New Research Has Uncovered Why Cats Live Longer Than Dogs

According to a recent study, dogs’ shorter lifespan compared with cats may be linked to brain size and the immune system.

advertisement

An international research team led by University of Bath examined evolutionary differences among mammal species and found that species with larger brains and longer lifespans invest more heavily in genes associated with the immune system. The results suggest that longevity is shaped not by individual genes but by broader genomic changes.

Ageing in mammals is regulated, among other things, by brain size and immune system function

This Is What the Research Found About Mammalian Lifespans

Lifespan is not simply a function of body size or environmental influences. Rather, it is the result of complex interactions involving brain size, metabolic regulation, the immune system, and ageing processes. The researchers examined the maximum lifespan potential (MLSP) of 46 mammal species and mapped the genes shared among them. Maximum lifespan potential (MLSP) refers to the longest lifespan ever observed in a given species, rather than average lifespan, which is influenced by factors such as the presence of predators and the availability of food and other resources.

According to the study published in Scientific Reports, genes belonging to immune-system-related gene families are present in greater numbers in longer-lived species. This suggests that the immune system may be a key driving force behind the evolution of longevity in mammals. For example, dolphins and whales – which possess relatively large brains – have maximum lifespans of around 39 years and up to 100 years respectively, while small-brained animals such as mice live only 1–2 years. Larger brains generally require more metabolic energy, but they also provide advantages such as enhanced problem-solving and adaptability, stronger social structures and stress tolerance, and a greater ability to avoid predators and environmental dangers.

However, there were exceptions to this pattern, such as naked mole-rats, which can live for up to 20 years despite their small brains. Bats also live longer than expected relative to their brain size. Brain size alone therefore does not fully explain lifespan, which is why researchers are investigating other biological systems as well. Analysis of species’ genomes revealed that both groups contained greater numbers of immune-system-related genes. In other words, longer-lived species consistently carry more genes associated with immune functions. The findings suggest that the immune system plays a central role in maintaining long life, probably by removing ageing and damaged cells, controlling infections, and preventing tumour formation.

Why Dogs Live Shorter Lives Than Cats

Although the study did not directly compare dogs and cats, the difference in their lifespans fits well within broader evolutionary patterns observed among mammals. Domestic cats generally live longer than dogs, both in terms of average lifespan and maximum lifespan potential (MLSP). Cats typically live between 12 and 18 years, with some reaching their twenties, whereas dogs live on average 10–13 years, although this depends heavily on body size and breed.

Cats have a higher brain-to-body ratio than most dog breeds, which among mammals is often associated with greater longevity. Their evolutionary history as solitary, opportunistic hunters likely promoted greater neurological efficiency and behavioural adaptability.

Beyond this, cats’ immune systems also demonstrate remarkable resilience. They have lower rates of certain age-related cancers than dogs, their immune responses to infections are more effective, and chronic inflammatory processes progress more slowly in them. These patterns further support the hypothesis that investment in the immune system is a key factor in long life.

The Research Could Play a Major Role in Cancer Prevention and Treatment

An efficient immune system not only protects against pathogens but also suppresses tumour formation by recognising and eliminating abnormal cells. Researchers identified expansions in immune- and cancer-related genes among long-lived species, prompting further investigation into how these genes influence ageing and disease development.

Species with larger brains do not live longer solely for environmental reasons; their genomes also show parallel expansion of genes associated with survival and maintenance. This indicates that brain size and immune-system resilience likely evolved together along the evolutionary pathway towards longer lifespans.

advertisement