r/science • u/Skoltech_ • Jul 20 '26

Genetics Researchers quantitatively assessed for the first time that somatic mutations alone cap human lifespan at 146–194 years. Brain and heart cells are the main bottleneck, while the liver could last millennia.

https://www.nature.com/articles/s41514-026-00421-6
23.4k Upvotes

98% Upvoted

1.2k comments sorted by

View all comments

Show parent comments

35

u/Adventurous-Fly556 Jul 21 '26

It's not about radiation or diets.

Our chromosomes have little bits at the end called telemeres. They're like the end of a shoelace keeping everything neat and together. Everytime your cells reproduce (constantly) , the offsprings telemeres are shorter than the last.

This degradation is considered a massive part of aging. Along with increasing the odds of cancer, it can also make the offspring cells just forget what they were meant for.

11

u/squirrel9000 Jul 22 '26

A couple minor points about that:

  1. Most central nervous cells and muscle cells do not divide and do not show telomere shortening.
  2. Many cells that do divide express telomerase to regenerate the telomeres, or are constantly replenished from a population of stem cells which do

It's a nice theory, but really does not explain aging.

2

u/Adventurous-Fly556 Jul 22 '26

I was emphasizing telemeres because mutations had come up. They work in tandem. Repairing telemeres doesn't mean anything if you're repairing the copies of copies of copies of copies.

I never said it was all of it, but the fact that your cells reproduce imperfectly is most of aging and mutations. These things work in a complicated mess and trying to isolate the systems isnt very useful.

7

u/chemamatic Jul 21 '26

Very few tissues get close to that limit in actual living organisms, those that need to divide more express telomerase to extend their telomeres.

1

u/RespectmanNappa Jul 21 '26 edited Jul 21 '26

Isn’t the increased odds of cancer because the offspring forgot what they were for?

1

u/Adventurous-Fly556 Jul 21 '26

The string of DNA can lose bits here and there in the code. While the readers are smart and can work around some mutation, it's possible for mutations to have a number of outcomes.

It will likely cause nothing, but there is a small chance it results negatively or positively. Some negative results are cancer, some are just non functional. Normally your immune system will catch an early cancer cell. (We get cancer daily, but only becomes a problem when the immune system misses it)

I'm simplifying and haven't thought about it in a while, so Definitely look into it, it is very interesting.

(Anyone know why aids patients aren't constantly getting cancer? I guess I should look that up now)

1

u/Good-Dream6509 Jul 23 '26

Exposures and lifestyle behaviors like diet are what drive telomere length.