Evolution of death

We often contemplate “The evolution of life”, but "The evolution of death" is a phrase which appears paradoxical. It is contradictory in that the very idea of dying seems to be the adversary of life, which evolution strives to preserve. However, upon scrutiny, it becomes evident that evolution is not racing to beat death but instead using it as a formidable preserving mechanism. Before we explore this relationship, it is essential to understand the framework of evolution we approach this with, the gene-centred view, proposed by Richard Dawkins. Revolutionising our understanding of natural selection, Dawkins shifts our view away from organisms or species towards the most basic replicating molecules—genes. He does this by proposing them as the primary unit of natural selection, replicators, which are acted upon by evolution through the adaptations they provide to their host organism. For example, picture a tiger stalking its prey; when it pounces upon it and secures a meal, it does so in pursuit of survival. But the desired survival is not its own or its species, but rather that of its genes, ensuring their propagation into the next generation. Thus, it appears obvious why death can be favoured by evolution. Evolution demands the replicator’s survival above the organism which carries the replicator. For tigers, these are interlinked; its survival safeguarding its genes, but this is not always the case. Illustrating this is Apis mellifera (honeybee), which represents genes before life beautifully. Stinging a predator in self-sacrifice may kill the bee, but in turn will protect the hive. Altruistic acts like this conceptually seem to betray the bee; nevertheless, it is a common sight. Beholding such phenomena makes sense when the genetic profiles of the fellow bees are devolved. Every Apis mellifera in the hive is at least 25% related, some 75%. Martyrdom of one bee is therefore favourable, an exemplar of sacrificial genetic preservation. Hamilton puts this flawlessly, exploring this exact scenario in inclusive fitness, even proving altruism mathematically. Furthermore, he uses it as a vessel to investigate extreme protective behaviour in parents, especially that which leads to their death. Under gene survival, it would appear to be beneficial for a parent to lay down its life for 3 children (each child being 50% related, a high chance of containing a copy of a parent’s gene). Despite this, many animals habitually self-sacrifice for only one or two children. To decipher this, we must consider future reproduction. A child lacks means to effective survival, but when a young adult, is usually much fitter and reproductively active than its parents. Parents must therefore consider their offspring’s potential for rearing grandchildren. In their own sacrifice, they could indirectly save 8 immediate descendants, each 25% related. This raises questions about how infertility and asexual reproduction affect this dynamic. An infertile adult's genetic lineage depends upon its child's survival, no matter the cost. Likewise, children who are products of asexual reproduction are more vital as the likelihood they contain a copy of a gene is 100%. We can also consider sacrifice on the cellular level. Programmed cell death, apoptosis, is a common and vital occurrence - destroying cancer, preventing anatomical abnormalities, and stopping infection. Whilst not directly propagating genes, it is still a preserving trait, ensuring survival long enough for reproduction. This seems to be the antithesis of the evolution of self-sacrifice. Continued existence is needed for gene replication. However, this does not disprove the possible benefits of death; merely gives it context. To invalidate our point, it assumes that firstly, an organism can reproduce, and secondly, will not save more identical genes by its sacrifice. Our honeybee worker satisfies neither of these, and many parents do not satisfy the latter. Simply put, when an organism’s genes gain more from its host’s sacrifice than its living, sacrifice will occur. But when the organism’s life is favoured, evolved death still plays a role in safeguarding its genes at the cellular level. "The evolution of life" is a rational phrase. Most organisms, most times, must survive - they ensure genetic preservation by doing so. But sometimes, under certain circumstances, their sacrifice secures their gene’s legacy in a way living never could. Perhaps it’s time to appreciate "The evolution of death".