Male domestic cat neutering effect on mating behaviour and longevity. Infographic.

The infographic summarises the information that I wish to publish in this article while I have extended the discussion below it.

Male domestic cat neutering – effect on mating behaviour and longevity. Infographic. by Michael Broad

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SOME MORE ON THIS TOPIC (the infographic is a very brief summary of what is stated below).

Research indicates that castrated men live longer than uncastrated men. One researcher said that this applies to all mammals. Does it apply to male domestic cats?

The idea that castration or neutering increases longevity has been observed in many mammals, including humans, but applying this principle to male domestic cats specifically involves considering the unique factors that affect their lives. My research indicates that at present we don’t really or fully know why male humans live longer when castrated – if you know better, please comment 👍😉🙏.

Evidence in Male Domestic Cats:

Research strongly supports the notion that neutering (the equivalent of castration in humans) increases the lifespan of male domestic cats. Key factors include:

1. Reduced Risk of Roaming and Accidents:
   • Intact (unneutered) male cats tend to roam more, often crossing roads and engaging in fights with other animals. This behavior increases the likelihood of injuries, infections, and fatal accidents.
2. Lower Risk of Disease:
   • Unneutered cats are more prone to contracting diseases like FIV (feline immunodeficiency virus) and FeLV (feline leukemia virus), often transmitted through bites during fights or mating.
3. Hormonal Stress Reduction:
   • Neutering eliminates testosterone-driven behaviors, which can lead to chronic stress and its associated health risks.
4. Cancer Prevention:
   • Neutering eliminates the risk of testicular cancer and significantly reduces the risk of prostate-related diseases.

Comparative Longevity:

Several studies have demonstrated that neutered male cats live significantly longer than their intact counterparts. The exact extension of lifespan varies depending on the study and environmental factors, but neutered males often live several years longer on average.

Does This Apply to All Mammals?

The longevity effect of castration or neutering varies between species and is influenced by many factors:

• Humans: Castrated men have historically shown longer lifespans in some studies, possibly due to reduced testosterone-related health risks, though other lifestyle and historical factors complicate this finding.
• Other Mammals: Laboratory and agricultural studies have shown castration increases lifespan in many animals, including cattle and dogs.

Conclusion for Male Cats:

Yes, castration (neutering) increases the lifespan of male domestic cats. The primary reasons are behavior-related (reduced roaming and fighting), health-related (lower risk of disease and cancer), and stress-related (hormonal balance). While the principle applies broadly to mammals, its degree and reasons vary significantly across species.

If we eliminate the behaviour-related benefits does castration still improve lifespan?

If behavioral benefits like reduced roaming, fighting, and mating-related risks are removed, the lifespan benefits of castration in male domestic cats still exist but may be less pronounced. Here’s why:

Health-Related Benefits Independent of Behavior

1. Hormone-Driven Disease Risk Reduction:
   • Testosterone can contribute to the development of certain health issues. For example, neutering removes the risk of testicular cancer entirely and reduces the likelihood of prostate-related diseases. While prostate issues are less common in cats compared to humans or dogs, their elimination still positively impacts lifespan.
2. Lower Stress Levels:
   • The removal of testosterone reduces the drive for territoriality and mating, which can otherwise create chronic physiological stress. Stress can negatively impact the immune system and overall health, even in a controlled environment.
3. Metabolic Changes:
   • Castration reduces metabolic demands associated with testosterone production. This can moderate energy expenditure and reduce the risk of hormone-related imbalances. However, neutered cats also tend to gain weight more easily, so diet and exercise need to be monitored to ensure the benefits are not offset by obesity-related issues.

Studies Controlling for Behavior:

Research in controlled environments, such as studies on laboratory cats or strictly indoor cats (where behavioral risks are minimized), still shows some health advantages in neutered males. However, the gap in lifespan between neutered and intact males becomes smaller compared to scenarios where behavioral factors like fighting and roaming play a role.

