& SCIENCE NEWS: January 2002
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& science news > space & science news: January 2002
Five more Martian meteorites found
(Jan. 30, 2002)
Researchers have recovered five meteorites from Antarctica and the
deserts of Oman and the Sahara that have been identified as having
come from Mars. This boosts the number of known Martian stones to
24. The new additions includes one weighing 13.7 kg, making it the
second largest Mars meteorite fragment ever found.
For more, go here.
Mars-like bugs on Earth
(Jan. 18, 2002)
Two different types of microbial colonies found in extreme environments
on Earth have boosted hopes of finding similar organisms on Mars.
They also provide scientists with a way of developing techniques to
search for Martian equivalents. The first consists of microbes (some
of which are shown in the photo) discovered in extremely salty soil
at depths of up to 8 cm below the surface of the dry valleys of Antarctica.
For more on this go here.
The second alien environment – 200 m below the surface of the
Beaverhead Mountains of Idaho in a region of hot springs – yielded
life-forms unlike any previously encountered. These microbes, 90%
of which are archeans, use hydrogen gas, released from deep inside
the Earth, as an energy source, and give off methane. They are exactly
the type of creatures scientists would expect to find underground
on Mars. If there are such "methanogens" on the Red Planet they could
be detected indirectly by the Beagle
2 probe scheduled for launch next year which is able to sniff
out methane in tiny concentrations.
For more on this, go here.
Does extreme stellar radiation sterilize
or accelerate evolution?
(Jan. 12, 2002)
If a nearby star were to send a powerful burst of X-rays or gamma
rays our way, how would life on Earth be affected? How, in general,
are the biological prospects for a world influenced by energetic stellar
radiation? These questions have been addressed by a team of researchers
at the University of Texas at Austin. Many variables are involved,
including the type, intensity, and duration of the radiation source,
and the amount of protection provided by a planet's atmosphere. The
radiation need not be lethal, but may instead induce episodes of intense
mutational damage and error-prone repair, leading to evolution along
very different lines than that on Earth. Evolution on a planet around
a flare star – a red dwarf prone to occasional high-energy outbursts-could
actually accelerate the evolution of life.
For more, go here.
First exoplanet found around a giant star
(Jan. 10, 2002)
To add to the recent flurry of exoplanet discoveries, astronomers
have found the first planet in orbit around a giant star – the
100-light-year distant Iota Draconis, also known as Edasich. Like
all giant stars, Iota Dra has exhausted its core supply of hydrogen
(i.e. it has left the main sequence). It has expanded to be 13 times
bigger than the Sun. In fact, it provides a glimpse of what will happen
to the Sun itself in another five billion years or so. Until now,
no one knew if planets could survive close by a red giant. The Iota
Dra discovery shows that worlds can indeed endure the post-main-sequence
evolution of their host star. The new planet completes one orbit every
1.5 years and has a mass 8.7 times the mass of Jupiter. Because the
Doppler technique determines only the minimum mass of a companion,
it is possible that the true mass of this object is higher and that
it may be a brown dwarf. If this is is the case, however, it will
still be a breakthrough-the first detection of a brown dwarf around
an evolved star.
Out of the shadows: a brown dwarf revealed
(Jan. 9, 2002)
The earliest seafloor hydrothermal vents – supposedly more than
three billion years old – may be nothing more than deposits
from underground springs active in the last few thousand years. That
is the claim of two US geologists who carried out a new analysis of
rocks from South Africa which were previously dated to the Archaean
period – when life first began to diversify. The findings could
have important implications for our understanding of the early Earth
and the microbial life forms that lived there. But one authority on
the geology of the Barberton greenstone belt – where the rocks
are found – launched a vigorous defence of evidence that they
contain ancient hydrothermal vents.
more. Source: BBC
Genes and multicellularity: a chicken-and-egg
(Jan. 6, 2002)
Sean Carroll, a University of Wisconsin-Madison professor of genetics,
and his colleagues believe they have found a clue to the origin of
multicellularity-a major landmark on the road to advanced life, including
ourselves. In the Dec. 18 Proceedings of the National Academy of
Sciences, Carroll et al. report the discovery of a key intercellular-communication
gene in modern, single-celled microbes known as choanoflagellates.
In other words they have found a set of instructions needed by a multicelled
organism in a creature consisting of only a single cell. This supports
the long-held suspicion that choanoflagellates living at least 600
million years ago were ancestral to all today's animals (for a primer
on choanoflagellates, go here).
But it also leads to a tricky chicken-and-egg problem. If this cell-to-cell
communication gene is only useful to a multicelled organism, what
is it doing in something that's unicellular?
Science is full of chicken-and-egg problems – and they're always
the hardest to crack. For example, where did the universe come from?
Cosmologists claim that it may have come from a spaceless, timeless
nothing. But then, before there's time, how can nothing change into
something; doesn't change require time? Closer to home, humans with
essentially our mental capacity and capability were alive around 100,000
years ago. They had the dormant mathematical, musical, and other skills,
that we employ today. But why would a brain with the potential to
solve complex systems of equations and compose symphonies evolve tens
of millennia before that potential was needed?
An answer that might work for both the early human brain and the choanoflagellate
gene set is that nature is parsimonious. That is, if it's already
evolved something that works for one task it will adapt it for use
for another rather than developing something new from scratch. In
particular, biologists have come to appreciate that nature is thrifty
in its use of genes. Instead of inventing new genes to accomplish
new tasks, animals tend to redeploy existing genes, inherited from
more primitive ancestors, in new ways. Having said this, it isn't
clear what a choanoflagellate would use a cell communication gene
for. An alternative, and highly speculative idea, is that the appearance
of genes ahead of their time, as it were, argues for panspermia, and
specifically the introduction of ready-made genes into the terrestrial
gene-pool from an extraterrestrial source. Intriguing, but far from
the scientific mainstream (see this
well-organized website for more on this notion.)
All we can be reasonably sure of at this stage is summed up by Carroll:
"We're starting to get a glimpse of the genetic tool kit we have in
common. In choanoflagellates, we've found genes that heretofore were
believed to exist only in animals. It's a confirmation of the idea
that the genes come first, before their exploitation by organisms."
For more on this work, go here
(University of Wisconsin).
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