How to Break the Two Bottlenecks Restricting the Development of Life?
The emergence of the first life on earth was a fantastic transformation in the history of our planet. The earliest microorganisms appeared some 3.5 billion years ago, amidst an extremely hostile environment where every possible stressor conspired to keep lifelessness as the dominant state. And yet life flourished: prokaryotes, eukaryotes and finally advanced multicellular organisms evolved independently but in parallel on multiple continents (i.e., no single “Garden of Eden”). But there was a catch. Although the pre-biotic conditions were ripe for biogenesis, it still took several hundred million years before the first hyperthermophilic archaea began replacing their less efficient ancestors. In other words, after all the necessary ingredients were available, it took almost two billion years for life to take off and reach its current variety and complexity.
Two bottlenecks in the evolution of life
Life's first two bottlenecks are i) the rate of evolution - the chemical reaction that produces genetic novelty, which lowers with time as the species becomes more adapted to its environment; ii) the availability of new environments where life can spread. The first bottleneck is intrinsic to biology, but the second depends on geological events and certain planetary properties. If life is to flourish, it must be able to reproduce, evolve, and adapt to its environment, so that each generation can be better than the previous one. To do this, life requires several components: a means to replicate, a way to store information, a source of energy, and a way to transfer nutrients and chemicals between individual organisms.
Evolutionary bottlenecks
Evolutionary bottlenecks are periods of extremely slow genetic change that occur in all species as they adapt to their environment. The first of these, the “long bottleneck”, occurred after the first prokaryotes appeared some 3.5 billion years ago. The rate of evolution was so slow, that it took another two billion years for eukaryotes to emerge. The second bottleneck, the “short bottleneck”, began when multicellular organisms emerged and lasted until the first animals appeared some 600 million years ago. Finally, the present “long bottleneck” began about 100 million years ago and is still ongoing.
The “Consequences” Bottleneck
The “consequences” bottleneck occurs when a species becomes so adapted to a certain environment that it becomes unable to reproduce and thrive in other, similar environments. The first bottleneck is believed to explain why the first prokaryotes were so different from modern archaea. After eons of adapting to hyper-thermophilic conditions, the first prokaryotes were unable to survive in cooler environments. The second “consequences” bottleneck explains why the second evolutionary bottleneck lasted longer and was more severe than the first one. The first eukaryotes were so different from modern cells that it took another 1.5 billion years before multicellular organisms emerged.
The “Knowledge” Bottleneck
The “knowledge” bottleneck occurs when a species becomes so adapted to one or a few narrow niches that it fails to thrive in other, more general environments. The first example of this bottleneck occurred when prokaryotes began degrading their environment so much that the first eukaryotes could not thrive there. The second example took place when oxygen levels rose so high that multicellular organisms began dying in the water.
Which bottleneck is more important?
The “consequences” bottleneck is an intrinsic property of biology while the “knowledge” bottleneck is a characteristic of geography and geological events that are outside of biology’s control. Therefore, the “consequences” bottleneck is more important than the “knowledge” bottleneck. While it is true that life’s first two bottlenecks were caused by biology and are therefore intrinsic to it, they would have had little effect without the third bottleneck, which was caused by the geography and the specific properties of our planet.
Conclusion
The first two bottlenecks that limited the development of life were the slow rate of evolution and the inability of organisms to survive in environments other than their own. The inability of early organisms to survive in new environments meant that life would be contained to Earth. In order for life to spread to other planets, these bottlenecks must be broken. The third bottleneck, the distance between planets, is the one that must be overcome in order for life to flourish beyond Earth. With new propulsion methods, this bottleneck can be broken. New propulsion methods such as solar sails, ion drives, and fusion engines can break the two first bottlenecks and allow life to flourish beyond our planet.
