOWER
From Ron Baalke <baalke@ssd.jpl.nasa.gov>
Nov 01 1999 07:38:17 ET
WASHINGTON (Reuters) - The U.S. Air Force said Friday it will be
watching closely for any damage to U.S missile-warning,
communications
and other military satellites when the earth passes through the
Leonid
Meteor Storm on Nov. 17.
The storm, consisting of tiny sand-like particles traveling
faster than
140,000 mph, is essentially a cloudy tail of space debris from
the
comet Temple-Tuttle.
Although there was some concern when the earth first passed
through the
comet's tail in 1998, the Air Force said scientists expect this
year to
be the largest display from Temple-Tuttle since 1966.
Full story here:
http://www.space.com/news/leoniddamage_9901101_wg.html
==============
(3) LEONIDS LIVE! BALLOON FLIGHT SCHEDULED FOR NOVEMBER 18, 1999
From NASA Science News <expressnews@sslab.msfc.nasa.gov>
NASA Space Science News for November 1, 1999
NASA Meteor Balloon Rises Again: NASA scientists and ham
radio
amateurs are teaming up for a weather balloon flight to the
stratosphere during the Leonid meteor shower on November 18,
1999. The
balloon will transmit a live webcast of the meteor shower from an
altitude of 100,000 ft or more, far above any bad weather or
obscuring
clouds. The transmission will include audio from a VLF radio
receiver
designed to capture natural radio signals from the meteors.
FULL STORY at
http://science.nasa.gov/newhome/headlines/ast01nov99_1.htm
==============
(4) CREATING THE MODEL COMET
From Ron Baalke <baalke@ssd.jpl.nasa.gov>
Creating the Model Comet
By Andrew Bridges
Nov 01 1999 05:50:27 ET
When they deign to grace the heavens above, comets are among the
brightest objects visible in the nighttime sky.
But up close, peering within the bright coma and tail that
distinguish
it, a comet's nucleus can be unexpectedly dark, often blacker
than
coal.
Scientists are interested in comets because they are thought to
contain, preserved by the deep freeze of space, the
original
ingredients that made up our solar system, including organic
material
that may have helped spark life here on Earth.
But comets' nuclei are obscured by abundant clouds of gas and
dust.
This makes them difficult to study from Earth. And rendezvousing
with
them -- or any small body, like an asteroid -- in space is an
even
trickier proposition.
Due to the fact comets are so fast moving, and small -- often
just
miles or kilometers across -- spacecraft are increasingly being
given
broad autonomy in navigating the final steps to close encounters.
Full story here:
http://www.space.com/news/planetarymissions/comet_model_991101.html
==============
(5) SURVIVAL OF LIFE ON ASTEROIDS, COMETS & OTHER SMALL
BODIES
B.C. Clark*), A.L. Baker, A.F. Cheng, S.J. Clemett, D. McKay,
H.Y.
