Vol.2, No.10, 1164-1170 (2010) Natural Science
http://dx.doi.org/10.4236/ns.2010.210144
The factorial structure of self-reported
androgen-promoted physiological traits
Lee Ellis1, Shyamal Das2
1University Malaya, Department of Anthropology, Kuala Lumpur, Malaysia;
2Elizabeth City State University, Elizabeth City, USA;
Received 27 June 2010; revised 29 July 2010; accepted 4 August 2010.
ABSTRACT
Androgens make major contributions to aver-
age sex differences in anatomy, physiology, and
behavior. Despite having established their cru-
cial role in sexual differentiation, much remains
to be learned about how androgens coordinate
their influences. The present study was under-
taken to shed light on androgenic effects on the
body using self-reported survey data. We ana-
lyzed the ratings provided by over 11,000 col-
lege students on the magnitude of eleven traits
that previous research has shown to be influ-
enced by testosterone or other androgens. Pre-
dictably, the average values for all eleven traits
were significantly greater in males than in fe-
males. Nevertheless, when data were analyzed
separately according to sex of the respondents,
some of the traits failed to positively correlate
with one another, suggesting that not all an-
drogen-influenced traits differentiate in a simple
fashion. Factor analysis of these eleven traits by
sex reinforced this view by identifying four fac-
tors. In men, the primary factor loaded most
heavily on: masculine body build, masculine
mannerisms, overall physical strength, upper
body strength, and lower body strength. The
primary factor for women was limited to: upper
body strength, lower body strength, and overall
physical strength. In both sexes, the primary
factor was interpreted as reflecting the influ-
ence of perinatal and postpubertal testosterone
exposure. The other three factors may reflect
the effects of other androgens (e.g., andros-
tenediol), or the influence of female hormones
such as estradiol. Findings were discussed in
terms of future use of self-reported physiologi-
cal measures for assessing androgenic effects
on the human body.
Keywords: Androgen-promoted physical traits;
Testosterone; Masculinization; Physical strength;
Factorial structure; Sex differences
1. INTRODUCTION
A recent literature review provided evidence that the
sexes differ in a mired of ways, ranging from easy-to-
measure traits (e.g., birth weights and adult body size) to
many complex characteristics (e.g., susceptibility to nu-
merous diseases, detailed biochemistry, neurology, per-
ceptual sensitivities, motor coordination, and even many
cognitive and behavioral patterns) [1]. This evidence
raises questions about how sex differences are produced.
Although the details are still far from fully understood,
numerous studies have implicated bodily exposure to
androgens as primarily responsible for sex differences in
traits [2-5].
In broad terms, the sexual differentiation of animals
occurs as follows: The default sex at least for mammals,
is female, meaning that males are a genetic variant on
the female sex [6-9]. Early in the gestation process of
nearly all males, the would-be ovaries are made to begin
differentiating into testes instead by genes located on the
Y-chromosome [10]. As this occurs in humans during the
first five months of gestation, the genitals of males
gradually take on a masculine rather than a feminine
appearance [11-12].
The gestational aspects of sexual differentiation are
referred to as its organizational stage, a stage in humans
extending from the first month of gestation into about
the fourth month following birth [13]. The second phase
of sexual differentiation is known as the activational (or
postpubertal) stage. It is marked by the appearance of
so-called secondary sex characteristics, but also includes
enlargement of the penis and testes in males [14-17].
The traits that are masculinized by bodily exposure to
androgens are numerous. They include the following:
 Growth of body hair [18-20]
 Darkening of the iris of the eye [21,22]
 Facial acne [23-25]

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 Darkening of hair color [26,27]
 Increase in height [28-32]
 Lowering of the voice [33-37]
 Increase in upper body strength [15,38,39]
 Increase in lower body strength [40,42]
 Increase in masculine body appearance [43-44]
 Increase in masculine mannerisms [45,46]
Despite the abundant evidence that androgens mascu-
linize many aspects of human development, the details
are still only vaguely understood. The purpose of the
present study was to examine the eleven androgen-in-
fluenced traits listed above using self-ratings, with the
following three questions in mind. First, are all of these
traits in fact sexually dimorphic? Second, within each
sex, how well do the eleven traits correlate with one an-
other? Third, do the within-sex expressions of these
traits cluster together, thereby suggesting that they may
be resulting from a limited number of similar androgenic
regimens?
2. METHODS
As part of a broad-ranging investigation, a standar-
dized questionnaire was completed by a large sample of
college students at twenty United States and two Cana-
dian universities between 1988 and 1998 involving 3,786
males and 7,697 females [47]. Subjects ranged in age
from 18 to 56, with a mean of 22 for both sexes. In terms
of race and ethnicity, the subjects were 85% white, 4%
black, 2% Native American, 2% Asian / Pacific Islander,
1% Hispanic, and 6% providing no answer.
