Skeptic March 2020

ing functionally useful conscious discriminations
(e.g., redness or roughness) and evaluative feelings
(e.g., beauty or bitterness) will continually both refine
and enhance these attributes and, at the same time,
modify the neural structures and processes that gen-
erate these experiences.
If we look inside the engine of a car we are not
going to find an emergent property like acceleration,
because it only exists as an extrinsic property that de-
pends on the coordinated interactions of many spa-
tially distributed parts. However, this coordination
requires a precise timing signal so that fuel injections,
electrical sparks, etc. occur at the precise time that
each piston reaches its top dead center position.
These observations are also true for the emergent
properties of a biological brain. We are not going to
find a conscious experience like beauty in a brain, but
we should expect to find a temporal mechanism that
coordinates the neural activity and binds together the
distributed processes that ultimately evoke this evalu-
ative experience in a human’s mind. But before ex-
amining this neural response we need to establish
that physical beauty is indeed a functionally useful
feeling that enhances reproductive success.
Although physical beauty appears to be a minor
factor in human mate selection, it plays a major role in
other sexually reproducing species. Testosterone me-
diated mating dances, melodic songs, and displays of
brightly colored iridescent tails are some of the lures
employed by males to seduce members of the opposite
sex. Hormone mediated fertility signals such as chest
blisters, labial swelling, or face reddening are common
enticements displayed by other female primates. Fe-
males use such signals to attract males, and those
males who are attracted by such cues certainly enjoy
reproductive benefits. What do human males find at-
tractive in females? To address this question male
students were asked to generate their most beautiful
female face using a computer-simulated evolution
(a genetic algorithm). By rating female faces (pheno-
types) generated from binary strings (genotypes) that
crossed over and mutated between generations, the
male students evolved attractive facial composites that
were consistently different from the average female
face (Figure 1). Specifically, the attractive female face
had larger lips and eyes and a shorter, narrower chin
than the average. Like other female primates, these at-
tractive features have a hormonal origin.
Young boys and girls enter puberty with almost
identical proportions of muscle, fat, and bone, but
they rapidly mature into reproductive adults with
very different body shapes and compositions. These
anatomical changes are, to a large degree, controlled

by steroid hormone levels. Under the influence of es-

trogens, a young woman gains about 35 pounds of fat,

changing the size and shape of her breasts, hips,

thighs, and lips. In contrast, a young man acquires

about one and half times as much muscle and bone

mass, regulated by the complex action of androgens

(and aromatized androgens) acting both directly and

indirectly (through release of growth hormone) on

bone and muscle tissues. As a result, the adult male’s

face has a longer and broader lower jaw than that of a

female, and the growth of brow ridges results in more

sunken narrow eyes. From this hormonal perspective,

attractive female faces are displaying physical features

indicative of higher than average levels of pubertal es-

trogens (full lips) and lower levels of androgen expo-

sure (short narrow chin and large eyes).

In artificial insemination studies (to control for

sperm quality), this combination of hormones has

volume 25 number 1 2020 W W W. S K E P T I C. C O M 1 9

Figure 1. Differences between attractive (At) and average (Av) female

faces.

Figure 2. Attractive male and attractive female faces.