Sex and gender: what is the difference?

IT IS CLEAR THAT SEX IS A key biological variable that should be considered in all basic physiological and biological research. However, despite a long history of interest in sex-based investigations, this topic has historically not been well studied. The current importance of sex research is obvious by the recent rise in articles reporting on sex-based biology across scientific journals, including the Journal of Applied Physiology. There are two terms being used in this contemporary dialogue to describe the sex-based research: “sex” and “gender.” The term gender is becoming more common in scientific publications to describe biological variation traditionally assigned to sex, and this nonspecific language merits a standardized approach. Increasingly, researchers are becoming aware of the appropriate use of the terms sex vs. gender. Still, some scientists are vaguely aware that a distinction exists between these terms or that this difference is an important one. The purpose of this article is to publicize the necessity for implementing a standardized use of the terms sex and gender in physiology. Thus this article will present a general history examining the transition in the frequency of use of the term gender instead of sex in physiology, present standard definitions by promoting the recommendation from the Institute of Medicine (IOM), and provide examples of appropriate use of these terms in reference to specific contexts. Coming to a consensus in the use of terminology is a worthwhile endeavor for disciplines such as physiology that rely heavily on specific language to explain phenomena. Other disciplines, including psychology and anthropology, have put into practice distinguishing between the terms sex and gender in their discourse (4, 11, 12). As physiologists, we will likely find that adopting this distinction can only improve communication within as well as outside our discipline. Physiologists are at the forefront of the nationally and internationally recognized work on sex-based research and women’s health. Although certainly sex-based research is growing in all areas of science, it is critical to understand the history. Physiologists are aware of and socially sensitive to a history of science where the long-standing norm was a 70-kg man. The prominence of research investigations using the established “norm” of a 70-kg man shaped an understanding of human biology that lacked information in regard to femalespecific biology, anatomy, pathology, and treatments for disease. In 1985, the US Public Health Task Force on Women’s Health declared that “the historical lack of research focus on women’s health concerns has compromised the quality of health information available to women as well as the health care they receive” (7). This report prompted federal legal action and started a momentum of sex-based research that has led to fundamental changes in science. By the mid-1990s, the National Institutes of Health, the Food and Drug Administration, the Government Accounting Office, the Congressional Caucus on Women’s Issues, and most prominently the Society for Women’s Health Research had collectively established the Women’s Health Equity Act, and new National Institutes of Health policies demanding the inclusion of women in federally funded clinical trials and ensuring that women and minorities are included in all human subjects research (7). The American Physiological Society (APS) has been a leader in integrating sex-based research into its journals and has devoted issues of the Journal of Applied Physiology to sex-based differences, including the Highlighted Topics series on “Genome and Hormones: Gender Differences in Physiology.” In the series editorial by Dr. Gary Sieck, physiologists are recognized for their ever-growing efforts in sex-based physiology research and interdisciplinary approaches to these investigations (9). Importantly, the editorial highlights the confusion within APS over the use of these terms. In this editorial, sometimes “gender,” sometimes “sex,” and sometimes “gender/sex” is used to describe the recent advances that physiologists are making in recognizing the important implications of sex difference on all physiological systems. The growing interest in sex-based research and growing publications related to this work have led to the increased use of the term gender instead of the term sex. Before the 2001 Journal of Applied Physiology Highlighted Topic series, from July 1948 through December 2000 there were 59 Journal article titles that contained the words sex and/or gender. From January 2001 through December 2004 there have been 60 titles containing the terms sex and/or gender. Notably, in the last 5 years the Journal has included more sex-based research articles in the journal than in the last 50 years. However, this increase in sex-based research is connected to the appropriation of the term gender as a synonym for sex and has led to misuse of that term in physiology. The increase in frequency of the use of the term gender in the American Physiological Society journals is highlighted in Table 1. In the journals of the American Physiological Society, gender was first introduced into a title in 1982, whereas sex had been used since the early 1920s. It was not until the mid-1990s that use of the term gender began to exceed use of the term sex in APS titles, and today gender more the doubles that of sex (Table 1). The term gender appears to have undergone appropriation by some scientists as a politically correct way to talk about sex. This may be because some scientists are sensitive to the verity that discussing sex often means discussing difference and gender may be construed as a less loaded term. Accordingly, it is imperative that scientists and editors come to a consensus on these terms to alleviate any confusion in their usage. These words have specifically different etymologies and meanings. In the most basic sense, sex is biologically determined and gender is culturally determined. The noun sex includes the structural, functional, and behavioral characteristics of living things determined by sex chromosomes. Sex (noun) is derived from the Latin word “sexus,” meaning either of two divisions of organic nature distinguished as male or female, respectively (8). According to the Oxford English Dictionary, sex (noun) has a definition as “the sum of those differences in the structure and function of the reproductive organs on the ground of which beings are distinguished as male and female, and of the other physiological differences consequent on these; the class of phenomena with which these differences are concerned” (8). Gender can be thought of as the Address for reprint requests and other correspondence: C. T. Minson, Dept. of Human Physiology, 1240 Univ. of Oregon, Eugene, OR 97403 (e-mail: [email protected]). J Appl Physiol 99: 785–787, 2005; doi:10.1152/japplphysiol.00376.2005.