The adaptive significance of the scrotum and the evolution of the descent of the testicles and epididymis have been a focus of interest among biologists for a long time. In this paper we use three anatomical character states of the scrotum and descensus: (1) testicles descended and scrotal; (2) testicles descended but ascrotal; (3) testicles not descended (testicondy). These states are then mapped on an up to date phylogeny of the Mammalia. Three main points arise out of this mapping procedure: (1) the presence of a scrotum is either primitive in extant Mammalia or primitive within eutherian mammals except Insectivora; (2) evolution has generally proceeded from a scrotal condition to progressively more ascrotal; (3) loss of testicular descensus is less common in mammalian evolution than is loss of the scrotum. In the light of these findings we discuss some current hypotheses regarding the origin and evolution of the scrotum. We find that these are all incomplete in so far as it is not the presence of the scrotum in various mammal groups that requires explaining. Instead, it is the reverse process, why the scrotum has been lost in so many groups, that should be explained. We suggest that the scrotum may have evolved before the origin of mammals, in concert with the evolution of endothermy in the mammalian lineage, and that the scrotum has been lost in many groups because descensus in many respects is a costly process that will be lost in mammal lineages as soon as an alternative solution to the problem of the temperature sensitivity of spermatogenesis is available.

Animals↗

PubMed1995

Preference for sex on amphetamine: a marker for HIV risk behaviour among male intravenous amphetamine users in Stockholm.

Two hundred injecting drug users at the Remand Prison in Stockholm participated in an interview study of sexual behaviour in parallel to an ongoing HIV epidemiological study. Fifty-four subjects were women and 146 were men. Amphetamine was the main drug used by 115 and heroin by 85. Twenty-six were HIV seropositive. Sexual activity was reported as the preferred activity on amphetamine by 51% of the male and 20% of the female amphetamine injectors. Among the 74 men who mainly injected amphetamine the characteristic of preferring sex on amphetamine was strongly associated with positive HIV serostatus in bivariate analysis, but was not independently predictive of HIV serostatus when injection frequency was controlled for. The results suggest that preferring sex on amphetamine may be viewed as a marker of high risk behaviour, both sexually and with needles, for HIV among male but not among female amphetamine injectors.

Adult↗

PubMed1993

The relationships between personality traits and plasma gastrin, cholecystokinin, somatostatin, insulin, and oxytocin levels in healthy women.

In earlier studies performed on a group of women with gastrointestinal symptoms, significant positive correlations between the gastrointestinal hormone gastrin and anxiety, and a negative correlation with socialization were obtained. These and other relationships were tested on 33 healthy women. A comprehensive and concise statistical model was used for the analysis of correlations between, on one hand, the levels of oxytocin and the gastrointestinal hormones gastrin, cholecystokinin, somatostatin and insulin, and, on the other hand, personality traits. Almost all explained variance of the hormone levels could be referred to three personality trait factors, Anxiety, Aggressive non-conformity, and Detachment. The statistical explanation of the gastrin level variance was most successful, the three personality trait factors explaining 48% of this variance. Gastrin "increased" Anxiety while reducing Aggressive non-conformity and Detachment. A similar pattern for insulin was also reliable. Considering general trends, the negative correlations between all hormones and Detachment are interesting. Present data suggest that there is a psychoendocrinological antithesis to the fight-flight individual, characterized by high activity in the sympathoadrenal system: these contrasting persons, with high levels of the gastrointestinal hormones gastrin and insulin, tend to be warm and caring and non-aggressive--but often not free from anxiety. We do not think that the demonstrated associations between hormone levels and personality traits implicate a direct causal relationship. They rather may mirror the activity of centrally acting or hypothalamic control systems which influence both behavioural and endocrine profiles.

Adult↗

PubMed1988

Speech characteristics as indicators of depressive illness.

Measures of the rate of change of voice fundamental frequency, fundamental frequency variability, reading and counting times, and different measures of pause time were compared in 28 depressed patients and 13 healthy controls. The fundamental frequency variables were lower in the depressed group, and the pauses between the interviewer's questions and the patient's answers were longer. The remaining speech variables, including the summed duration of interdigit pauses in counting from 1 to 10 (speech pause time), did not differ between the groups.

Adult↗

PubMed1988

Measuring the rate of change of voice fundamental frequency in fluent speech during mental depression.

A method of measuring the rate of change of fundamental frequency has been developed in an effort to find acoustic voice parameters that could be useful in psychiatric research. A minicomputer program was used to extract seven parameters from the fundamental frequency contour of tape-recorded speech samples: (1) the average rate of change of the fundamental frequency and (2) its standard deviation, (3) the absolute rate of fundamental frequency change, (4) the total reading time, (5) the percent pause time of the total reading time, (6) the mean, and (7) the standard deviation of the fundamental frequency distribution. The method is demonstrated on (a) a material consisting of synthetic speech and (b) voice recordings of depressed patients who were examined during depression and after improvement.

Depression↗

PubMed1987

Acoustic analysis of speech variables during depression and after improvement.

Speech recordings were made of 16 depressed patients during depression and after clinical improvement. The recordings were analyzed using a computer program which extracts acoustic parameters from the fundamental frequency contour of the voice. The percent pause time, the standard deviation of the voice fundamental frequency distribution, the standard deviation of the rate of change of the voice fundamental frequency and the average speed of voice change were found to correlate to the clinical state of the patient. The mean fundamental frequency, the total reading time and the average rate of change of the voice fundamental frequency did not differ between the depressed and the improved group. The acoustic measures were more strongly correlated to the clinical state of the patient as measured by global depression scores than to single depressive symptoms such as retardation or agitation.

Depressive Disorder↗

PubMed1982

Melatonin and cortisol levels in psychiatric illness.

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Depression↗