Larger Brains Linked to Longer Lifespans in Mammals

Researchers from the University of Bath have discovered a potential link between the size of a mammal's brain and its lifespan, suggesting that larger brains may be associated with stronger immune systems and longer lifespans. The study, published in Scientific Reports, analyzed genomic data from 46 different mammal species, including cats, pandas, and dolphins. The findings indicate that species with larger relative brain sizes, such as humans, elephants, and primates, tend to have longer lifespans. This is due to expansions in immune-related gene families, which are crucial for maintaining a robust immune system and overall health.

The study identified 236 gene families that showed significant positive correlations with maximum lifespan potential (MLSP) across the mammalian phylogeny. These gene families are enriched in immune system functional annotations and are associated with aging and longevity. MLSP refers to the age reached by the longest-lived individual in a species, which can vary significantly. Unlike average lifespan, which is influenced by environmental factors, MLSP reflects the species' biological limit.

According to the World Health Organization, the average human life expectancy in 2021 was 71.3 years. The current oldest living human is 115 years old, while the oldest person ever recorded lived to be 122. In contrast, the average life expectancy of a dog ranges from 10 to 13 years, with the oldest verified dog living to be 29. Research into the relationship between brain size and longevity has been ongoing for decades, and this study builds on previous findings to uncover the genetic basis of MLSP.

The researchers accounted for physical traits such as body and brain size, as well as life history factors like age at maturity and gestation time, when analyzing the genetic patterns linked to lifespan evolution. They found evidence of a shared molecular machinery associated with the evolution of MLSP and relative brain size, with 161 gene families significantly related to both phenotypes. This common genomic signature aligns with the established evolutionary relationship between lifespan and relative brain size in vertebrates. No associations were found with gestation time, age at sexual maturity, or body mass.

Beyond the number of genes, the researchers discovered that the genes linked to MLSP were more active in humans and could be used in more varied ways to produce different proteins. This suggests that both the level of gene activity and the flexibility in how genes are used might support longer lifespans. Many of these genes were already known to be connected to human longevity, indicating possible shared biological patterns between what influences species-wide lifespan and what affects individual longevity.

The study's findings suggest that both immune system function and brain size play a central role in the evolution of long lifespans, and that the same genetic mechanisms may underlie lifespan differences across species and within humans. These discoveries enhance our understanding of the mechanisms underpinning the aging process and illuminate promising avenues for therapeutic interventions in aging and age-related ailments, including cancer. The reversible nature of epigenetic data opens up new possibilities for future research and potential treatments.