Eight of the androgen-promoted physiological traits
were measured by asking subjects to rate themselves
regarding each trait using a 1 to 100 scale, with 100 rep-
resenting maximum expression of each trait. These eight
traits were: masculine mannerisms, masculine body ap-
pearance, physical strength, low deep voice, upper body
strength, lower body strength, body-hair development,
and facial acne. Height was measured simply in terms of
feet and inches (converted to inches). Eye color and hair
color were measured, first, by asking subjects to give a
one- or two-word description of their eye color and
natural hair color. These descriptions were then inter-
preted and transcribed into four categories. From highest
to lowest values, eye color was coded as being Black,
Brown, Hazel / Green, and Blue. For hair color, the four
categories were Black, Dark Brown, Light Brown, and
Blond. (A copy of the questionnaire is available upon
request)
Analysis was carried out in three stages. First, the
sexes were compared regarding their average scores on
all eleven traits using a t-test. Second, to determine how
well the eleven traits correlated with one another, a cor-
relation matrix was created for the sexes separately.
Third, factorial analysis was performed on the eleven
traits to assess whether or not some of the traits would
form into clusters.
3. RESULTS
Table 1 shows that all eleven androgen-promoted traits
are significantly more pronounced in men than in wo-
men, with p = 0.000 in all cases except for eye color
(which attained significance only at the 0.05 level). This
is entirely predictable, given that the levels of testost-
erone (and other androgens) are higher for males than
for females throughout both the organizational and acti-
vational stages of sexual differentiation ([1], pp. 89-93).
Table 2, however, reveals that within each sex, some
of the androgen-promoted traits are not positively corre-
lated with one another. Such a rather surprising finding
can be interpreted as suggesting that the enhancement of
androgen-promoted traits does not occur through a uni-
tary process. Most notably, the variables of eye color and
especially adolescent facial acne correlate negatively
with many of the other androgen-influenced traits among
both sexes.
The results for factor analyzing responses regarding
the eleven androgen-promoted traits are presented in
Table 3 for each sex separately. Regarding males (Table
3(a)), the first factor to emerge was named masculinity /
strength since it was comprised of masculine manner-
isms, masculine body build, and all three of the physical
strength measures. We named the second factor pigment
because it only loaded strongly on hair color and eye
color. Body hair development and adolescent facial acne
loaded most heavily on the third factor (with some sec-
ondarily strong loadings on upper and lower body
strength), which was named dark pigmentation. Finally,
height and low-deep voice comprised a fourth factor,
which we named physical prowess since both height and
low-deep voice are likely to have evolved primarily to
intimidate rivals (and possibly impress prospective
mates).
Turning to females (Table 3(b)), four factors also
emerged. The first factor had to do with stren g th. Mascu-
line mannerisms and body build loaded along with
low-deep voice onto a second factor; therefore, we called
it female masculinity. The remaining two female factors
were identical to those in males, a dark pigmentation fac-
tor and a skin-hair factor. It is interesting to note that
height loaded heavily on the physical prowess factor in
males but failed to load on any factor among females.
4. CONCLUSIONS
While there is no doubt that androgens play a pivotal
role in differentiating males from females, much remains

L. Ellis et al. / Natural Science 2 (2010) 1164-1170
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Table 1. Descriptive statistics for androgen-promoted physical traits by comparing males with females.
Traits N Mean Std.
Dev
Effect
Size
(d)
Variance
Explained
Std. Error
Mean
t-Test Results for
Equality of Means
Masculine Mannerisms
Female
Male
7,456
3,757
21.84
74.88
21.89
74.88
2.59 0.62 0.254
0.309
132.748***
Masculine Body Appearance
Female
Male
7,447
3,767
12.90
76.82
19.27
19.29
3.32 0.74 0.223
0.314
165.808***
Physical Strength
Female
Male
7,697
3,786
60.48
70.00
18.89
17.72
0.52 0.06 0.215
0.288
26.473***
Height
Female
Male
6,655
3,282
65.15
70.88
2.70
2.88
2.05 0.51 0.033
0.050
95.150***
Low Deep Voice
Female
Male
6,540
3,217
21.22
54.98
24.84
23.92
1.38 0.32 0.307
0.422
64.699***
Upper Body Strength
Female
Male
5,016
2,483
52.46
61.57
22.12
22.23
0.41 0.04 0.314
0.446
16.698***
Lower Body Strength
Female
Male
5,834
2,827
57.91
65.72
21.19
21.01
0.38 0.03 0.279
0.395
16.136***
Body-Hair Development
Female
Male
5,806
2,828
46.56
52.06
21.64
23.96
0.24 0.01 0.285
0.451
10.304***
Facial Acne
Female
Male
5,793
2,816
29.88
34.39
25.73
25.42
0.17
0.008 0.338
0.479
7.699***
Hair Color
Female
Male
6,399
3,128
2.47
2.68
1.01
0.99
0.21
0.01 0.013
0.018
9.762***
Eye Color
Female
Male
3,881
2,002
1.84
1.89
0.90
0.92
0.05
0.003 0.014
0.021
2.249*
Notes: p < 0.001 = ***, p < 0.01 = **, and p < 0.05 = *; d = Cohen’s d
Table 2. Inter-correlation matrix for androgen-promoted traits by sex. The coefficients for males (bolded) appear in the upper right
quadrant; those for females (italicized) are in the lower left quadrant (the sample sizes used in calculating each correlation are repre-
sented in parentheses).
