During the recent launch of a book I was able to briefly discuss a physicist about the existence of life on other planets. One of his statements was that, if there were life on other planets, their DNA should be fundamentally different from life on Earth. My opinion on the matter was completely different, and in this brief essay I present my arguments.

1. We are not alone ... and we are not so different
GAIA, DNA and Exobiology
By Alexis López Tapia
Director
New Age Ecological Corporation
September 2005
(1)
During the recent launch of a book I was able to briefly discuss a physicist about the
existence of life on other planets.
One of his statements was that, if there were life on other planets, their DNA should be
fundamentally different from life on Earth.
My opinion on the matter was completely different, and in this brief essay I present my
arguments.
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2. The conditions for the emergence of life
are discrete and restricted
What we know so far of the emergence of life on Earth, and recent discoveries about Mars-
bacterial activity traces (2) in a Martian meteorite found in Antarctica (Science, August 1996)
and the current exploration Spirit and Opportunity robots (3) they have detected traces of the
old concrete presence of surface liquid water (August 2004) - clearly indicate that the
conditions for the emergence of life are discrete and restricted.
Both the Spirit and the Opportunity had found evidence of ancient water on Mars in his
previous missions, but new data recently collected by Spirit's scientific instruments suggest
that the life-creating liquid was once more abundant than previously thought.
"This is different from the rocks on the plain, where we saw strata and veins apparently due to
effects of small amounts of water. Here is a larger and deeper alteration, suggesting a much
larger amount of water."
These findings point to the possibility that Mars may have generated life in the past, as their
conditions makes about 3,200 million years were similar to those on Earth at that time.
These conditions depend on several factors, which are related to the genesis of a planet in any
solar system.
a) The Materials of Life
Recent evidence suggests that planets that emerge around new stars can form relatively
quickly:
"We found that the new young stars of 10 million years show all indicators that may be
forming new planetary systems similar to our Solar System. This suggests that planet formation
is a quick process that only takes a few million years " (5).
However, the composition of these planets-new-star kids, it can be very different from the
planets formed around second generation stars, like our Sun
Indeed, these planets are second generation stars-stars product of previous supernova
explosion disrupting a nebula, which are composed of most of the elements necessary for the
emergence of life. In comparison, the materials available for a Planet son of a new star-
emerged from a nebula not altered by the explosion of a supernova, are not as varied.
What happens with the formation and evolution of a second generation star is directly
determined by the initial mass formed: if its mass is less than 0.075 M (M = mass of the Sun:
2x1030 kg.), Then you can transformed into a yellow star like our own, or if the mass is even
greater, in one of the many giants who are unstable.
If the protostar has a mass less than 0.075 M, then brown dwarfs form calls. This year has
proved the capability that dwarfs even these, if they accumulate enough matter in a
protoplanetary disk could form several planets. This was out from among a team of
astronomers from the Harvard-Smithsonian Center for Astrophysics, led by Kevin Luhman:
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3. "This brown dwarf and its disk could progress to end in a miniature version of our solar
system," said Luhman. "There could be a host of miniature solar systems out there, in which the
planets orbit brown dwarfs," he added.
Can a planet orbiting a brown dwarf breed and sustain life?
According to Luhman and his colleagues cannot be excluded. A brown dwarf is much cooler
than our sun, and, as is too small to initiate at its core nuclear reactions, cooled slowly during
its life span. Therefore, to maintain the water in liquid state, a much more planet should orbit
around this star which makes the earth.
Furthermore, Luhman notes, "if life exists on that system, would have to be adapted
continuously to the dwindling temperatures of a brown dwarf. However, the possibility cannot
be dismissed that, as the star cools slowly as they age, may remain a planet in the "habitable
zone" that allows liquid water over a long period of time, perhaps enough to the evolution of
life "(6).
However, the point is that, even in the event of life arising in a solar system-a brown dwarf, it
would be determined by the materials available on the planet itself, and that these materials
were varied, necessarily should have been originally made into a supernova.
