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Thorarche—a seasonal influence but no secular trend R. J. Levin
a
a
Department of Physiology , University of Sheffield , Sheffield, S 10 2TN, England Published online: 11 Jan 2010.
To cite this article: R. J. Levin (1976) Thorarche—a seasonal influence but no secular trend, The Journal of Sex Research, 12:3, 173-179, DOI: 10.1080/00224497609550936 To link to this article: http://dx.doi.org/10.1080/00224497609550936
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution,
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-andconditions
The Journal of Sex Research Vol. 12, No. 3, pp. 173-179 August, 1976
Thorarche—a Seasonal Influence But No Secular Trend
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
R. J. LEVIN* The term 'thorarche' is proposed for the first seminal ejaculation in boys. A retrospective study on thorarche with 142 male, undergraduates (aged 18-21 years) indicated that 80.3% remembered their thorarche. Less than a third had had any instruction about its occurrence compared to the 91.7% of 133 female undergraduates who were instructed about menarche. The cause of thorarche for 92.4% was sexual, it occurred in sleep for only 25.6%. Approximately 43% felt thorarche made them aware that a milestone in masculinity had been attained but only 12.4% told anyone about it while just under half (41.7%) tried to hide its occurrence. In the case of the girls, 46.2% reported that menarche made them feel that a milestone in female development was attained and 49.1% told other girls about its occurrence. Of those who could recall the time of year of their thorarche a strong seasonal effect was apparent, the highest incidence occurred in the spring (40.6%) and summer (34.8%) sharply decreasing in the autumn (15.9%) and winter (8.7%). This was in contrast to menarche which was evenly distributed between spring, summer, autumn and winter. Unlike menarche, there was no evidence for a secular trend in thorarche.
Virtually all our ideas about the influence of seasonal, social, geographical, nutritional and environmental factors on pubertal sexual maturation in humans comes from menarchal studies on girls. There is a remarkable paucity of data about the masculine equivalent of menarche, the first seminal ejaculation of boys. Nearly thirty years ago Kinsey, Pomeroy and Martin (1948) stated that 'the published studies on younger boys completely lack data on the most significant of all adolescent developments, the occurrence of the first ejaculation'. Apart from their own paramount contribution there has been no addition to our knowledge about the first ejaculation and factors influencing its timing. The reason for this may be an attitude that pervades since the Kinsey studies that studying the first ejaculation is difficult and of little value. Statements like 'menarche . . . is the most obvious and easily ascertained sign of puberty in girls. No parallel event occurs in boys' (Brown, 1966), and 'the menarche is often used as a dividing line between preand postpuberty in the female. No such division can be used in boys' * Dr. R. J. Levin belongs to the Department of Physiology, University of Sheffield, Sheffield, S 10 2TN, England 173
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
174
R. J. LEVIN
(Watson, 1954). Similar remarks, as for instance, reproductive ability is more obvious in the famale than in the male since the first semen emission or the realization that one is capable of ejaculation is not as marked as menarche' (Ramirez, 1973) are frequently found in the literature. It is claimed by some, moreover, that boys have great difficulty remembering their first ejaculation and pay much less atten-^ tion to the experience compared to the impact that menarche makes on girls (Gagnon, 1973). Tanner (1962) contributed the opinion that 'the time of the first ejaculation is to some extent culturally as well as biologically determined' but no data were offered to support the concept. The lack of data about the first ejaculation is matched by the absence of a specific term for this unique occurrence. This is so despite an abundance of specific terms for the many other phenotypic and endocrinologic changes of puberty i.e. for the sprouting of pubic hair (pubarche), for the initiation of breast bud growth (thelarche), for the appearance of the menses (menarche) and for the initiation of the increased adrenal cortical hormone output (adrenarche). In order to remedy the deficit I asked Professor R. Crossland, of the Department of Greek at the University, to suggest a term for the first seminal ejaculation compatible with the previous terminology for the progression of pubertal changes. He reported that while the ancient Greeks had a wealth of words for copulation, penetration, and masturbation (mostly metaphorical and often colourful), apparently they, like ourselves, had no specific word to describe the 'first ejaculation'. He suggested 'thorarche', based on the rare but specific Greek word for semen 'thoros'. It is possible