Membrane pacemaker theory

Impact: New theory explaining the different, but distinctive, maximum life spans of different species

A research collaboration centred on investigating the reason for differences in the process of ageing between species that began over 30 years ago continues to build understanding of health and longevity and inspire researchers today.

In 1979, Tony Hulbert and his Honours student, Paul Else, wanted to discover processes responsible for very different rates of energy use by animals and later their different rates of ageing.

Their research compared reptiles, from lizards to crocodiles, and mammals, from mice to cows, as examples of low and high energy systems.

Later, it examined the body-size related variation in the pace of metabolism and duration of life of different species. It involved detailed study of the powerhouses of the cell (mitochondria) as well as events occurring across the membranes of cells.

A key finding was that high-energy animals, such as mammals, had ‘leakier’ cells and ‘faster’ membrane pumps. These differences were associated with more polyunsaturated fats in the membranes of ‘high-energy’ animals.

In a key publication in 1999, their findings were synthesised into a theory named the ‘membrane pacemaker theory’. This theory, the researchers believed, could also explain the vastly different but distinctive maximum lifespans of different species, which has become a major focus of their research.

These long-term studies have produced work now cited in key international textbooks, garnered around 3000 scientific citations and featured across popular science media. They also have significant implications for the contemporary study of several diet-related modern diseases.