# Evolutionary Theory of Aging: Old Age as a Statistical Failure of Selection

Алекс Ней

A sharp evolutionary argument: ageing as the statistical collapse of selection on late‑life gene expression.

Evolutionary Theory of Aging: Old Age as a Statistical Failure of Selection


Living forever - and remaining reproductively capable while doing so - is biologically advantageous if we remember that the metaphorical task of a gene code is to launch its copies into the future, much like a computer virus spreads its code across a network. Genes are inventive creatures: some use the minimal interface of viroids, almost naked RNA; others operate through more complex viruses and cells. The more copies a code produces, the better. Many copies = biological success.


Gene codes spread their copies in various ways. A method works until it doesn"t. For example, a small subset of genes learned to build multicellular organisms - from sponges and simple worms to elephants and cockroaches. The task remains the same: the more copies of the gene code reach the future, the better. Those that lacked the metaphorical drive to spread through time and space disappeared. Gene codes behave pragmatically - they must copy themselves, or the line ends.


Multicellular organisms solve the task differently: they produce offspring in the form of babies, seeds, or spores. Successful multicellular organisms pass on their genes, increasing the number of carriers of the code. The longer an organism lives and produces viable offspring, the better for the code.


In principle, the code does not change during an organism"s lifetime. Somatic mutations occur, but for simplicity we ignore them. The main changes happen at conception - mutations and recombination. In this essay, we focus on the regulation of gene expression.


Genes create different cell types (skin, liver, bone, etc.) through regulated expression. In short: genes behave differently in different parts of the organism, under different conditions, and at different developmental stages. The algorithm is more complex than any computer program, and through it the organism acquires its various cell types and stagespecific changes: infants don"t grow beards, and teenagers don"t go bald.


We exclude somatic mutations and treat changes in geneexpression regimes as the primary material subjected to selection at each stage.


By default, expression regimes are chaotic: nature plans nothing. Dawkins"s blind watchmaker or Drobyshevsky"s "not your auntie" - that"s evolution. Random expression changes that turn out to be fatal kill the organism. If a switch in gene expression is not fatal, life continues. Thus, selection acts not only on the gene code itself but also on successfully realized expression patterns during ontogenesis.


Selection requires sufficient statistical samples. If a population has only three individuals - one eaten by a leopard, one starves, one dies by chance - selection becomes impossible. "Expressionlevel" selection requires statistically meaningful numbers of individuals at each stage.


If the population survives reasonably well, the number of individuals capable of passing more stages of ontogenesis without fatal expression failures increases. Correspondingly, the number dying from maladaptive expression decreases. The more consecutive stages an organism passes, the more successful the gene codes.


But the environment is often hostile: an infant may be eaten by a clanmate, bitten by a snake, or die from hunger or competition. The annual probability of death may be, say, 3%. By age 70, only about 12 out of 100 individuals remain. There is almost no statistical material for selection after that.


Random expression beyond this point remains chaotic. Even if a leopard or a falling baobab brick doesn"t get you, a fatal regulatory failure may. That is what we call old age.


In the elderly, hair doesn"t grow inward and heels don"t replace hearts, but unpleasant changes occur because there is no selection acting on geneexpression regimes. Telomeres, mitochondria, and other molecular processes certainly exist, but in this essay they are not the primary cause of aging - they become fatal only once systemic stability is lost.


Dawkins proposes a couchtheorist scheme: legally forbid reproduction before age 30, then after 5-6 generations raise the threshold to 40. Theoretically possible, practically impossible - people want to live and reproduce here and now.


There are documented cases of individuals living past 100 and of children born to parents over 60. A lucky random switch in gene expression, even with insufficient sampling, can become fixed.


The age at which extrinsic mortality reduces the population to a critical level (say, 70 years) is the point where selection on expression effectively stops. Genes with antagonistic pleiotropy remain, and their effects manifest.


The classical formulation of antagonistic pleiotropy: genes beneficial in youth become harmful in old age. In reality, old age arises because genes stop undergoing selection for expression quality. Random expression after 70 can easily be fatal.


For clarity, consider an allegory with balls: a person balances a ball on their palm. One ball is easy. A second is still manageable. A third requires more coordination, a fourth - skill, a fifth, a sixth... Sooner or later even a professional juggler loses the structure.


Each ball is a stage of ontogenesis and its associated expression regime. For life to continue, the system must remain functional at every stage. One fatal failure renders the "perfect" work of subsequent stages irrelevant.


As more balls are added, the demands for precision and coordination increase, and the acceptable range of fluctuations narrows. Even without external mortality, the probability of losing stability rises. This is not "wear and tear" but increasing system complexity.


The statistical collapse of selection at late stages combines with rising regulatory demands, limiting maximum lifespan.


We do not age because nature is cruel, but because it is indifferent. Selection simply stopped looking in our direction after a certain age. When leopards and other factors reduced ancestral populations, selection on expression ceased. Everything that happened afterward is statistical debris. If Homo erectus routinely lived to 200, we might have as well. Instead, we pay with wrinkles, arthritis, and long lists of diagnoses.