that this word is itself connected with the verbal stem 'thor'—(leap), an apposite coincidence in relation to a word for ejaculation! A minor criticism of the term is its similarity to thorax, but in fact the two terms actually have distinct stems, namely 'thor' and'thorak' respectively. For the rest of the article 'thorarche' will be used to describe a boy's first seminal ejaculation. In order to see if further useful information on thorarche could be obtained and to compare its impact on boys in relation to the effect menarche has on girls a simple, retrospective, yes/no, trial questionnaire was created and was given to undergraduates, aged approximately 18-21, taking courses in medicine and biology. Both sexes were asked to fill in the questionnaire anonymously and, whether completed or not, hand it back in its envelope at a later date thus avoiding possible embarrassment to students notwishing to take part in the study. Only two questionnaires
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
THORARCHE
175
were handed back unfilled. Some of the questions and the answers received are listed in Table 1. The students were also asked to give their best estimate of the age that their thorarche or menarche occurred. These data are plotted as cumulative frequency histograms in Figure 1. together with those obtained by Kinsey et al. (1953). A number of interesting features about thorarche are highlighted in this present study. Firstly, 80% of boys claim to remember their thorarche, which was caused overwhelmingly by sexual activities as only 7.6% of boys reported it to be caused by asexual activity. For most (74.4%), the sexual activity occurred while they were conscious as only 25.6% experienced their thorarche as a nocturnal emission. While a large number (56.6%) claimed that thorarche did not create a significant impact in terms of feeling that a milestone in masculine development had been reached, a significant percentage (43.4%) felt that it did make such an impact. Thorarche is still a private, personal affair, for only 12.4% reported telling anyone else about it. The embarrassing nature of the event is clearly underlined by the fact that 41.7% of the boys actually tried to hide its occurrence and that despite sex education and the 'permissive society' only 28.3% had any instruction about its occurrence during puberty. This contrasts strongly with the 91.7% of girls that received instruction about menarche. A dramatic finding from the survey is the possible influence of season on thorarche. Of the 69 boys who remembered the season in which their thorarche occurred, 40.6% (28) experienced it in the spring and 34.8% (24) in the summer. Only 15.9% (11) reported thorarche in the autumn and 8.7% (6) in the winter (at 3 degrees freedom, x 2 = 19.319). This early seasonal bias to thorarche (75.3% in spring and summer) contrasts strongly with the lack of effect of season on the incidence of menarche which appeared to be practically equally distributed through the year for the 103 girls who recalled their seasonal date (at 3 degrees freedom, x 2 = 0.534). Previous studies on the influence of season on the incidence of menarche have not shown a consistent effect (Zacharias, 1969 & 1970). Comparison of the percent of the population that had experienced menarche or thorarche at specific ages with the figures obtained by Kinsey et al published in 1948 and 1953 reveals an interesting feature (Figure 1). With the girls it is clear that menarche occurred earlier amongst the Sheffield undergraduates than in the American population. This finding, of course, merely confirms the many previous studies that have reported the secular trend in the initiation of menarche. The mean
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
TABLE 1 The Absolute Number of Undergraduates Answering the Questions Are Given in Brackets. The Percentage Responding Were Calculated from the Total Number of Males or Females Who Answered the Particular Question BOYS „ f
GIRLS
A
YES t
1. Can you remember your first . . . ejaculation? . . . period (menses)? 2. Did it occur in the i) Spring ii) Summer iii) Autumn iv) Winter 3. Did you have any instruction about its occurrence, were you told to expect it? 4. Was the cause of the ejaculation i) sexual (e.g. masturbation, nocturnal emission, sexual contact etc.)? ii) asexual (e.g. physical activity, fear, fright, fighting, clothing friction etc)? 5. Did it occur when you were asleep? 6. Did it make a significant impact on you i.e. make you feel i) a milestone in masculine development had been reached? ii) a milestone in female development 7. Did you tell anyone about it? 8. Did you try to hide its occurrence?
A
.. S
A
S
I
\
I
NO
YES
•*.
\
(
NO
A
•N
I
A
\
%
(Number)
%
(Number)
%
(Number)
%
(Number)
80.3
(114)
19.7
(28)
97
(129)
3
(4)
40.6 34.8 15.9 8.7 28.3
(28) (24) (11) (6) (30)
— — 71.7
— (76)
23.3 25.2 26.2 25.2 91.7
(24) (26) (27) (26) (122)
— 8.3
— (11)
92.4
(97)
—
—
—
—
—
7.6
(8)
—
—
—
—
—
—
25.6
(34)
74.4
(99)
—
—
—
—
43.4
(59)
56.6
(77)
—
—
—
—
46.2 49.1
(60) (55).