McSween, C.M. Pieters, P. Thomas, M. Zolensky: Survival of life
on
asteroids, comets and other small bodies. ORIGINS OF LIFE AND
EVOLUTION
OF THE BIOSPHERE, 1999, Vol.29, No.5, pp.521-545
*) LOCKHEED MARTIN ASTRONAUT,ADV PLANETARY STUDIES GRP,DENVER,CO
The ability of living organisms to survive on the smaller bodies
in our
solar system is examined. The three most significant sterilizing
effects include ionizing radiation, prolonged extreme vacuum, and
relentless thermal inactivation. Each could be effectively
lethal, and
even more so in combination, if organisms at some time resided in
the
surfaces of airless small bodies located near or in the inner
solar
system. Deep within volatile-rich bodies, certain environments
theoretically might provide protection of dormant organisms
against
these sterilizing factors. Sterility of surface materials to tens
or
hundreds of centimeters of depth appears inevitable, and to
greater
depths for bodies which have resided for long periods sunward of
about
2 A.U. Copyright 1999, Institute for Scientific Information Inc.
===============
(6) HOW TO FIND AN IMPACT ORBIT FOR THE EARTH-ASTEROID COLLISION
G. Sitarski: How to find an impact orbit for the Earth-asteroid
collision. ACTA ASTRONOMICA, 1999, Vol.49, No.3, pp.421-431
*) UNIVERSITY OF BIALYSTOK,INST PHYS,UL LIPOWA 41,PL-15424
BIALYSTOK,POLAND
The Earth-crossing asteroids can approach the Earth at
dangerously
small distances. If the observation are of a single apparition
orbit is
short the determined orbital elements and hence a prediction of
the
future encounter with the Earth are uncertain. We presented the
method
of finding an impact orbit by the least squares correction with
the
'forced' equality constraints. As a solution we obtain: (i)
initial
values of rectangular coordinates and velocity components (and
hence
the orbital elements) allowing the asteroid to collide with the
Earth, and (ii) the minimum value of the rms residual resulting
from
the impact orbit. The latter value is very important since it may
serve
as a kind of measure of probability of the collision, and in any
case
it allows us to exclude a possibility of the expected
catastrophe.
We performed computations of the impact orbits for two asteroids:
1997
XF11 and 1999 AN(10). We found two impact orbits for hypothetical
collisions of 1997 XF11 with the Earth in 2028 and 2033, and four
orbits for 1999 AN(10) colliding with the Earth in 2027, 2034,
2036,
and 2039. Based on the 101 observations of 1999 AN(10) from 1999
Jan.
13 - May 16, we shaw that its collision with the Earth in 2027 is
impossible, but in 2039 it would be more probable. We made also a
numerical simulation of the fictitious asteroid which would
certainly
collide with the Earth. We show that in this case we can easily
find
the impact orbit, and the rms value evidently does not allow us
to
exclude a possibility of the collision. Copyright 1999, Institute
for
Scientific Information Inc.
=============
(7) COORBITAL DYNAMICS AT LARGE ECCENTRICITY & INCLINATION
F. Namouni*), A.A. Christou, C.D. Murray: Coorbital dynamics at
large
eccentricity and inclination. PHYSICAL REVIEW LETTERS, 1999,
Vol.83,
No.13, pp.2506-2509
*) UNIVERSITY OF LONDON QUEEN MARY & WESTFIELD COLL,ASTRON
UNIT,MILE END RD,LONDON E1 4NS,ENGLAND
We show that coorbital dynamics at large eccentricity and
inclination
exhibit hitherto unknown types of stable motion in the
gravitational
three-body problem. In the solar system, the secular stability is
observed in the evolution of specific near-Earth asteroids. In
particular, the slow diffusion of such objects through the
Earth's
coorbital region which leads to temporary capture suggests the
existence of undiscovered retrograde moons of the Earth. In the
Coulomb
problem, the Kozai resonance is a primary candidate for stable
low
angular momentum states in two-electron atoms. Copyright 1999,
Institute for Scientific Information Inc.
===========
(8) MAGNETIZATION OF ASTEROIDS
R. Bingham*), and M. Dawson: Magnetization of asteroids. PHYSICA
SCRIPTA, 1999, Vol.T82, p.137
*) RUTHERFORD APPLETON LAB,DIDCOT OX11 0QX,OXON,ENGLAND
It is shown that non-parallel density and temperature gradients
can
produce magnetic fields which can account for the asteroid Gaspra
surface magnetic field of about one Gauss.
============
(9) DAMAGE FROM COMET-ASTEROID IMPACTS WITH EARTH
J.G. Hills*) & M.P. Goda: Damage from comet-asteroid impacts
with
earth. PHYSICA D, 1999, Vol.133, No.1-4, pp.189-198
*) LOS ALAMOS NATL LAB,DIV THEORET,THEORET ASTROPHYS GRP,T-6,MS
B288,LOS ALAMOS,NM,87545
Only a small fraction of the Earth-crossing asteroids, ECAs, have
been
found and cataloged. Uncataloged ECAs can hit the atmosphere of
Earth
without warning. Long-period comets may give as little as two
months
warning before impact. The damage ranges from fires and
blastwaves from
energy dissipation in the atmosphere to craters, earthquakes, and
tsunami from ground impact. Tsunami damage is particularly
severe. An
asteroid 5-6km in diameter impacting in the mid Atlantic would
cause
substantial tsunami damage to both Europe and North America: the
tsunami would run all the way to the Appalachians in the upper
two-thirds of the United States and to the mountains of the
Iberian
Peninsula in Europe. Tsunami heights along the Iberian Peninsula
can
reach several hundred meters. The tsunami heights would be less
in
Northern Europe due to the shallow continental shelf in this
region.
