信息素是动物进行社会交流的重要媒介, 它是否同样影响着人类的行为尚无定论. 人类所具有的高度适应性的社会行为模式、驳杂多变的外分泌物、以及部分退化的嗅觉解剖结构, 使得对人类信息素的行为效应、物质组成以至神经机制的探索充满了希望与挑战. 现有的证据提示人体的气味在多个方面表现出类似信息素的效应, 包括触发固有行为、调节内分泌水平、传递社会信息、诱发情绪起伏甚至认知变化等等. 其中, 两种类固醇物质雄甾二烯酮和雌甾四烯被视为“准人类性信息素”, 二者依据接收者的性别和性取向而选择性地传递性信息、调节情绪与注意, 并对下丘脑产生特异性激活. 这些发现深化了对人类化学信号与人际交流的认识, 也为进一步的研究提供了铺垫.

Social communication via airborne chemicals is ubiquitous in the animal kingdom. Such active substances were designated as “pheromones” by Karlson and Luscher in 1959. As specified by the original definition, pheromones refer to substances that are secreted to the outside by an individual and received by a second individual of the same species, in which they release a specific reaction, for example, a definite behavior or a developmental process. Over the past fifty years, a number of pheromones with distinct functions have been identified in invertebrates as well as in mammals. In the case of mammalian pheromones, recent findings reveal that some of them are processed in the main olfactory system, contrary to the traditional belief that mammalian pheromones are exclusively encoded by the vomeronasal organ and act through the accessory olfactory system. Humans are thought as the most highly scented ape of all in terms of numbers and sizes of sebaceous and apocrine glands. The search for human pheromones, however, has met with less success. The challenges lie in several aspects: (i) Human behavior is highly complex and multifaceted; (ii) Human secretions contain an enormous number of components with changeable concentrations; and (iii) Unlike most mammals, humans do not have a functional accessory olfactory system and rely solely on the main olfactory system to process airborne chemical compounds. Nonetheless, humans possess at least one functional V1r-like gene, a counterpart of the V1r genes that express pheromone receptors in rodents. Moreover, there has been accumulating evidence indicating that human body odors exert a range of pheromone-like effects on odor recipients. These include triggering innate behavioral responses, modulating endocrine levels, signaling social information, and affecting moods and cognition, in line with the roles of releaser, primer, signaler, and modulator pheromones, respectively. In particular, two human steroids—androsta-4,16,-dien-3-one, the most prominent androstene present in male semen, in axillary hair, and on axillary skin surface, and estra-1,3,5(10),16-tetraen-3-ol, first identified in female urine, are considered “putative human sex pheromones”. They have been shown to convey sexual information, modulate mood state, alter autonomic responses, and activate the hypothalamus in manners contingent on the recipient’s gender and sexual orientation yet below his or her awareness. The findings to date have furthered our understandings of human chemosignaling and interpersonal communication, and have paved the way for future investigations of human pheromones. Identifying the mechanisms underlying the release and detection of human pheromones and molecularly characterizing them represent important directions for future work.