53.8 50.9
(70) (57)
—
—
—
—
—
—
—
12.4 41.7
(17) (43)
87.6 58.3
(120) (103)
—
t< Z
THORARCHE
177
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
GIRLS
Age (years)
FIG. 1. Upper graph represents the cumulated percentages of girls achieving menarche amongst undergraduates at Sheffield (O) and from data of Kinsey et al on American females (A). Lower graph is the cumulated percentages of boys achieving thorarche amongst undergraduates at Sheffield (O) and from data of Kinsey et al on American males (A).
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
178
R. J. LEVIN
age ± S.D. for the 88 female undergraduates in the present study who reported their menarche date was 155.4 ± 17.6 months. This agrees remarkably well with the 'all data' mean of 151.7 ± 14.6 months reported from 6,217 American girls in 1970 by Zacharias et al (1970). Thus, despite the small number employed, the data obtained agree well with previous much larger surveys. Interestingly, the thorarche of the male undergraduates does not show any evidence of an earlier initiation when compared to the American male population studied by Kinsey et al (Fig. 1). Indeed the data purport to show it occurring a little later but the small sample size of the present male study compared to the huge American group suggests that it would be a sensible cautionary device to simply state that thorarche has not occurred earlier than in the American boys, but in line with them. Certainly there seems to be no evidence of any lateral shift in the cumulative curve to the left as there is for girls. This is so despite the oft-voiced comment that our culture is deluged by psycho-sexual stimulation via sex education, magazines, books, films, television and theatre notwithstanding more revealing dress and freer sexual habits. The only quantitative data on thorarche that the present data can be compared to is that of Kinsey et al (1948). They calculated a mean age of thorarche at 13.88 yr and a median of 13.77 yr for 3,573 American males. The values for the present study give a mean of 13.1 yrs (± S.E.M. 0.16 yrs) and a median of 13.17 yrs. It should be emphasised that our data are obtained from a highly selected educational group of boys (University undergraduates) enjoying a high standard of living who were all within ten years of their thorarche. Kinsey's material was obtained across the whole spectrum of educational (social?) groups and included retrospective data from interviews with boys and mature adults. Because of these differences emphasis should not be placed on the comparison of the mean and median values from the two studies, rather the strong similarities between the two sets of data, obtained more than thirty years apart, should be stressed. In Kinsey's population 90% had their thorarche between 11 and 15 inclusive, a similar figure fits the present data. In regard to the cause of thorarche, 98.1% of Kinsey's group said it was due to sexual causes (masturbation, nocturnal emission, petting, coitus etc) compared to the 92.4% in the present study. Of the Sheffield undergraduates, 25.6% reported their thorarche as happening when asleep (nocturnal emission) this compares with the 22.2% for the Kinsey group. The agreement between the various occurrences suggests, as with
THORARCHE
179
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
the data for the girls, that the small sample of boys has not created a gross bias. In summary, the results of this survey has revealed two important hitherto unsuspected features about thorarche in boys. It appears that it is seasonally affected and that unlike menarche is not showing a secular trend. It is expected that independent surveys will confirm the findings from this pilot study. References BROWN, P. E. British Journal of preventive and social medicine. 20:9-14 (1966). GAGNON, J. H. AND SIMON, W. Sexual Conduct: the social sources of human sexuality, p. 58, London: Hutchinson, 1973. KINSEY, A. C., POMEROY, W. G. AND MARTIN, C. E. Sexual behaviour in the human male; p.
184, 190. Philadelphia: W. B. Saunders, 1948. KINSEY, A. C., POMEROY, W. B., MARTIN, C. E. AND GEBHARD, P. H. Sexual behaviour in the
human female; p. 131. Philadelphia: W. B. Saunders, 1953. RAMIREZ, V. D. Endocrinology of puberty, in Handbook of Physiology, Section 7; Endocrinology, Volume 11, part 1. (edited by R. 0 . Greep, and E. B. Astwood); Chapter 1, p. 1., Washington, D.C.: American Physiological Society, 1973. TANNER, J. M. Growth of Adolescence p. 35. 2nd edition; Oxford: Blackwell, 1962. WATSON, E. H. AND LOWREY, G. H. Growth and development of children; p. 207. Chicago: The year book publishers Inc., 1954. ZACHARIAS, L. AND WURTMAN, R. J. New England Journal of Medicine. 280:868-875 (1969). ZACHARIAS, L., WURTMAN, R. J. AND SCHATZOFF, M. American Journal of Obstetrics and
Gynaecology. 108: 833-846 (1970).
