But such thinking is hard to find. No matter the extent
to which scientists will admit organic "building blocks" of
extraterrestiral origin to the terrestrial "broth" from which
life is assumed to have arisen, the broth remains unchallenged as the
essential womb of the first Earthly cells. A nascent geocentrism
seems to lurk in the minds of men. The new research on protostellar chemistry
should challenge the necessity of terrestrial broth to account for life
on Earth. The job of championing that heresy fell to the eminent
British astronomer Sir Fred Hoyle.
During the
last decades of his life, Hoyle argued that biology cannot be native
to Earth, but must be of extraterrestrial origin. Hoyle did not originate
the hypothesis, called panspermia, and he acknowledged its
long history. But, with new research data in hand, Hoyle waved the
dust off the old idea and, in collaboration with astrochemist Chandra
Wickramasinghe, labored to bring it to public attention. Wickramasinghe
and colleagues continue the project today.
Hoyle's
campaign met with resistance from the scientific community generally,
and to the extent that he was not overtly attacked or dismissed, he
was just 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
to amino
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." Cosmic-scale
organic chemistry was not predicted by any scientific theory. It was
an empirical surprise.
It
was an Empirical Surprise.
Hoyle and
Wickramasinghe insisted that the infalling organic material responsible
for life on Earth was itself alive. They proposed that viable bacterial
cells and viruses rained down on the early Earth and that biology took
root from those extraterrestrial seeds. They insisted moreover that
the rain continues and that some epidemic diseases are the result of "genetic
storms"—of exceptionally active episodes of infall. The
heresy went further. They argued that the evolution of complex life
was itself largely the result of genetic infall from outer space.
This part
of the argument has been bolstered by the growing body of evidence
for horizontal
gene transfer as a significant evolutionary mechanism. Researchers
have demonstrated that when viruses insert their genes into their 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 scientists look to outer
space for novel genetic material.
"Thus
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."
— Cardinal Newman
on the "Illative
Sense" in the Grammar Of Assent, 1870
As for the
means by which interstellar bacteria and viruses might make their way
to planets, Hoyle identified comets as the likeliest vehicles. Comets
originate in, and during their eccentric orbits travel through, interstellar
clouds of organic dust and gas. Hoyle contended that organic material
evaporates off of comets as they round their host stars, a well-documented
phenomenon in the case of our own solar system, and that the freed
material, including whole cells and viruses—the controversial
part—makes its way through planetary atmospheres to the planets
below.
In short,
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 will 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, that which includes the
assortment of elements produced by previous stars and that constitutes
the necessary building material for making planets. The growing body
of evidence for Hoyle's version of panspermia theory is archived and
updated regularly by advocate Brig Klyce at www.panspermia.org.
The star
larvae hypothesis extends the model of Hoyle/Wickramasinghe/Klyce by
positioning evolution—phylogeny—in
an overarching ontogeny and by doing so adding a teleological dimension
to their (and the normal) account of evolution. As radical as their
model might seem, it is conservative insofar as it fails to challenge
natural selection working on genetic variation as the sole mechanism
of evolutionary change.
H/W/K contribute
mechanisms to normal evolution theory that extend the range of genetic
variability and which thereby give selection more to work on. But this
is all they do to extend the theory. The mechanisms they propose are
(1) horizontal gene transfer from viruses and bacteria to unicellular
eukaryotes and metazoans, a process itself amplified by (2) continuing
infall of viruses and bacteria from space. Horizontal transfer is becoming
less controversial as genetic sequencing data accumulate. Infall from
space, however, remains outside the boundaries of normal science. Regardless,
the H/W/K model honors science's bias against teleology.
Hoyle conceived
of planets as being like petri dishes in which bacteria multiply, only
to 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 phylogenetic development. His is another theory of evolutionary
purposelessness.
Tiny
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
little critters are natives of Earth.
The
star larvae hypothesis, in contrast, proposes that multicellular
life 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—bacterial life—and genetic sorters—viruses—to
planets. Beyond that it proposes that the natural cycle includes
a "return trip," the graduation of biological life to the
adulthood of extraterrestrial civilization and ultimately stardom.
That graduation
is a complex process that bridges the divide separating 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.
Stars constitute
a genus of organism.
The stellar life cycle includes a larval phase.
Biological life constitutes the larval phase of the stellar life cycle.
Elaboration: The
hypothesis presents a teleological model of nature, in which
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