This is vital, since in terms of "poverty" of chemical elements on the possibility of the
emergence of complex molecules is severely limited: the tendency in such conditions is to
generate crystals (even in the presence of water, as in Geodes ), but the complexity required
for the emergence of hydrosols (mixture of solids, liquids and gases), and colloid stabilization
as they give rise to coacervates, or monomers stable bases of complex polymers, requires
qualitative and quantitative presence of many more the chemical elements needed for the
formation of a single crystal.
b) The orbital belt of Life: Temperature and Energy
The second aspect to consider in the conditions for the emergence of life is precisely that a
planet's orbit is around its sun: planets too distant or too close quickly tend to freeze or boil
would be permanent: both ends are completely unsuitable for the existence of surface liquid
water, and therefore for the emergence and stability of complex molecules.
However, not only must the planet orbits around the star in the strip where the presence of
liquid water is possible: it is also necessary that the environmental energy available is of the
magnitude needed.
In this regard, the father of the Gaia theory, James Lovelock, says:
"A physicist nineteenth, Reynolds noted that the turbulence of liquids and gases appeared only
when the flow exceeded a certain critical level in relation to local conditions. To calculate the
dimensionless Reynolds enough to know the properties of the medium in question and local
flow conditions. Similarly: to bring life, energy flow has to be sufficiently important, not only in
quantity but also in quality, potential. If, for example, the temperature of the outside surface of
the sun at 500° C rather than of 5000° C and their distance to the earth is correspondingly
reduced, so that might receive the same amount of heat, climatic differences regarding actual
conditions may be rare, but life would never have been present. Life requires a powerful
enough energy to break chemical bonds: not enough merely lukewarm.
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4. If we were able to establish dimensionless quantities like Reynolds to characterize the energy
conditions of a planet would be able to build a scale whose implementation would allow us to
predict where life possible and where not. Those who, like Earth, receive a continuous flow of
solar energy than the aforementioned critical values would be in the first case, while the outer
planets colder fall within the second "(7).
Taking this into consideration, above possibility of the emergence of life on planets orbiting
around brown dwarfs is doubtful: the temperature would be ideal, but would it be enough
power?
Yet even when the above conditions are met, elements, energy and proper temperatures-the
emergence of life does not necessarily result in a Living Planet: Mars and the evidence seems
to indicate. If the physical evolution of the planet generates chemical physical processes
limiting or preventing complete initial reproduction processes pre-biotic, generating self-
regulating ecosystem becomes uncertain: life occupy the entire physical environment that
allow its existence, but if the environment does not exist, life cannot exist.
The Brick of the Life
Where on Earth say "Organism" are saying "Carbon".
Indeed, all of the planet's life forms are determined by structures on carbon basis, and not by
chance:
The carbon chemistry is unique in that it forms a number of compounds greater than the sum
total of all other components combined.
By far the largest group of these compounds is composed of carbon and hydrogen. It is
estimated that a minimum of 1,000,000 known organic compounds and this number is growing
rapidly each year. Although the classification is not rigorous, carbon forms another series of
inorganic compounds considered in a much smaller number to the organic.
The fact that life has arisen around carbon molecules is fundamental physical processes
necessary for the emergence of the first self-replicating element required an unlimited ability
to establish relationships with others: it should be a very promiscuous, and as we shall see, not
all are:
There are some items that simply are complete "misanthropes" are called "noble gases" that
are not in regular conditions unions even among their own atoms: helium, neon, argon,
krypton, xenon and radon. Given the arrangement of their atomic layers are chemically inert,
and because of this lack of chemical reactivity, are not diatomic molecules, but which are
composed of individual atoms, and can therefore be excluded as material for the construction
of complex molecules.
Other items are "monogamous" by nature, are diatomic elements, which are always in pairs:
hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine and cunning. In the last five are
known as halogens (salt-forming), and are too reactive to free FOUND in fair condition, so
always form compounds, and its atomic bonds are very strong: they are a couple and jealous
too stable to Based be complex molecules, although certainly hydrogen, nitrogen and oxygen
atoms of which are usually involved.