The Journal of Sex Research Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/hjsr20
Thorarche—a seasonal influence but no secular trend R. J. Levin
a
a
Department of Physiology , University of Sheffield , Sheffield, S 10 2TN, England Published online: 11 Jan 2010.
To cite this article: R. J. Levin (1976) Thorarche—a seasonal influence but no secular trend, The Journal of Sex Research, 12:3, 173-179, DOI: 10.1080/00224497609550936 To link to this article: http://dx.doi.org/10.1080/00224497609550936
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution,
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-andconditions
The Journal of Sex Research Vol. 12, No. 3, pp. 173-179 August, 1976
Thorarche—a Seasonal Influence But No Secular Trend
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
R. J. LEVIN* The term 'thorarche' is proposed for the first seminal ejaculation in boys. A retrospective study on thorarche with 142 male, undergraduates (aged 18-21 years) indicated that 80.3% remembered their thorarche. Less than a third had had any instruction about its occurrence compared to the 91.7% of 133 female undergraduates who were instructed about menarche. The cause of thorarche for 92.4% was sexual, it occurred in sleep for only 25.6%. Approximately 43% felt thorarche made them aware that a milestone in masculinity had been attained but only 12.4% told anyone about it while just under half (41.7%) tried to hide its occurrence. In the case of the girls, 46.2% reported that menarche made them feel that a milestone in female development was attained and 49.1% told other girls about its occurrence. Of those who could recall the time of year of their thorarche a strong seasonal effect was apparent, the highest incidence occurred in the spring (40.6%) and summer (34.8%) sharply decreasing in the autumn (15.9%) and winter (8.7%). This was in contrast to menarche which was evenly distributed between spring, summer, autumn and winter. Unlike menarche, there was no evidence for a secular trend in thorarche.
Virtually all our ideas about the influence of seasonal, social, geographical, nutritional and environmental factors on pubertal sexual maturation in humans comes from menarchal studies on girls. There is a remarkable paucity of data about the masculine equivalent of menarche, the first seminal ejaculation of boys. Nearly thirty years ago Kinsey, Pomeroy and Martin (1948) stated that 'the published studies on younger boys completely lack data on the most significant of all adolescent developments, the occurrence of the first ejaculation'. Apart from their own paramount contribution there has been no addition to our knowledge about the first ejaculation and factors influencing its timing. The reason for this may be an attitude that pervades since the Kinsey studies that studying the first ejaculation is difficult and of little value. Statements like 'menarche . . . is the most obvious and easily ascertained sign of puberty in girls. No parallel event occurs in boys' (Brown, 1966), and 'the menarche is often used as a dividing line between preand postpuberty in the female. No such division can be used in boys' * Dr. R. J. Levin belongs to the Department of Physiology, University of Sheffield, Sheffield, S 10 2TN, England 173
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
174
R. J. LEVIN
(Watson, 1954). Similar remarks, as for instance, reproductive ability is more obvious in the famale than in the male since the first semen emission or the realization that one is capable of ejaculation is not as marked as menarche' (Ramirez, 1973) are frequently found in the literature. It is claimed by some, moreover, that boys have great difficulty remembering their first ejaculation and pay much less atten-^ tion to the experience compared to the impact that menarche makes on girls (Gagnon, 1973). Tanner (1962) contributed the opinion that 'the time of the first ejaculation is to some extent culturally as well as biologically determined' but no data were offered to support the concept. The lack of data about the first ejaculation is matched by the absence of a specific term for this unique occurrence. This is so despite an abundance of specific terms for the many other phenotypic and endocrinologic changes of puberty i.e. for the sprouting of pubic hair (pubarche), for the initiation of breast bud growth (thelarche), for the appearance of the menses (menarche) and for the initiation of the increased adrenal cortical hormone output (adrenarche). In order to remedy the deficit I asked Professor R. Crossland, of the Department of Greek at the University, to suggest a term for the first seminal ejaculation compatible with the previous terminology for the progression of pubertal changes. He reported that while the ancient Greeks had a wealth of words for copulation, penetration, and masturbation (mostly metaphorical and often colourful), apparently they, like ourselves, had no specific word to describe the 'first ejaculation'. He suggested 'thorarche', based on the rare but specific Greek word for semen 'thoros'. It