In our daily lives, we constantly interact with people. We maintain relationships with families and friends. We collaborate with colleagues. We seek passion with our lovers and avoid conflicts with our enemies. How we divide the world into these and many other categories of people is initially guided by our first impressions of how they look and sound. Many times we are surprised when we hear someone on the phone whom we have not yet met face-to face; they sound different from what we imagined. There are, however, many things that we are not surprised about in such situations. People are accurate at identifying sex, health, emotions, and age by both voices and faces. [3][4][5][6][7][8][9][10][11][12] There is good evidence that many seemingly disparate ornaments such as body and face, 13 body and voice, [14][15][16] and face and odor 19 may convey either backup signals of the same underlying quality 20,21 or convey signals of different underlying qualities that are used in conjunction to provide a more robust view of the organism's overall fitness. 22,23 Is this also true of face and voices? Until recently, little attention has been given to the idea that people's faces and voices might both signal the same underlying qualities related to hormone levels, and that we might use these hormonal fitness markers to provide a better picture of the signaler's overall mate value. 20,21,24 In this paper I first argue that aspects of voices and faces can be used as markers of hormonal status. Second, I argue that both vocal and facial features associated with hormonal status are used by people to assess mate quality.
HORMONAL SIGNALS OF MATE QUALITYSexually dimorphic body features, or ornaments, that are enhanced by testosterone are candidate signals of male mate quality for two main reasons. First, dominant men most often have higher testosterone levels and higher reproductive success than subordinate men do. 25,26 Second, testosterone has been implicated as a handicapping hormone (Box 1), providing not only suppressed immune function, 18 but a tendency to participate in risky physical and sexual behavior.16 Given these points, we might predict that men displaying large ornaments, indicative of high testosterone, might be displaying their dominance and resistance to infectious diseases, both of which are qualities to be sought after by mates among most social species.
27Ornaments that are positively related to estrogen levels are candidate signals of female mate quality because it has been demonstrated that estrogen, within the normal range, positively predicts various measures of women's ability to become fertilized. 28,29 Thus, men may find women with traits indicating relatively high estrogen levels to be the most attractive.The first question addressed here is whether or not men's and women's faces and voices signal testosterone and estrogen levels, respectively. It has long been known that castrating a boy before puberty will stifle a surge of testosterone at puberty, inhibiting the male-typical pubertal drop in voice...