At the conference one of the things that was discussed was the variation in lifespans of control experiments using C Elegans. That had me thinking about whether or not there was a variation in the initial mtDNA. I then searched to see if any research had been done and found the above paper which also has a good summary of the research covering other species as well as human beings.
I have also added a section into my poster web page about this:
https://citrate.science/2025poster/poster2025.html
At the BSRA Conference a slide was shown which demonstrated quite a variation in the lifespan of C. Elegans controls. It seemed clear that the controls were not controlled for the initial value of mtDNA even if they were genetically the same from a nuclear DNA perspective. An obvious experiment would be to see the effect of varying the worm parental age in order to vary the starting mtDNA. However, this is experiment was reported in 2023 and I link to it below this paragraph. What I find interesting is that the paper makes reference to the effect of deterioration of the mtDNA germline without identifying that in fact it is the mtDNA germline that is causing these effects. Obviously there are individuals in a range of species that age at slower rates. For those people the effect is not as great, but for most people the issue of maintaining mtDNA germline quality is a material issue. The paper itself is worth reading and there is no sense me rephrasing a lot of it for this web page.
Obviously this could cause issues with reproducibility in lifespan experiments. It also has broader questions.