(C) 1999 Elsevier Science B.V. All rights reserved.
==============
10) PEER REVIEWED SCIENCE FICTION
From Benny J Peiser <b.j.peiser@livjm.ac.uk>
As Kelly Beatty and Andrew Glikson have pointed out, one of the
main
consequences of the WWW is the fact that we are increasingly
inundated
by a flood of scientific (and pseudo-scientific) information
which
assails them from all directions, most of it 'unrefereed' and in
the
form of press releases and self-promotion etc.
Part of my job as the moderator of the CCNet is to sift through
this
information an re-distribut a *selected* portion, selected on the
basis
of subject material and (to some extent) the 'quality' of the
material.
Given that this selection process is done by a single person, and
often on an the basis of ad hoc decisions, I try to be as liberal
as
possible in order not to restrict the information flow too much.
The problems involved in this selection process, however, are not
always related to unrefereed material circulating on the WWW. A
recent
abstract search has come up with rather weired paper by the
Russian
scientists E.M. Drobyshevskii on the “Danger of the
explosion of
Callisto and the priority of space missions” which was
published in an
peer reviewed journal under the auspice of the American Institute
of Physics.
I am told that Count Edouard Drobyshevskii is a proponent of
exploding
planets, through a variety of schemes, including a curious
hypothesis
for "runaway" impacts in which a crater forms, then its
ejecta creates
even more craters, and so on until the entire planet is
resurfaced or
destroyed. In the 1980s, Drobyshevkskii published a paper in
which he claimed that Phobos was a planet that had just barely
survived
explosion, as evidenced by its layered fracture pattern, which
supports
his piezoelectric energy storage hypothesis. These explosions, of
course, create the asteroids and the comets, and all of the
albedo
markings on the Earth, Moon and other planets.
Now Drobyshevskii's paper provides us with a good example that
problems
of science communication are often totally unrelated to the
internet:
after all, his paper has been refereed and is written by someone
with
apparently-solid academic credentials. How, then, should such
peer-reviewed information be handled on the CCNet (and in
general)?
Does the fact that this unsubstantiated and rather apocalyptic
paper
was published in a reputable, peer-reviewed journal make it more
acceptable and 'better' than unrefereed press releases as a
source of
information? Clearly, what is relevant here is not the form of
its
presentation but the way in which it is received. Instead of
being
worried about the circulation of flawed and misleading scientific
information (which, as this example impressively shows is a
logical
byproduct of open scientific debates), it is the task of
skeptical
researchers to attempt a falsification of such claims and
predictions.
While this unthankful task is time-consuming, it certainly is, I
would
argue, a major part scientific research. In fact, such critical
response is required for *all* scientific (or pseudo-scientific)
claims
- no matter how rediculous they are or appear to be. Only by
proving
such nonsense wrong a more realistic picture of our cosmic
environment
can be established.
But what is a reputable journal? As far as I am aware, the
Proceedings
of the National Academy of Sciences (USA) is NOT refereed, as
such.
Members/Fellows can publish more-or-less what they want there.
The
early papers by the Alvarez team (which, due to its controversial
theory, may had been rejected by reviewers of other journals),
and the
first major paper by Raup & Sepkoski on periodicities in mass
extinctions were published in this way. Should papers, I ask,
published
there not be admissable to CCNet too?
I leave you with Count Edouard Drobyshevskii’s paper that
raises even
more such philosophical questions. Rather than being outraged or
embarrassed about its contents, Drobyshevskii’s claims
should be
answered and rejected in a sober and matter-of-fact manner. As
long as
his apocalyptic theory remains unchallenged by his critics, it
will be
perceived as a scientific hypothesis just as valid as others.
