Thursday, March 7, 2019

Does Death Have a Biological Function?


Living beings display a tremendous range of lifespans. For example, it appears that at the colony level, if not at the individual level, many species of bacteria are virtually immortal, and examples of bacteria that apparently live for millions of years have been discovered. Sequoia trees are known to reach the age of 5,000. Conversely, many insects are very short-lived, living just a few days, or a few months at best, and many flowering plants are annuals. Humans find themselves in somewhat of a middle position (although not exactly so) in this astonishing range. Given such a wide breadth of lifespans in nature, we ask, why does death come to some beings so much more quickly than to others? Is there an evolutionary basis for death? More philosophically, perhaps, we ask, why do we die at all, what purpose does this serve? If the goal of life (at the biological level) is reproductive success, then why do humans age, lose the ability to reproduce, and get taken out of the game permanently? Countless humans have yearned for immortality throughout the ages. Why has natural selection not bestowed it on us, or at least given us the kind of vast lifespan granted to so many beings? No definitive answers to these questions can be given, but I have some of my own thoughts and conjectures about them.

First, natural selection operates solely on the basis of whatever works. It is a process, not a conscious entity possessing volition and moral agency. As I have noted, many of the solutions that natural selection has “devised” to meet the challenges of life are clumsy and suboptimal. We are a product of the Law of Whatever Works. We are not evolved to be immortal because mortality “works” for beings like us. The fact that we die does not set up an insurmountable barrier to reproductive success. We can reproduce and then die, and that system works. Moreover, there is an unconscious trade-off life seems to have made. In exchange for their multicellularity and ability to move independently through the air, landscape, or seascape, animals have been given limits. Bacteria, being simple, can be immortal. Living animals, being complex and mobile, cannot be. The support systems required to keep animals alive are orders of magnitude greater than those required for bacteria. From a biological standpoint, death might simply be a more efficient way of cycling the resources necessary to perpetuate life in general. We need to remember: the life of the individual animal isn't the chief issue: the survival of the species to which it belongs is. And more than 99.9% of all species have gone extinct. They went extinct largely because environmental conditions changed, rendering their genetically-produced adaptations to previous conditions either useless or downright harmful. Humans are the product of this biological ferment.

Could humans, through their own efforts, attain physical immortality? One could argue that the repair processes of a human’s body could be made so efficient that the human could live indefinitely, but such a vast “upgrade” of our repair capabilities would require a fundamental reconfiguration of our entire physical being. It would be the ultimate in unnatural selection. It is possible, perhaps, but humans, like all other animals, are constructed out of basic, simple materials, as I have pointed out several times. The very stuff out of which we are made is impermanent, and subject to all the changes that every physical substance anywhere is subject to. Reconstituting a human to be immortal would involve inconceivably huge efforts. And these efforts would fly in the face of an immutable truth: We’re not built to last because we don't need to be.

I do not want my words to be misinterpreted as misanthropy, but I have to be completely honest about my views here. The existence of the human race on this planet is not in itself a required condition for the survival of either the planet or the life on it. In fact, as far as the latter point goes, far from being essential for life, humans are the only beings on the planet with the capacity to abolish it. It will sound incredibly harsh, but from a biological standpoint, it did not “matter” whether humans came to exist or not. They were a by-product of the planet Earth’s physical, chemical, and biological processes, a particularly unique example of an emergent phenomenon, perhaps, but nothing more. Humans, naturally, see themselves as extraordinary, and in the context of this world they are, of course. But they are not necessary. Life—and this planet— would go on without them.

We are no different than anything else that exists. The Earth will be destroyed by the Sun. The Sun itself in turn will die. Our Universe will end. This means that our species will not survive, no matter where our descendants run to. We will die out. Why? Because ultimately, it does not matter. There is no why to death. There is only the fact of it.

“Earth to earth, ashes to ashes, dust to dust.” So the phrase from a prayer book goes. We are of this planet. When the bodies we are finally and irrevocably break down, the atoms and molecules out of which we were composed will again join the mass of those from which the Earth itself is made. Our chemical elements will find their way into new forms and arrangements, perhaps even other living beings. Most people take consolation from the belief that a metaphysical existence will follow this one. The truth or falsity of that proposition cannot be demonstrated, and must necessarily be a matter of individual faith. But one thing is sure: our physical lives are fleeting and impermanent. We are, as I have said, probably the only animal that knows that death will come to everyone. One of the foundations of human cultural and social life has been our response to this knowledge. Human history is the story of physical beings, limited, vulnerable—and mortal.

From such stuff as this has the human world been made.

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