Life on our planet emerged quickly or, at least, it did so on a geological timescale. Fossils reveal that micro-life existed on our planet at least 3.5 billion years ago. The rapid emergence of life on our planet has led some scientists to a rather interesting question: does our planet produce life on its own or does it need a ‘helping hand’?
The most accepted theory concerning the origins of life is abiogenesis. Abiogenesis suggests that life evolved from non-living chemical compounds. Abiogenesis suggests that a playground for the chemicals was created on earth by the oceans, the atmosphere, and around volcanoes. Amino acids, lipids, and nucleotides were produced as a result of a reaction. After a long time, the chemical compounds evolved to end up in biology. There are experiments to confirm the production of the chemical compounds.
But the question of the transition from chemistry to the first self-replicating cell is still out of our understanding. Robert Endres, a biologist from Imperial College in London, has used mathematical models to calculate the probability of the formation of a functional protocell by natural processes. In his study using Information Theory, he concluded that abiogenesis is possible, but the problem of abiogenesis is larger than people think. And this alone is sufficient to look for alternative theories in addition to the current paradigm.
These include the panspermia theory that proposes the existence of life or life-building material between planetary bodies. In the “directed” version of the theory that was proposed by Francis Crick, a Nobel Prize winner, and Leslie Orgel, a biochemist in 1973, a highly developed alien civilization could use other planets as a nursery. In other versions of the theory, life could ride on an asteroid or a comet. Spacecraft have discovered amino acids, sugars, and nucleic acid bases in meteorites and cometary material.
However, recent research has also produced some interesting new findings. Analysis of samples from the asteroid Bennu has provided a complex mixture of nitrogen-containing molecules, racemic amino acids, and exotic nucleobases, none of which match biological systems on Earth, and all of which provide strong support for their extraterrestrial origin. This kind of organic compound, which would have been seeded on Earth by large asteroid impacts, may have supplemented the early Earth inventory of prebiotic molecules. On the other hand, laboratory simulations have shown that some microorganisms, such as Deinococcus, can survive for long periods of time, even years, in space under the harsh conditions of space when grouped in large clusters, so interplanetary transfer becomes feasible even in the absence of rock protection. But surviving the transfer is only half the problem. Studies of the shock of impact have shown that even the most resistant organisms have their limits; for instance, tardigrades can survive strong cold, a vacuum, and radiation but not shock pressures above 1.14 gigapascals.
This eliminates a high-speed transfer but will enable a softer transfer, perhaps of ejection material gently placed on a nearby moon or harvested from the plumes of the icy moons such as Enceladus with a soft collector such as aerogel. Another realm in which this discussion is being impacted is in the development of modern astronomy. ‘The detection of the presence of biosignatures like the signature of biological activity and the formation of complex organic molecules in the icy mantles of dust grains orbiting young stars provides evidence for the possibility that the biological seed for life could be present elsewhere in the universe, although the spark of life itself remains an enigma for scientists.
That which matters to Endres et al. is not the fact that life was seeded on Earth by aliens but rather the possibility that it could be done. As he writes: Science must not close its eyes to how implausible it may sound. Whether life originated in a ‘warm little pond’ on our planet or on a piece of cosmic debris that brought it to our planet, it is our search for truth that brings us to the edge of our own knowledge and to the possibility that our own story may be part of an even bigger one that is playing out in the universe.
