The Snake: Change in swimming techniques under the pressure of selection

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We know that natural selection brought marine mammals to favor lift-based propulsion rather than drag-based propulsion. Curiously, none of these techniques is favored in swimming competitions by professional swimmers. Is it possible to invent new swimming styles under the pressure of selection as marine mammals did? We wondered if 61 athletes would be able to replicate the techniques used by the species most adapted to the aquatic environment, without being forced to it and with the sole intention of swimming faster. We imagined a system of shoulder-to-shoulder duel in ascent/descent. There were two swimmers in each lane. In each lane, a weighted object was placed at the bottom of the water, 15 meters from the pool deck. The first to grab the object in his lane won the duel and moved up one lane for the next trial. After eight duels, the best swimmers were in lane eight, the slowest in lane one. Six techniques have emerged from the 244 duels in forced immersion (488 divesfollowed by 15-meter races): (i) moving with the legs only, arms along the body (beats), (ii) total breaststroke, (iii) hybrid breaststroke (simultaneous and symmetrical arm movements, synchronous to the leg beats), (iv) gallop: undulation of the body with leg beats, (v) undulation of the whole body, (vi) the snake technique:characterized by a leg beat synchronous to an oscillation of the upper part of the body, with the arms along the trunk. Although the matching is not perfect, the processes used by swimmers fit the models presented to describe the odyssey of mammals that have been going back to the water for 60 million years: the fastest swimming techniques are the ones that best mimic the marine mammals that are best adapted to speed ("pectoral oscillation" like sea lions; "caudal oscillations" like whales). The later favor lift forces over propulsive drag forces (drag forces which can be observed in dogs, rats and other swimmers in Johnny Weissmuller’s freestyle that use "quadrupedal paddling" and "alternative pectoral paddling”). The competition swimmers observed were able to experimentally reproduce the choices of natural selection. But today, the fastest ways of moving in the water are not found in the Swimming Federation training sessions.