The notion of panspermia has been in the news lately. And soon it will be on the tip of everyone’s tongue.
The idea that life on Earth came from another planet has been around for a while but now it appears that other planets could have been seeded from Earth.
Life may come to another planet from Earth, but that planet might already have its own life. This raises the possibility of two great kingdoms of life waging war on an evolutionary battlefield. The carbon based life forms against the silicon based life forms. Interesting, but unlikely. It seems that since there are organic molecules drifting round in space, and since these probably give rise to planetary life, the organisms would be similarly carbon based. Furthermore, unless there are multiple different strands of DNA that can produce any of the proteins that life relies on, it is probable that all life shares the same basic components of the DNA code.
Asteroid or comet hits are fairly common. We know of several on Earth and within the past decade we have witnessed a comet impacting Jupiter. Given this, the ejecta of such collisions must be littered throughout space, teased into globs and streams by the dynamics of space. We can imagine interstellar space cris-crossed with streams of life bearing planetary ejecta, perhaps seeding planets millions of light years away.
Most of this life probably consists of dormant spores that can survive the extreme conditions of outer space, but let’s assume for a moment that some of this life is normal living matter, maybe a rock with some cracks that harbor extremophile bacteria. Is there any reason why they could not survive, breed, adapt and evolve in outer space?
And despite adapting and evolving, would they still yearn for the warmth and nutritional riches of a planet, would they migrate, perhaps in great herds, from planet to planet grazing, fattening, breeding perhaps before setting off into space again. And would they be, as most grazers are, followed by carnivores and scavengers?
This effectively makes the galaxy and perhaps even the entire universe, a single ecosystem, and we are in that ecosystem, sedentary (at least at present) creatures among the migrating competitors. It is perhaps a step too far, but one can imagine humans, velociraptors, ants, squid and condors travelling between the stars, competing with each other for dominance in different planetary ecological niches. Perhaps this could be achieved by sending ‘generation ships’ between the stars loaded with out most prolific or versatile species. Or perhaps the competition is between the evolved intelligent descendants of these animals, not competing with warfare but to see who can best survive the evolutionary pressures of each planet, pressures such as global warming or cooling, volcanic action, rising sea level, desertification and disease.
So much for the notion that the galaxy is fundamentally inimical to life. Or perhaps it still is. Perhaps most of the universe cannot support life, but tolerates its passage, and reserves its musty fetid corners for life's infestations.
Could life take control of this mechanism, using asteroid impacts to spread to other planets as a plant on Earth uses the wind to spread its seed. A life form with a long term view could prepare itself and just wait, but I think that evolution is not that patient. A more intriguing idea is that once they are ready, they are able to summon the asteroid. Any idea how that could be done?
However, once all this speculation is done and new and wondrous ideas have been penned and flow from the printing presses, one unresolved problem still exists. One problem that panspermia has never addressed. Where did life first arise, which planet gave rise to the first living thing in the universe? And could we trace life back to that planet? That would be a challenge worthy of a great expedition. Of course, it is likely that life arose many times independently, but even so, somewhere, a long time ago, the first life wriggled and squirmed, and perhaps we are its children.