Two-stage aging

If we plot the human mortality intensity curve, we will see that mortality intensity initially declines up to adolescence (this is a kind of selection phase, where individuals poorly adapted to life are eliminated from the population), then from ages 13 to 35 mortality intensity is roughly stable and minimal – this is the phase of a young healthy organism’s functioning, after which the aging phase begins and mortality intensity rises monotonically with acceleration. If we look more closely at the aging phase, we can identify a couple of turning points where mortality intensity rarely accelerates, around ages 45‑50 and then around 65‑70.

Aging as a multifactorial disorder with two stages (Gems et al., 2025)
The authors propose a new concept of aging: aging is not a single process but a two-stage disorder, in which early damage and late changes in gene expression interact and lead to disease.
Main ideas of the article
Aging is a multifactorial disorder, not merely an accumulation of damage.
It develops in two stages, each contributing to late‑age diseases.
Early damage can remain hidden for a long time, but becomes dangerous when the organism loses the ability to control it.
Late changes in genetic activity are not adaptation but “dysregulation,” which impairs the functioning of repair systems.
Aging diseases are the result of interaction of these two stages, not just age or just damage.

Stage 1 — early damage (early-life damage)
It begins already in childhood and youth.
Sources of damage:
infections
physical injuries

genetic mutations
toxic exposures
cell division errors
The organism usually copes, but not perfectly. Some damage remains as:
latent mutations
epigenetic marks
micro‑inflammation
tissue abnormalities
These “sleeping” defects do not cause disease immediately, but lay the foundation for future problems.

Stage 2 — late-life gene dysregulation (late-life dysregulation)
It occurs in middle and old age.
What happens:
gene expression begins to change to the organism’s detriment
immune system function is impaired
restorative capacity declines
chronic inflammation intensifies
control over early damage worsens
It is at this stage that the “sleeping” problems from Stage 1 are activated and turn into:
cancer
type 2 diabetes
cardiovascular diseases

Original post taken from TG:

I remember working with the registry office database. I decided to look into what is written about here. For myself. In my sample, it turned out that the peak in mortality was around retirement age, 55–60 years old. And the second highest was the age when teenagers leave adolescence, 16–20. That surprised me. If we take the late 19th century (these are already observations from parish registers), then the peak was under 5 years old. 

Wow, cool, just to take it and check.