Commentary for “Sex Steroids as Modulators of Gestural Communication”

Adam Kendon wrote, “Willingly or not, humans, when in co-presence, continuously inform one another about their intensions, interests, feelings and ideas by means of visible bodily action” (1). Geneviève Calbris described “The movements of the hands and arms in particular, generally referred to as ‘gestures’ are usually regarded as expressing something that is part of the meaning the speaker is conveying” (2). Clearly, gestural communication is associated with speech for facilitating communication in humans. So, it is very fascinating to learn that steroids could modulate gestures in various animal species and humans in this short review authored by Tobiansky and Fuxjager (3). Animals communicate with each other through sounds and gestures even they do not have a true language like humans. Typical examples of gestural communication in animals include honeybees’ round dancing (4), dogs’ tail-wagging, and male chimps’ chest-pounding. Brains and nerve systems certainly play central roles in the learning, controlling, and displaying of these gestural displays. However, we know very little how these gestures are regulated. Tobiansky and Fuxjager summarized interesting findings on steroid regulation of the gestures. They first reviewed brain areas associated with co-speech gestures in humans, then pointed out the presence of steroid receptors in these brain areas and possible effects of circulating estrogen and testosterone on language production, and possible organizational effects. Finally, they indicated cancer patients treated with androgen-deprivation therapy had gray-matter decrease, whereas patients with congenital adrenal hyperplasia, a condition leading to the overproduction of adrenal androgens, showed enhanced performance on gross motor and visuomotor tasks. Steroids and their cognate receptors could function in the brain regions associated with co-speech; however, big questions remain as to whether effects of these steroids are directly or indirectly associated with the modulation of co-speech in humans. As the authors indicate, we know very little on how sex steroids affect co-speech gestures, partly because of limited number of studies. Additional studies in human and animal models will advance our understanding.

The authors then reviewed steroid-regulated gestural displays in rats and birds starting with the well-studied lordosis (an excessive inward curve of the spine) mating gesture in female rats. Many of these mating postures in animals are regulated by steroid signaling via genomic and nongenomic signaling (5, 6). However, whether these steroid-regulated reproductive behaviors are acquired late through learning and social interactions, whether the brain regions responsible for these reproductive behaviors in animals are similar to those brain areas responsible for co-speech in human, and whether these reproductive behaviors qualify as “gesture communication” per se are questionable.

Several bird species are well-established models of the effects of steroids on their gesture displays. As these authors indicate, we still know little about how the brain controls, and steroids modulate, these gestures. Narrowing down specific brain regions and neurocircuits would be helpful. Importantly, development of cell-specific knockouts or knockin of steroid receptors using the latest gene editing tools such as CRISPR in model species would solve many unanswered questions. Research in gesture regulation is still in its infancy. Development of additional animal models, breakthrough knockout, and imaging techniques in well-established animal models are required to further our knowledge.

Additional Information

Disclosure Summary: The author has nothing to disclose.

Data Availability

Data sharing is not applicable to this article because no data sets were generated or analyzed during the present study.