scholarly journals Decision letter: Comment on 'Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age'

2019 ◽  
Author(s):  
Caleb Finch ◽  
Laurence Mueller
Keyword(s):  
Mortality Rates ◽  
Mole Rat ◽  
Naked Mole Rat ◽  
Letter Comment

scholarly journals Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
J Graham Ruby ◽  
Megan Smith ◽  
Rochelle Buffenstein
Keyword(s):  
Mortality Rates ◽  
Substantial Portion ◽  
Maximum Lifespan ◽  
Heterocephalus Glaber ◽  
Risk Of Death ◽  
Kaplan Meier ◽  
Mole Rat ◽  
Naked Mole Rat ◽  
Data Points ◽  
Increasing Risk

The longest-lived rodent, the naked mole-rat (Heterocephalus glaber), has a reported maximum lifespan of >30 years and exhibits delayed and/or attenuated age-associated physiological declines. We questioned whether these mouse-sized, eusocial rodents conform to Gompertzian mortality laws by experiencing an exponentially increasing risk of death as they get older. We compiled and analyzed a large compendium of historical naked mole-rat lifespan data with >3000 data points. Kaplan-Meier analyses revealed a substantial portion of the population to have survived at 30 years of age. Moreover, unlike all other mammals studied to date, and regardless of sex or breeding-status, the age-specific hazard of mortality did not increase with age, even at ages 25-fold past their time to reproductive maturity. This absence of hazard increase with age, in defiance of Gompertz’s law, uniquely identifies the naked mole-rat as a non-aging mammal, confirming its status as an exceptional model for biogerontology.

scholarly journals Comment on 'Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age'

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Philip Dammann ◽  
André Scherag ◽  
Nikolay Zak ◽  
Karol Szafranski ◽  
Susanne Holtze ◽  
...  
Keyword(s):  
Full Range ◽  
Mortality Rates ◽  
Mole Rat ◽  
Naked Mole Rat ◽  
Total Observation ◽  
Observation Period

Ruby et al. recently analyzed historical lifespan data on more than 3200 naked mole-rats, collected over a total observation period of about 38 years (Ruby et al., 2018). They report that mortality hazards do not seem to increase across the full range of their so-far-observed lifespan, and conclude that this defiance of Gompertz's law ‘uniquely identifies the naked mole-rat as a non-aging mammal’. Here, we explain why we believe this conclusion is premature.

scholarly journals Author response: Comment on 'Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age'

2019 ◽  
Author(s):  
Philip Dammann ◽  
André Scherag ◽  
Nikolay Zak ◽  
Karol Szafranski ◽  
Susanne Holtze ◽  
...  
Keyword(s):  
Mortality Rates ◽  
Author Response ◽  
Mole Rat ◽  
Naked Mole Rat

scholarly journals Response to comment on 'Naked mole-rat mortality rates defy Gompertzian laws by not increasing with age'

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
J Graham Ruby ◽  
Megan Smith ◽  
Rochelle Buffenstein
Keyword(s):  
Survival Analysis ◽  
Mortality Rates ◽  
Historical Records ◽  
Demographic Analysis ◽  
Heterocephalus Glaber ◽  
Risk Of Death ◽  
Kaplan Meier ◽  
Mole Rat ◽  
Naked Mole Rat

For most adult mammals, the risk of death increases exponentially with age, an observation originally described for humans by Benjamin Gompertz. We recently performed a Kaplan–Meier survival analysis of naked mole-rats (Heterocephalus glaber) and concluded that their risk of death remains constant as they grow older (Ruby et al., 2018). Dammann et al. suggest incomplete historical records potentially confounded our demographic analysis (Dammann et al., 2019). In response, we applied the left-censorship technique of Kaplan and Meier to exclude all data from the historical era in which they speculate the records to be confounded. Our new analysis produced indistinguishable results from what we had previously published, and thus strongly reinforced our original conclusions.

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