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.
