Why did we evolve to associate Pain with Pleasure? Is BDSM a fluke?

I accidentally got my hand caught between my hammer and the lumber.  A question kept swirling in my mind: “When one person derives pleasure from pain and another experiences pain in the pursuit of pleasure, do they ultimately feel the same? Do their sensations have the same essence?”

Within the broad scope of BDSM, the relationship between sadomasochism and pleasure has always been one of the most perplexing and fundamental issues. This complexity is a key reason why this niche community is often misunderstood.

Why do some people enjoy inflicting pain and seek to do so in relationships? Why do others enjoy receiving pain and actively seek it out? Does this challenge the moral and ethical boundaries of human society?

According to sex psychologist Havelock Ellis, "If we solve this problem, we might be able to establish a general theory of extreme love.”

Historically, there has been a considerable amount of psychological analysis on BDSM, but there is still no widely accepted explanation for why some people enjoy it.

So, I decided to take a different approach and look at what happens biologically in the body during BDSM activities.

After reviewing various studies, I found that they often mention a part of the brain called the amygdala, which looks like a tiny tomato in the brain.

The amygdala is essentially the source of human emotions. Whenever you experience an emotion, the amygdala initiates a basic emotional response and informs your cerebral cortex, which then translates this basic emotion into feelings of joy, sadness, anger, and so on.

If the environment is dangerous and life-threatening, the brain categorizes the primary emotion as fear. If a loved one passes away, the brain categorizes it as sadness.

The relationship between the amygdala and the cerebral cortex is like that between gasoline and an engine: the amygdala fuels the engine, and the engine determines its speed based on the fuel.

However, this doesn't explain the intertwining of pain and pleasure. In 2003, a scientist named Fanselow conducted an experiment that revealed something intriguing: when people feel pain or sexual pleasure, the amygdala secretes the same hormone—adrenaline.

This means that when a person feels pain or sexual pleasure, the amygdala secretes adrenaline to signal the cerebral cortex, which then determines whether this primary emotion should be categorized as pain or pleasure based on the context.

This allows the brain's consciousness to potentially deceive and transform the resulting emotion. In BDSM, the submissive (Sub) knows they are safe, allowing their primary emotion to be processed into other emotions. Pain or fear is thus redirected into sexual pleasure due to changes in adrenaline levels. This principle hinges on mutual consent and the dominant (Dom) ensuring the Sub feels safe. Any coercion can disrupt this emotional reorientation.

In simpler terms, people might enjoy BDSM because their cerebral cortex has the ability to reframe the emotions elicited by pain into sexual pleasure. Imagine that during BDSM play, your cerebral cortex is continuously tricking your amygdala.

Revisiting my initial question—“When one person derives pleasure from pain and another experiences pain in the pursuit of pleasure, do they ultimately feel the same?”—it now seems to have a new layer of understanding.

However, I noticed another issue: pain and sexual pleasure are only parts of the BDSM spectrum. Some people in the BDSM community don't require pain or sexual pleasure; they derive satisfaction from dominance and submission, or simply being with their master can make them feel content.

Why is this the case? The previous theory doesn't explain this phenomenon.

This brings us to endorphins, the brain's natural opioids. Endorphins can relax a person and create a feeling of euphoria. During sexual activity, endorphin levels are suppressed but significantly increase after the activity.

For some BDSM practitioners, who do not engage in sexual activities, endorphins are linked to the master-submissive relationship. In social animals, dominant individuals naturally assume leadership roles, while subordinates feel secure in their presence.

In a clear master-submissive dynamic, simply being with the dominant can increase the submissive’s endorphin levels, providing a sense of security. For instance, a flock of hens becomes calm when a rooster is introduced.

In self-inflicted pain scenarios, the absence of a real master requires the individual to imagine the relationship, promoting endorphin release.

Based on this analysis, we understand why some people enjoy BDSM. Since the mechanism of emotional reorientation exists in everyone, theoretically, anyone can develop this mechanism and become interested in BDSM, provided there is mutual consent and trust.

Given that anyone can potentially develop an interest in BDSM, I pose a further question: Do other species exhibit BDSM-like behaviors?

Research shows that BDSM behaviors are common in nature. For example, during mating, female gray geese stretch their necks to signal readiness to the male, who bites the female’s neck feathers without interrupting mating.

Large cats like lions and tigers engage in biting and light scratching during mating, with the females not resisting these behaviors.

Gebhard observed over 24 mammalian species displaying BDSM-like behaviors during mating. He noted that "from an evolutionary perspective, it’s not surprising to find SM practitioners."

Exploring BDSM through evolutionary or biological lenses reveals it as a natural sexual preference among mammals rather than a deviant behavior. Unfortunately, BDSM still carries significant social stigma, causing psychological distress to those who discover this preference in themselves and are hesitant to acknowledge it.

“Am I normal?” This is the most frequently asked question among participants in BDSM studies.

Medically, BDSM has long been recognized as normal. In the 1960s, the American Psychiatric Association (APA) removed BDSM from the Diagnostic and Statistical Manual of Mental Disorders. The World Health Organization (WHO) also excluded BDSM from the disease category in the latest International Classification of Diseases (ICD-11).

In China, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) requires meeting four criteria to classify BDSM behavior as a disorder:

1. It persists for over six months.
2. It causes significant distress.
3. It impairs daily functioning.
4. It involves non-consensual sexual practices.

Ultimately, I hope readers understand that respecting all harmless interests and hobbies is crucial. The most abnormal thing in the world is the belief that only what is mainstream is normal.

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