A REVIEW OF
59, 1998 March)
concluded that all existing naturalistic origin of life hypotheses are
highly untenable. Consequently, some prominent evolutionists have
hypothesized an alternate origin of life theory called exobiogenesis,
or the theory that life evolved elsewhere in the universe and was
carried to earth. Those who reject both the theistic world view and the
possibility of abiogenesis on the ancient earth must assume a set of
conditions existed elsewhere in the solar system or the universe which
were more favorable for the origin of life or biological molecules.
Recognizing that conditions on earth historically precluded the
spontaneous origin of life forces exploring exobiogenesis to maintain
the naturalistic world view. This view has also motivated the
reintroduction of an intelligent design theory called directed
panspermia. Nowhere does the literature reveal as vividly the
impossibility of a naturalistic origin of life on the earth than in
this field. The fact that an entirely hypothetical scenario has been
proposed in a theory which is supported by virtually no empirical
evidence forces a review of the major exobiogenesis
of the role of organic molecules from outer space in causing the
origin of life on earth, is receiving increased discussion in both
scientific and popular media. The term exobiology was coined by Joshua
Lederberg and refers to the study and distribution of life in the
universe. The three basic types of exobiogenesis are the delivery to
earth of complete organisms such as bacteria, the delivery of complex
organic molecules, and the delivery of simple organic molecules
which synthesize on their way to earth from energy sources such as
ultraviolet light or electrical discharges, or as a result of impact
shocks (Chyba and Sagan, 1992, p. 125).
that during a past heavy bombardment of the earth, which is
have resulted from the
collision of the earth with planetesimals left over from our solar
system's planetary formation 3.5 billion years ago, may "have had
important consequences for the origin of life" on earth (Chyba and
Sagan, 1992, p. 125). Modern researchers are also exploring ideas such
as the seeds of life came from dust clouds which the earth had at one
time passed through during its orbit around the sun:
orbit sweeps up some 16,000 tons of interplanetary matter each year
much of it the remnants of decaying comets. Are new life forms present
in this stellar gift? Did viruses evolve in comets or interstellar dust
bring novel genes to influence earthly evolution? Did earth's life
itself evolve from these cosmic seedings? (Cowen 1978, p. 6)
theorized that during the bombardment of earth, volatile-rich impactors
may have delivered essential 'biogenic' elements to our terrestrial
surface. Moreover, since comets, carbonaceous asteroids, and
interplanetary dust particles (IDPs) are rich in organic molecules,
some speculate these sources may also have contributed directly to
terrestrial prebiotic inventories. The force of the impact of these
compounds with the earth may have shock synthesized some organics in
the atmosphere (Chyba and Sagan, 1992, p. 125). Some simple organic
molecules can remain intact if caught in dust particles small enough to
decelerate them sufficiently to prevent significant pyrolysis (chemical
break down by heat). Many have taken this as evidence that complex
organic molecules, or even bacteria could likewise have survived an
eons-long trip from outer space. This paper reviews exobiogenesis
theory involving the delivery of both simple and complex organic
molecules to the earth, and the motivation behind current speculations
in this field.
The Types of
basic classes of
exobiogenesis are the theories that life arrived on earth from outer
space either from extraterrestrial molecules which later evolved on
earth, or as developed life in the form of seeds, bacteria or of other
organisms, the latter idea called panspermia. The two main types of
panspermia (which is from the Greek, and means "seeds everywhere") are:
Deliberate or Directed Panspermia — the conclusion
that the seeds of life deliberately were brought to earth by beings
from other planets, and Accidental Panspermia — the position
that simple forms of life accidentally were carried here by comets,
meteorites or even from garbage left by past space visitors (Gold,
1960, p. 65).
The History of
exobiogenesis has a long history, dating back to the ancient Romans and
Greeks. The modern panspermia theory was probably originated by the
nineteenth century Swedish chemist Svante Arrhenius (1859-1927), a
Nobel laureate who concluded that life must have come from outer space
because it could not have begun on earth by naturalistic means
(Arrhenius, 1908). He speculated that the earth was seeded by spores
that came from another planetary system and which adhered to specks of
dust propelled by light waves from stars. As a consequence, life was
diffused throughout the universe and took hold where it could exist,
including possibly Mars (Asimov 1972). Scottish physicist Lord Kelvin
(1824-1907) argued that, "seed bearing meteoric stone from another
world started life on earth" (Brush 1982, p. 12). Other past panspermia
advocates include Enrico Fermi, the Nobel laureate who designed and
constructed the first atomic pile that ushered in the atomic age, and
the Hungarian Nobel laureate Leo Szilard who eventually became
professor of biophysics at the University of Chicago. Even the first
great defender of evolution, Thomas Henry Huxley (1825-1895),
speculated that some type of panspermia could have been the source of
au life on earth.
Verne's novel, From
the Earth to the Moon (1865) and H. G. Wells' The War of the
Worlds (1898), both served as catalysts to encourage exploring the
possibility of life in outer space in our century. More recently, the
popular 1950s Flash Gordon television show, and now Star
Trek, Star Wars, Carl Sagan's highly acclaimed Cosmos
series and Sir Fred Hoyle's novel Black Cloud, all have made
the life-from-other-worlds idea feasible in the minds of much of the
public. Much science fiction has eventually become science fact —
journeying to the moon, for example — and this should not surprise us.
Science fiction writers are often scientists by profession, or at least
trained in a science field at the graduate level. The best known
examples are Isaac Asimov, a biochemistry Ph.D., and H. C. Wells, a
biologist. Writing good science fiction requires both a grasp of
science and a vivid imagination. Exobiogenesis is one of the latest
science fictions which is fast becoming respectable science theory
(1988, p. 364)
observes that hundreds of thousands of comets exist and, if life exists
throughout the universe, it could have been carried here by this means.
