Why Do Humans Sweat

Take one step back in your mind and consider the fact that every human sweats, and this emanating fluid sits on the surface of the flesh only to roll off in beads of a mixture of water and electrolytes. This strange, and uniquely human phenomenon is our central cooling system and necessary for our survival.

Why do humans sweat, and how did this trait evolve into being?

Sweating, like so many automatic occurrences within the body, can often feel as if it is a thing that happens to us rather than for us. Furthermore, for many individuals perspiration is not considered as something to develop or enhance, but rather to minimize, and perhaps even avoid. In reality, everyone can improve their ability to sweat. Similarly, to go to the gym to workout certain muscles, the truth is that we can all become better with practice.

At its core, a sauna is a place where individuals go to sweat. In the abstract this is such an unusual and bizarre concept, but in its essence there is something very magical about the fact that humans sweat. In fact, it may be the single most defining characteristic of human evolution as these great apes separated themselves from all other animals to find themselves out pacing their rivals in the hunting game.

To sauna is to capitalize on the most uniquely human biological process, and the dividends are highly profitable. Sweating is so natural to the human experience most people haven’t thought much about its very unique power.

Find out why humans developed the extraordinary genetic ability to sweat, how the process of sweating occurs in your body, as well as how you can enhance your own ability to sweat even if you are not able to sweat very much naturally, and finally the health benefits inherent to the process of sweating.

The Evolution of Perspiration: Humans Sweat to Regulate Internal Temperature Which Gives Them An Edge Over Other Species in the Wild

Humans are mostly hairless with skin covered with sweat glands. This fact makes them distinct amongst all other earth bound mammals, including other primates. This adaptation over years of evolution is the result of a genetic mutation that has served humans to rise to the top of the animal kingdom.

Some have thought that language, or an enlarged cerebral cortex (front of the brain) was what separated humans from other animals, but the truth may be much simpler than this. One genetic mutation in an ‘enhancer’ region of human DNA called hECE18 may be singularly responsible for early human success in the wild, and this genetic expression is the reason why humans sweat so prolifically. (1)

When humans lived in mostly dry and very hot regions as hunters and gatherers, temperature regulation was of utmost importance. (2) Unlike humans, prey animals do not sweat, but rather depend upon rapid panting to cool themselves off. This means that as humans hunted they were ultimately able to outpace their prey by virtue of a cooling mechanism known as sweating.

For example, if an ancient human was hunting a gazelle in the hot plains of Africa eventually the gazelle would begin to overheat and need to find a cool spot (preferably a still body of water) where they could cool off and pant. Meanwhile the human hunter could continue to run and exert energy without any need to cool off from external environmental factors as their own perspiration did the job.

Penn Medicine published an article in 2021 entitled ‘The Chillest Ape: How Humans Evolved A Super-High Cooling Capacity: Penn Medicine discovery illuminates human sweat gland evolution’, (1) and the authors describe this uniquely human evolutionary trait when they write.

“This adaptation, coupled with the loss of fur in early hominins, which promoted cooling through sweat evaporation, is thought to have made it easier for them to run, hunt, and otherwise survive on the hot and relatively treeless African savannah, a markedly different habitat than the jungles occupied by other ape species.” (1)

Humans have 10 times the density of sweat glands embedded into their skin compared to other apes such as the chimpanzee or macaques. (1) This is considered a ‘hyper-cooling trait’ and is an asset that no other creature on earth has access to. The human ability to sweat is like having central air-conditioning built in genetically.

Over time this trait continued to enhance with human evolution, and scientists are now able to pinpoint the exact gene expression for sweat. The same publication from Penn Medicine writes this as an exposition of the biological expression of the perspiration gene.

“Over time, humans gradually evolved a stronger enhancer for activating Engrailed 1 gene expression, resulting in more sweat glands and making them the sweatiest of the Great Apes… The enhancer region called hECE18 that boosts the production of EN1 in skin, to induce the formation of more eccrine glands…The higher density of sweat glands in humans is due, to a great extent, to accumulated changes in a regulatory region of DNA—called an enhancer region—that drives the expression of a sweat gland-building gene, explaining why humans are the sweatiest of the Great Apes.” (1)

Human evolution has revealed the genetic expression hECE18 in DNA, and it is this specific enhancer region that has given humans the power to self-regulate temperature and overcome their prey in the hunting game. This is not where the story ends, as nature is relentless in her power to unveil mysteries of the human body, perhaps more potent than just cooling the body off to catch more meat; the power to sweat is the power to heal.

As it turns out the action of sweating is not only important to cool the body off but is a catalyst for so many biological processes that it is one of the greatest healing tools available to humans. What started out as an unprecedented hunting tool has evolved into the greatest medicine humans have ever known— The power of perspiration.

So, now that we understand the cause of sweating in humans, namely the enhancer region in human DNA known as genetic expression hECE18, what exactly is happening in the human body that causes sweat to occur mechanically?

What Are the Biomechanics of Sweating?

After understanding the astounding story of why humans sweat it is also important to understand how we sweat. Each droplet of sweat seen on the surface of the skin begins in an eccrine gland which is a coiled structure that lies within the skin. This coil embedded into the skin contains water and electrolytes, and this is essentially what makes up each droplet of sweat excreted onto the surface of the skin. (2)

An article published by Science Direct entitled ‘Diversity and evolution of human eccrine sweat gland density’ (2) describes in detail what is happening inside of each and every eccrine gland when the authors write this.