Conclusion:

Even if behavior-related benefits are excluded, castration still provides some lifespan extension for male domestic cats due to its impact on hormonal health, cancer prevention, and stress reduction. However, the overall benefit may not be as significant as in scenarios where behavioral risks are also mitigated.

Do we know if neutered male domestic cats live longer than spayed female cats?

The comparison of lifespan between neutered male domestic cats and spayed female cats shows some general trends, though specific outcomes can vary based on factors like environment, breed, and healthcare access.

General Lifespan Trends

1. Neutered Males vs. Spayed Females:
   • Studies generally show that both neutered males and spayed females live significantly longer than their intact counterparts. However, spayed females often have a slight edge in average lifespan compared to neutered males. This trend is likely influenced by biological differences and varying susceptibilities to certain diseases.
2. Average Lifespan:
   • Neutered males: On average, they can live 13–15 years or more.
   • Spayed females: On average, they can live 14–17 years or more.
   • These are broad ranges and depend on factors like diet, living conditions, and access to veterinary care.

Factors Influencing Lifespan Differences

1. Disease Susceptibility:
   • Neutered males have reduced risks of hormone-driven diseases like testicular cancer and certain prostate issues, but they can still develop urinary blockages, which are more common in males due to their narrower urethras.
   • Spayed females benefit from a complete elimination of uterine infections (pyometra) and a significant reduction in mammary cancer risk when spayed before their first heat.
2. Biological Differences:
   • Females typically have slightly more robust immune responses and may be less prone to some chronic conditions seen in males.
3. Behavioral and Lifestyle Factors:
   • Males, even when neutered, may still engage in activities like roaming (to a lesser extent than intact males), potentially exposing them to risks. Spayed females are generally less likely to roam or engage in risky behaviors.

Controlled Environments:

In strictly controlled indoor environments where both genders receive equal care, spayed females may still have a slight advantage in longevity. This suggests that biological and disease-related factors are key contributors to the lifespan difference.

Conclusion:

Spayed female cats tend to live slightly longer than neutered male cats on average, primarily due to differences in disease susceptibility and biological factors. However, with proper care and monitoring, the lifespan difference between the two can be minimal, and both spayed females and neutered males can enjoy long, healthy lives.

You are saying that without testosterone male domestic cats live longer and are therefore better survivors. And yet evolution gave animals testosterone to procreate and promote the survival of the species. Is this a balancing act between survival of individuals and survival of a species?

Absolutely, your observation highlights a fascinating evolutionary trade-off between individual survival and reproductive success, which is a core principle in evolutionary biology. Here’s how it works:

The Role of Testosterone in Evolution

1. Reproductive Success:
   • Testosterone drives behaviors that increase the chances of mating success, such as aggression, territoriality, and competition for mates. These behaviors may improve the individual’s ability to pass on their genes, even at the expense of personal survival.
   • Evolution selects for traits that maximize the number of viable offspring, not necessarily the longevity of the individual.
2. Costs of Testosterone:
   • While beneficial for reproduction, testosterone can impose survival costs, such as:
     • Increased risk-taking behaviors (e.g., roaming, fighting).
     • Higher metabolic demands.
     • Suppression of the immune system, making individuals more susceptible to diseases.

The Balancing Act

Evolution operates on a trade-off between longevity and reproductive fitness:

• In the wild, most animals face high mortality rates from predators, diseases, and accidents, so the emphasis is often on reproducing early and frequently. Traits like high testosterone levels are beneficial in this context because they boost reproductive opportunities.
• Longevity beyond the prime reproductive years may contribute little to the individual’s genetic legacy in the wild. Therefore, evolutionary pressure favors short-term reproductive success over long-term survival.

Domestic Animals and the Modern Environment

1. Reduced Pressure for Reproductive Success:
   • In domesticated or controlled environments, animals like cats no longer face the same evolutionary pressures. They are often neutered or spayed and do not need to compete for mates or defend territories.
2. Shift Toward Longevity:
   • Without the need for reproductive behaviors driven by testosterone, the costs associated with these traits (e.g., stress, disease, risky behaviors) are eliminated, leading to increased lifespan. This is why neutered male domestic cats can live longer—they are effectively removed from the evolutionary “game” of mate competition.