Many scientists are currently actively testing this theory in the lab
and on computers (Lawren, 1986, p. 32). Hoyle hypothesizes that life
originated in space and migrated by chance to earth by comets,
meteorites, or even dust clouds. Some speculate that a meteorite trade
between earth and Mars may have seeded the later planet, and these
spores may have flourished on Mars when water freely flowed there
(Lawren, 1986, 37) This conclusion is unlikely though, because, in
Phinny's words, "the conditions on Mars are sufficiently extreme that
any microbes that survived the trip in space would probably be killed
on its desolate surface (quoted in Eberhart, 1989, p. 191).
The Reasons for the
noting the level of evidence against the theory of the spontaneous
generation of living molecules on earth, have concluded that life must
have come from outside our solar system. For example:
after almost four decades is still in hard pursuit of life's biggest
secret, agrees that the field needs a dramatic finding to constrain the
rampant speculation. I come up with a dozen ideas a day, and I usually
discard" — he reflects for a moment — the whole dozen'… Unlike some
origin-of-life theorists, Cairns-Smith cheerfully admits the failings
of his pet hypothesis: no one has been able to coax clay into something
resembling evolution in a laboratory; nor has anyone found anything
resembling a clay-based organism in nature. Yet he argues that no
theory requiring organic compounds to organize and replicate without
assistance is likely to fare any better... There is one other way out
of this frustrating theoretical impasse. If neither the atmosphere nor
vents provide a likely locale for the synthesis of complex organic
compounds, maybe they were imported from somewhere else: outer space
Joan Uro of the University of Houston raised this possibility as early
as the 1960s (Horgan, 1991, p 125-126).
It is only one
farther to assume that organic molecules or even "simple" life came to
earth in this way. Likewise it has "long been speculated that earth
accreted prebiotic organic molecules important for the origins of life
from impacts of carbonaceous asteroids and comets" during past major
comet-asteroid showers (Chyba et al. 1990, p. 366). Since some eminent
scientists have championed this theory, it has now achieved surprising
credibility among respected scientists:
and Wickramasinghe in developing the concept of the cosmic cradle [have
based] their theory partly on their own interpretation of the infrared
signatures of some space chemicals [and because] they reject Darwin's
warm shallow pond or Stanley Miller's and Harold Urey's
lightning-created chemical mixtures as birthplaces or organic life.
"The concept of primeval soup' Dr. Wickramasinghe remarked in an
interview, 'is just a confidence trick which people have bought without
much critical analysis. It would be too dilute for anything to happen"
(Cowen, 1978, p. 6).
Wickramasinghe and Sir Fred Hoyle have written more about this topic
than any other researchers. Their books on the subject include Lifecloud,
Diseases From Space, Evolution From Space, and From
Grains to Bacteria. Adler's summary of Hoyle's view that:
living cells originated in comets and were "seeded" on earth early in
its history. In Lifecloud he also pointed out that earthly
organisms are strangely out of tune with conditions in the rest of our
solar system; the wavelengths of light that chlorophyll uses most
efficiently, for example, are not these in which the sun's spectrum is
concentrated. Such speculation…has led Hoyle to exactly the view that
seemed self-evident in the Middle Ages: that life did not arise
spontaneously on earth (1982, p. 55).
who advocate the theory that the origin of life is from outer space via
rocket ships, comets, or similar vehicles, or at least conclude that
the theory has merit, include Francis Crick. In 1962 he shared the
Nobel Prize with James D. Watson for his deoxyribonucleic acid (DNA)
research, a substance that had previously been identified as the master
molecule of heredity (Lear, 1978; Watson, 1968). In 1953 he and his
co-workers demonstrated the now famous double helix molecular
structure carries the four-base code that forms the blueprint which
directs the cell's polypeptide construction. Their discovery spawned
the now famous genetic revolution, including gene mapping technology,
recombinant DNA, and gene therapy (Crick, 1981).
scientists who have publicly stated Panspermia has merit include Salk
Institute for Biological Studies researcher Leslie Orgel, University of
Toledo astrophysicist Armand Delsemme; Joan Oro, professor of
biochemical and biophysical sciences at the University of Houston, and
Harvard astrophysicist Brian Marsden (Cowen 1978). University of
California's Gustav Arrhenius and Richard Gammon of the National Radio
Astronomy Observatory "suggested that solar nebula seeded earth with
life-forming chemicals" (Cowen, 1978, p. 6). Flindt and Binder (1974)
advocated a similar theory as did Von Däniken (1969) and Cohane
(1977). NASA expert Maurice Chatelain (1978) even concludes that the
only way to understand earth history is to postulate some visitation
from outer space which started the events that be concludes caused "the
sudden evolution" which eventually produced humans.
theorizes that the first humans arrived on earth via a spacecraft that
landed about 6,000 years ago. The evidence be uses to support his
theory includes the well documented knowledge that many of the earliest
known civilizations were highly advanced and have enjoyed from their
very beginning highly developed religion, culture and language, both
written and spoken. He notes the time before these advanced
civilizations existed, about 6,000 years ago, is called "pre-history"
because virtually nothing is known today about this period.
Creationists view this as an inadequate attempt to interpret the facts
of history without a creator.
