The fact that people age and die has always stimulated extensive philosophical and medical investigations in all societies. The early theories of ageing that arose in ancient Greece and revived in the Middle Age saw old age as a consequence of the gradual consumption of the innate heat with the inevitable loss of body moisture, according to Hippocrates’ system of four‐humours (fifth century BC). The idea that senescence was itself an illness, the image of the aged body as a lamp in which life‐fuel has run out, the character alterations of elders, the attempt to prolong life through specific diet or by substituting damaged body parts were the main themes around which research into ageing and senescence revolved from the Renaissance to the eighteenth century. The fresh tools provided by evolutionary theory and molecular biology have opened new vistas, sometimes retrieving old conceptions, of the intimate mechanisms underlying the recent prolongation of life expectancy.

Key Concepts:

• Early speculations on ageing were focussed on the bodily humoural imbalance and on the gradual loss of inner heat.
  
• Rejuvenating or stopping the ageing process was a major concerns of Medieval and Renaissance medicine.
  
• Prolonging human lifespan through specific dietetic regimens was a long running theme in the history of gerontology.
  
• Evolutionary approaches and molecular disciplines gave a new impetus to the researches into ageing.
  
• No more considered itself a disease, senescence is nowadays sees as a successful form of remodelling and adaptation to a lifelong series stressors.
  
• In the past decades, ageing researches have concentrated their efforts in four major directions: cellular theories, immune‐metabolic models, evolutionary explanations and molecular biology‐based approaches.