Biologist Peter Lidsky argues that aging evolved to protect relatives from chronic infections, making immune rejuvenation the best bet for longevity research; he proposes testing the theory by showing that naked mole-rats die when infected with almost any virus
Biologist Peter Lidsky argues that aging evolved to protect relatives from chronic infections, making immune rejuvenation the best bet for longevity research; he proposes testing the theory by showing that naked mole-rats die when infected with almost any virus
On October 27, Ivan Morgunov’s channel posted an interview with Peter Lidsky of City University of Hong Kong, a coauthor of the pathogen control hypothesis.
Aging is explained either as the accumulation of damage or as an evolved program. According to Lidsky, the main arguments for damage rest on objections to programmed aging raised by evolutionary biologists 50–70 years ago: why would an organism kill itself? His group offers an answer in the pathogen control hypothesis.
Some chronic infections leave their hosts alive but impair reproduction. In evolutionary terms, such a host contributes nothing and poses a danger to relatives, especially those living nearby. The probability of acquiring such an infection rises roughly linearly with age, and Lidsky expects every animal to be infected beyond a certain age. Selection could therefore have favored death at a set age as a way to eliminate potential carriers preemptively.
Without a theory explaining why aging occurs, Lidsky says, researchers resemble doctors treating a disease such as leprosy before its pathogen has been identified: they treat inflammation and DNA damage separately, achieve small effects, and remain uncertain about the cause. If the hypothesis is correct, aging is part of the defense against infection and thus part of the immune system. Rejuvenating the immune system would then probably offer the best return on investment. Lidsky sees the thymus, the gland where immune T-cells mature, as a target. He does not know how to rejuvenate it, since he is not an immunologist.
Immune rejuvenation is a long-term project, and Lidsky’s laboratory needs results sooner. It therefore turned to senescent cells, which have stopped dividing but remain alive and release inflammatory substances. These cells are considered harmful; Lidsky sees them as a defense against viruses.
A virus can induce cellular senescence: SARS-CoV-2 does this, although the authors of the 2021 Nature paper interpreted these cells as a source of inflammation in COVID-19. In a paper with Mikolaj Ogrodnik, who supports the damage theory, Lidsky writes that these cells should disappear once the virus has been defeated. If the immune system fails to clear them, they may accumulate and sustain chronic inflammation. The immune system regulates their numbers. Lidsky therefore predicts that restoring its ability to clear them would extend lifespan more than directly removing the cells, which has produced only a small increase.
Lidsky had planned to test the hypothesis in worms or flies, comparing environments with and without viruses. But there is no good model for viral infection in worms, flies have a complex life cycle, and he expects a reviewer to conclude that the experimental system was chosen to produce the desired result.
One prediction of the hypothesis concerns naked mole-rats, rodents that show almost no aging. They live in colonies with a queen, like ants and bees. In his paper with Ogrodnik, Lidsky writes:
“These animals are predicted to die in response to any infection, thereby keeping the colony free of pathogens.”
If this defense is more effective than aging, naked mole-rats have no need for aging. According to Lidsky, isolated reports of deaths already support this prediction; a reproducible study using different viruses would provide further support. In a 2026 preprint (a paper that has yet to undergo peer review), he and his coauthors cite a 2009 experiment as indirect evidence: a herpes simplex virus that was harmless to mice killed naked mole-rats. The authors of that experiment attributed the deaths to massive infection.