Crick and most other proponents concluded that existing abiogenesis
evolution theories are untenable, partly because the primeval soup was
far too dilute for significant biological activity to occur.
the restless Crick…began stalking the greatest secret of all: the
origin of life itself. Along with other biologists, Crick was troubled
by the prevailing explanations of how life began on earth. In 1973, he
and Leslie Orgel... published an article in the journal Icarus
theorizing that life on earth originated with micro-organisms sent by
rockets from another planet in our galaxy. They call this act of
deliberate seeding "Directed Panspermia" (1981, p. 62).
caused them to "dismiss" neo-Darwinism especially Darwin's "warm
shallow pond" theory and Stanley Miller's and Harold Urey's
lightning-created chemical mixtures in the earths oceans as the birth
place of organic life (Cowen, 1978, p. 6) and to conclude:
evolution has been guided not by natural selection but by repeated
invasions of 'cosmic genes' [and] insects in particular…are such
successful predators and so resistant to human attack that the y must
be alien invaders, perhaps carrying out the plan of a higher
intelligence (Kunzig, 1988, p. 68).
other developments also caused a major shift from abiogenesis on earth
to exobiogenesis as explained by NASA researcher Chyba:
production of organics on earth depends on the details of earth's
primitive atmosphere. Once again, scientists are hindered by a lack of
data. About forty years ago, when the first key experiments on organic
production in early terrestrial atmospheres were performed, scientists
thought earth's earliest atmosphere consisted of methane and ammonia…
But most geochemists no longer think that earth's early atmosphere
consisted of methane and ammonia. The composition of the atmosphere of
early earth was governed by the chemistry of earth's mantle and crust,
and the clues we have about this chemistry now point toward an early
atmosphere rich in carbon dioxide and molecular nitrogen, not methane
and ammonia. In this case, laboratory experiments have shown that it is
vastly more difficult to synthesize organics in earth's atmosphere. So
it is exactly in this case where the extraterrestrial sources loom in
importance. In this less hospitable kind of atmosphere, IDPs could have
been the dominant source of organics on early earth (Chyba, 1992, pp.
Among the many
for the new theory, Johnson suggests the following:
the difficult points is one way to solve an intractable problem;
another is to send the problem off into space. That was the strategy of
one of the world's most famous scientists, Francis Crick, co-discoverer
of the structure of DNA. Crick is thoroughly aware of the awesome
complexity of cellular life and the extreme difficulty of explaining
how such life could have evolved in the time available on earth. So he
speculated that conditions might have been more favorable on some
distant planet (1991, p. 108).
have also expressed much dissatisfaction with the prevailing theories
about how life originated on planet earth. They have concluded that,
given what we know about the environment necessary for life, it could
never have spontaneously generated here (Yockey, 1992; Thaxton, Bradley
and Olsen, 1984). Both Aleksandr Oparin's theory of Coacervates,
microstructures of water surrounded by a few proteins, and Sidney W
Fox's proteinoid microspheres theory have totally failed to bridge the
stupendous gap between life and non-life (Bergbauer, 1993, p. 8).
Milner summarizes the exobiogenesis argument as follows:
conditions for the origin of life may have been better among the vast
amount of organic matter he believes floats through interstellar space.
Unimaginably immense quantities of chemical molecules colliding in
space might make the rare and improbable combinations more likely,
almost inevitable (1990, p. 354).
are looking elsewhere in search of a viable explanation for life's
origin. And in so doing, Adler concluded:
origins of life on earth, a biologist and an astronomer have performed
the improbable feat of reinventing religion. Conventional science has
invoked the workings of chemistry over almost limitless time to bring
the order of life out of the planet's primitive chaos. But life seems
to have begun rather quickly: the more scientists have looked, the
further back they have found signs of life; the earliest fossil
cells,…are almost as old as the solar system itself. Pondering such
mysteries, Nobel Prize winning biologist Francis Crick and Sir Fred
Hoyle, the distinguished astronomer, have independently supposed a deus
ex galaxia to explain the sudden appearance of life on earth: the
seeding" of space by intelligent beings from dis¬tant corners of
the universe (1982, p. 55).
Crick's book, the
seller Life Itself, has received mixed reviews — many
scientists were extremely favorable; others, such as Niles Eldredge,
were very critical. Eldredge (1981, p. 94) called Crick's book "nothing
short of a disaster:" partly because, as Eldredge concluded, "Crick
develops his notion of 'Directed Panspermia' unhampered by such
pedestrian considerations of testability." Ironically, one of
Eldredge's main criticisms of Crick's work was his tendency to see
an alternative to religion and [his lashing] out at "antiscientific
fanatics" who fail to hearken to the clarion call of the twentieth
century gurus of the West, the enlightened scientists… Crick's
characterization of religion as an amalgam of arcane, outmoded beliefs
is intemperate in light of his own views on how life came to exist on
the planet earth (1981, p. 94).
The fact that
some of the
greatest of the world's foremost scientists disagree to this extent on
this topic illustrates how much we have yet to learn about life's
lesser man, Directed Panspermia might well be written off as science
fiction. But Crick is a giant among scientists, and his ideas are not
taken lightly. While he concedes the weaknesses in his theory and does
not hesitate to expound the strengths of others, he insists that
Directed Panspermia is built on a foundation of scientific detail…
Crick allows that he has several times sworn off further writing on the
origin of life "because there is too much speculation running after two
few facts:' but he confesses that "the subject is so fascinating that I
never seem to stick to my resolve" (Jaroff, 1981, p. 62).
Relate to Exobiogenesis
unprecedented scientific advancements finds scientists still arguing
over the views that Jules Verne and H. C. Wells outlined in their
science fiction, and scientists today do not seem to be any closer in
arriving at a reasonably well supported theory of abiogenesis. As Adler
observed, we are still "running after too few facts," and:
Hoyle may have the most far-out hypothesis, but they are not alone in
asking whether life on earth was made possible — or at least influenced
— by objects from the far reaches of the solar system. Astrophisicist
Armand Delsemme…believes that the stuff of living things — including
hydrogen, carbon and oxygen — came from comets, which brought gas and
organic material to lifeless, airless earth… (1982, p. 55).
Delbruck to state about existing abiogenesis and exobiogenesis theories:
these theories seem quite plausible and very intelligent, in my opinion
they tell us very little about the origin of life. I have made it my
rule not to read this literature on prebiotic evolution until someone
comes up with the recipe that says "Do this and do that, and in three
months things will crawl in there" When someone is able to create life
in a shorter time than was originally taken by nature, I will once more
start reading that literature (1986, p. 31).
Frank and Huyghe
have discovered evidence that each minute about 2,100 small comets
consisting primarily of water and ice dump tons of water on the earth.
