No matter the extent
to which scientists welcome organic building blocks of
extraterrestrial origin to the terrestrial "broth" from which
life is presumed to have arisen, that broth remains unchallenged as the
womb of the first living cells. A nascent geocentrism
lurks in the minds of men. But new research in astrochemistry
challenges the need for a terrestrial broth. The job of championing the heresy of an extraterrestrial, not Earthly, origin of life fell to the eminent
British astronomer Sir Fred Hoyle.
last decades of his life, Hoyle presented the case in a number of books and articles that biology cannot be native
to Earth, but must have arrived from space. Hoyle did not originate
this idea, called panspermia, and he acknowledged its
long history. But, with new research data in hand, Hoyle waved the
dust off this old idea and, in collaboration with astrochemist Chandra
Wickramasinghe, labored to bring it to public attention. Wickramasinghe
and colleagues continue the project today.
campaign met with resistance from most of the scientific community,
and to the extent that his evidence and arguments were not overtly attacked or dismissed, they
were ignored. But ongoing research continues to expand
the catalog of organic molecules identified in interstellar space, and
in comets, a catalog that now includes everything from alcohols
acids (and HERE).
And increasingly complex organics continue to be found. In 2011, Researcher
Sun Kwok of the University of Hong Kong analyzed spectral data from
the European Space Agency's Infrared Space Observatory and NASA's Spitzer
Space Telescope and found
evidence of unsuspected organic complexity. "We know that
these organics are being made in the circumstellar environment," Kwok
said. According to an article
on physorg.com, "The team's discovery suggests that complex
organic compounds can be synthesized in space even when no life forms
are present." "Our work has shown that stars have no problem making
complex organic compounds under near-vacuum conditions," says Kwok. "Theoretically,
this is impossible, but observationally we can see it happening."
organic chemistry was not predicted by any scientific theory. It was
an empirical surprise.
in the controversy about the Plurality of worlds, it has been considered,
on purely antecedent grounds, as far as I see, to be so necessary
that the Creator should have filled with living beings the luminaries
which we see in the sky, and the other cosmical bodies which we
imagine there, that it almost amounts to a blasphemy to doubt it."
Lecture by Sir Fred Hoyle to the Sri Lanka Institute of Fundamental Studies, December 1982, "From Virus to Cosmology", on the theory of cometary panspermia
Wickramasinghe insisted that infalling organic material from space consisted of bacterial
cells and viruses and that biology took
root from those extraterrestrial seeds. They insisted moreover that
the rain continues and that epidemic diseases sometimes are the result of "genetic
storms"—of exceptionally active episodes of infall. And the
heresy went even further to propose that evolution itself was largely the result of genetic infall from outer space.
The evolutionary angle has been bolstered by the growing body of evidence
gene transfer as a significant evolutionary mechanism. Researchers
have demonstrated that when viruses insert their genes into host
organisms—the normal mode of infection—the viral genes
can infect germ cells and appear in the next generation of hosts. In
this way, the genome of a species can be augmented
with new genes. Scientists increasingly invoke this process of
gene transfer in their explanations
of evolutionary change. But in whatever ways scientists might concede
that genes get shuffled among organisms, few of them look to outer
space for novel genetic material.
As for the
means by which interstellar bacteria and viruses might make their way
to planets, Hoyle identified comets as the likeliest delivery vehicles. Comets
originate in, and during their eccentric orbits travel through,
clouds of organic dust. Hoyle contended that as organic material
evaporates from comets when they round their host stars—a well-documented
phenomenon in the case of our own solar system—that the freed
material, including whole cells and viruses—the controversial
part—makes its way through planetary atmospheres to the planets
Hoyle proposed that comets harbor microscopic life and disperse it
across the orbital paths of planets. Whether life "takes" or
not on a particular planet will be influenced by various contingencies
idiosyncratic to that planet. Such contingencies include whether
the planet is positioned within a "habitable zone" surrounding
its star. The idea is that only planets at the proper distance from
their stars will provide suitable conditions for complex ecosystems
to evolve. Habitable zones have been proposed for entire galaxies,
as well, being defined as the space at a given distance from galactic
center that includes stars of certain types, namely those that form
from "enriched" starter material, which includes the
assortment of elements produced by previous stars and includes
the necessary building material for making planets.
A research team of which Wickramasinghe was a member found evidence early in 2013 that a meteorite that broke up over Sri Lanka in December 2012 contained fossilized microbes. The evidence has been disputed, but earned coverage in MIT Technology Review's blog. The growing body
of evidence for panspermia theory is archived and
updated regularly by advocate Brig Klyce at www.panspermia.org.
larvae hypothesis extends the model of Hoyle and Wickramasinghe by
positioning evolution within
an overarching developmental cycle, on- and off-planet, and in the process adding a teleological dimension to evolutionary theory.
of planets as functioning like petri dishes in which bacteria flourish and then rejoin the life suspended in the interstellar medium when the planets
they inhabit meet their ultimate fates. This aspect of his thinking
seems to be Hoyle’s least satisfying conjecture. Panspermia is
a one-way street in his model, with no apparent role for complex, multicellular
life other than to host bacteria and viruses. As outside of mainstream
thinking as Hoyle’s proposals were, and to a significant degree
still are, they nonetheless were highly conventional in their nihilistic
view of evolution. His is another theory of evolutionary
star larvae hypothesis, in contrast, proposes that biology
plays an essential role in the natural evolution of the cosmos.
The hypothesis incorporates panspermia, which it takes to be the
critical process in the stellar life cycle that delivers biological
building blocks—bacteria and viruses—to
planets. Beyond that it proposes that the stellar life cycle includes
a "return trip," the graduation of biological life to the
adulthood of extraterrestrial civilization and ultimately stardom.
bridges the divide that separates the organic
from the inorganic. It involves the metamorphosis of biological metabolism
into nuclear metabolism. The technological dimension of the process
culminates in a replenishing of the universe's essential building blocks, protons.
animals called Tardigrades survive
the vacuum of outer space and extremes of radiation, pressure
and temperature, even though these conditions have had
no opportunity to exert selection pressures on the creatures
so as to shape their evolution—if in fact these odd
critters are natives of Earth.
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