is possible that this word is itself connected with the verbal stem 'thor'—(leap), an apposite coincidence in relation to a word for ejaculation! A minor criticism of the term is its similarity to thorax, but in fact the two terms actually have distinct stems, namely 'thor' and'thorak' respectively. For the rest of the article 'thorarche' will be used to describe a boy's first seminal ejaculation. In order to see if further useful information on thorarche could be obtained and to compare its impact on boys in relation to the effect menarche has on girls a simple, retrospective, yes/no, trial questionnaire was created and was given to undergraduates, aged approximately 18-21, taking courses in medicine and biology. Both sexes were asked to fill in the questionnaire anonymously and, whether completed or not, hand it back in its envelope at a later date thus avoiding possible embarrassment to students notwishing to take part in the study. Only two questionnaires
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
THORARCHE
175
were handed back unfilled. Some of the questions and the answers received are listed in Table 1. The students were also asked to give their best estimate of the age that their thorarche or menarche occurred. These data are plotted as cumulative frequency histograms in Figure 1. together with those obtained by Kinsey et al. (1953). A number of interesting features about thorarche are highlighted in this present study. Firstly, 80% of boys claim to remember their thorarche, which was caused overwhelmingly by sexual activities as only 7.6% of boys reported it to be caused by asexual activity. For most (74.4%), the sexual activity occurred while they were conscious as only 25.6% experienced their thorarche as a nocturnal emission. While a large number (56.6%) claimed that thorarche did not create a significant impact in terms of feeling that a milestone in masculine development had been reached, a significant percentage (43.4%) felt that it did make such an impact. Thorarche is still a private, personal affair, for only 12.4% reported telling anyone else about it. The embarrassing nature of the event is clearly underlined by the fact that 41.7% of the boys actually tried to hide its occurrence and that despite sex education and the 'permissive society' only 28.3% had any instruction about its occurrence during puberty. This contrasts strongly with the 91.7% of girls that received instruction about menarche. A dramatic finding from the survey is the possible influence of season on thorarche. Of the 69 boys who remembered the season in which their thorarche occurred, 40.6% (28) experienced it in the spring and 34.8% (24) in the summer. Only 15.9% (11) reported thorarche in the autumn and 8.7% (6) in the winter (at 3 degrees freedom, x 2 = 19.319). This early seasonal bias to thorarche (75.3% in spring and summer) contrasts strongly with the lack of effect of season on the incidence of menarche which appeared to be practically equally distributed through the year for the 103 girls who recalled their seasonal date (at 3 degrees freedom, x 2 = 0.534). Previous studies on the influence of season on the incidence of menarche have not shown a consistent effect (Zacharias, 1969 & 1970). Comparison of the percent of the population that had experienced menarche or thorarche at specific ages with the figures obtained by Kinsey et al published in 1948 and 1953 reveals an interesting feature (Figure 1). With the girls it is clear that menarche occurred earlier amongst the Sheffield undergraduates than in the American population. This finding, of course, merely confirms the many previous studies that have reported the secular trend in the initiation of menarche. The mean
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
TABLE 1 The Absolute Number of Undergraduates Answering the Questions Are Given in Brackets. The Percentage Responding Were Calculated from the Total Number of Males or Females Who Answered the Particular Question BOYS „ f
GIRLS
A
YES t
1. Can you remember your first . . . ejaculation? . . . period (menses)? 2. Did it occur in the i) Spring ii) Summer iii) Autumn iv) Winter 3. Did you have any instruction about its occurrence, were you told to expect it? 4. Was the cause of the ejaculation i) sexual (e.g. masturbation, nocturnal emission, sexual contact etc.)? ii) asexual (e.g. physical activity, fear, fright, fighting, clothing friction etc)? 5. Did it occur when you were asleep? 6. Did it make a significant impact on you i.e. make you feel i) a milestone in masculine development had been reached? ii) a milestone in female development 7. Did you tell anyone about it? 8. Did you try to hide its occurrence?
A
.. S
A
S
I
\
I
NO
YES
•*.
\
(
NO
A
•N
I
A
\
%
(Number)
%
(Number)
%
(Number)
%
(Number)
80.3
(114)
19.7
(28)
97
(129)
3
(4)
40.6 34.8 15.9 8.7 28.3
(28) (24) (11) (6) (30)
— — 71.7
— (76)
23.3 25.2 26.2 25.2 91.7
(24) (26) (27) (26) (122)
— 8.3
— (11)
92.4
(97)
—
—
—
—
—
7.6
(8)
—
—
—
—
—
—
25.6
(34)
74.4
(99)
—
—
—
—
43.4
(59)
56.6
(77)
—
—
—
—
46.2 49.1
(60) (55).