Broader Perspective: Species vs. Individual

1. Survival of the Species:
   • Testosterone-driven behaviors ensure the survival of the species by maximizing the reproductive output of individuals, even if it means some individuals die young.
   • In the wild, this is a necessary trade-off because species survival depends on a constant influx of new individuals to offset high mortality rates.
2. Survival of the Individual:
   • When reproductive pressures are removed (as in the case of neutered cats or castrated humans), the focus shifts to individual health and longevity. The absence of testosterone reduces stress and disease, allowing individuals to live longer but without contributing to the gene pool.

Conclusion

Yes, it’s a balancing act. Testosterone is essential for the survival of the species by promoting reproduction, but it comes at the cost of individual longevity. In domestic settings, where survival and reproduction are managed by humans, the removal of testosterone tips the balance in favor of individual longevity, highlighting how environmental and evolutionary contexts shape the trade-offs between survival and reproduction.

Male domestic cat castration removes all or nearly all testosterone?

Yes, castration (neutering) in male domestic cats removes all or nearly all testosterone production, but not entirely under certain circumstances. Here’s how it works:

The Role of Castration in Testosterone Reduction

1. Removal of Testes:
   • The testes are the primary producers of testosterone in male cats. When they are surgically removed during castration, the body loses its main source of testosterone production.
2. Residual Testosterone:
   • Small amounts of testosterone can still be produced by the adrenal glands, which are located near the kidneys. However, the adrenal glands produce far less testosterone than the testes—typically not enough to sustain behaviors or physiological processes heavily dependent on testosterone.

Post-Castration Testosterone Levels

• Behavioral Effects:
  • Testosterone-driven behaviors, such as marking territory with urine, fighting, and roaming, usually decrease significantly after neutering.
  • In some cases, remnants of these behaviors may persist if they were learned before neutering, but they are not fueled by ongoing testosterone production.
• Physiological Effects:
  • The reduction in testosterone alters the cat’s metabolism and muscle maintenance. Neutered cats may experience changes in body composition, such as increased fat deposition and reduced muscle mass, unless their diet and exercise are carefully managed.

Exceptions or Variations

1. Age at Neutering:
   • If a cat is neutered after reaching sexual maturity, some testosterone-driven behaviors may take longer to subside because of residual hormone levels in the bloodstream and learned habits.
   • Cats neutered before puberty (around 4–6 months of age) often show fewer lingering behavioral traits.
2. Cryptorchidism:
   • If a cat has undescended testicles (cryptorchidism) and only one testicle is removed during surgery, residual testosterone may persist.

Summary

Castration in male domestic cats effectively removes almost all testosterone by eliminating its primary source, the testes. While tiny amounts of the hormone can still be produced by the adrenal glands, these are generally not sufficient to sustain testosterone-driven behaviors or physiological effects.

Testosterone is not the only driver for the male to desire sex. Correct?

You’re correct that testosterone is not the sole driver of sexual behavior in males, including male domestic cats, though it plays a major role. Other factors, both biological and behavioral, contribute to sexual desire and mating behaviors. Here’s a breakdown:

Biological Factors Beyond Testosterone

1. Other Hormones and Neurochemicals:
   • Dopamine: This neurotransmitter is crucial for motivation and reward, including sexual behavior. Elevated dopamine levels can stimulate sexual activity even in the absence of testosterone.
   • Oxytocin and Vasopressin: These hormones are involved in bonding and mating behaviors and can influence sexual activity.
   • Estrogen (in small amounts): Testosterone is converted to estrogen in males by the enzyme aromatase. This estrogen can influence brain areas associated with sexual behavior.
2. Neural Pathways:
   • The brain’s hypothalamus and limbic system are critical for sexual behavior and are influenced by testosterone but can retain some level of activity even when testosterone is low or absent.

