Mediterranean climate, tropical climate… Curiously, the origin of the word climate is due to the subdivisions that the Greek geographers drew on their maps: the climata . It comes from the Greek word clima , which means tilt, because the length of the day depends on the tilt with which the Sun is seen from each specific location. In this way, climata were defined as those areas in which the length of the longest day was the same . Ancient geographers did not agree on the number of zones that should be distinguished. Of all the disputed diagrams the most popular was Pliny’s, which divided the known Earth into seven zones north of the equator.
If the word climate changed its original meaning, it was due to the comments of authors such as Strabo, who associated the characteristics of fauna, flora, and human beings with those bands along the equator. Thus, the dark complexion of the Ethiopians was due to the hot sun of the tropical climate and the blond hair of the northerners was caused by the coldness of the arctic climate .
It’s hot
There are days when we have no choice but to go outside at 4 in the afternoon. Then we feel that scorching heat that melts the stones and we usually remember, not too indulgently, the Sun. However, the fault is not theirs, but our planet. The Sun emits the same amount of light every day of the year – and has been doing so for 6 billion years – but it is the tilt of the Earth’s axis of rotation that is responsible for the seasons . In summer it is not hot because we are closer to the Sun; in fact, we are further away than in winter. What happens is that the Earth is tilted in such a way that the sun’s rays fall perpendicularly on our heads; that warms up the atmosphere… and our ideas.
But the most curious thing is that if it weren’t for the Moon, the Earth’s axis would nod off as if it were drunk. Our enormous satellite – astronomers say that ours is a double planetary system – is responsible for the evolution of the seasons being maintained for centuries and centuries.
As the song by Los Rodríguez says, it’s hot, especially this summer. If someone tells us, we understand immediately. Apparently ‘heat’ is one of the easiest concepts to understand, it’s so common that everyone knows what it means. Or not? Because what is heat? Think about it for a moment. When you say “I’m hot”, what are you saying? It is curious that the verb to have is used together with heat or cold, with which it is expressed that something is possessed or that something enters the body. Perhaps some kind of substance or matter that penetrates our body and commits barbarities such as making us sweat. At the end of the 18th century, scientists believed the same thing, that heat was a weightless substance , and therefore undetectable, that passed from one body to another: caloric. We have this idea so implanted in our brain that it is quite difficult for us to accept what heat really is. Heat is not a substance, it is not a thing . Heat is nothing more than a process, a way of transmitting energy from one body to another with a clear effect: to increase the temperature of the body in question.
Why do we sweat?
We may not know exactly what heat is, but what is certain is that because of it we can sweat like pigs. It’s all because of being warm-blooded animals. Our metabolism, the chemical reactions that make our body work, are very sensitive to temperature and therefore we must have a good thermoregulatory mechanism. Hence we sweat.
Most mammals sweat through the nasal mucosa, tongue and mouth. We do it differently. We regulate temperature with five million sweat glands spread across the skin, dissipating 95% of the heat generated by the body when we exceed normal operating temperature . The sweat combined with the outside air produces a cooling effect. The drier the air and the faster it strikes, the more it cools.
Apparently, sweating, running – the human being is capable of leaving behind any animal when it comes to long distances – and having a big brain are related . Millions of years ago, a large brain allowed Homo erectus to run for a long time, even in the hot midday sun: having spare nerve cells decreased the chance that his brain would suffer heat damage.
So sweating is good, but it’s not so good if one hot afternoon we have to take the city bus at rush hour. With the heat and full of people it becomes a perfect place to appreciate body odor in all its intensity. An odor that, despite appearances, is not produced directly by sweat.
The problem of axillary odor is due to the fact that heat and humidity combine in that area , two key factors for the development of an important bacterial flora. It is these tiny hosts, who live, proliferate, die and decompose in the armpits, that are responsible for the odor that stinks public transport in summer.
By the way, it’s not just bacteria that make feet smell like cheese. A few years ago in the United States, some new brand carpets were found to smell like cat urine. After the appropriate analysis, the culprit was discovered: certain bacteria that emit butyric acid, whose smell is very similar to that of urine.
Now you know. The sweat does not smell . The fault lies with the stowaways that we all carry with us…
Deodorants and antiperspirants
Fighting underarm stink has been a constant throughout history. The Egyptians took aromatic baths and applied scented oils to their armpits . They also found that shaving armpit hair significantly reduced the odour. For an obvious reason: hairs provide extra surface area for bacteria to grow. Greeks and Romans followed the Egyptian recommendations, which basically was none other than perfuming the armpits to cover one odor with another. The only effective deodorant, apart from regular washing, is the one that attacks the root problem: the perennial humidity under the arms. These are antiperspirants, which first appeared in 1888. It was called Mum and consisted of a zinc compound in a cream base . At the beginning of the 20th century, others appeared that used aluminum chloride and that we can find in a large part of modern deodorants. It is not very well known how they work, but what is certain is that their effect is not prolonged. And there is nothing like washing…