Only
extreme masochists, I guess, would be happy with the prospect of
a
"nuclear winter every 60 years".....:-)
Benny J Peiser
-------------
E.M. Drobyshevskii: Danger of the explosion of Callisto and the
priority of space missions. TECHNICAL PHYSICS, 1999, Vol.44,
No.9,
pp.1009-1013
RUSSIAN ACADEMY OF SCIENCE,AF IOFFE PHYSICOTECH INST,
ST PETERSBURG 194021,RUSSIA
Ice is a protonic conductor, as has been demonstrated many times
by
electrolysis experiments. The dirty ices which comprise the thick
(similar to 10(3) km) crusts of several distant moonlike bodies
are
subjected to bulk electrolysis by currents excited by the motion
of
such bodies in cosmic magnetic fields (for example, Voyager-1
measured
a current amounting to similar to 10(7) A flowing through the
Jovian
satellite Io and its surroundings). The accumulation of
electrolysis
products in ice in amount equal to 10-15 wt. % renders such a
solid
solution capable of detonation. Global explosions of the crusts
of
moonlike bodies account for the origin and the known properties
of many
asteroids, short-period comets, planetary rings and small
satellites,
the formation of Titan's atmosphere, the differences between
Jupiter's
Galilean satellites, etc. Many predictions made on this basis
have
already been confirmed, and others are awaiting testing.
According to
all the signs, only the ices of the fourth Galilean satellite
Callisto
have not yet exploded. If they explode, the Earth will be
subjected to
concentrated bombardment by cometary nuclei, which will create a
'nuclear winter' once every 60 years on the average. Therefore, a
very
high priority should be assigned to in situ investigations of
Callisto
for the purpose of determining the degree of saturation of its
ices
with electrolysis products. (C) 1999 American Institute of
Physics.
===============
(11) THE CCNET AS A SELF-CORRECTING FORUM
From William B. McKinnon <mckinnon@levee.wustl.edu>
Dear Benny:
With respect to the necessity of references and so forth, the
CCNet
does *in fact* represent a self-correcting forum, where if
someone
wants to report a known fact as a new discovery, someone else
will send
in an e-mail corrective. I think very little needs to be done on
your
end. Kelly Beatty's excellent points refer to the world at large,
which
is generally not self-correcting unless the story is big enough
that it
stays in the news (e.g., cold fusion, life in martian
meteorites).
Mostly newespapers print what comes over the wire, and in many
cases
the wire story is based on a press release, which may not be
written by
the scientists involved but by a hired PR type. This leads
to stories
without context that leave readers wondering what's going on
(e.g., I
keep hearing about water and life on Pluto's moon, but I can't
find any
scientific paper or presentation that even outlines the rationale
behind this assertion) or thinking that scientists are charlatans
squandering the public purse (i.e., endless psychological or
medical
*studies* announcing the obvious). All of this is beyond
our control.
The best we can do is speak up or e-mail when this stuff comes
along.
I believe most of our collegues would be sufficiently embarassed
when
gently exposed as to simply cut it out. Silence guarantees
the present
state of affairs and worse to come.
Sincerely,
Bill McKinnon
William B. McKinnon
Professor of Earth and Planetary Sciences
Department of Earth and Planetary Sciences and
McDonnell Center for the Space Sciences
Washington University
One Brookings Drive
Saint Louis, MO 63130
314-935-5604 (w)
314-935-7361 (f)
314-935-5610 (main office)
mckinnon@levee.wustl.edu
===============
(12) SCIENCE & SCIENCE FICTION ON CCNET
From Michael Paine <mpaine@tpgi.com.au>
Dear Benny,
I for one am comfortable with the manner in which material is
presented on CCNET. It is a good mix of announcements of
important
scientific research and (more in my line) some scientific
speculation
to keep the pot on the boil. For example, we should not overlook
Fred
Hoyle's contribution to science - some of the great scientific
discoveries in the past few decades have resulted partly from a
desire
to "prove Fred wrong" (ref: Violent Universe by Nigel
Calder, BBC
Publishing 1969 pp 149!). And, of course, Arthur C. Clarke's
contribution to the space industry.
You nearly always publish author's email address and organisation
with
each article, and sometimes a URL. People who are concerned about
the
accuracy of an article can either post a response on CCNet or, as
has
happened to me several times, contact the author directly and
sort out
the problem. In such cases it might be appropriate for the
original
author to post a clarification/correction on CCNet. The asteroid
tsunami
issue is a good example. I did some risk calculations with
estimates of
tsunami size and range based on several pre-1997 research papers
and
books. Some scientists working in the tsunami field subsequently
contacted me to inform me that more recent research suggested a
greatly
reduced range for tsunami from asteroid impacts. I therefore
reviewed my
risk estimates, updated my web page and sent a brief note about
the
changes to you.
