Whenever centenarians are studied, there must be a process in place to verify their reported age. In the 1960s and 1970s there were many reports of extremely long-lived populations in a number of places, including Georgia in the Caucasus and Vilcabamba, Ecuador. Some individuals claimed to be up to 180 years old. When these claims were investigated in further detail, proof of age was not available. Detailed life histories, with discussion of historical events in relationship to what age the person was at that time, were inconsistent. Dr. Thomas Perls, a geriatrician at Harvard University, and colleagues developed a rigorous age verification protocol for use in the New England Centenarian Study. They prefer a birth or baptismal certificate, or if these are not available, a passport or military certificate issued many years before. Other records, such as a family Bible, are also acceptable. Multiple supporting documents are preferred over a single document.
The longest proven life span for a human is 122 years, for Jeanne Calment, a woman who died in Arles, France, in 1997. Her age was carefully validated. She was a model of health most of her life, and lived alone until the age of 110. The longest verified life span for a male was that of Christian Mortensen, a Danish man who emigrated to the United States; he died in 1998 at the age of 115.