A Story About Mortality: The Evolution of Aging and Death
A flatworm (Pseudocerus liparus) crawling on a sponge – passing through a forest of hydroids and tunicates. (Image credit: Christa Rohrbach, CC BY-NC-SA 4.0)
Tag Archives: aging
A Story About Mortality: What Jellyfish Can Teach Us
The hydromedusa of Podocoryna borealis. (Image credit: Lara Beckmann, NorHydro, CC BY-SA 4.0)
Our existences are often centered around the hope that we will live a long and fulfilled life. At the same time, while we aim to grow old, many of us abhor the aging process, dreaming of remaining young and healthy for as long as possible. It explains why we are so fascinated by the concept of immortality. Think of vampire stories, constant quests for the fountain of youth, or even the newest anti-aging products in the drugstore next door. But apart from the few extra years we gain nowadays through modern medicine and improved life circumstances, many of us can’t extend our lives much further.
We share this fate with many other animals that go through the stages of birth, growth, reproduction and death. But despite that, we don’t need to rely on science-fiction to get a glimpse of everlasting life: some organisms on our planet don’t follow these stages and some cheat it altogether – escaping death almost completely.
Read moreGetting Older is Favored in Choosy Species
One of the timeless (get it?) questions in biology is why did we evolve to age? What benefit is there to getting older and deteriorating before we die? (Image Credit: medienluemmel, Pixabay licence, Image Cropped)
Evolution favours aging in populations with assortative mating and in sexully dimorphic populations (2018) Lenart, P. et al., Scientific Reports, 8, https://doi.org/10.1038/s41598-018-34391-x
The Crux
We as humans are familiar with aging as the slow deterioration of our bodies and minds over time, and we can see this in other animals as well (think of the old family dog with white around its muzzle). The interesting thing is that not every species ages in the way that we do, that is to say that they stay forever “young” until they die. In a biological sense that means that while these organisms can and do die, their risk of death remains the same throughout the course of their lives. This would be akin to your grandparents, in their old age, having the same risk of death as you during the prime of your life. Or, conversely, you being just as likely to die in your sleep as a senior citizen.
The authors of this study note that, while theories for the evolution of aging abound in the scientific literature, they are not broadly applicable and some of them even require the existence of aging for the evolution of aging to even happen. They wanted to find out in what situations aging individuals could outcompete non-aging individuals, and vice-versa.
Ecology for the Masses 