Why can cats last up to 20 years, while dogs of similar size usually live only 12-15? What allows dolphins to survive for decades, while similar-sized mammals may only have a fraction of their time?
A study published in a scientific report found compelling evidence that longer-lived mammals have key genomic adaptability, especially among immune-related gene families. This study provides new insights on how evolution affects the lifespan of different species, which may ultimately help us better understand human lifespan and diseases related to aging.
An international team led by researchers at the University of Bath analyzed the genomes of 46 mammalian species with different lifespans to identify patterns in the evolution of the gene family. Their findings suggest that longer-lived mammals undergo significant expansion in gene families related to immune system function—a link that remains even considering differences in body size, pregnancy time, and sexual maturity age.
Brain size and lifespan: a shared evolutionary path
The study confirmed a good relationship between brain size (relative to body weight) and maximum lifespan potential, with large brain species generally living longer. This connection seems to be driven by a common fundamental genetic mechanism rather than just a coincidence of correlations.
“It is well known that relative brain size is related to lifespan – these two traits share a common evolutionary path, and having a larger brain may lead to behavioral advantages,” explains Dr. Benjamin Padilla-Morales.
However, this relationship is not universal. Some species like naked moles and bats live significantly longer than their brain size predicts. When the researchers examined these exceptions, they found that the animals also expanded the gene family associated with immunity, indicating a variety of evolutionary pathways for lifespan.
The amazing role of immune system genes
Perhaps the most important finding is consistent enrichment of immune system genes in species with the longest and longer life spans. The researchers identified 236 gene families that were significantly positively correlated with lifespan across mammals, many of which involved immune functions, such as:
- Defense response mechanisms that help organisms fight infections
- Adaptive immune response process that allows targeted defenses against specific threats
- Antigen processing and demonstration systems that help identify potential hazards
- Regulation of inflammatory response, balanced defense and tissue protection
- DNA repair mechanisms that maintain cell integrity over time
“However, our study also highlights the surprising role that the immune system plays not only in fighting disease, but also in supporting longer lifespans in mammalian evolution,” said Dr. Padilla-Morales. “This suggests that brain size and immune resilience seem to be moving side by side in the evolution towards longer lifespans.”
Beyond all genes: the expansion of the entire household
This study is particularly valuable because its focus is on gene family expansion—the evolutionary process in which certain related genes increase the number of repetitive events. Instead of studying individual mutations, the researchers studied the growth or shrinkage of the entire gene family during the evolutionary period.
The findings challenge the simple view of longevity evolution and show that wider genomic changes play a crucial role in extending mammals’ lifespan. As species develop longer lifespans, they appear to expand immune system function through gene replication.
This pattern has evolutionary significance – long-lived organisms must maintain their bodies for a long time, requiring stronger mechanisms to remove damaged cells, control infections and prevent cancer. The expanded family of immune genes may provide enhanced surveillance systems that maintain tissue health over decades rather than years.
Impact on human health and aging
Although the study focuses on evolutionary patterns of various species, these findings have potential implications for understanding human aging and disease. Long-lived species are consistent with our understanding of human aging enriches the immune system and DNA repair genes, in which case decreases in immune function and accumulated DNA damage contribute to age-related conditions.
Will these insights ultimately lead to interventions that promote healthy aging? This study provides important clues about which biological systems are most important for sustaining them for decades. Understanding how different mammals develop longer life spans may help identify key mechanisms worth targeting human medicine.
What explains why mammals like whales can live for more than a century, while other mammals of similar human sizes live much shorter? The precise balance of brain development, immune function, and other adaptations seems to be the answer. As researchers continue to unravel these connections, we gain a richer understanding of how evolution shapes one of the most basic characteristics of life, its duration.
The team now plans to study cancer-related genes highlighted in their research to further understand the relationship between these genes and lifespan differences between mammals. Their ongoing work may ultimately help explain why some species last for life, despite their longevity – a conundrum of potential impacts on human health.
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