If the evidence proves valid, our lakes and oceans must have been
formed relatively recently, which poses serious problems for most
existing naturalistic theories of life's origin. The implications for
the current naturalistic origin of life scenario is obvious; without
enormous quantities of water, most existing theories break down. Frank
realizes that for this reason some type of exobiogenesis is the only
savior of atheistic abiogenesis. An exogenesis is also argued for on
the grounds that many of the biochemicals necessary for life could not
have formed here, and thus must have had heir origin elsewhere.
Consequently, in Frank's words many scientists "now believe that much
of the organic molecules needed to create the first forms of life on
earth could well have been brought in by comets that bombarded the
planet early in its history" (1990, p. 56). He cites the work of a
number of researchers who conclude that "a cometary bombardment could
have brought in a hundred to a thousand times as much organic material
as the earth itself would have produced photochemically during the same
period" (1990, p. 56). And, the oxygen problem is likewise solved by
that these small comets provided not only the chemical seeds for life
on earth, but the oxygen to protect it from the sun, as well as the
marine incubator — the ocean — in which it could grow and thrive. That,
in essence, would make us all the children of comets (1990, p. 57).
used here is appropriate because no evidence yet exists that small
comets were historically the source of large amounts of either complex
organic molecules or oxygen, and we now have only controversial
evidence that small comets today are bringing vast quantities of water
and some simple organic compounds from outer space to earth (Marcus,
interview with William D. Hamilton of Oxford University by the senior
editor of New Republic, science author Robert Wright reveals another
reason for the attraction of exobiogenic theories. A theory of the
universe "that I rather like," Hamilton says, is the idea that our
planet is a "zoo for extraterrestrial beings" who planted the seeds for
life, hoping to create interesting intelligent creatures. And these
creatures watching the zoo here every now and then…see something that
doesn't look quite right…the zoo is going to kill itself off if we let
you do this or that. So they insert a finger and just change some
little thing. And maybe these are the miracles which the religious
people like to so emphasize" (1992, p. 44). He recognizes that this
view is fully speculation, yet states, "It is a kind of hypothesis that
is very, very hard to dismiss...if I were setting up an aquarium…this
is virtually the way I would do it. I would try to make as interesting
an aquarium as I could. And I would try to make sure that this big fish
didn't molest little fish too much. And I would occasionally insert a
finger and try to stop him." The anthropomorphic projection here, and
the parallels with a theological world view of a caring God who takes
an active role in his creation, is obvious. The theory also answers the
evidence that this intervention occasionally must have happened — there
are too many disasters which were highly likely, but have never
happened, and the fine tuning of the natural world often seems too
precise to be natural. Hamilton, Wright claims, is "considered by some
to be the most important evolutionary biologist of the second half of
this century" (p. 44). In the words of Crick and Orgel, one of the
strongest arguments for the exobiological origin of life is:
composition of living organisms must reflect to some extent the
composition of the environment in which they evolved. Thus the presence
in living organisms of elements that are extremely rare on the earth
might indicate that life is extraterrestrial in origin. Molybdenum is
an essential trace element that plays an important role in many
enzymatic reactions, while chromium and nickel are relatively
unimportant in biochemistry. The abundance of chromium, nickel, and
molybdenum on the earth are 0.20, 3.16, and 0.02%, respectively. We
cannot conclude anything from this single example, since molybdenum may
be irreplaceable in some essential reaction — nitrogen fixation, for
example. However, if it could be shown that the elements represented in
terrestrial living organisms correlate closely with those that are
abundant in some class of star — molybdenum stars, for example — we
might look more sympathetically at "infective" theories.
uncritical speculation that exobiogenesis has produced. North even
concludes that exobiogenesis has influenced the speculation of persons
such as Von Däniken:
second example is
the genetic code. Several orthodox explanations of the universality of
the genetic code can be suggested, but none is generally accepted to be
completely convincing. It is a little surprising that organisms with
somewhat different codes do not coexist. The universality of the code
follows naturally from an "infective" theory of the origins of life.
Life on earth would represent a clone derived from a single
extraterrestrial organism. Even if many codes were represented at the
primary site where life began, only a single one might have operated in
the organisms used to infect the earth (1973, pp. 344-345).
are not skilled scientists but who have come to believe in the
doctrines of evolution are therefore easy targets for the Von
Dänikens of the world. Von Däniken seems to be able to answer
questions that standard scientists cannot answer. How is it that
mankind could have evolved so rapidly both technologically and
philosophically? How is it that his intellect is so advanced compared
to changes in his body? How is it that the mind of man seems to have
evolved much more rapidly than changes in man's environment would have
accounted for? Questions such as these baffled Alfred Russell Wallace,
the cofounder of the doctrine of evolution through natural selection
and led him into occultism and spiritism in the late nineteenth
century. Similarly, modern readers are baffled by these obvious
questions or variants of these obvious questions, and when they find
that modern science has no answers, they easily pick up on
pseudoscientific answers. Von Däniken's answer sold millions of
copies (1986, p. 307).
a prolific and influential popular writer (1969, 1970, 1973, 1973a,
1974, 1982), his works having sold millions of copies and resulted in
several films. Most scientists classify his works as un-scholarly,
often containing unfounded and unsupported speculation.
The Major Problems
to exobiogenesis is the fact that we simply have no direct evidence
that any form of natural exobiogenesis has ever actually occurred.
