Camels. With their long, slender legs, their necks that drop and rise again to meet their heads, and of course their famous humpbacked loin, with one or two humps, it’s very difficult to mistake them for any other animal.
In fact, we are talking about three animals, not just one. The most common type of so-called “camel” is the dromedary, which has only one hump and is also known as the “Arabian camel”. They make up approximately 90% of the world’s camel population and have been domesticated over 3,000 years ago.
The second species, officially called “Bactrian camel”, is known in Portuguese as just “camel” and has two humps. They were domesticated even before dromedaries, between 4,000 and 6,000 years ago, and are native to Central Asia.
And there are also wild camels, very similar to bacterial camels, as they also have two humps, and whose scientific name is Wild Camel. This species lives in the Gobi Desert, Asia, being found in Mongolia and northwestern China. Unlike its cousins, this type of camel was never domesticated.
Surprisingly, some survive without difficulty by drinking water with a higher concentration of salt than seawater. Not only are they different animals, but with a thousand fewer representatives of their species, they are among the most endangered large mammals on the planet.”
The question that remains…
What, after all, exists inside the humps? We often hear that these humps would be full of water, and this is what would allow a camel to survive long periods of time in the desert.
As interesting as this may sound, it is a myth, completely false. The humps are actually not filled with water, but with fat.
How long a camel can survive on its stored fat depends on how active it is and the climate. Hump size may vary depending on your diet. When food is scarce, the body consumes the fat stored in the hump, which causes it to tip over and fall to the ground.
Storing fat on your back rather than in layers all over your body helps prevent overheating, with the added benefit that these humps offer some protection and shade from direct sunlight.
Camels can survive in some of the most hostile and extreme regions on the planet. In the desert, temperatures can range from scorching 49º C to freezing -40º C.
To help them cope with these extreme temperature changes, the bacterial camel’s hair (two humps) gets thicker in winter.
A camel can go a whole week without water—and survive even longer without knowing it if it isn’t working hard. They withstand a weight loss of about 4%, which for an adult bacterial translates to approximately 19 kg.
They can also, however, absorb water like a sponge. A thirsty camel can drink 130 liters in just 13 minutes — that is, 10 liters every 60 seconds.
Another important adaptation of camels is their ability to limit perspiration. One might imagine that the last thing an animal living in extreme heat needs is a fur coat. However, if a camel lost its thick coat it would consume 50% more water.
The fur provides great insulation. In addition to being useful on cold desert nights during the day, when outside temperatures are much higher than the camel’s body, this blanket prevents heat from entering your body.
In many ways, the camel’s secret lies in its ability to stay “cool” and barely sweat.
During the night, its body temperature fluctuates around 34º C. This gives the camel a kind of shock absorber so that it can withstand more heat the next day.
The camel only needs to sweat when its body temperature reaches around 41°C. With its fur coat acting as a barrier against external heat, it’s possible that it’s only sweating for a couple of hours, later in the day, which means considerable water savings.
In fact, in a hot, dry desert, a camel that can weigh at least five times as much as a human uses only a quart of water every hour.
And here’s a curious fact: many of these adaptations to extreme weather come from their arctic ancestors. Modern camels evolved at the North Pole.
Colds like a camel
The camels’ amazing evolutionary strategies for keeping cool have greatly attracted the interest of scientists who are looking for ways to keep food and medicine cool, for long periods of time, without a refrigerator or any form of external energy.
Achieving this would undoubtedly bring enormous benefits to preserving such products and extending their shelf life.
But not just that. According to the International Energy Agency, world demand for energy for cooling —measured by demand for refrigerators, freezers and air conditioners—is expected to triple by 2050.
As the negative impact of this increase in climate change would be enormous, there is a need to develop new ways to prevent products from heating up without the use of electricity.
These methods are known as passive cooling. We’ve experienced a great example of passive cooling ourselves: when we get hot and start to sweat, the evaporation of our sweat cools our body.
One of the most promising solutions is based on the evaporation of hydrogels.
What is hydrogel?
A hydrogel is a polymeric material, which is composed of long repeated chains of molecules and which, depending on the molecules, have different properties.
The properties of hydrogels are that, in addition to absorbing and retaining a lot of water, they can release it through evaporation, without the need for an external energy source.
This is why scientists in search of passive cooling methods have been so interested in them for quite some time.
The challenge, however, has always been how to make this effect last for longer periods of time — and camels could have the solution.
A team led by Jeffrey Grossman, at the Massachusetts Institute of Technology (MIT), in the United States, found their inspiration in camels.
Combining a layer of hydrogel with a thin layer of another gel called airgel —or icy smoke—, composed of between 90.50% and 99.98% of air and which is an insulating material, the group imitated the biological cooling system of the camels.
To understand it better, there are two layers. The hydrogel one, underneath, is like the sweat gland on a camel. It allows water to evaporate and provides a cooling effect.
The airgel layer above plays the same role as a camel’s fur, providing crucial insulation and preventing the surrounding heat from passing through, while allowing water vapor from the hydrogel to escape as it is highly porous.
one centimeter protective
By achieving evaporation and insulation at the same time, the cooling period is significantly extended. This combination of two layers of gel, or bilayer as it is technically called, is only an inch thick.
The MIT team tested their bilayer in the laboratory using a special chamber, with controlled temperature and humidity, and found it was able to cool an object to 7º C less than the temperature around it.
Compared to a single layer of hydrogel, the length of time the bilayer could keep an object cool increased by 400%. As Grossman pointed out, that means more than 250 hours, or ten days of cool down.
The team said their project could also help cool buildings and thereby reduce overall energy consumption.
The next step for the group of scientists is to make the material more scalable. In other words, they need to find a way to more easily produce it in larger sizes and quantities.
When you consider how often we need to transport food and medicine, sometimes to places where there is little or no access to refrigerators or even power, the value of such a passive cooling system is clear. The Covid-19 pandemic, with the need to transport vaccines at low temperatures, reminded us once again of this common challenge.
A solution like the one sought by the MIT team would be fantastic for the environment, with the potential to become a technology that saves lives. All thanks to the camel, this curious creature that inhabits the desert.
This report is an adaptation of the episode “Camel and Cold Medicines”, from the series “30 Animals That Made Us Smarter”, from the BBC World Service.