# Epitalon lifespan results in female SHR mice

> Epitalon lifespan results | Keystone Peptide — Keystone Peptide considers an Epitalon experiment in female SHR mice: maximum lifespan, the unchanged mean, leukaemia and total tumour incidence.

**The survival experiment**

Every animal deserves a place in a lifespan account, including the ones whose survival leaves the headline less tidy.

## The maximum and the mean

In the [female Swiss-derived SHR mouse experiment](https://pubmed.ncbi.nlm.nih.gov/14501183/), Epitalon increased maximum lifespan by 12.3%, while mean lifespan remained unchanged. The study also reported a 13.3% increase in survival of the last 10%. These are results about the upper end of survival alongside an unchanged group average.

A record age is an irresistible opening to a story. An animal reaching further into old age suggests a biological question worth pursuing. For a general longevity claim, survival across the group deserves greater weight. Choosing that emphasis is a judgement about the claim’s breadth, rather than a reason to discard the unusually long-lived animals.

The awkwardness is productive. An unchanged mean prompts a question about how the survival experience was distributed, whereas a higher maximum directs attention to the furthest survivor. The [published outcome](https://pubmed.ncbi.nlm.nih.gov/14501183/) supports both descriptions. It supplies no single number that can do the work of both.

![Mean lifespan unchanged beside a 12.3% increase in maximum lifespan in female SHR mice](images/survival-outcomes.svg)

*Reported Epitalon outcomes in female Swiss-derived SHR mice: unchanged mean lifespan and a 12.3% increase in maximum lifespan. [The study](https://pubmed.ncbi.nlm.nih.gov/14501183/).*

## Leukaemia and total tumour incidence

The [same paper](https://pubmed.ncbi.nlm.nih.gov/14501183/) reported 6.0-fold inhibition of leukaemia and no change in total tumour incidence. I object to smoothing those outcomes into a general cancer-protection claim. A change in a particular disease and the result across all tumours deserve separate consideration.

Nor does unchanged total tumour incidence in these female mice settle the safety question for people. That would ask the experiment to answer for a population it did not study. The finding is useful precisely at its stated scale: this mouse population, this treatment experiment, these survival and disease outcomes.

The sweeping longevity version loses much of that texture. The unusual survivor remains memorable, while the unchanged average and the total tumour result can slip out of the account. An explanation owes those outcomes equal consideration.

## The fruit-fly experiment

Another [lifespan study used Drosophila melanogaster](https://pubmed.ncbi.nlm.nih.gov/11087911/). Epitalon applied during development increased the lifespan of the adult flies by 11-16%. Exposure during development is a particularly consequential feature of that experiment: the intervention began before the adult life whose duration was measured.

This result broadens the organismal work beyond mice. Developmental exposure, specifically, gives me a fresh question to pursue. A developmental experiment in flies and an experiment in female SHR mice are different biological propositions, even when their summaries both contain the word lifespan.

An independently repeated shift through the whole survival distribution, accompanied by a clear account of harms, would earn a different place in my argument. Until then, the [mouse result](https://pubmed.ncbi.nlm.nih.gov/14501183/) remains an interesting problem with an unusually easy-to-misplace average.

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Keystone Peptide is my argument with the published Epitalon experiments, especially the mouse near the middle of the group, and these essays provide no medical advice.