Panspermia is more speculative because it presumes both that life
exists on other planets and that, given the right conditions, life is
able spontaneously to generate itself there. The whole theory, as many
of its critics point out, is almost purely speculation. Although
several kinds of amino acids have evidently been found in meteorites,
we have not detected evidence even for the simplest amino acid,
glycine, in outer space, though astronomers "have looked like mad for
glycine" (Kunzig, 1988, p. 7). The Murchison meteorite found in
Murchison, Australia, "is rich in simple amino acids" and an estimated
300 tons of organic molecules annually fall to the earth. But no
complex polypeptides or similar "organic" molecules have yet been found
(Chyba, 1992, p. 30; Pendleton and Cruikshank, 1994).
molecules identified by astrochemists in outer space, as is also true
on earth, most are simple organic having up to only thirteen atoms
(Pendleton and Cruikshank, 1994). The most complex example found so far
is simple ethanol (C2H6O) discovered in some
outer space clouds — a finding which Kunzig states, "is not surprising
[because] after hydrogen, helium and oxygen, carbon is the most
abundant element in space" (1988, p. 70). Because of the major gaps in
our knowledge of early earth conditions, the confidence of scientists
in the exobiogenesis theory is mixed, as explained by NASA Ames
Research Center scientist Chyba:
about the composition of earth's early atmosphere is far from settled.
Remarkably, though, it appears that whatever the primitive atmosphere's
exact nature, the heavy bombardment played an important role in
stocking the primordial soup of organics available for the origin of
life. If the atmosphere was methane and ammonia-rich, the heavy
bombardment produced organics copiously by shock chemistry in the
atmosphere. If the atmosphere was far less hospitable for organic
chemistry, composed of carbon dioxide and nitrogen, say, then the
asteroids and comets responsible for the heavy bombardment, and the
ever-present interplanetary dust particles, may have played a key role
by providing organic-rich dust to seed earth's ancient surface. Either
way, the case for an important extraterrestrial connection for the
origin of terrestrial life is too intriguing to ignore (Chyba, 1992, p.
the building blocks of protein, they are "rather simple substances" and
a long way from most proteins. The amino acid leucine consists of only
22 atoms, whereas most proteins contain many thousands. Further Hoyle
estimates that it requires 200,000 types of protein assembled in an
incredibly complex way to make up a cell (1983, p. 12). The compounds
found in outer space and in meteorites, while organic, are a long way
from life, actually about as far as a bucket of bolts is from a Ferrari
(Sandilands 1986, 1986a). Labeling something an organic compound
implies to the uninformed that it is a "living organism, or something
close to it, when it is actually only any compound that contains carbon
and hydrogen (Dorin, 1984). Carbon readily combines with most other
elements — actually almost all known types of compounds are carbon
based; over 10,000,000 are "organic" compared to only about 1,000,000
non-organic. Iron is a necessary transport molecule for many forms of
higher life; yet the discovery of iron on a planet would hardly prove
that life was close to formation there. Crick and Orgel conclude:
unlikely that extraterrestrial living organisms could have reached the
earth either as spores driven by the radiation pressure from another
star or as living organisms embedded in a meteorite. As an alternative
to these nineteenth-century mechanisms, we have considered Directed
Panspermia, the theory that organisms were deliberately transmitted to
the earth by intelligent beings on another planet…[and] that it is
possible that life reached the earth in this way, but...the scientific
evidence is inadequate at the present... (1973, p. 341).
A major problem
explaining the origin of life by exobiogenesis is that it only moves
the origin-of-life problem to another location, relocating elsewhere
all unanswered questions to a place where they are almost impossible to
answer (Wyson g, 1976). As Christian (1986, p. 364) notes, pushing "the
problem light-years away to some unknown location" does not solve the
question of how naturalistic origins can occur. This speculation
results from the assumption that there may be other types of planets "on which the origin of life ab initio is greatly more probable
than on our own" (Crick and Orgel, 1973, p. 341). From what we know
about the conditions in outer space, though, it seems that it is far
more hostile to the formation of organic molecules than the earth ever
was. Heat or other forms of energy are critical to form most compounds,
and interstellar space gas is at most only about 25 to 30 above
absolute zero and stars are far too torrid (Kunzig, 1988, p. 71). Some
simple compounds that exist there may have been formed by cosmic ray
energy, but this is also a major means by which many compounds are
destroyed (Friedlander, 1989).
the low likelihood that extraterrestrial life would be compatible with
earth's environment, or even survive traveling for millions and
millions of years in a space environment which is extremely hostile to
life and still be viable. We know of no possible source of life within
fewer than about five light years away from the earth. Consequently,
any possible origins are at the minimum many centuries travel away,
depending on how fast the carrier can travel. The transport problem was
summarized by Angelo as follows:
difficulty most scientists today have with Arrhenius's original
panspermia concept is simply the question of how these "life-seeds can
wander through interstellar space for up to several billion years,
receive extremely severe radiation doses from cosmic rays and still be
"vital" when they eventually encounter a solar system that contains
suitable planets. Even on a solar system scale, the survival of such
microorganisms, spore or bacterial would be difficult. For example,
"life seeds" wandering from vicinity of the earth to Mars would be
exposed to both ultraviolet radiation from our Sun and ionizing
radiation in the form of solar-flare particles and cosmic rays. This
interplanetary spore migration might take several hundred thousand
years in airless, hostile environmental conditions of outer space
(1991, p. 127).
(1966, p. 209) estimated if the earth were seeded by a planetary
system, it would have to have occurred "several billions of years ago"
to fit current evolutionary theory, and thus must have been from a star
no more than about 6,000 light years away. This limits the potential
concern is that
ultraviolet x-rays and other radiation, and the high vacuum (1 atom per
cm-3 conditions and the lack of oxygen in space would likely
destroy life or life's seeds during its long journey. Crick and Orgel
argue "any known type of radiation-resistant spore would receive so
large a dose of radiation during its journey to the earth from another
solar system that it would be extremely unlikely to remain viable"
(1973, p. 341). A further hazard is the large regions of hot ionized,
interstellar gas pockets that evidently existed in early space
(Shklovskii and Sagan, 1966). One objection is answered by assuming
that the seeds of life were shielded from space radiation by a
meteorite's outer shell (Lawren, 1986). How life got inside of a
meteorite without being destroyed by the heat that formed the meteorite
rock originally, or how it survived the heat generated in its travel
through space dust or the earth's atmosphere, is not clear. Shklovskii
and Sagan note that if a life bearing meteorite was ejected from a
planet that is near a star which probably includes most planets,
hazards cannot be avoided by providing a protective shielding for the
bug. With a shielding thick enough to be useful for radiation
protection, the bug would be too large to be ejected by solar radiation
pressure. Similarly, we cannot save the panspermia hypothesis by
imagining interstitial spores locked within the fissures of some
interplanetary dust particles or meteors and there shielded from the
harmful radiation (1966, pp. 209-210).