In this logic we could continue with the elements triatomic, polyatomic and well, but what
really matters is the ability of an item to combine with many others, not only with himself, and
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5. yes there are limitations: of the 118 known chemical elements, There is a particular family that
has this property: Carbon precisely the family, which includes silicon, germanium, tin, lead.
All are electronegative elements, because they tend to take electrons becoming anions, and of
them all, the most electronegative-precisely-Carbon (2.55 electronegativity in Pauling table). In
other words, the carbon is always looking to attract electrons, "does not like being alone."
In addition to the above, the carbon has a valence of 4, i.e., 4 bonds can be set simultaneously
with other atoms or with itself. This is one of the highest values in the small atoms chemistry.
Second, carbon is able to bind to itself to form long chains, or even three-dimensional
networks, and it is very strong unions, the most extreme case we have when each carbon atom
joins four others, thus constituting a structure made solely of carbon: this structure is the
diamond, the hardest substance known.
Without going to such extremes, it is clear that the union of 2 or 3 carbon atoms will be very
strong. Moreover, those carbon chains or networks may join other atoms, especially above the
other, hydrogen, oxygen and nitrogen. Many compounds are formed so enormously complex,
just the kind of complexity that makes life possible.
Would it be possible to replace the carbon by another element?
It should be an abundant element, and to form many bonds with itself and other elements. Of
the five most abundant elements, and discard the helium because it forms compounds. The
hydrogen and oxygen having valence 1 and 2, so that only very simple compounds can form. In
theory, there could be a chain of oxygen atoms, but the closest thing is the hydrogen peroxide
formed by two hydrogen atoms and two oxygen (the main component of hydrogen peroxide).
Nitrogen has valence 3, and you can join three other atoms. However, there are known several
chains nitrogen atoms. Therefore, we only carbon, between 5 most abundant elements in the
universe.
Is not there someone else who, without being so plentiful, is sufficiently abundant to be
taken into account?
The best candidate is a family of silicon-carbon, which is a very abundant element in rocks and,
therefore, on any Earth-like planet. Silicon form silica with oxygen, forming the sands of the
beaches. And most rocks are silicates, i.e. silica derivatives. Further, silicon has a valence of 4,
like carbon.
What could be silicon based life? : It's hard.
For start, because silicon does not form chains or networks by himself. Atom is too large to
form such structures. The most similar to the structures as oxygen bond between two silicon
atoms, thus forming three dimensional networks and chains of large size, but the result is
almost always a rock.
These compounds of silicon and oxygen (i.e. silica) lack the complexities of the compounds of
living beings, are too simple, in addition, are all insoluble solids which react only being melted
at temperatures of 1.000° C (temperatures typical of molten lava, but not living things).
There are only a silicon compound having some properties of the compounds known in living
beings are silicones, silicon compounds, carbon, oxygen and hydrogen. There could be living
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6. somewhere silicones, but if we look closely, and we snuck carbon by the way ... Anyway, all
known silicone compounds are artificial, none known naturally in a living being.
What was the first self-replicating?
Recent studies indicate that early autopoietic structures, have been fruit of ribonucleic acids
(RNA), and not DNA product (8).
"In regard to DNA, the problems are different. As RNA, DNA also requires proteins to
autoduplicarse, so that in the primitive atmosphere of the Earth, the hypothetical primordial
DNA could not have served as template to be copied without the help of enzymes. Furthermore,
deoxyribonucleotides (units joined together to form the DNA) are produced by current living
beings from the ribonucleotides (the units are joined together to RNA), indicating that the DNA
must have appeared much more recently that RNA during the evolutionary history of the Earth.
Moreover, the DNA is more resistant than RNA hydrolysis decomposition (in the case of DNA
hydrolysis is the separation of the constituent deoxyribonucleotides by incorporation of water)
and this would make more difficult the recycling of monomers (deoxyribonucleotides) from
discarded polymers by natural selection. The facts set out suggest that it is unlikely to have
occurred a colonization of the aquatic environment of the primordial Earth through self-
replicating DNA molecules. "
"An additional argument in favor of RNA is that all components participating in the chemical
synthesis of RNA have been obtained in the laboratory under conditions simulating the
environment of the earth primitive while despite the efforts made, it has yet been possible to
synthesize in the same conditions at the deoxyribose sugar of DNA structural component ".
