A couple of recent articles which make it harder for those who maintain
as an article of faith that there must be extraterrestrial life and one which
throwing doubt on the date of key Homo erectus fossils found in Java:
1. It seems the Martian meteorite ALH84001 does not contain fossils of
once liviing organisms. Here is an article from a recent
Scientist:
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Death knell for Martian Life
Bob Holmes, Santa Cruz
AS 1996 draws to a close, those heady days of summer seem like a
dream. In August, scientists led by NASA's David McKay stunned
the world by producing evidence of past life on Mars. But now two
new analyses could put the final nail in the coffin of that claim.
The evidence for Martian life centres on the meteorite ALH84001,
which chipped off the surface of Mars some 15 million years ago and
landed in the Allan Hills region of Antarctica about 13 000 years ago
(This Week, 17 August, p 4).
Fissures in the meteorite contain carbonate globules. Inside these are
tiny tubular structures that look like fossilised bacteria. The globules
also contain crystals of the minerals magnetite . and iron sulphide that
are similar to those produced by some terrestrial " bacteria, and
polycyclic aromatic hydrocarbons (PAHs), oily organic molecules
often formed during the decomposition of living organisms.
The two new papers, one published this week in Geochimica et
Cosmochimica Acta, the other accepted for publication in the same
journal, provide nonbiological explanations for the magnetite particles
and the PAHs. "The biological explanation is becoming less and less
plausible," says John Kerridge, a planetary scientist at the University
of California at San Diego who is familiar with both studies.
In the paper published this week, the magnetite particles in
ALH84001 are analysed by geoscientists Ralph Harvey of Case
Western Reserve University in Cleveland, Ohio, and Harry McSween
of the University of Tennessee in Knoxville, working with John
Bradley of MVA in Norcross, Georgia, a company which specialises
in microscopic analysis. After cutting a thin section from one of the
carbon globules of the meteorite, they used a jet of argon ions to
erode the slice until it was just 50 nanometres thick-a process known
as ion milling-and examined it under an electron microscope.
Wherever the section sliced through a magnetite particle lengthwise,
the researchers could see a dark line running up its centre. "These
things grew like a tightly wound spiral staircase, and [this line is] the
axis around which the staircase winds," says McSween.
This crystal growth pattern, known as an axial screw dislocation, is
rare in terrestrial magnetites and is totally unknown in those produced
by living organisms, says McSween. The only place on Earth that
they are known to form is at fumaroles, volcanic vents that release
hot gases. The gases condense to form long "whiskers" that grow in
the shape of a staircase. Temperatures of between 500 degrees C and
800 degrees C are needed to produce the mineral vapours, a finding
which ties in with McSween's earlier chemical analysis, which had
argued that the carbonate globules must have formed at more than
450 degrees C (This Week, 26 October, p 5). "I know of no biogenic
mechanism for growing whiskers, and I don't know of any biogenic
magnetite that contains screw dislocations," agrees Peter Buseck, a
geochemist at Arizona State University in Tempe. But he concedes
that scientists have not yet looked at enough biologically produced
magnetites to completely rule out the possibility.
In the second study, Luann Becker and her colleagues at the
University of California, San Diego, report that the PAHs found in
the meteorite could be contaminants from the Antarctic ice. Becker
used a mass spectrometer to analyse the PAHs in several samples of
Antarctic ice, including some from the site where the meteorite was
found. All the PAHs that McKay's team found in the Martian
meteorite were discovered in their ice samples. The PAHs also turned
up in other meteorites collected in Antarctica, including several that
did not originate from Mars. When the researchers added carbonate
granules to water containing PAHs, they found that the PAHs
collected on the surface of the granules. McKay's team had claimed
that the presence of PAHs on granules deep within fissures of the
meteorite and not on its outer surface-argued against external
contamination. The new tests provide a nonbiological explanation for
this unusual distribution of PAHs. "This meteorite sat in the ice for at
least 12 000 years. That gives you plenty of time to accumulate
PAHs," says Becker.
McKay and most of his colleagues were away from their offices last
week and unavailable for comment. However, Hojatolla Vali, a
member of McKay's team at McGill University in Montreal, stands by
the original interpretation. He insists that biological activity is the best
explanation for the PAHs, magnetite, iron sulphide and carbonates
occurring together. "You have to [explain] all those things together,
and as far as I know they don't address this," says Vali. "As long as
they don't do so, I will go for the interpretation that it might be
biological."