Some have tried
with these problems by speculating that
of the kinetic energy of a comet with a density of 1 g cm-3
will be partitioned not into heating the impactor but into kinetic
energy of ejecta and target heating, it is possible that aerobraking
(slowing by atmospheric drag) and uneven distribution of shock energy
throughout the impacting projectile will conspire to yield some region
of the comet for which temperatures remain low enough to allow at least
the hardier organics to survive (Chyba et al., 1990, p. 367).
The ability of a
surviving during a trip from outer space to earth has been researched
by many scientists, and the most optimistic are Leiden and Greenberg
who speculated that: "While 'naked' spores had a life expectancy of
only 150 years in space, at least 10 percent of those with molecular
shields could last up to 45 million years — more than long enough to
survive an interstellar journey" (Lawren, 1986). The spores used in
this research, though, were those of the highly developed Bacillus
subtilis, a hardy bacterium which, in contrast to most except a few of
its cousins, is very difficult to kill. Further, to be able to produce
a set of events in controlled laboratory conditions says only what may
be possible, not what actually has occurred historically. The
45-million year survival time is pure speculation which assumes a set
of ideal conditions and ignores the extremely destructive effect of
cosmic rays. No one is denying the potential contributions of this
experiment, but it argues far more for over design of bacteria than for
atheistic evolution of them, illustrating the extent to which some
researchers will go to deny a designer to explain design.
concern is how the spores could break away from their home base gravity
and travel into space. This is no easy task, as our space program
engineers are keenly aware (Lawren, 1986, p. 32). In the words of Crick
and Orgel "The probability that sufficiently massive objects escape
from a solar system and arrive on the planet of another one is
considered to be so small that it is unlikely that a single meteorite
of extrasolar origin has ever reached the surface of the earth" (1973,
p. 341). Crick does an admirable job attempting to explain many of
these difficulties but falls far short, leaving most of the major
objections unanswered. Many of these objections were recognized long
ago. Wells, Huxley and Wells summarized the problem a full half-century
ago as follows:
origin of life must always remain a secret: even if man succeeds in
artificially making life, he can never be sure that Nature did not
employ some other means. Some thinkers have supposed that life was
carried to this earth in a dormant state within meteorites. But this is
to think timorously and to balk the issue; it only removes the problem
of life's origin one step farther back. It does not absolve us from
asking how and when life originated, but merely introduces an extra
difficulty (1935, p. 8).
recognized these problems with the theory that accidental exobiogenesis
was the source of life on earth, so they have proposed the intelligent
design theory called directed panspermia. Crick and Orgel attempted to
resolve the above fatal problems of evolution.
the directed-panspermia hypothesis…in the early 1970s they suggested
that an ancient, intelligent alien race could have con¬structed
suitable interstellar robot spacecraft; loaded these vehicles with an
appropriate cargo of microorganisms, spores or bacteria; and then
proceeded to "seed the Galaxy" with life, or at least precursors of
life (Angelo, 1991, p. 127).
In their words,
reason that life could have begun on earth
of infection by microorganisms sent here deliberately by a
technological society on another planet, by means of a special
long-range unmanned spaceship?... If we are capable of infecting an as
yet lifeless extrasolar planet, then, given that the time was
available, another technological society might well have infected our
planet when it was still lifeless. The spaceship would carry large
samples of a number of microorganisms, each having different but simple
nutritional requirements, for example blue-green algae, which could
grow on CO2 and water in "sunlight". A payload of 1000 kg
might be made up of 10 samples each containing 1016
microorganisms, or 100 samples each of 1015 microorganisms
(Crick and Orgel, 1973, p. 343).
The purpose of
effort by these aliens to spread life, according to Crick and Orgel,
was "missionary zeal" (1973, p. 344). In Johnson's words, the
exobiogenesis theory of Crick and Orgel includes
idea...that an advanced extraterrestrial civilization, possibly facing
extinction, sent primitive life forms to earth in a spaceship. The
spaceship builders couldn't come themselves because of the enormous
time required for interstellar travel; so they sent bacteria capable of
surviving the voyage and the severe conditions that would have greeted
them upon arrival on the early earth (1991, p. 108).
spacemen were discussed in more detail by Angelo:
extraterrestrial civilization undertake this type of project? Well, it
might first have tried to communicate with other races across the
interstellar void; then, when this failed, it could have convinced
itself that it was alone! At this point in its civilization, driven by
some form of "missionary zeal" to "green" or perhaps "blue" the Galaxy
with life as it knew it, the alien race might have initiated a
sophisticated directed-panspermia program. Smart robot spacecraft
containing well-protected spores, microorganisms or bacteria were
launched into the interstellar void to seek new "life sites" in
neighboring star systems. This effort might have been part of an
advanced-technology demonstration program, a form of planetary
engineering on an interstellar scale. These life-seeding robot
spacecraft may also have been the precursors of an ambitious
colonization wave that never came — or is just now on its way! (1991,
Not only the
life, but also its extinction has been postulated by scientists as
occurring by extraterrestrial events. The best example is the Chicxulab
impact Crater, now estimated to be 185 miles wide and 15 miles deep,
the largest crater in the universe, even surpassing the 175 mile wide
Mead Basin on Venus (Sharpton et al., 1993). It is speculated to have
wiped out 60 to 80 percent of all animal species then, allowing the
evolutionary diversification of mammals.