“The base of the eccrine gland is a coiled structure, lying in the dermis and surrounded by a capillary cage that provides water and electrolytes for sweat production. The secretory coil leads to a duct that extends through the epidermis and opens onto the skin surface as a pore. Each gland is innervated by multiple sudomotor nerve fibers of the sympathetic nervous system using the neurotransmitter acetylcholine.” (2)

This self cooling process is deeply refined in humans such that it occurs automatically as soon as it is sensed that the internal temperature is beginning to reach a degree that could be perilous to the human body.

If You Don’t Use it You Lose: You Can Train Yourself To be a Better Sweater!

Eccrine glands are dispersed across the human body in varying levels of density, and to some extent with diverging goals. Eccrine glands on the palms and the soles of the feet excrete sweat under psychological duress, whereas the rest of the body sweats primarily for the reasons of temperature regulation.

If you have ever had sweaty palms in response to a situation that made you feel nervous then you understand the difference between palm sweat and the rest of the body perspiration!

Not all people have the same density of eccrine glands, and like a muscle, if an individual is not exposed to high temperatures where the eccrine glands are recruited into use the ability to sweat is reduced. In theory, this indicates that you can either lose or gain the ability to sweat depending on the environment you are in.

This means that you can actually train yourself to sweat more by purposely putting yourself into situations where sweating is necessary such as exercise, or in a sauna!

An individual with a greater level of eccrine glands due to early childhood environments or due to genetics will likely always be able to sweat more than someone with less density of eccrine glands. Even if you were born with less eccrine glands than someone else, you can still train the ones you do have to produce more sweat. Each eccrine gland can be trained to deliver greater levels of sweat in its location with appropriate conditions.

So, if you choose to train your eccrine glands via exercise or through sauna, or other passive heat tools you can become a better sweater. Some folks may not feel that sweating is a skill to be sought after in the modern world where air conditioning is abundant and sweating profusely can sometimes be embarrassing. The reality, however, is that sweating is so much more than a thermoregulatory system, it actually has the power to heal many diseases, improve immunity, and free the body of unwanted toxins.

How Does Sweating Serve Human Health In The Present Day?

You may not be striving to outrun a deer or antelope by the power of your supercharged evolutionary trait passed down to you from your ancestors, but this capacity to sweat can still serve you today. The ability to perspire and engage the eccrine glands can improve countless aspects of health.

As the old adage from Parmenides in 500 BC goes: “Give me the power to produce fever and I’ll cure all disease”, still holds true to some extent today. The power of the human thermoregulatory system is so unique and so impactful that it can be used as medicine to treat diseases as severe as dementia, chronic heart failure, diabetes, autoimmune disorders, and so much more.

Sweating occurs automatically from the nervous system when it receives the signal that the body is becoming overheated. Once this message is received a host of bio-chemical reactions occur within the body due to the genetic enhancement in our DNA called hECE18. This mutation evolved to allow humans to cool themselves down during the hunt, but the real magic lies within the physiological changes that occur as a result of this gene deviation.

There are so many health benefits directly linked to intentional sweating that they are too numerous to mention here. So, take a look at the phenomenon of the Heat Shock Protein produced during any kind of temperature stress.

When the body is under heat stress as experienced in a sauna for example, heat shock proteins are produced. These protein chaperones are responsible for incredible feats such as sending out anti-inflammatory signaling. When inflammation is decreased pain is typically resolved for the arthritic as an example. Heat Shock Proteins are heavily involved in T-Cell production which are necessary to bridge both the adaptive and innate immune system to improve overall immune reactions. (3)

From the tiniest molecules in the body to larger particles of plastics released through sweat nearly every physiologic function is improved with perspiration. So, whether you are healthy and just looking to improve health, or if you are very ill, then you can turn to the power of perspiration to promote vitality within your body.

The plethora of benefits correlated with sweating and the body’s natural ability to regulate internal temperature are too many to mention in this article. However, it is clear that the evolutionary trait of sweating has given rise to many more advantages than just an incredible central cooling system.

The Ancients Knew the Power of Sweat Across Cultures and Still Today We Can All Harness The Magic of Perspiration To Restore Health

Humans have turned to different variations of heat therapy for millennia, and perhaps beyond to harness the power of the uniquely human ability to sweat. From dugouts in East Africa where patients were placed over simmering coals (on an open bed), to the great plains of the Americas where indigenous people erected sweat lodges, to Turkish Hammans, Japanese hot springs, to the incandescent light baths of Dr. Kellogg, and even Finnish saunas, humans choose to sweat, not in order to cool themselves off during a hunt, but to harness the healing power of passive sweating.

There are now an abundance of ways to choose to passively sweat from in home saunas, to public bath houses. It is just a matter of choosing to lean into the supercharged aspect of human DNA that allows our mostly naked skin the ability to release fluid of water and electrolytes we call sweat.

You may not feel like a superhero, but you do have a superpower, the ability to sweat. Remember even if you are not a person that sweats a lot naturally, you can always train yourself to improve.

A very small percentage of the population cannot sweat due to a condition called Anhidrosis. If you have been diagnosed with this condition please refrain from sauna use. Children do not develop their full eccrine glands until puberty and should be carefully monitored during a sauna session.

If you do choose to harness the power of sweat in a sauna, please remember to stay well hydrated and refuel with healthy fluids and plenty of electrolytes.

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