The longer, more speculative items can continue to be posted as
essays/letters that are separate from CCDigest and people can
read them
if they wish or delete them. Next week Explorezone will publish
my
rather speculative article on the possibility of transfer of
micro-organisms between Earth and Mars via meteorites. Assuming
that you
are happy to circulate the article on CCNet then it would be
appropriate
as an essay since it is around 1200 words.
Regards
Michael Paine
The Planetary Society Australian Volunteers
http://www1.tpgi.com.au/users/tps-seti/spacegd.html
P.S. For more about the "fine line" between fact and
fiction (speculation)
see http://news.bbc.co.uk/hi/english/sci/tech/newsid_501000/501832.stm
I have similar concerns about "Walking with dinosaurs".
My wife plans to
use it in her primary school classroom but she will be making the
point
to students that they should be skeptical about some of the
scenes in
the show.
=============
(13) THE ORIGIN OF MODERN HUMANS - GRADUAL OR SUDDEN?
From ScienceWeek <prismx@scienceweek.com>
SW BULLETIN - November 1, 1999
ON MODERN HUMAN ORIGINS
The study of human origins, the field called paleoanthropology,
has
intrinsic difficulties because of the relative scarcity of data,
but
these difficulties are magnified enormously by the simple fact
that
paleoanthropology, in essence, represents a species attempting to
reconstruct its own early history. As might be expected, an
objective
reconstruction, one without biases and preconceptions, is far
from
easy. The human group we call the "Neanderthals" lived
in much of
Europe, part of Asia, and the Middle East between 150,000 to
probably
less than 30,000 years ago. Neanderthals were the first fossil
humans
to be discovered, and they have long been the focus of
anthropological
investigation. More bones of Neanderthals are known than for any
other
human-related (hominine) fossil group, including 30 nearly
complete
skeletons, so the preoccupation of the anthropology community
with the
Neanderthals is perhaps understandable. One of the important
questions
concerning the Neanderthals is what happened to them? Hypotheses
have
shifted back and forth since the first discovery in 1856 of
Neanderthal
bones, with two major views. One view is that the Neanderthals
were the
direct ancestors of modern Europeans. The other view regards the
Neanderthals as a side branch of human evolution, with extinction
as
their fate. This latter view is apparently the majority view in
the
paleoanthropology community.
G.A. Clark (Arizona State University, US) presents a review of
current
research controversies and methods concerning the transition from
early
humans to modern humans that apparently occurred during the
period from
50,000 to 10,000 years ago (Middle-Upper Paleolithic transition).
A
central question is whether the transition occurred abruptly or
gradually. The author makes the following points:
1) Insufficient data is only part of the reason the question of
human
origins remains unresolved. Researchers in this area come from
various
research traditions, and in each of these traditions different
assumptions about the remote human past determine what is
considered
relevant data, which questions are asked of the data, and how the
data
are interpreted. More data do not remove the paradigmatic bias
implicit
within each research tradition, and in consequence people from
the
different relevant fields fail to communicate effectively.
2) The disciplines that contribute to the field (archeology,
human
paleontology, and molecular biology) tend to be discovery-driven
and
focused on methodology. The result is a common absence of concern
for
the logic of inference underlying claims of knowledge. European
archeological studies of modern human origins are a particularly
good
example of such epistemological naivete. These studies are based
on a
century-old typological systematics that emphasizes retouched
stone
tools, coupled with a set of biases and preconceptions concerning
the
relationships between developments in tool-making and
developments of
cultures.
3) On the surface, the voluminous literature produced by the
debate
concerning modern human origins suggests an informed and
sophisticated
interdisciplinary research in which data are absorbed and
digested,
arguments assimilated, and methodologies understood, compared,
and
evaluated. The author suggests "this is a gross
simplification of a
much more complex reality."
4) The author concludes: "We are, in effect, consumers of
one another's
research conclusions, but we select among alternative sets of
research
conclusions in accordance with our biases and preconceptions.
These
biases and preconceptions must be subjected to critical scrutiny.
As
long as there is no explicit concern with the logic of inference
-- how
we know what we think we know about the past -- there can be no
consensus."
-----------
G.A. Clark: Highly visible, curiously intangible.
