Scientists are of the opinion that man has evolved after being first born in the sea. Historians will attest to the fact there a are cave drawings in Egypt that people swan even at that time but had probably been swimming from long before that time. Even the first written reference to swimming are over 4000 years old. We also know that there were swimming competitions organized in Europe at the beginning of the 19th century, and such competitions were held even prior to that date for certain.
As far as swimming styles are concerned, John Arthur Trudgen popularized the front crawl in 1873, but it was probably already widely used at the time. However, until that year, the breaststroke was the more popular swimming style in most of Europe and the US. Much later, the butterfly stroke became popular in 1952, even though it existed earlier but was considered a variation of the already popular breaststroke.
Although the composition of our bodies is largely water itself, there is also a lot of oil content which effectively makes the body lighter than water. Thus our bodies must float on water at around 50% below the surface. This is true under normal circumstances and one can make one's body float higher by paddling the water downwards, which in turn pushes the body upwards. Similarly one may move forward by pushing the water backward. Hence, in effect, when a combination of the two is used, a person is able to 'swim' and keeps his body above the water and keeps moving forward at the same time.
The density of the body being lighter than water also means that it is easier for humans to swim in salty water than it is in fresh water. This is because salt water is denser and causes the body to float higher in it, thus reducing the force needed to keep your body afloat. A lot of the swimming depends on the action of your hip, as the amount of water displaced by your hands is not enough to support the displacement needed to keep your body afloat.
Thus the arm muscles are insignificant but the thigh muscles are important to create a continuous and rhythmic beat as well as maintain co-ordination, which is also equally necessary. The next critical part of swimming is the breathing. Your body is under continuous exertion and breathing in rhythm is necessary. Most swimmers will benefit from inhaling on the first stroke, holding the breath in for the next stroke and then exhaling on the next two strokes. This will require you to lift your nose above the water surface only once in every four strokes.
Women Underwater UV Swimsuit
Finally, swimming is widely recognized as an excellent form of exercise as it extends and contracts many muscles of your body simultaneously and still does not put any pressure on your hips, knees or your ankles. Regular swimmers easily develop a well-toned body. Swimming increases the amount of Oxygen in blood and also causes your body to hold the air in and use all the benefits from the inhaled air. Thus the art of swimming comes with a ton of health benefits as well!