Reproducible research into human semiochemical cues and pheromones: learning from psychology’s renaissance

Abstract

As with other mammals, smell in the form of semiochemicals is likely to influence the behaviour of humans, as olfactory cues to emotions, health, and mate choice. A subset of semiochemicals, pheromones, chemical signals within a species, have been identified in many mammal species. As mammals, we may have pheromones too. Sadly, the story of molecules claimed to be ‘putative human pheromones’ is a classic example of bad science carried out by good scientists. Much of human semiochemicals research including work on ‘human pheromones’ and olfactory cues comes within the field of psychology. Thus, the research is highly likely to be affected by the ‘reproducibility crisis’ in psychology and other life sciences. Psychology researchers have responded with proposals to enable better, more reliable science, with an emphasis on enhancing reproducibility. A key change is the adoption of study pre-registration which will also reduce publication bias. Human semiochemicals research would benefit from adopting these proposals.

Titrating the Smell of Fear: Initial Evidence for Dose-Invariant Behavioral, Physiological, and Neural Responses

“…The question of whether human body odor can shape social communication has been considered among the 125 most compelling multidisciplinary scientific challenges (Kennedy & Norman, 2005; cf. Wyatt, 2020, for a constructive critical view on human pheromone research). Here, we bring new evidence that despite the great chemical complexity of odor stimuli, different levels of fear sweat can be chemically anchored to their original categorical source in the environment (a fearful sender; Smeets et al, 2020) while adaptively modulating fear-specific neural, behavioral, and physiological responses in receivers.…”

“…One striking capacity humans share with other animals is that our body odors can transmit social information (e.g., McGann, 2017; Parma et al, 2017; Roberts et al, 2020; cf. Wyatt, 2020, for a critical view). Physiological changes impact the quality (Smeets et al, 2020) and quantity of odor molecules emitted by senders, providing receivers with cues about the sender’s internal state.…”

Major histocompatibility complex-associated odour preferences and human mate choice: near and far horizons

“…Sadly enough, we still cannot even conclude whether MHC-associated preferences affect real-life mate choice and if so, under what circumstances. Interestingly, many of the issues that we raise are ones currently being discussed in the behavioural sciences and psychology in particular (see also [90]). For one, we base most of our knowledge on studies from Western populations and often too readily generalize them to all human beings [93].…”

“…(i) Researchers should always perform a priori power analysis to obtain sufficient sample size (see also [90]). Power analysis is becoming a standard procedure in other fields of behavioural research, but it is particularly needed here due to both extreme variability in MHC genes and what appear to be, at best, small effect sizes.…”