However, in the late 80s, Robert Shapiro and Gerald F. Joyce made a critique of this theory
when asked
Can RNA, with all its components, be synthesized in primitive conditions at a higher speed
than its destruction by ultraviolet radiation, by hydrolysis or by reaction with other
molecules in the environment? The answer was that this was not possible. (9)
"Difficulties such as these are leading researchers to seek other polymer primordial self-
replicating. This could be, perhaps, very similar to the RNA as it is thought that have existed
substances such behavior, or "RNA analogs."
Many substances of this type exists.
Attention is focused on a particular type of RNA analogues that could exist in the aquatic
environments of early Earth: the acyclonucleosides glycerol derivatives. (The prefix "acyclo"
indicates that the compound, replacing the ribose lacks the closed cyclic ring structure of the
ribose). These compounds may have been formed in two steps: first by the condensation of
glycerol with formaldehyde and hemiacetals generation and then by the reaction of these
hemiacetals with nitrogenous bases. In primitive atmosphere, incorporation of phosphate
from polyphosphates may be generated ribonucleotides analogs.
An attractive aspect makes this hypothesis is the fact that the stability of glycerol is far
superior to that of the ribose, which may have allowed their accumulation in aquatic
environments early Earth in sufficient quantity to form acyclonucleosides. An additional
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7. advantage is that these compounds have optical isomers "undesirable". The polymerisable
aciclonucleótidos (generating RNA analogs) and molds required to form the self-replication of
these polymers. Similar processes may have occurred with other RNA analogs.
For that reason, the problem today concerns researchers is to determine how he spent the
"world of RNA analogs'' to" RNA world ".
Perhaps, the first RNA analogs were composed of different varieties of analogs and may
contain even some "authentic" ribonucleotides. Natural selection in the "world of RNA
analogues" must have favored those polymers had a better relationship between self-
replication capacity and resistance to destruction.
In a short period in terms of evolution (not more than 0.4 aeons) would have been gradually
selecting those polymers with the most "authentic" ribonucleotides. Thus, little by little, it
would have appeared the "RNA world". During this process, analogs would initiate RNA
synthesis of proteins by mechanisms the first primitive. The former proteins may have played
an important role in the selection of RNA positive. "
The role of the Virus
Another line of research has emerged recently with the study of retroviruses and their role in
evolution: apparently they would have a much more important role than hitherto assigned in
terms of their health effects (10).
For Dr. Max Sandin, Autonomous University of Madrid, the virus would be really the
cornerstones of evolution, since they would have been the first "carriers" of the gene, and its
role would be crucial in the emergence of multicellular organisms . It states: "... the Welsh
astronomer Alfred Hoyle, published in 1982 a booklet entitled" Evolution from Space "in which
he speculated about the possibility that the ability of the virus to integrate into the genomes of
living organisms and remain there as a "provirus", could be a mechanism for the acquisition of
complex sequences of genes available for possible use in response to environmental changes.
Although his proposal was ignored, if not ridiculed, by some biologists "orthodox", the truth is
that would address the issues raised above. That is, would the "unconventional hypothesis"
could explain the strange "basic facts" of evolution.
Are there data to seriously consider this hypothesis?
Here are some: in recent years, molecular studies of animal and plant genomes are yielding
surprising results. In all of them have been identified abundant DNA sequences are
"endogenous virus."
Most derivatives are considered exogenous virus "infected" the various species in the past, and
they have become by inserting endogenous germ cells. Some have mutated, although it is still
possible to relate them to current viruses.
Having lost their pads have lost their ability to leave their insertion site. But others have not
lost are in the form of movable elements or transposable elements that, in some cases, such as
Drosophila Gypsy retroelement are able to rebuild its capsid and reinfect again. "
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8. In this regard, in a later paper adds: "Are viruses a (mysterious)" special case "between
different possible manifestations of life, or are a fundamental element of it?. Here we suggest
the data:
In animal and plant genomes have been identified varying amounts of DNA called "endogenous
virus." There are different types and most derivatives are considered exogenous virus "infected"
the various species in the past, and they have become endogenous by insertion into germ cells.
