Figure 1. Scored facial redness in the scale on aging-related health and functioning. Perceived age was rated by darkness of facial redness on the present scale on aging-related health and functioning in rhesus macaques. Representative animals scored 1, 2 and 3 are shown in A, B and C, respectively. Reduced aging-related health and functioning was supposed to be in parallel to the increased darkness of facial redness. The high interrelationship of items in the scale indicated both convergent and discriminate validity.