53.8 50.9
(70) (57)
—
—
—
—
—
—
—
12.4 41.7
(17) (43)
87.6 58.3
(120) (103)
—
t< Z
THORARCHE
177
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
GIRLS
Age (years)
FIG. 1. Upper graph represents the cumulated percentages of girls achieving menarche amongst undergraduates at Sheffield (O) and from data of Kinsey et al on American females (A). Lower graph is the cumulated percentages of boys achieving thorarche amongst undergraduates at Sheffield (O) and from data of Kinsey et al on American males (A).
Downloaded by [University of Auckland Library] at 12:44 25 November 2014
178
R. J. LEVIN
age ± S.D. for the 88 female undergraduates in the present study who reported their menarche date was 155.4 ± 17.6 months. This agrees remarkably well with the 'all data' mean of 151.7 ± 14.6 months reported from 6,217 American girls in 1970 by Zacharias et al (1970). Thus, despite the small number employed, the data obtained agree well with previous much larger surveys. Interestingly, the thorarche of the male undergraduates does not show any evidence of an earlier initiation when compared to the American male population studied by Kinsey et al (Fig. 1). Indeed the data purport to show it occurring a little later but the small sample size of the present male study compared to the huge American group suggests that it would be a sensible cautionary device to simply state that thorarche has not occurred earlier than in the American boys, but in line with them. Certainly there seems to be no evidence of any lateral shift in the cumulative curve to the left as there is for girls. This is so despite the oft-voiced comment that our culture is deluged by psycho-sexual stimulation via sex education, magazines, books, films, television and theatre notwithstanding more revealing dress and freer sexual habits. The only quantitative data on thorarche that the present data can be compared to is that of Kinsey et al (1948). They calculated a mean age of thorarche at 13.88 yr and a median of 13.77 yr for 3,573 American males. The values for the present study give a mean of 13.1 yrs (± S.E.M. 0.16 yrs) and a median of 13.17 yrs. It should be emphasised that our data are obtained from a highly selected educational group of boys (University undergraduates) enjoying a high standard of living who were all within ten years of their thorarche. Kinsey's material was obtained across the whole spectrum of educational (social?) groups and included retrospective data from interviews with boys and mature adults. Because of these differences emphasis should not be placed on the comparison of the mean and median values from the two studies, rather the strong similarities between the two sets of data, obtained more than thirty years apart, should be stressed. In Kinsey's population 90% had their thorarche between 11 and 15 inclusive, a similar figure fits the present data. In regard to the cause of thorarche, 98.1% of Kinsey's group said it was due to sexual causes (masturbation, nocturnal emission, petting, coitus etc) compared to the 92.4% in the present study. Of the Sheffield undergraduates, 25.6% reported their thorarche as happening when asleep (nocturnal emission) this compares with the 22.2% for the Kinsey group. The agreement between the various occurrences suggests, as with
THORARCHE
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the data for the girls, that the small sample of boys has not created a gross bias. In summary, the results of this survey has revealed two important hitherto unsuspected features about thorarche in boys. It appears that it is seasonally affected and that unlike menarche is not showing a secular trend. It is expected that independent surveys will confirm the findings from this pilot study. References BROWN, P. E. British Journal of preventive and social medicine. 20:9-14 (1966). GAGNON, J. H. AND SIMON, W. Sexual Conduct: the social sources of human sexuality, p. 58, London: Hutchinson, 1973. KINSEY, A. C., POMEROY, W. G. AND MARTIN, C. E. Sexual behaviour in the human male; p.
184, 190. Philadelphia: W. B. Saunders, 1948. KINSEY, A. C., POMEROY, W. B., MARTIN, C. E. AND GEBHARD, P. H. Sexual behaviour in the
human female; p. 131. Philadelphia: W. B. Saunders, 1953. RAMIREZ, V. D. Endocrinology of puberty, in Handbook of Physiology, Section 7; Endocrinology, Volume 11, part 1. (edited by R. 0 . Greep, and E. B. Astwood); Chapter 1, p. 1., Washington, D.C.: American Physiological Society, 1973. TANNER, J. M. Growth of Adolescence p. 35. 2nd edition; Oxford: Blackwell, 1962. WATSON, E. H. AND LOWREY, G. H. Growth and development of children; p. 207. Chicago: The year book publishers Inc., 1954. ZACHARIAS, L. AND WURTMAN, R. J. New England Journal of Medicine. 280:868-875 (1969). ZACHARIAS, L., WURTMAN, R. J. AND SCHATZOFF, M. American Journal of Obstetrics and
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