Are being identified in increasing numbers, thousands of viral sequences that are actively
involved in the vital functions of different tissues (Coffin, 94). Some of these sequences can be
considered true "genetic fossils" are provirus "old" suffered multiple mutations, although it is
still possible to relate them to some existing retroviruses, and having lost their pads (are
defective viral particles), have lost their ability to leave their insertion site. But others, who
have not lost, are in the form of mobile elements or transposable elements (TE).
DNA sequences are able to move and inserted, or insert copies of themselves in different
locations of the genome. These elements are classified in two groups: Transposons, which are
reinserted directly through DNA copies and retrotransposons, which make copies of themselves
through performed by RNA by reverse transcriptase, DNA is transcribed into which is inserted
elsewhere genome. The implication of these elements in the formation of "repetitive sequence"
in the genome (which are calculated in man constituents 25%) is obvious.
And although the assumptions of the calculations of population genetics will attribute a "non-
functional" (Charlesworth et al., 94), necessary to fit the selfish DNA hypothesis, the fact is that
such sequences, as LINE (Long inserted elements) (Mathias et al.: 91) encoding proteins with
reverse transcriptase activity necessary for the mobility of various kinds of retroelements,
among which there are some involved in the formation and functioning of the mammalian eye
lens (Brosius & Gould, 92).
As to the origin (and condition) of these elements viral recently (Kim et al., 94) it has been
shown that the Gypsy retroelement of Drosophila is actually a retrovirus capable of rebuilding
their capsid and reinfect again .
Perhaps the explanation for the existence of transposons shared by man with arthropods,
nematodes and flatworms (Auxolabéhère, 92; Garcia et al., 95; Oosumi, 95). (11)
Based on this evidence, Dr. Sandin proposes a new evolutionary model:
"This model could be summarized thus: the origin and evolution of life is a process of
integration of complex systems in other systems autoorganizarían higher level.
The basic units that bacteria would have all the processes and mechanisms of cellular life,
whose components appear to have been preserved with very few changes along the
evolutionary process.
Viruses, by chromosomal integration mechanism, would be those, either individually or in
combinations including introduce new sequences responsible for control of the embryonic
development of new tissues and organs as well as for regulating its operation. "
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9. The Pregnant Life
We still need to add another consideration for greater reach:
The emergence of life on a planet is the possibility of the expansion of that life to other
planets, "reproduction planetary", as a correlate of the reproduction of the species.
It is the thesis of Dr. Miguel Garcia Casas, the Institute of Secondary Education Morería of
Valencia, in Valencia, who argues that the result necessarily Living Planet, is the evolution of
their species to create conditions for "export" to life other planets:
"Is life a messenger between planets?, And if so what can you bring to them? Is life an inertial
system that opposes the energy loss of the planet?, This could explain why planets with high
greenhouse life as Venus did not exist because the clouds would replace its function, but yes
airless planets life should be, since the heat from the sun fades quickly.
Is life a strange way to open windows even stranger to energy, how we explain it if we do not
know what is the nature of energy? "
"Panspermia contemplates that life has its origin in an alien place. Embedding in a universal
mechanical panespérmico type, the terrestrial biological system should contribute to the
spread of life. Certainly a very interesting question is: what would be more effective to spread a
biological system, trust in comets and chance to from lifeless molecules, arise by spontaneous
generation of life, or energy use living beings are able to get to direct certain seed alive long,
laborious trip?
In all cases in which it had been believed that spontaneous generation processes, scientific
evidence has not produced. We can say that the only case that science supports as possible is
leading to the emergence of life on Earth. Obviously, if you have not been on this planet, earlier
elsewhere has had to rise to life on occasion for the first time. However once appeared and
reached the level of technology that currently has our species and therefore the terrestrial
biological system, it is possible to consider bringing life to other planets. In fact there are plans
containing scientific transformation strategies of the Martian surface including bringing life to
Mars.
