Testosterone, Social Behavior, and Dominance

Testosterone, Social Behavior, and Dominance

3 New Testosterone Studies
Three studies give us some new insights about our favorite hormone. Check ’em out.

1. Testosterone and Social Behavior
When you think of testosterone, you probably think of its role in social status and competition (the “alpha male.”) Or maybe you think of aggression, at least under certain circumstances (1). Well, a new study tells us that exogenous testosterone also encourages more prosocial behavior, especially when you know that someone is watching (2).

Researchers gave men transdermal testosterone or a placebo gel and asked them to donate to a charity with varying monetary costs. They found that exogenous testosterone increased the likelihood an individual would donate to a charity if someone was watching. The researchers call this the “audience effect,” and it increased with testosterone versus placebo.

Testosterone promotes prosocial or antisocial behavior depending upon the circumstances but with the same end goal of improving or maintaining social status. In this case, performing helpful acts with an audience might help elevate or maintain one’s status in a group. From an evolutionary standpoint, these types of acts could be associated with leadership.

2. Testosterone and Scary Voices
A deep, masculine voice is associated with other masculine features and signals to other males the level of potential dominance of that male. With this in mind, a group of researchers administered 150 mg of transdermal testosterone gel or a placebo to men and measured their sensitivity to more masculine-sounding voices (3).

They found that men receiving testosterone experienced a reduced sensitivity (a reduced perception of vocal dominance) to these voices as compared to the placebo. The authors concluded that testosterone likely plays a role in the perception of dominance of other males.

3. Rodents vs. Men: Testosterone Dosage and Muscle Mass
Mice and rats are frequently used as animal models for humans, even though those studies sometimes fail to translate to people. Case in point, this testosterone dose-response study.

Researchers wanted to determine at what point an escalating dose of testosterone given to rats would no longer increase the size of various target tissues (4). These data would then be used to extrapolate the equivalent human dose.

The authors concluded that the “anabolic” activity of testosterone reached a point of saturation at 1 mg/kg in the rat, while the prostate was saturated at 5 mg/kg. The authors utilized allometric scaling via body surface area (BSA) scaling to extrapolate the rat dose to a potential human dose. They concluded that an equivalent human weekly dose of 83.3 mg and 416.7 mg reached the point of saturation for anabolic and androgenic activity, respectively.

Of course, we know from dose-response studies in people that doses up to 600 mg/week of testosterone enanthate (yielding around 432 mg of free base testosterone) failed to reach a point of saturation for increased lean mass and muscle volume, calling into question the usefulness of the data in this study (5). The prostate, meanwhile, has no relationship to dose in humans and is largely unaffected in dose-response studies with exogenous testosterone (6).

Incidentally, serum levels in rats given a claimed human equivalent dose of 83.3 mg/week and 416.7 mg/week, were 154 ng/dl and 814 ng/dl, respectively. Further convoluting the comparisons, however, the preparations, frequency, and routes of administration were different than those typically performed in humans.

So what does this mean? The dose of testosterone at which human muscle no longer significantly responds is still unknown, but is likely higher than 600 mg/week of testosterone enanthate.

Rodents aren’t a good animal model for what occurs with testosterone in humans. The pharmacokinetic and pharmacodynamics differences between rats and humans for exogenous testosterone make such extrapolations questionable.

Note: While beyond the scope of this article, the Levator ani muscle of rats has been controversially used in the Hershberger assay as a surrogate for the anabolic activity in skeletal muscle in humans since rat skeletal muscle doesn’t respond very much to androgens. Also, interspecies dose scaling via BSA is controversial because it doesn’t take into account pharmacokinetic and pharmacodynamic differences between species.