Life and Panspermia Theory

is the process by which life
arises from inorganic matter. Fossilised primitive bacteria have been
found which are 3.5 billion years old, which means life could have
existed for much longer. Although, given the age of the Earth at
around 4.3 billion years, scientists estimate that life has probably
been around for no more than 3.9 billion years on the planet. But
what is ‘life’ and how do you distinguish it from ‘inorganic matter’?

Erwin Schrodinger in 1944 defined life as matter which avoids the
Second Law of Thermodynamics, which says that entropy (disorder)
always increases. Living things resist this entropy by taking in
nutrients. Therefore, some scientists have tried to define life in
terms of metabolism,
the ability to take in energy and use it for activities and then get
rid of waste by-products. But this definition faced a problem. In an
experiment carried out on Mars in 1976 by the Viking Lander’s Labeled
Release Experiment, it was found that inorganic matter also showed
signs of having a metabolism. This definition of life was soon

more modern, narrow definition of life, which excludes inorganic
matter, is the ability to self-replicate.
The astrobiologist Benton Clark, from the University of Colorado,
says life has three main qualities: being able to reproduce, being
able to use energy and having a set of genetic instructions. It seems
that the first and third qualities are unique to life. Richard
Dawkins has said that the origin of life involved some sort of
primitive molecule which could replicate itself, using probably a
primitive genetic code. He also says, however, that he, nor anyone,
has any idea how life
originated. Well, no-one knows for sure, but there are some
interesting hypotheses.

most famous is probably the “primordial soup” theory. Alexander
Oparin proposed this theory in his book The Origin of Life
(1924) and was later adopted
J.B.S Haldane around the same time. Oparin and Haldane argued that in
the early Earth, there organic molecules could have formed in
“primeval soups” using the energy of sunlight. The molecules
would grow in increasingly complex ways until they were able to

Then in 1952, in the Miller-Urey experiment, a mixture of
water, hydrogen, methane and ammonia (Earth’s early chemical make-up)
was given electrical sparks (to simulate lightning striking Earth’s
early oceans). After only a week, organic molecules were found,
including amino acids, which are the building blocks of proteins and
essential to life. This famous experiment has since been repeated,
yielding even more kinds of amino acids than Milley and Urey had
found themselves. It was a great achievement, but amino acids are
still a long way off from a self-replicating molecule with a genetic

de Duve, the Nobel prize-winning chemist says in his book Vital
, that the first forms of
life could have been RNA molecules. RNA molecules are essentially a
single strand of DNA and are capable of storing information and
catalysing (speeding up) chemical reactions. Since short RNA
molecules have been easily produced in lab conditions, scientists
like Duve have suggested that in the early conditions of the Earth,
RNA strands could have joined together, eventually creating a
self-replicating molecule. Once this molecule was created, natural
selection would take over and prefer the self-replicating RNA over
those which cannot self-replicate. So may have been the precursor to
DNA as we now know it.

scientists have taken a different route and have instead focused on
where life could have
originated on Earth. In the 1970s Thomas Gold claimed that life might
not have begun on the surface of the Earth in some “primordial
ocean”, but well below the Earth’s surface. In the 70s it was found
that simple organisms (called Archaea)
were found living in extreme conditions, such as in hydrothermal
vents, which are insanely hot. Therefore, these organisms were called
extremophiles, since
they seem to thrive under extreme conditions (extreme from our point
of view anyway).

It has since been found that these organisms can
also thrive in conditions without any oxygen, which is significant
because the early Earth’s atmosphere was not made up of any oxygen.
Oxygen has only been present in the atmosphere since photosynthetic
creatures evolved around 300 million years ago. Some scientists have
argued that life could have originated in these hydrothermal vents.
Bacteria have also been found a foot below the surface of the Atacama
Desert, which is extremely dry and lacking in water. This might mean
that bacteria are thriving underneath
the surface of Mars! These ideas are exciting, but there is one more
hypothesis which is even more weird.

is the idea that the
seeds of life came from outer-space, most likely from another planet.
Central to the theory is the idea that life exists throughout the
universe and is transported from planet to planet by asteroids and
meteorites. Extremophiles play an important role in this theory,
since if life is transported across space, then that life must be
able to survive the harsh conditions (coldness, lack of oxygen, solar
winds, ultraviolet radiation etc.) of space. The idea can be traced
back to the 5th
Century BC. The Greek philosopher Anaxagoras claimed that the
universe is made up of an infinite number of “seeds” and that if
these seeds reached Earth, they would give rise to full-fledged life.
Anaxagoras coined the term panspermia
which literally means “seeds everywhere.”

