Astrobiology is perhaps the newest scientific discipline, and a noteworthy feature of astrobiology is its highly interdisciplinary nature. The boundary between intellectual disciplines are largely social, not natural nor cognitive, constructions and this point is worth reflecting upon when thinking of the so called “demarcation problem” in philosophy.
Science and philosophy, just like astronomy and biology, or physics and chemistry, are not really separate, highly demarcated, endeavours. They can be, and are, quite symbiotic. The interesting thing about both analytical and continental philosophy is that, by and large, both assume a sharp demarcation, something a true card carrying naturalist, such as myself, would not countenance.
When we discuss life and biology we of course have a wonderful living laboratory, that being the Earth. It would be great to have more, of course. As we know more about Mars, but also life on Earth, we can kind of use Earth and Mars as a type of paired example to frame hypotheses and deepen our understanding of the fundamental nature of life.
The New York Times, toward that end, recently carried a most fascinating detailed article on the work of biologists in the deep gold mines of South Africa. Amazingly, they find deep underground in the rocks the existence of self sustaining ecosystems.
Life lived at the surface, in the soil or in the oceans. At the bottom of the food chain, the so-called primary producers, were plants and microbes that used photosynthesis and sunlight to power the conversion of carbon dioxide into organic molecules. Other creatures ate the plants and microbes, and then larger creatures ate the smaller ones.
In someplace that was always dark, it seemed obvious there could be no primary producers and therefore no life at all.
However, this assumption has been confounded
Maggie Lau, a postdoctoral researcher in Dr. Onstott’s laboratory, started examining the genetic snippets for clues of how the Beatrix community of microbes worked.
With the newest data, it turned out there was a wider community of primary producer microbes, eating nitrogen and sulfur compounds.
In essence, the waste of one microbe helped feed its neighbor, and only a little bit of methane, an energy-rich molecule, was enough to power the entire community.
The NASA Curiosity rover has found methane on Mars, and so speculation is that perhaps life migrated to the Martian depths, there exists reason to suppose life once existed on Mars, where it has survived in a niche environment.
That was a surprise, because sunlight and chemical reactions destroy methane; any methane there would have had to have been released recently. There are two ways to produce methane. One is a geological process that requires heat and liquid water. The other is methanogens…
… Perhaps an underground population of methanogens and methanotrophs is creating, then destroying methane quickly, accounting for its sudden appearance and disappearance from the atmosphere. If Beatrix is a guide, the methane could be providing the energy for many other microbes.
10 to 20% of the Earth’s biomass comes from the deep biosphere, and in the mines The Times reports that even worms can be found as a part of the underground ecosystem.
This is suggestive of an evolutionary process.
Imagine, at the outer limits of speculation, that there are indeed methane producing microbes on Mars and that they provide the primary basis for an ecosystem.
Why would not this support an evolutionary process, no matter how tenuous? Could there be worms on Mars, that is animal life?
Two evolutionary processes on two different planets might tell us something about how evolution fundamentally works. Imagine if there is a one to one correspondence between the ecosystems and evolutionary processes in the depths of both Earth and Mars, assuming that there are ecosystems on Mars of course.
That would be grist for the determinist mill. It would boost the case for convergent evolution, although two planets not far apart would not necessarily settle the matter.
Finally, there is a fantastic little article on trilobite migration, again at The New York Times, the first known example of animal migration on Earth. It would appear that lines of trilobites, they were blind, used chemical signals to establish migratory caravans
Because the creatures were blind, they most likely relied on chemical cues to queue. This process, called chemotaxis, is seen in present day crustaceans like spiny lobsters, which also line up in an antennae-to-tail procession as they migrate.
Trilobites are a favourite of many, including yours truly.
The conga line of trilobites Peter Kropotkin would have readily recognised; that would be “mutual aid” what he called a “factor of evolution,” a factor present at the origin of complex animal life.
Trilobites and the like figured in the Cambrian explosion, not without relevance to the discussion above, for Stephen J Gould in his superb rendering of this the most wondrous period of evolutionary experimentation of life on Earth, held that the Cambrian explosion demonstrates the contingent, as opposed to determinist, nature of evolution.
To Mars we go; if Duck Dodgers could, so can we.