(Holmes B., "Death knell for Martian Life", New Scientist, Vol. 152,
No. 2061/2, 21/28 December 1996, p4)
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And here is one from Hugh Ross about the most recent SETI failure:
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ET'S NOT HOME
Our deficit-conscious leaders have recently cut government spending
on the search for extraterrestrial intelligence (SETI). So the small
team of diehard astronomy researchers has found a new source of
funding: zealots committed to finding an "Encyclopedia Galactica,"
the book of answers to all humanity's problems. (Obviously, they
reject the book already provided for that purpose.) In late summer
1996, the team announced its first significant research result. Tuning
in to 202 solar-type stars within a radius of 155 light years, listening
for radio signals as strong as those routinely produced by large radar
systems on Earth, they detected nothing, not even a single mysterious
blip. 1
This null result has weakened at least a few scientists faith that life
arises by natural processes alone and evolves by the same processes
into intelligent life. Others will only admit that it may not arise quite
as easily as they had thought, or that it may exist at a different stage
of development. Zoologist Ernest Mayr points out, for example, that
only one of Earth's 50 billion species has acquired technology. 2 No
lack of evidence will discourage the SETI faithful, for their pursuit
has more to do with spiritual fervor than with scientific rationalism.
Those I have met say that finding an Encyclopedia Galactica is worth
any amount of effort, time, and money that the human race could
possibly expend. The only price they will not pay is the humility of
heart necessary to pick up a Bible and submit themselves to its
transgalactic, supra-cosmic, life-transforming Gospel.
REFERENCES:
1. Christopher F. Chyba, "Life Beyond Mars," Nature,
volume 382 (1996), p.577.
2. E. Skindrad, "Where Is Everybody?" Science News, volume 150
(1996), p.153.
(Ross H, "ET's Not Home", Facts & Faith, Reasons To Believe:
Pasadena CA, Vol. 10, No. 4, Fourth Quarter 1996, pp5-6)
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3. Here is another newspaper article, this time throwing doubt on
the date of some Homo erectus fossils found in Java:
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THE WEST AUSTRALIAN SATURDAY DECEMBER 14 1996 3
Fossil dates test theories of man
SYDNEY
A STARTLING study of the age of ancient Indonesian fossils threatens
to topple theories about the origins of modern humans and the settlement
of Aboriginal Australia.
The bones of contention, found in the 1930s in Java, come from a
species of prehistoric humans known as Homo erectus generally believed
to have died out nearly 400,000 years ago.
Drawing on sophisticated new dating techniques, a team led by Carl
Swisher at the Berkeley Geochronology Centre in California claimed
in the latest Science journal the remains of this Solo Man were a
"surprisingly young" 27,000 to 53,000 years.
If true, this meant the hominid existed at the same time as the direct
ancestors of modern people. It also indicated that Homo erectus survived
on Java at least 250,000 years longer than on the Asian mainland, and
perhaps a million years longer than in Africa, the scientists said.
The new age would almost scuttle the multi-regional hypothesis which
argues that Australia, like the rest of the world, was first colonised by
groups of Homo erectus which emerged from Africa nearly two million
years ago and evolved into modern people everywhere they went.
The competing Out of Africa hypothesis holds that Homo sapiens
appeared in Africa and fanned out from there between 100,000 and
200,000 years ago, pushing aside their burly and less clever Homo
erectus cousins.
But the report has sparked a major row in the scientific community after
two of the original Indonesian authors removed their names from the
Science paper before publication. Another two reportedly were not told
their names would appear.
One of the Indonesians said he disagreed with the research, which put
the age too young.
Many leading scholars agree with Australian National University
anthropologist Colin Groves, who says Dr Swisher's group members are
painstaking researchers, but the dates are probably wrong because the
hominid fossils were mixed with younger animal bones.
The study dated the animal bones because pieces of the precious hominid
fossils could not be taken. A separate non-invasive test in Paris dated
similar fossils at about 300,000 years.
"Fossil dates test theories of man", The West Australian, Saturday
December 14, 1996, p3)
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Happy New Year!
Steve
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| Stephen E (Steve) Jones ,--_|\ sejones@ibm.net |
| 3 Hawker Avenue / Oz \ Steve.Jones@health.wa.gov.au |
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