The Empirical Evidence
for the Theory
method exists to test
the theory that the first living cells which gave rise to life on earth
formed in space about 4.6 billion years ago. Since, Hoyle and
Wickramasinghe (1978, 1984) concluded that this influx of life from
outer space (mainly via comets) may be occurring today, it is feasible
to determine empirically whether or not the recent visit of other
comets brought germs or complex organic matter of any kind aside from
amino acids to earth. For a control population, satellites or high
flying airplanes could be used to accurately evaluate the contents in a
certain area of space. Then, when a comet makes a close enough
appearance (as Halley's tail does occasionally) a germ or organic
molecule count of the same area can again be taken. If it increases
significantly, and if this increase cannot be accounted for by other
causes, the result would indicate that the comet was carrying germs or
some type of complex organic molecules.
piece of evidence
Hoyle uses to support his view is that smallpox and other diseases tend
to appear and disappear at "mysterious intervals" throughout history.
Some scientists have even speculated that each return of some comet
could herald disaster because of the germs and other life that they
believe it carries, a theory not supported by the research completed on
the 1986 return of Halley's comet. A space craft sent to Halley's comet
to determine, among other things, if it contained complex organic
molecules or germs, found no evidence of such.
only simple "organic" compounds have been identified in Halley's comet from
infrared detectors in telescopes on earth (Cowan, 1993). Wickramasinghe
and Allen used this equipment to measure waves emitted by the comet
beyond the visible light spectrum. They found a 3.4 micron wavelength,
which indicates that some hydrogen-carbon molecules are present in the
comet. Only about 100 compounds so far have been identified in Outer
space out of over ten million known. Most were found in the thousands
of giant molecular clouds that are from 30 to 180 light years across
and about 700 times the density of outer space. The density is such
that 700 molecules exist in the cloud compared to each one existing in
outer space (Cowen, 1978, p. 6). The study of the chemistry in these
clouds, called astrochemistry, has grown to the extent that
Drs. Hoyle and Wickramasinghe are willing to stake their professional
reputations on these audacious theories shows how fast the young
science of astrochemistry is developing. (Cowen, 1978, p. 6)
Implications for Abiogenesis
emphasizes the fact that serious difficulties exist with the assumption
that life could have originated spontaneously eons ago in a primordial
soup of speculated composition somewhere on the earth's surface. The
literature on the various theories of how the spontaneous generation of
life on earth could have occurred eons ago is based on the a priori
assumption that, since life is clearly here and it is not "scientific"
to resort to a creator to guide the process, we therefore must
speculate on how life could have generated spontaneously.
That scientists of the stature of Hoyle, Crick, Ginsburgh and
Wickramasinghe seriously question the assumption that life could have
originated on earth without outside direction clearly portends that
serious difficulties exist in all
of the current origin of life
theories (Thaxton, et al., 1984; Johnson, 1991). In the words of Chang,
"the primeval soup theory scientists were once confident was valid is,
because of much more knowledge, no longer viable and the consensus that
once prevailed, the conviction that the basic ingredients of the
'primeval soup' have been worked out, is gone" (Kunzig, 1988, p. 68).
In the end, we do not know, in spite of a score of theories, how life
could have evolved on earth, a far easier question than knowing how it did
were the organics brought in from out there for the origin of life down
here? Because scientists don't really understand the origin of life,
this question can't be answered with confidence. One way to approach
the issue, though, is to compare the extraterrestrial sources with
likely sources of organics made on earth. Since the early 1950s,
scientists have worked out a number of ways for making organics via
chemical reactions in earth's atmosphere (Chyba, 1992, p. 34).
And as Chyba
shows, the subject is far more complex today than the 1950s.
Consequently, researchers have appealed to exobiogenesis to explain the
many existing abiogenesis problems and thus to develop plausible
abiogenesis theories. Many researchers also recognize that at least
directed panspermia has clear similarities to the intelligent design
view of creationists. Hoyle recognizes its similarity to the religious
world view, but stresses that many scientists endeavor to deny this
because, in his words, "orthodox scientists are more concerned with
preventing a return to the religious excesses of the past than in
looking forward to the truth" (1983, p. 9). The view of directed
panspermia also argues against the "purposeless outlook of orthodox
opinion" and argues against the nihilistic outlook which "has dominated
scientific thought through the past century" (p. 9). He goes further
than this, stressing that publication of the Origin of Species "committed mankind to a course of automatic self-destruction" and that
many people sense something is "fundamentally amiss with society." It
is not only the implications of atheistic evolution that has motivated
Hoyle to develop his theory, but his conclusion that the accidental
origin of life is more unlikely than solving the Rubik's cube at
random, an activity which he concludes mathematically approaches the
impossible. If one could make one random move a second, Hoyle concluded
that it would take an average of 300 times the estimated age of the
earth, or 1,350-billion years, "of just one of our body's proteins
having evolved randomly by chance." Since about 200,000 types of
proteins exist in each cell, the odds against random creation, Hoyle
concludes, are "unimaginably vast" (1983, p. 12).
motivations for both
earth abiogenesis and exo¬biogenesis involve philosophical
presuppositions. A good example is the work of one of the pioneering
researchers whose theories have influenced the field for several
decades, Soviet scientist A. I. Oparin. In his classic work on
evolutionary theory, he reviews the history of atheistic theories of
the origin of life. He appropriately mentions that in the 1870s
Frederick Engels, the co-founder of communism with Karl Marx, believed
that atheistic evolutionary development of matter was the only path by
which life could have arisen. According to Engels, life arises by a
process of matter evolution whenever conditions are favorable (Oparin,
1957, p. 92). Oparin explained the difficulty in synthesizing life in
the lab by quoting the "distinguished Russian botanist and cytologist,"
V Velyave who stated in 1893, "in the great laboratory of nature…we are
hardly likely to succeed in obtaining quickly that on which nature has
spent thousands of years" in our efforts to create life (Oparin, 1957).
