People refer to their children as their immortality. If the children live and reproduce, having more children, then a person’s heritage, his or her line, some bit of his or her flesh, will continue into the future. The conscious “I” may not accompany those fragments of DNA and that bit of tissue, but a link will exist. Your existence will continue. There will be some sign that once you existed.
The process works in reverse as well. As I sit here today writing this—as you sit there reading this—you and I share flesh with every bit of life on Earth. Our line goes back, and not just among the humans, those Homo sapiens who developed in Africa and walked out among the neanderthalensis, habilis, and erectus to conquer the planet. But we also go back much farther than that.
We share the developing DNA structure and tissue makeup of all primates, all mammals. We participate in the branching that separated and developed the mammalian line from the reptiles, the reptilian line from the amphibians, and the amphibians from the fish. We go back to the first eukaryotes, the multiple-celled animals that sequestered their DNA inside a nucleus, picked up organelles like the mitochondria from competing creatures, and learned to differentiate their cell types to support a larger organism. We go back to the prokaryotes, the single-celled organisms that lived on their DNA and RNA organizing a soup of proteins and other chemicals inside a cell membrane. We go back to the time before the ancestral lines of plants and fungi separated from the protists that became us.
We are cousins not just to every human being that ever lived, but to every animal that roamed the forests and the plains. We are distant cousins to the dinosaurs, lizards, and mouselike mammals that survived the impact at Chicxulub. We share grandparents with fish and scorpions and spiders. We share great-great-grandmothers with the flowers and the trees. We can honor the myriad kinds of bacteria that inhabit our own bodies as distant brothers.
Just sitting here, we share the original organizing principle, the DNA-RNA-protein regime, the coding system that violated entropy and established the first life on this planet. That means that each of us, inside our cells, also carries a pinch of that original, primordial protoplasm. It has been replenished, filled up, and refined a million, a billion times since the protista first cooked it up, but we share the same soup of amino acids and proteins that the first cells enclosed.
And if you follow certain lines of thought, which question how it came to be that all life on this planet uses that single, unique DNA-RNA-protein regime as its coding system, without a hint of any other information-recording chemicals or any of DNA’s possible variations in the evolutionary matrix, then you must begin to wonder if that system even originated on Earth.1 And if not—that is to say, if the cells and their DNA-RNA-protein regime were either seeded here or carelessly left behind in the lining of an astronaut’s glove—then we share much more. We may be distant cousins to the life out among the stars.2
This is not immortality of the self or soul or consciousness. The person who answers to your name, collects all your thoughts and memories, and has your particular hopes and dreams for the future was not and will not be involved. You do not remember being your own grandfather, either. Or a chimp, a mouse, a lizard, or a fish. And neither will the immortality going forward from your cells, through your children and grandchildren, if any, carry your personality into the far future.3 Family lines eventually die out, or they become so mixed that you would not recognize your far-future offspring. And eventually, however slowly, the human race will evolve, too, into something that will look back on you sadly as some kind of shambling ape. That, too, is inevitable.
The true immortality is to embrace the fact of life itself: the promise of the DNA that it will change, that the next generation will evolve to meet the requirements of the environment it finds. If we are all cousins in life, then the best we can do is celebrate its continuing, down through the ages to us, and further down from us to whatever our kind becomes. We will be immortal as long as the Sun shines and the Earth survives. And if we ever master the trick of going out among the stars, we may be as immortal as the universe itself.
That may be as good as it gets.
1. See the thoughts in Communicating with Aliens from July 28, 2013.
2. When you stop to think about it, seeding the stars with microbes may be the only way to colonize distant planets. Microbes are tough, can form spores when ambient conditions become too rough, and have almost no expectations. Why go to all the trouble of trying to terraform a distant world, achieving just the right balance of gravity, atmospheric gases, and pH levels to suit your particular kind of life? That’s a lot of work, takes a lot of planning and foresight, and can lead to disaster if you miscalculate even one tiny factor among hundreds or thousands of needed changes. Instead, why not “planiform” your future life? Send a microbial sample to any star within reach that has a planet in the habitable zone—that is, with liquid water necessary to support your kind of chemistry—and let the microbe and its progeny adapt from there. If the microbe survives and evolves, its succeeding generations will grow up on a planet that has everything they need. They will view that planet as a special, beautiful, gentle, God-given place, even if it remains inimical to their parent’s life form, who once lived on a distant, horribly acidic or alkaline, harshly radiated, or heavy world under a too-bright or too-dim star.
3. Immortality in personal form is a nice dream, but it does not square with reality. We would all like a few extra years of life, even a few hundred. That would give us time to really accomplish something, to develop not just skills but mastery, to focus on perfection in whatever we do—from piano playing to novel writing to beer drinking. But immortality? Life without end? Staying alive and thinking forever and ever? Waiting for the Sun to burn out? For the universe to expand into separate molecules of cold gas that never react with one another? That’s not a promise but a sentence of doom.