Behavioral and Learned Factors

1. Experience and Conditioning:
   • Mating behaviors can become habitual or learned. A male who has mated before castration might still exhibit sexual behaviors due to ingrained patterns or prior conditioning, even if testosterone is no longer present.
2. Environmental Cues:
   • External stimuli, such as the presence of a female in heat (and her pheromones), can trigger sexual behaviors in males. These cues may provoke a response even in neutered males, although the intensity is typically reduced.

Observations in Neutered Males

1. Residual Sexual Behavior:
   • Some neutered males may still display mating behaviors, such as mounting or attempting to mate, despite the absence of significant testosterone. These behaviors are usually less frequent and less intense compared to intact males.
   • Such behaviors are likely driven by neural circuits and learned patterns, not hormonal impulses.
2. Adrenal Testosterone:
   • As mentioned earlier, a small amount of testosterone produced by the adrenal glands may contribute to residual sexual behaviors, though this is minimal.

Conclusion

While testosterone is a primary driver of sexual behavior in male cats, it is not the only factor. Neural circuits, other hormones, environmental stimuli, and learned behaviors can also contribute. However, the removal of testosterone through castration significantly diminishes both the intensity and frequency of sexual behaviors in male domestic cats.

Can the instinct for the male to mate be handed down the generations in DNA?

Yes, the instinct for males to mate is encoded in DNA and handed down through generations. This instinct is a product of evolutionary selection, where behaviors that increase reproductive success become ingrained in an animal’s genetic makeup over time. Here’s how it works:

The Genetic Basis of Mating Instinct

1. Hardwired Neural Pathways:
   • Genes influence the development of neural circuits in the brain that drive mating behaviors. These pathways are activated by hormones (like testosterone) and environmental cues (like pheromones from a female in heat).
   • These circuits are conserved across generations because they enhance reproductive success, ensuring the survival of the species.
2. Innate Behaviors:
   • Mating behaviors are largely instinctual, meaning they do not need to be learned and are present even in animals that have never observed mating. This strongly suggests a genetic basis.
   • For example, male cats instinctively know to respond to the scent of a female in estrus, even if they’ve never encountered one before.
3. Sexual Dimorphism in Behavior:
   • Genes on the sex chromosomes contribute to differences in behavior between males and females. For instance, genes that influence testosterone sensitivity in male cats drive their unique mating behaviors, like marking territory and seeking out females.

Evolutionary Pressure to Preserve Mating Instinct

1. Natural Selection:
   • Individuals with stronger or more effective mating instincts are more likely to reproduce and pass on their genes. Over time, this reinforces the genetic basis for these instincts in the population.
2. Adaptation to the Environment:
   • While the core instinct to mate is genetically encoded, specific mating behaviors may adapt to the environment. For example, in social animals, courtship rituals can evolve to suit social structures, but the underlying drive remains.

Interaction Between Genetics and Environment

1. Hormonal Triggers:
   • While the genetic code provides the blueprint, hormones like testosterone activate the behaviors at appropriate times, such as during puberty or in response to environmental stimuli.
   • If the hormonal system is disrupted (e.g., through castration), the behaviors may diminish, but the underlying genetic coding remains intact.
2. Learned Modifications:
   • Though instinctual behaviors are inherited, they can be modified by learning or environmental constraints. However, the basic drive itself does not require learning and is passed genetically.

Implications of the Genetic Basis

1. Neutering and Instinct:
   • Neutering prevents reproduction but does not erase the genetic coding for mating instincts in the population. These instincts remain in the gene pool and are expressed in future generations of unneutered animals.
2. Domestication and Evolution:
   • Over time, selective breeding could reduce certain mating instincts if animals with lower drives were consistently chosen for reproduction. However, in wild or unmanaged populations, strong mating instincts are continually reinforced by natural selection.

Conclusion

The instinct for male animals, including cats, to mate is deeply rooted in their DNA and is handed down through generations. It is a product of millions of years of evolutionary pressure to maximize reproductive success. While environmental factors and hormonal states can modulate this instinct, the genetic foundation ensures its persistence in future generations.