Xenohormesis explains how certain molecules such as plant polyphenol

Polyphenol

Polyphenols are a structural class of natural, synthetic, and semisynthetic organic chemicals characterized by the presence of large multiples of phenol structural units...

s, which indicate stress

Stress (biology)

Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...

 in the plants, can have a longevity-conferring effect in consumers of plant (i.e. mammals). It was first used in the paper "Small molecules that regulate lifespan: evidence for xenohormesis." by Dr. David Sinclair

David Sinclair (biologist)

David A. Sinclair PhD is a biologist best known for his research on the biology of lifespan extension and driving research towards treating diseases of ageing.-Current position:...

 and colleagues from Harvard Medical School. Further studies then picked up the term.

If the plants an animal is eating are under stress, their increased polyphenol content may signal forthcoming famine

Famine

A famine is a widespread scarcity of food, caused by several factors including crop failure, overpopulation, or government policies. This phenomenon is usually accompanied or followed by regional malnutrition, starvation, epidemic, and increased mortality. Every continent in the world has...

 conditions. It could be advantageous for the animal to begin to react—i.e. to hunker down to prepare for the lean times to come. The effects researchers have observed from resveratrol

Resveratrol

Resveratrol is a stilbenoid, a type of natural phenol, and a phytoalexin produced naturally by several plants when under attack by pathogens such as bacteria or fungi....

may be just such a response.