Our technology is in an expansive phase and very little we know of the technical means
available to us within a few thousand years. The question concerning the way in which
terrestrial life can reach other places remain open and will be resolved in the future. At the end
of the universe is full of paths and space-hungry stars continually throwing stuff disguised siren
songs of gravitational energy to attract the Ulysses spacecraft that carries the genes of
universal life "(12).
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10. Our thesis:
Life forms are similar
anywhere in the Universe
With all the above, we come to the central proposition of this essay: life forms are basically
the same everywhere in the universe.
This, both because the conditions for its emergence and development are-as we saw-discrete
and restricted, and because the generation of initial self-replicating molecular structure, must
overcome the same selective processes that occurred in our planet.
These structures will be based primarily on carbon and not in other elements such as silicon,
which is not determined quantitatively –there is more silicon than carbon on Earth–, but
qualitatively: all items available, as we saw, is Carbon best suited to be the building block of
life anywhere in the universe where the necessary conditions.
For the same reason, the molecular genetic structure of an alien species is not fundamentally
different from ours: the conditions that allowed the emergence of similar RNA, the RNA itself
and finally DNA be homologous on any planet where conditions occur so that this process
develops.
Thus, the genetic end should be neither critical nor radically different from ours: the possibility
of generating long molecular chains of carbon links are also discrete, and only a limited
range meets the conditions of stability and structural plasticity necessary for emergence of
viable self-replicating.
Additionally, there is the fact that Nature is Economic: after establishing the conditions for
self-replicating generated, immediately begin to govern adaptive criteria, selective and
speciation. Probably it, aliens Viruses also play a key role in allowing the combination of gene
segments early viable.
Established predominant primary genetic sequence, all life forms be developed from it, and
there will be very few opportunities for new experiments: genetic economy is set from the
beginning.
In the same logic, although the possible phenotypes in a living planet could be very different,
or at least as or more varied than those that arose on Earth, these life forms should be
adapted to planetary conditions –Gaianics– which will be similar to our planet. Thus, one
might expect to find species by evolutionary convergence will result analogous and
homologous to those developed here, although their phyletic lines could be completely
different.
Furthermore, if any intelligent species and "rational" in these planets, the ecological, social
and cultural evolution also allowed are similar to those that allowed our own evolution: will
not be fundamentally different from ourselves.
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11. And finally, if the thesis of the "Pregnant Earth" is correct, not surprising that intelligent
species and older than ours have started to "grow" its Galaxy Life long ago: perhaps simply
"infected" with viruses and Living bacteria potentially other planets.
That might even mean that even our own living planet is the result of an old panspermia
exogaiana therefore, under these conditions, our DNA would be the local result of a more
widespread pattern: a general pattern.
Or maybe the other way around: if humanity can overcome its present tendency to self-
destruction, it is possible that some hundreds of thousands of years, we can get DNA from
Earth find a new planet to populate.
A planet where, in some eons-when there is no earth-and if the conditions are right, other
intelligent beings also wonder: how will life on other planets?
Maybe then, looking into deep space, some of them will surprise with his own face reflected
in the Stars.
Notas
(1) Luis Heinecke Scott, “Método de Intelección Estratégica”, "Universidad de las Américas”, 11 de Agosto 2005.
(2) http://www.solarviews.com/span/marslif6.htm
(3) http://marsrovers.jpl.nasa.gov/home/index.html
(4) http://www.terra.com/actualidad/articulo/html/act181575.htm
(5) http://www.cida.ve/~briceno/formacion_estelar.html
(6) http://ciencia.astroseti.org/planetary/articulo.php?num=2318
(7) Lovelock, James E. «La Hipótesis Gaia, una nueva visión de la vida sobre la tierra», Hermann Blume, Madrid, 1986.
(8) http://www.ciencia-hoy.retina.ar/hoy17/origen.htm
(9) Origins of Life, vol. 18, 1988, págs. 71-95, y Nature, vol. 338,1989, págs. 217-224
(10) Dr. Máximo Sandín, “La Función de los Virus en la Evolución”
(11) Dr. Máximo Sandín, "Teoría Sintética, Crisis y Revolución"
(12) Dr. Miguel García Casas; “La Tierra Embarazada”
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