Buss attributed the male preference for younger females to certain youthful cues. In females, relative youth and apparent physical attractiveness (which males valued more compared to females) demonstrated cues for fertility and high reproductive capacity.[1] Buss stated the specific age preference of around 25 years implied that fertility was a stronger ultimate cause of mate preference than reproductive value as data suggested that fertility peaks in females around mid-20s.[38] From a life history theory perspective, females that display these cues are judged to be more capable of reproductive investment.[41] This notion of age preference due to peak fertility is supported by Kenrick, Keefe, Gabrielidis, and Cornelius's study, which found that although teenage males would accept a mate slightly younger than they are, there was a wider range of preference for ages above their own. Teenage males also report that their ideal mates would be several years older than they are.[42]