Why do cats outlive dogs? Clues found in their genes

Why do cats often outlast dogs? The answer may lie deep within their genes. Scientists from the University of Bath explored evolutionary patterns in mammals, uncovering how brain size and immune system complexity might hold the key to extended lifespans.

Unlike earlier studies that focused on single genes, this research highlights broader genomic changes that shape longevity.

Bigger brains, immune genes and lifespan

The researchers examined the maximum lifespan potential (MLSP) of 46 mammal species.

They focused on the longest recorded life span in each species, eliminating factors like predation, food scarcity, and environmental stress. This approach offered a clearer view of genetic influences on longevity.

The team found that mammals with larger brains and longer lifespans carried more immune-related genes. Dolphins, with their complex cognitive abilities, can live up to 39 years. Whales, boasting even larger brains, can reach a remarkable 100 years.

Meanwhile, mice, with much smaller brains, rarely live beyond two years. This pattern reinforces the link between cognitive complexity, immune resilience, and extended life.

Immune genes expand to boost lifespan

The researchers identified gene family size expansion as a significant predictor of MLSP in mammals.

They analyzed 4,136 gene families and discovered 236 that showed positive correlations with longevity. Most of these expanding gene families contained immune system genes, highlighting the immune system’s central role in regulating lifespan.

Body mass did not significantly impact gene family expansion. Instead, relative brain size emerged as the primary factor.

The findings suggest that cognitive development and immune resilience may share an evolutionary path, linking brain complexity with immune function in the quest for longer life.

Some small-brained animals live longer

Not all species followed the big brain-long life pattern. Mole rats, despite their small brains, can live up to 20 years. Bats, known for their small brain size, also exhibit extended lifespans. Researchers found that both species carried an unusually high number of immune-related genes.

This discovery raises intriguing questions: Can immune complexity offset cognitive limitations in extending lifespan?

The data indicate that while a large brain often correlates with longevity, a sophisticated immune system might offer a different route to a longer life.

Immune system: The guardian of longevity

The study reveals the immune system’s crucial role in promoting longevity. By removing aging cells, managing infections, and preventing tumor growth, immune-related genes act as protectors against aging’s damaging effects.

“It’s been known for a while that relative brain size is correlated to longevity – the two characteristics have a shared evolutionary path, and having a larger brain potentially offers behavioural advantages,” noted Dr. Benjamin Padilla-Morales from the Milner Centre for Evolution.

”However, our study also highlights the surprising role of the immune system not just in fighting disease, but in supporting longer life across mammalian evolution.”

Gene splicing enhances lifespan potential

MLSP-associated genes in humans exhibited higher gene expression and increased alternative splicing. This mechanism allows a single gene to produce multiple proteins, effectively expanding its functional repertoire.

Why does this matter? In the context of aging, alternative splicing may offer an adaptive advantage. It enables cells to respond more effectively to stress, repair damage, and maintain tissue integrity.

The findings suggest that evolutionary pressure not only favors more immune-related genes but also promotes genes capable of producing diverse proteins.

A lifespan advantage for some animals

While immune genes dominated the findings, brain size remained a critical factor in determining lifespan.

Researchers noted that species with larger brains showed both higher gene expression and more extensive gene family expansions. This pattern suggests that cognitive development and longevity share a genetic foundation.

Dolphins, for example, exhibit both advanced cognitive abilities and long lifespans, living up to 39 years. Elephants, with their complex social structures and memory capabilities, can live even longer. These examples illustrate a broader evolutionary trend: cognitive complexity and life extension often go hand-in-hand.

DNA repair: Key longevity mechanism

While immune genes captured the spotlight, researchers also identified significant links between MLSP and DNA repair genes. Species with extended lifespans, such as whales and elephants, exhibited notable expansions in gene families related to DNA repair.

The researchers also found that DNA repair genes exhibited higher levels of alternative splicing.

This dual mechanism – gene family expansion and transcript diversification – may provide a multi-layered defense against cellular damage, preserving tissue function over longer lifespans.

Cancer resistance: The next frontier

The research team plans to investigate cancer-related genes further. They aim to uncover how specific genes contribute to both longevity and cancer resistance.

By analyzing long-lived species like whales and bats, researchers hope to pinpoint genetic targets that might help mitigate cancer risk in humans.

Evolution, immune genes, and longevity

The study reveals a complex evolutionary narrative. Longevity in mammals appears to hinge not only on brain size but also on immune system complexity.

Gene family expansions, especially in immune-related genes, suggest that natural selection may have prioritized immune resilience as a critical component of extended lifespan.

The researchers propose that further exploration of cancer-related genes and DNA repair pathways may offer deeper insights into how some species achieve exceptional longevity.

The implications extend beyond the animal kingdom, opening potential avenues for aging research in humans.

The study is published in the journal Scientific Reports.

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