Snakes are known for their ability to survive for months without eating, a fact that has intrigued scientists around the world for decades. The new international study led by researchers CIIMAR and the Faculty of Sciences of the University of Porto reveals that this extraordinary feat may be linked to the evolutionary loss of a key hormone that regulates hunger.

The team’s work, published in Royal Society Open Biology and highlighted by Science journal, shows that snakes have lost the gene responsible for producing ghrelin, a hormone that, in most vertebrates, stimulates appetite and helps control energy metabolism. This genetic change appears to have enabled a profound physiological reorganisation that favours the storage and efficient use of energy, allowing these reptiles to survive for months without feeding.

“This study demonstrates how evolution can produce radical adaptations not only through the emergence of new genes, but also through the strategic loss of old functions,” explains Rui Pinto, a researcher at CIIMAR and PhD student in Biology at the Faculty of Sciences of the University of Porto (FCUP). “By losing ghrelin, snakes seem to have developed alternative mechanisms to control appetite and manage energy reserves, becoming true experts in surviving long periods of food scarcity,” adds the researcher, who is involved in the field of metabolic evolution and is the first author of this study.

For scientists, this discovery helps to better understand how vertebrates can adapt to extreme and unpredictable environments, where food availability is irregular.

Filipe Castro, leader of the Animal Genetics and Evolution research group at CIIMAR and professor at FCUP, highlights the broader impact of the discovery. “This work reinforces a fundamental idea in evolutionary biology: losing genes can be as important as gaining new ones. Snakes show us how evolution can profoundly reconfigure complex physiological systems, opening up new perspectives for understanding energy metabolism and even human diseases related to appetite and metabolism control.”

The researchers emphasise that understanding these natural mechanisms may, in the future, contribute to new approaches in the study of obesity, diabetes and other metabolic disorders.