(Science 26 Mar 99 283:2029)
QY: G.A. Clark [gaclark@asu.edu]
-------------------
Summary by SCIENCE-WEEK [http://scienceweek.com]
28May99
-------------------
Related Background:
HUMAN EVOLUTION: THE FATE OF THE NEANDERTHALS
The current consensus in paleoanthropology is that the
Neanderthals
were an extinct side-line of human evolution. European
Neanderthals are
thought to have diverged from the lineage that gave rise to
modern
humans at least 500,000 years ago. The current view is that
approximately 30,000 to 40,000 years ago the Neanderthals were
replaced
by modern populations, probably from an ultimately African
source. A
present debate concerns how this population replacement occurred.
Paul Mellars, in a short review of a recent conference (28-30 Aug
1998,
Gibraltar, UK) on the Neanderthals, makes the following points:
1) The current consensus is that in the southern part of the
Spanish
peninsula, roughly to the south of the Ebro valley, the local
Neanderthals survived for at least 5000 to 10,000 years after the
arrival of modern populations in the adjacent parts of northern
Spain
and the Mediterranean coast.
2) The most likely explanation for the prolonged coexistence of
these
two populations lies in the ecological differences between the
northern
and southern parts of the Iberian peninsula.
3) Studies of Neanderthal skeletal remains reinforce the
conclusion
that the Neanderthals were a divergent lineage that probably made
no
contribution to the evolution of anatomically modern humans. This
is
consistent with the DNA evidence that the two lineages separated
at
least 500,000 years ago, and even longer divergence times are
favored
by some researchers.
4) The impression at the end of the conference was that the
Neanderthals were really quite different from humans -- well
adapted to
survive in the harsh glacial environments of Europe, but with
distinct
anatomical and behavioral patterns different from their modern
human
successors. The author concludes: "The eagerness of some
scientists to
claim close kinship with the Neanderthals could come close to
denying
that human evolution actually took place."
-----------
Paul Mellars (University of Cambridge, UK)
The fate of the Neanderthals.
(Nature 8 Oct 98 395:539)
-------------------
Summary by SCIENCE-WEEK [http://scienceweek.com]
6Nov98
-------------------
Related Background:
FIRST ANALYSIS OF DNA FROM A NEANDERTHAL BONE
About 10 kilometers east of Dusseldorf in Germany, in the valley
of the
Dussel, there is a little town called Neander. One hundred and
forty-one years ago, in the summer of 1856, some workmen broke
into a
cave to get at the limestone inside and discovered a set of
ancient
bones. Most of the bones were smashed to bits by the workmen, but
some
of the bones, including part of the skull, survived, and the
skeleton
was soon recognized by anthropologists as belonging to an ancient
race
of men who came to be known as the Neanderthals. A Neanderthal
fossil
had actually been discovered some years earlier in Gibraltar, but
not
recognized as such. Neanderthal-like fossils have also been found
in
France, Spain, Italy, Yugoslavia, Iraq, China, Java, and Israel.
For
more than a century, one of the central questions in
paleoanthropology
has been whether modern man evolved from this race -- or was the
Neanderthal a separate branch that became extinct? Until
recently, the
primary laboratory method of investigation of such a question was
analysis of the morphology of bone fragments. This week, the
field of
paleoanthropology has apparently crossed an important watershed,
as M.
Krings et al (University of Munich, DE; Pennsylvania State
University,
US) report the first analysis of DNA from an extinct human, in
this
case DNA extracted from the actual Neanderthal skeleton found
near
Dusseldorf in 1856. The key to the investigation was the analysis
of
mitochondrial rather than nuclear DNA. Mitochondrial DNA is
usually
present in concentrations two or three orders of magnitude
greater than
nuclear DNA, and they were able to find enough of it still intact
to
amplify with the PCR technique and piece together a total DNA
sequence
of 379 base pairs. Comparison of this sequence with contemporary
human
sequences leads to the conclusion that Neanderthal and modern man
are
separate evolutionary lines, and that the latter did not evolve
from
the former. The work will have to be replicated with other
Neanderthal
fossils, but most paleoanthropologists are excited by the results
and
expect them to be confirmed. The technology of evolutionary
paleoanthropology has evidently now progressed from caliper
measurements of bones to measurements of bone DNA fragments.
(Cell 11 July) (Science-Week 18 Jul 97)
[SW Bulletin 1 Nov 99]
If you have questions or comments about SW BULLETIN, send Email
to:
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Claire Haller, Managing Editor
Copyright (c) 1999 ScienceWeek, All Rights Reserved
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