Extremophiles: An Expansion on the Theory of Extraterrestrial Origins

Originally, it was thought that all life on Earth (or anywhere else, for that matter) needed two things to survive: the sun, and water. Also, life was thought to not survive at all beyond the limits of geochemical conditions that allow for the stability of the majority of organisms. It was so set in stone that life could not exist in extreme conditions, that much of our own planet was left undiscovered because it was so "impossible" to discover new species in the great unknown. Thankfully, there have been many discoveries made to pique our knowledge to the contrary - life can, and does exist in the most extreme conditions possible on earth...and possible elsewhere, too.

pan• sper• mi• a: (Greek, noun)

The theory that the seeds of life were originally planted on Earth by an extraterrestrial source, searching for adequate conditions to thrive.

What are extremophiles, and why are they so amazing?

At first, the discoveries of extremophiles was limited only to microbes and other tiny organisms. This was mainly because it's widely known (or believed) that the more minute the scale of the organism, the easier it might be for it to survive in extreme or otherwise detrimental conditions. However, as time progressed, discoveries were made of larger, normal sized lifeforms that exist in conditions that are so dangerous, many biologists still find it boggling that they even survive, never mind thrive in such conditions. Examples of these life forms are some that live attached to or close by to thermal vents in some of the deepest and most turbulent parts of the ocean - completely without any form of sunlight whatsoever and "breathing" in water with little or no oxygen at all. The fact that these extremophiles exist is proof that life is far more versatile and survivable than we thought possible.

There are many different types of extremophiles, classified by the conditions in which they live and/or how they absorb the nutrients they need to survive. Some of the most impressive extremophile classes are acidophiles and alkaliphiles, metallotolerant species, thermophiles and thermoacidophiles, and hyperthermophiles. As their names suggest, they are all adapted to surviving in the harshest, most acidic, metallic, or thermal environments the earth has to offer.

A well known example of conditions extremophiles dwell in are the thermal vents that rise up from the ocean floor. These vents spew sulfur and other harmful things that would eliminate most life that came in contact with a place even remotely close to this area of the ocean. The temperatures around this area reach over 350°F (~180°C). You would think by what we supposedly knew about the origins of life, that no organisms whatsoever could survive in a place that uninhabitable. We were very, very wrong.

These volcanic vents at the bottom of the sea are not only home to microorganisms, but to a vast variance of marine life, all coexisting with each other in a colorful, astounding harmony. These species include varieties of shrimp, fish, crabs, tube worms, and flower / coral like animals. Almost all of these species initially survived by using processes in their own bodies to break down the bacteria (which are also extremophiles themselves) that was living in the ashy sediment surrounding new forming volcanic vents beneath the water. The most common way to do this is by using chemosynthesis, which is the process of making organic material from sulfur compounds that pour from the vents. Chemo-synthetic bacteria form the basis for this mini ecosystem's food pyramid, letting more and more creatures become part of the community by feeding off each other, and so on. When put into perspective, many extremophile's living conditions were made in much the same way as any other system of life's conditions were made - growth over time using similar and local conditions to survive.

So how does this imply that life could have come from elsewhere?

Simply put - microbial life can be found in conditions that are more severe than those scientists have found on samples of rock from other parts of the solar system. This means that since we have sulfur eating bacteria at the bottom of the ocean, it's not impossible at all for their to be a similar sort of organism feasting off some other chemical anywhere else in the universe.

What makes this more interesting to humans in particular, is the fact that we are literally neighboring a planet that has conditions that may be even more suitable for life than the hydrothermal vents here on earth. There are some facts that let scientists hope for the future of extraterrestrial organism discoveries:

Mars is covered with sediment much like what is left after water evaporates. This implies what many scientists have thought all along - that water, in great quantities, once existed on Mars.

The red planet is also said to have layers the same thickness as the layers of sediment and the like on earth, making future probe sample-collecting missions to Mars all the more enticing. It may be possible very soon to collect perfectly intact sediment and environment samples, illustrating further the similarities in the two planet's compositions.

Markings on the Mars' surface (as well as the surface of other "possibly habitable" planets / moons) indicate that water, as well as perhaps streams carrying organisms, traveled through the landscape in the planet's far past. Because of this, scientists believe it is possible to eventually discover hidden geysers and chutes on or just below the surface, leading to possible organism discoveries.

Using the observations you can make yourself, as well as using the knowledge gained from the more recent years of extraterrestrial condition studies, it's possible to make an educated opinion on the possibility of life's otherworldly origins.

Helpful sources:
Microbiology: The beginning (www.theguardians.com)
The Search for Extremophiles (www.astrobiology.com)