Origin of Life on Planet Water - Index

Spontaneous Generation - The Primeval Soup
=>   Panspermia - Life Hitched a Ride to Earth from Space
Evolution Pathway and Links to the Climate and Atmosphere
Evolution of Planet Water
The First Forms of Life
Evolution of Life as We Know It
How Plants Change the Atmosphere
Is There Life Elsewhere ?

Panspermia - Life Hitched a Ride to Earth from Space

Did Life Originate from Space ?

This theory proposes that life originated out there and was brought to Planet Water on a meteorite or some other heavenly body.

While there is no evidence of living things on these bodies there is evidence of organic molecules. What this says is that the primeval soup is everywhere and that it is raining down upon our planet.

Whether this is only the precursors of life or the remnants of life itself out there, remains to be answered.

Certainly it shown that the building blocks for life are tumbling through the universe.

The evidence for these building blocks or life remnants is summarized below.

Evidence of Life Coming from Space: The Murchison Meteorite

A meteorite, that landed near Murchison, in Victoria, Australia on 28 September 1969, turned out to contain a variety of organic molecules including:

=>   purines and pyrimidines

=>   polyols - compounds with hydroxyl groups on a backbone of 3 to 6 carbons such as glycerol and glyceric acid. Sugars are polyols

=>   amino acids

Six of the amino acids found are present in all living things

=>   Glycine, Glutamic acid, Alanine, Valine, Aspartic acid but the others

=>  Isovaline, Norvaline, Proline, N-methylalanine, N-ethylglycine

are not normally found in living matter here on earth.

The same amino acids and their relative proportions were quite similar to the products formed in Miller's experiments.

The question is: were these molecules simply terrestrial contaminants that got into the meteorite after it fell to earth?

It appear that this was not the case: =>  Some of the samples were collected on the same day it fell and subsequently handled with great care to avoid contamination. =>  The polyols contained the isotopes carbon-13 and hydrogen-2 (deuterium) in greater amounts than found here on earth. =>  The samples lacked certain amino acids that are found in all earthly proteins. =>  Only L amino acids occur in earthly proteins, but the amino acids in the meteorite contain both D and L forms (although L forms were slightly more prevalent).

Evidence of Life Coming from Space: The ALH84001 meteorite

This meteorite arrived here from Mars. It contained not only a variety of organic molecules, including polycyclic aromatic hydrocarbons, but - some claim - evidence of microorganisms as well.

Furthermore, there is evidence that its interior never rose about 40° C during its fiery trip through the earth's atmosphere. Live bacteria could easily survive such a trip.

Evidence of Life Coming from Space: Organic molecules in interstellar space

Astronomers, using infrared spectroscopy, have identified a variety of organic molecules in interstellar space, including:

=>  methane (CH4),

=>  methanol (CH3OH),

=>  formaldehyde (HCHO),

=>  cyanoacetylene (HC3N) (which in spark-discharge experiments is a precursor to the pyrimidine cytosine).

=>  polycyclic aromatic hydrocarbons

=>  as well as such inorganic building blocks as carbon dioxide (CO2), carbon monoxide (CO), ammonia (NH3), hydrogen sulfide (H2S), and hydrogen cyanide (HCN).

Evidence of Life Coming from Space: Laboratory Synthesis of Organic Molecules Under

Conditions Mimicking Outer Space There have been several reports of producing amino acids and other organic molecules by taking a mixture of molecules known to be present in interstellar space such as:

=>  ammonia (NH3)

=>  carbon monoxide (CO)

=>  methanol (CH3OH) and

=>  water (H2O)

=>  hydrogen cyanide (HCN)

and exposing it to

=>  a temperature close to that of space (near absolute zero)

=>  intense ultraviolet (UV) radiation.

This is Miller's experiment and many other versions of it.

The Bottom Line: Precursors in Outer Space? - Yes Life in Outer Space? - Not So Far

The primeval soup rains down upon us and there is evidence of organic molecules out there in space.

But when and where the life that appeared on planet water, first developed remains to be answered.

If life did arrive from space, questions still remain about how it arose or was created out there?

Evolution pathway and links to the atmosphere - These are the keys to understanding Life as we know it

>>> Next See - Evolution Pathway and Links to the Climate and Atmosphere