In the 19th
Century Hermann Richter said life has always existed in the universe,
which seems to get rid of the need for explaining its origin.
Although you could still ask why
has life always existed? Anyway, panspermia theory gained popularity
in the 70s after scientist Fred Hoyle said that some “dust” in
the universe was mostly organic, that is, made up of carbon. He also
argued that there is evidence of bacteria and virus-like organisms in
space, particularly in comets. There are signs from the dust of
Halley’s Comet, for example, which indicate the presence of bacteria.

1973 Hoyle put forward the even more radical idea of Directed
, an idea
which Francis Crick
(co-discoverer of DNA) has also accepted as an explanation for the
origin of life. This is the idea that advanced civilisations had
evolved elsewhere (which they probably have) and that the germs of
life were transported to Earth on their spaceships. Or it could have
been that DNA was a molecule artificially made by an advanced
civilisation, given the fact that it is such a complex molecule.
Jeremy Narby, for example, in his book The Cosmic Serpent,
thinks that because DNA contains such astronomical amounts of
information that it can’t have come about through Darwinian
evolution. Directed panspermia is a very science-fiction type
scenario, but it is still in the realm of possibility.

evidence for panspermia as a more general theory, Earth was heavily
bombarded by meteors 3.8 billion years ago, the same time that life
was believed to have originated. Statistics have also shown that 7.5%
of rocks from Mars have reached Earth. Neil de Grasse Tyson has said
that billions of years ago when there was water on Mars, life could
have been plentiful. So life could have evolved on Mars, then
travelled on a piece of its rock to the Earth – it would take no
more than 16,000 years for the rock to reach Earth. Neil de Grasse
Tyson says we could all essentially be Martians.

Scientists have
analysed a meteorite in Antarctica which is 16
million years old. They say it might have been blasted off the
surface of Mars and a small group of scientists say that rod-like
structures on the rock indicate fossilised bacteria. But others are
more sceptical. Water oceans might also exist on moons such as
Europa, so if life didn’t travel from Mars, it could have travelled
from one of these moons as well. As more evidence for the panspermia
theory, researchers in Germany have exposed bacteria to outer-space
and the bacteria survived the harsh conditions.

course one obvious problem with the panspermia theory is that it
still doesn’t tell us how exactly life originated, that is, the
process which turned inorganic matter to life. Also, the theory
doesn’t tell us exactly where life came from, only that it travels on
comets and meteorites, which could travel from anywhere in the solar
system or even from anywhere in the galaxy. Others have objected that
the conditions in space could never allow bacteria to survive, but
the more we learn about extremophiles the less persuasive this
criticism becomes.



  1. Anonymous
    April 12, 2013 / 3:31 pm


  2. December 6, 2013 / 8:32 pm

    On life and kinetic thermodynamics
    Depending on the perspective, we can give different definitions of the phenomena of life. Therefore, there is no general definition.
    For example, from the position of kinetic thermodynamics can say the following.
    Life as a phenomenon is a set of cyclic metabolic processes in ontogeny, phylogeny and evolution. From the perspective of the dynamics of evolutionary transformations of structure of living things life is characterized by the changing of the thermodynamic stability of supramolecular hierarchical structures. In other words, cyclic metabolic processes constantly are enriched by the addition of more stable supramolecular hierarchical structures that are adapting to the changing environment. The thermodynamic design defines adaptation of living objects.

  3. Anonymous
    April 2, 2015 / 3:33 am

    All 287 hemoglobin units in a chimpanzee are identical to the 287 hemoglobin units in a human being. Man and the Chimp can exchange blood without dying. This means that Man did not evolve from the Chimp and that he is the same species. Plain and simple. Correct me if I am wrong. The other great apes and the monkey all evolved from the Chimp, and if they were to trade blood, it would kill them. Directed Panspermia has played a role in the origin of man.

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