Engels is important in the history of communism because "it is with
Engels, the former fundamentalist Christian, rather than Marx, the
formerly Jewish child who loved his father and his father-in law, that
the atheistic syndrome first enters the history of communism" (Koster,
1989, p. 164). Koster argues that atheism often develops from a hatred
of one's father, producing what he calls the atheist syndrome. Marx,
however, is a striking exception to the many examples that Koster
documented. Koster therefore concludes the incorporation of atheism,
and importantly Darwinism, into communism was primarily through Engels,
not Marx. Marx, though, did have "a greater intellectual admiration"
for Darwin "than for any other" of his contemporaries because of
Darwin's "theory of evolution and natural selection" (Berlin, 1963, p.
204). The relationship between Darwinism and communism is complex, but
ideas started to percolate through Europe, the Marxists seized on them
eagerly as a sort of antidote to organized religion…the Marxist…adopted
Darwin as a fixture of the new world view because he was an atheist and
because his theory of evolution by natural selection, taken at face
value, helped to undermine the Judeo-Christian view of man" (Kosler,
1989, p. 164).
Lenin and Stalin had come to accept, first, Darwin's theory of
evolution and the belief that "man was a mere animal and not a being
created by God" (1989, p. 164). Darwinism also influenced Stalin to
abandon his faith in God and to accept the view that "people were
descended from apes and not from Adam." Koster also argues that atheism
is a necessary plank for communist philosophy, at least that which
developed in the Soviet Union. Theistic evolution would not suffice
because it was imperative to totally remove the idea of God, especially
the Judeo-Christian God, in order to fully embrace the communist party
line. It was, consequently, especially necessary to show that the
origin of life itself can occur by natural means. Even many theists
accepted evolution from primitive animals to the more advanced
creatures including humans. Consequently, the final plank, that of the
origin of life itself, had to be dealt with, and this was the challenge
the origin of life theories accepted in his time were not viable, and
therefore devoted his life work to making the ancient spontaneous
generation of life views plausible. The view common then was, in
Oparin's words, "H. J. Muller…affirms his earlier hypothesis…as to the
random emergence of one successful gene among myriads of types of
molecules" (Oparin, 1957, p. 99, my emphasis). Recognizing the many
problems with this view Oparin noted one was that it was difficult to
accept the idea of one unique past event "because it completely shuts
the door on the scientific study of the most important event in the
history of our planet, which was the first emergence of organisms. How
can one study a phenomenon which, at best, can only have occurred once
in the whole lifetime of the earth?" He then hypothesizes that the
conditions must have been such that the origin of life was once common
and indeed inevitable — and in his classic work he discussed what he
felt these conditions were. The research reviewed above, though, has
shown that many of the early earth conditions he postulated are not
tenable, and the modern recognition that the spontaneous generation of
life on earth is highly improbable has led to the exobiogenesis
hypothesis in order to maintain the philosophical assumption that life
generated spontaneously. If this could not occur on earth, then it
occurred somewhere else.
(1993) argues that
life was designed both to look like the product of a single designer,
and secondly to resist all other interpretations of its origin. That
idea, called message theory, asserts that life's designer would
not create extraterrestrial life, because to do so would violate one or
both of these goals. For example, while all earthly life possesses
common designs to intentionally convey that they are the work of one
designer, the existence of extraterrestrial life like ours would
violate the second goal. If extraterrestrial life existed, it would
lend credence to the view that our creator did not create us, but that
we are the product of, evolved from, or that extraterrestrial life is
in other ways responsible for our existence. Naturalistic evolutionists
then could use evidence of extraterrestrial life to argue in favor of
naturalistic interpretations. Thus, studying the creation allows us to
learn about the traits of the creator, and within the creation is a
message. The creator deliberately precluded evidence of exobiology,
ReMine argues, because this would confuse the message he intended to
convey, namely that we are the product of the creator only, not
extraterrestrial life. The lack of evidence for extraterrestrial life,
he concludes, supports the message theory hypothesis (1993, p.441).
Although this lack is so far supported by science, many speculate that
evidence for extraterrestrial life will be found with continued
searching, but at this point this conclusion is based on belief, not
And in Conclusion
theory and the speculation it is based upon vividly illustrate how a
century of research has revealed many difficulties with all
naturalistic theories of life's origin. The evidence indicates both
outer space and the early earth were extremely hostile to life. In
Kunzig's words, "The profusion of hypotheses about the origin of
life…is a symptom of the fundamental problem in the field: the lack of
hard evidence" (1988, p. 76). Outsiders should be cautious and not
uncritically accept the many speculations put forth by contemporary
scientists and their students. It is recognized by many that even the
exobiological theories developed to explain abiogenesis cannot be "a
random process, but one carried out under the influence of a greater
cosmic intelligence" (Angelo, 1991, p. 128).
panspermia theory is
an intelligent design argument which is acceptable to the scientific
community because it assumes the creator of life itself evolved by
natural means. Would a God created by natural forces as opposed to an
eternal existing God be acceptable to secular scientists and the public
schools? Shklovskii and Sagan have concluded this view is an acceptable
theory because it "is not inconsistent with materialistic philosophy"
(1966, p. 11). The exobiogenesis theory also illustrates the extent
that some scientists will go to try to account for the complex reality
around us without a creator. We can do no better than conclude with the
words of Javor:
there is a crisis in
the field of chemical evolution. The best efforts of brilliant
scientists over the past 40 years have stalled in logical dead ends.
Increasing numbers of evolutionary scientists are accepting now the
concept of "pansperrnia" that life evolved elsewhere in space and was
imported accidentally or purposefully to the earth. First proposed at
the end of the past century after disproved the spontaneous generation
of life, this theory is an admission of failure to find a convincing
naturalistic account for the origin of life on earth. It pushes the
problem out of the realm of experimentation and gives up on suggesting
how life could have come about. But it is also a stubborn clinging to
the notion that somehow matter can self-organize into living matter —
if not on this earth, then elsewhere in the universe. What we know
about living matter makes it clear that this cannot happen (1993, p.
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