For the social security law, old age is a critical concept, since social security systems organize around it old age insurance aimed at protecting persons referred to as “older people” or “senior citizens”. Nevertheless, who are these “older people”, “senior citizens” according to old age insurance? What is considered as old age? is it a social old age? a biological one? a psychological one? a professional one? Without a doubt, social conventions as well as biology could provide answers to these questions.