Males smell threatening

Sometimes the simplest, most obvious things are missed for a long time in research. A recent study looking at pain responses in mice and rats suggests that the sex of the researcher affects how strongly the animal feels the pain. The June issue of Nature Methods reports that researchers Dr. Sorge and colleagues found that if while the pain response was being measured, a male experimenter was simply sitting on a chair a half metre away, the mouse exhibited less pain. Mice showed a degree of analgesia, or decrease in the feeling of pain, that was not evident if the seated person was a female, or if no person was present. (The pain response was measured from video tapes of the animals by researchers who were blind to the sex of the person seated in the room.) In fact, simply putting into the room a t-shirt recently worn by a male was enough to produce the analgesic response.

We have long known that stress can induce an analgesic response in animals. Small electric shocks given to rodents can result in a reduced response in a subsequent pain test. It is thought that this stress-induced analgesic response is a defense mechanism to help the animal in emergency situations. For those engaged in a life-and-death fight or flight from a predator, it would be advantageous not to be distracted by painful stimulation. Or picture an out-of-control car heading towards you: you need to get out of the way, not stop to remove a painful splinter.

This stress-induced analgesic response also involves an increase in the stress hormone, corticosterone, as well as other biological signs indicative of stress. Mice exposed to the presence of human males show an increase in all these biological measures of stress. In behavioural tests of stress that examine how willing animals are to explore an unfamiliar environment considered threatening, such as the centre of an open field (a one-metre square box), animals exposed to males (or male t-shirts) are more anxious or fearful in an open field than those not exposed to males or their clothing. The researchers found that the smell of a male induced a stress response in rodents that lasted for about 30 minutes and led to the reduced sensitivity to pain.


In this same study, the rodents’ analgesic response could be induced not only by smells coming from male humans but also by scents from a wide range of male animals. Whether they were predators of mice (cats and dogs) or non-predators (guinea pigs), males could induce the analgesic response, suggesting it was something that was common across all males. Male animals that had been neutered did not induce the effect, suggesting that male hormones were important in producing the signals. Specifically, males of every species responsible for the effect secrete molecules called pheromones. A small amount of these smells put on a gauze pad was enough to produce the reduced pain sensitivity.

In the research I’m involved in, we have never really paid attention to the sex of the experimenter and generally do not record it in our methodology sections; until now we considered it irrelevant. Now we may need to add a couple of new columns to our observation sheets: sex of person handling animals and sex of person collecting the data.

Perhaps something similar occurs when we read Scripture. Who we are may have a profound effect on what we see in God’s Word. If we are male and financially comfortable, we may see the Bible differently from a single mother who is struggling to survive. Because we see Scripture as a living document infused by the Spirit, this richness should not surprise us. But it should make us cautious about arguing that our understanding is the only true understanding of God’s Word. What the Spirit shows us in the Word may be a function of what we are able to hear.

We should be open to comparing how different Christians read the Bible. If we do this in a way that respects our differences, we may come to a more complete understanding of God’s love and how he wants us to live. What appear to be opposing findings from, or understandings of, God’s Word may be more reflective of our differences rather than right and wrong ways of knowing God.


  • Rudy Eikelboom

    Rudy Eikelboom is a Professor of Psychology, at Wilfrid Laurier University, who has emerged from the dark side of the University after being department chair for 9 years and now teaches behavioural statistics to graduate and undergraduate psychology students. His retirement looms and he is looking forward to doing more writing on the implications of modern science for our Christian faith. Currently, he serves as a pastoral elder at the Waterloo Christian Reformed Church.

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