Masculine
Mannerism
Masculine
Body
Build
Physical
Strength
Height
in
inches
Low-
Deep
Voice
Upper
Body
Stre ng th
Lower
Body
Stre ng th
Body
Hair
Facial
Acne
Hair-
color
Eye-
color
Masculine
Manner-
isms
1 0.737**
(3,751)
0.464**
(3,756)
0.053**
(3,246)
0.190**
(3,193)
0.326**
(2,458)
0.285**
(2,804)
0.129**
(2,813)
–0.121**
(2,794)
0.026
(3,100)
0.062**
(1,980)
Masculine
Body
Build
0.676**
(7,423) 1 0.550** (3,766)
0.062**
(3,255)
0.206**
(3,201)
0.398**
(2,468)
0.327**
(2,812)
0.149**
(2,813)
–0.098**
(2,802)
0.029
(3,108)
0.065**
(1,987)
Physical
Strength
0.194**
(7,447)
0.158**
(7,436) 1 0.052** (3,273)
0.215**
(3,216)
0.563**
(2,478)
0.390**
(2,822)
0.102**
(2,823)
–0.123**
(2,812)
0.007
(3,125)
0.049**
(2,001)
Height in
inches
0.087**
(6,394)
0.089**
(6,384)
0.096**
(6,629) 1 0.131** (2,738)
0.036
(2,381)
0.039
(2,375)
0.005
(2,376)
–0.014
(2,364)
–134**
(2,707)
–0.076 **
(1,949)
Low-
Deep
Voice
0.314**
(6,332)
0.284**
(6,321)
0.144**
(6,528)
0.087**
(5,496) 1 0.184** (2,470)
0.152**
(2,815)
0.149**
(2,816)
0.012
(2,806)
0.014
(3,115)
0.058**
(1,994)
Upper
Body
Strength
0.172**
(4,814)
0.140**
(4,806)
0.476**
(5,006)
0.063**
(4,844)
0.130**
(4,961) 1 0.588**
(2,477)
0.288**
(2,475)
–0.030
(2,463)
0.007
(2,408)
0.060*
(1,704)
Lower
Body
Strength
0.170**
(5,632)
0.100**
(5,624)
0.401**
(5,824)
0.083**
(4,837)
0.113**
(5,783)
0.648**
(5,002) 1 0.282** (2,823)
–0.008
(2,811)
0.014
(2,741)
0.033
(1,700)
Body Hair 0.073**
(5,607)
0.060**
(5,597)
0.049**
(5,796)
-0.019
(4,808)
0.086**
(5,756)
0.266**
(4,969)
0.279**
(5,791)1 0.066** (2,811)
0.058**
(2,742)
0.035
(1,701)

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Facial
Acne
0.080**
(5,592)
0.046**
(5,585)
–0.026*
(5,783)
0.016
(4,796)
0.052**
(5,743)
0.082**
(4,947)
0.089**
(5,772)
0.211**
(5,745) 1 –0.015 (2,730)
–0.073* *
(1,693)
Hair-
color
–0.039**
(6,153)
–0.021
(6,141)
–0.028*
(6,382)
–0.075**
(5,489)
0.022
(6,331)
–0.035*
(4,858)
– 0.040*
*
(5,663)
0.081**
(5,636)
–0.028*
(5,622) 1 0.440** (1,998)
Eye-
color
–0.023
(,3739)
0.001
(3,731)
–0.008
(3,871)
–0.085**
(3,824)
0.017
(3,847)
–0.014
(3,298)
–0.010
(3,297)
0.052**
(3,277)
–0.017
(3,267)
0.442**
(3,880)1
Note: * p < 0.05; ** p < 0.01
Table 3(a). Factor Loadings for Androgen-Promoted Traits for Males.
