New Study Reaffirms Naked Mole-Rats as Non-Aging Mammals
The naked mole-rat (Heterocephalus glaber) has long fascinated biologists due to its unusually long lifespan, especially given its small body size. Naked mole-rats can live over 30 years, which is around 5 times longer than expected based on their size. Understanding the biological mechanisms behind their exceptional longevity could provide crucial insights for human aging research.
In 2018, a groundbreaking study by Ruby et al. published in the journal eLife reported the astounding finding that unlike all other mammals studied, naked mole-rat mortality risk does not increase with age. In other words, an elderly 30-year old naked mole-rat has the same probability of dying as a young adult, defying the Gompertz-Makeham law of aging seen universally across species.
Now, five years later, the same research group has published a follow-up study in the journal GeroScience with double the amount of demographic data, powerfully reaffirming their original conclusions. Lead by J. Graham Ruby and senior author Rochelle Buffenstein, the team took advantage of 5 additional years of lifespan and survival data from their well-maintained captive naked mole-rat colonies, some of which have now been continuously studied for over three decades.
The massive dataset, encompassing nearly 7,000 individual naked mole-rats, enabled several new analyses. Most importantly, it allowed the researchers to independently analyze only the data collected after their original 2018 publication as a robust replication study. This new data alone, reflecting 5 years of observation, was sufficient to clearly show constant mortality risk with increasing age, validating the conclusions of the original paper.
Some additional intriguing findings emerged from the wealth of new data. The researchers found that naked mole-rat breeders (the queen and a few males) enjoy significantly lower mortality risk compared to non-breeders at all ages. Interestingly, non-breeding mole-rats living in smaller colonies with fewer animals had higher mortality than those living in larger colonies, possibly reflecting increased intra-colony competition when resources are more limited.
To put the naked mole-rat aging pattern into evolutionary context, the researchers also analyzed demographic data from another mole-rat species - the Damaraland mole-rat (Fukomys damarensis). Damaraland mole-rats split from naked mole-rats around 26 million years ago and are also eusocial, but have a more typical mammalian lifespan. The analysis revealed that Damaraland mole-rat mortality risk does gradually increase with age, but much more slowly than in other mammals like mice or humans.
The fact that both naked mole-rats and Damaraland mole-rats exhibit slower "aging" compared to other mammals suggests that their shared ecology and evolution of eusociality may have created selective pressure to evolve enhanced longevity. However, naked mole-rats have taken this to the extreme with their complete lack of mortality risk increase over time. Comparative studies between naked mole-rats and other mole-rat species may help uncover the step-wise genetic and physiological adaptations behind their divergent aging patterns.
In conclusion, this comprehensive new study provides the most robust evidence to date that naked mole-rats do not conform to the Gompertz-Makeham laws of aging that constrain the lifespan of most animals. Excitingly, the fact that evolution has found a way to completely decouple mortality risk from chronological age in a mammal suggest it is biologically possible. With further research, we may be able to translate the insights from naked mole-rats and uncover ways to dramatically slow human aging. The naked mole-rat continues to establish itself as a uniquely promising model species for aging research.
The naked mole-rat (Heterocephalus glaber) has long fascinated biologists due to its unusually long lifespan, especially given its small body size. Naked mole-rats can live over 30 years, which is around 5 times longer than expected based on their size. Understanding the biological mechanisms behind their exceptional longevity could provide crucial insights for human aging research.
In 2018, a groundbreaking study by Ruby et al. published in the journal eLife reported the astounding finding that unlike all other mammals studied, naked mole-rat mortality risk does not increase with age. In other words, an elderly 30-year old naked mole-rat has the same probability of dying as a young adult, defying the Gompertz-Makeham law of aging seen universally across species.
Now, five years later, the same research group has published a follow-up study in the journal GeroScience with double the amount of demographic data, powerfully reaffirming their original conclusions. Lead by J. Graham Ruby and senior author Rochelle Buffenstein, the team took advantage of 5 additional years of lifespan and survival data from their well-maintained captive naked mole-rat colonies, some of which have now been continuously studied for over three decades.
The massive dataset, encompassing nearly 7,000 individual naked mole-rats, enabled several new analyses. Most importantly, it allowed the researchers to independently analyze only the data collected after their original 2018 publication as a robust replication study. This new data alone, reflecting 5 years of observation, was sufficient to clearly show constant mortality risk with increasing age, validating the conclusions of the original paper.
Some additional intriguing findings emerged from the wealth of new data. The researchers found that naked mole-rat breeders (the queen and a few males) enjoy significantly lower mortality risk compared to non-breeders at all ages. Interestingly, non-breeding mole-rats living in smaller colonies with fewer animals had higher mortality than those living in larger colonies, possibly reflecting increased intra-colony competition when resources are more limited.
To put the naked mole-rat aging pattern into evolutionary context, the researchers also analyzed demographic data from another mole-rat species - the Damaraland mole-rat (Fukomys damarensis). Damaraland mole-rats split from naked mole-rats around 26 million years ago and are also eusocial, but have a more typical mammalian lifespan. The analysis revealed that Damaraland mole-rat mortality risk does gradually increase with age, but much more slowly than in other mammals like mice or humans.
The fact that both naked mole-rats and Damaraland mole-rats exhibit slower "aging" compared to other mammals suggests that their shared ecology and evolution of eusociality may have created selective pressure to evolve enhanced longevity. However, naked mole-rats have taken this to the extreme with their complete lack of mortality risk increase over time. Comparative studies between naked mole-rats and other mole-rat species may help uncover the step-wise genetic and physiological adaptations behind their divergent aging patterns.
In conclusion, this comprehensive new study provides the most robust evidence to date that naked mole-rats do not conform to the Gompertz-Makeham laws of aging that constrain the lifespan of most animals. Excitingly, the fact that evolution has found a way to completely decouple mortality risk from chronological age in a mammal suggest it is biologically possible. With further research, we may be able to translate the insights from naked mole-rats and uncover ways to dramatically slow human aging. The naked mole-rat continues to establish itself as a uniquely promising model species for aging research.