Have you ever wondered why cats tend to live longer than dogs, or why whales can live for over a century while mice barely make it past two years?
New research led by scientists from the University of Bath suggests the answer may lie in their brains and immune systems.
The study, published in Scientific Reports, found that mammals with larger brains and stronger immune systems tend to live longer.
The researchers looked at 46 different species of mammals, comparing their maximum lifespan potential (MLSP)—the longest recorded lifespan for each species. They found that animals with bigger brains generally lived longer.
Dolphins, for example, can live up to 39 years, while whales can reach an impressive 100 years. In contrast, smaller-brained animals like mice only live one or two years.
The scientists believe that a larger brain offers more behavioral advantages, such as better problem-solving and adaptability, which can help these animals survive longer.
But brain size isn’t the only factor. The researchers discovered that the immune system plays a crucial role in longevity too.
When they studied the genes of these mammals, they found that species with longer lifespans had more genes related to immune function.
This suggests that a strong immune system helps keep these animals healthier for longer by removing aging cells, fighting off infections, and preventing diseases like cancer.
Interestingly, there were some exceptions to this pattern. Mole rats and bats, for example, live much longer than expected given their small brain sizes. Mole rats can live up to 20 years, and bats can survive for decades.
The researchers found that despite their small brains, these animals had stronger immune-related genes, which might explain their unexpected longevity.
Dr. Benjamin Padilla-Morales, the lead author of the study from the Milner Center for Evolution, explained that while it’s been known for some time that bigger brains are linked to longer lives, this study also highlights the surprising importance of the immune system. It’s not just about fighting off diseases; the immune system also seems to help maintain the body and slow down aging.
The study also points out that it’s not just small genetic changes that matter; large-scale genomic shifts, like the duplication of entire gene families, seem to drive this longevity. The team now plans to explore cancer-related genes to understand even more about why some mammals live so much longer than others.
This research opens up new ways of understanding how evolution shapes lifespan in mammals, suggesting that both brain size and immune resilience work together to support longer, healthier lives.