Items Factor 1 Factor 2 Factor 3 Factor 4
Masculine Mannerism 0.806 –0.001 –0.125 0.056
Masculine Body Build 0.845 0.011 –0.064 0.071
Height 0.002 –0.158 –0.145 0.835
Low Deep Voice 0.178 0.157 0.290 0.633
Overall Physical Strength 0.780 0.059 0.043 0.082
Upper Body Strength 0.679 0.046 0.445 0.026
Lower Body Strength 0.592 0.023 0.481 0.028
Body Hair 0.172 0.081 0.692 0.066
Facial Acne –0.263 –0.154 0.566 –0.022
Hair Color 0.004 0.832 0.018 –0.064
Eye Color 0.046 0.829 –0.042 0.036
Table 3(b). Factor Loadings for Androgen-Promoted Traits for Females.
Items Factor 1 Factor 2 Factor 3 Factor 4
Masculine Mannerism 0.091 0.856 –0.057 0.050
Masculine Body Build 0.025 0.860 –0.015 0.000
Height 0.132 0.206 –0.212 –0.254
Low Deep Voice 0.119 0.589 0.063 0.017
Overall Physical Strength 0.746 0.164 –0.012 –0.216
Upper Body Strength 0.858 0.096 –0.024 0.134
Lower Body Strength 0.825 0.047 –0.013 0.195
Body Hair 0.299 0.017 0.123 0.677
Facial Acne –0.054 0.101 –0.121 0.775
Hair Color 0.004 0.002 0.835 0.009
Eye Color –0.010 0.028 0.830 0.003
to be learned about which androgens are involved in
particular traits and when they have their greatest influ-
ences. The present study sheds light on the process by
suggesting that in both sexes, four independent factors
emerge when eleven androgen-promoted physiological
traits are measured. The structures of these four factors
are slightly different for males and for females.
In males, the primary factor loads most heavily on
masculinity and strength, whereas in females, the load-
ing is strictly on strength. We hypothesize that in both
sexes this primary factor is the result of perinatal and
postpubertal exposure to testosterone. This hypothesis is
consistent with studies showing that testosterone is by
far the most consequential sex hormone regarding both
masculine mannerisms [46] and muscular strength [15,
41]. To explain why mannerisms in females would not
be masculinized by testosterone, we suspect that the lev-
els of this hormone to which most females are exposed

L. Ellis et al. / Natural Science 2 (2010) 1164-1170
1168
are insufficient to significantly affect this trait while
muscular strength responds to even low amounts of tes-
tosterone. Another possibility is that high (female-typical)
exposure to estradiol or other female hormones may
counteract the effects of testosterone on masculine man-
nerisms.
The fact that the same factors for the dark pigmenta-
tion factor and the skin-hair factor emerged in both sexes
suggests that these traits are a) the result of androgens
other than testosterone, and b) that the androgen(s) pri-
marily responsible for hair growth and facial acne is
different from those influencing hair and eye color.
Regarding the three questions posed in the introduc-
tion, one can conclude the following: First, all eleven
traits that other studies have shown to be androgen-
promoted are, as expected, more pronounced in males
than in females. Second, within each sex, most of the
eleven traits are positively correlated. The fact that there
are exceptions leads one to expect that different andro-
gens are operating in somewhat different ways within
each sex. Third, factor analysis supports this expectation
by demonstrating that there are four clusters of andro-
gen-promoted traits amongst the eleven traits examined
in the present study. We named these four factors and
hypothesized that testosterone is responsible for the first
(and most prominent) factor for both sexes. In males,
this primary factor involved both strength and masculine
mannerisms, while in females it only involved strength.
Research is needed to verify these four factors and to
look for other androgen-promoted traits within each sex.
In future studies, direct measurement would almost cer-
tainly provide more reliable data than self-reports. How-
ever, the time required for obtaining direct measures
with a sufficiently large sample of subjects needed for
factor analysis could be prohibitive. It can also be said
that the extent to which people can provide accurate in-
formation about themselves may surpass expectations. In
this regard, we compared the average heights of our
subjects to estimates recently given by the Center for
Disease Control based on direct measurements [48]. The
results were very similar: 70.88 inches or 5’9.1” tall in
our male sample compared to 5’9.2” for the national
sample, and 65.15 inches or 5’4.3” tall in our female
sample compared to 5’3.8” for the national sample.
If the four factor structure of androgen-promoted traits
revealed in the present study can be replicated, the next
phase in this line of research would be to identify each
of their specific causes. In other words, what are the ac-
tual androgens involved in producing each factor and
what is the developmental timing involved?
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