At a glance, humans look pretty out of place in the ocean. We have low-capacity lungs, lack insulation, and our concept of "swimming" is laughably inefficient compared to our finned mammalian cousins. But thanks to a handful of adaptive traits, we might be much more at home in the lineup than we realize.
01. Finger and Toe Pruning
Wrinkly phalanges aren't just an indicator that you've shunned your land responsibilities for far too long. When humans are in an aquatic environment for extended periods of time, the blood vessels in our fingers and toes constrict, causing them to prune. All of those wrinkles actually increase your grip. A study conducted by Newcastle University in England showed that individuals move wet objects 12 to 15 percent faster with pruned fingers. So if you're going leashless, pruned toes might just be the difference between bragging about your last turn and fetching your board from the kids in the shorebreak.
02. Mammalian Diving Reflex
Ever feel your heart stop when you duck dive that first icy set? Well, it didn't stop, but it did slow down a little bit. When the human face hits cold water, a process known as the mammalian diving reflex initiates. This causes the body to experience bradycardia, slowing the heart rate by 10 to 25 percent. As the heart rate slows, the need for blood-stream oxygen is reduced, leaving more oxygenated blood for vital organs. Peripheral vasoconstriction ensues, sealing capillaries in the extremities. All of these phenomena result in increased survivability underwater, which is good news for big-wave surfers.
03. Underwater Vision
When we see a shadow underwater, we're hard pressed to tell if it's a shark, a dolphin, or some guy on a bodyboard. The curved corneal surface of the eye is what accounts for the majority of its refractive power, and we lose that power in water. But, according to one study, exposing your eyes to underwater environments frequently can improve underwater vision. A tribe of sea gypsies in Southeast Asia known as the Moken relies heavily on foraging food from the ocean floor. Analysis conducted on this population showed that their underwater vision was actually two to three times better than the average European eye. Through years of exposure to aquatic environments, the Moken increased their maximum pupil constriction, allowing for better vision underwater.
04. Controlled Breathing
Breathing is an involuntary process for most terrestrial mammals, but we have substantial control over our respiration. Selective pressures on our evolutionary ancestors caused the relocation of the larynx from our nose to our throats—a feature shared by many aquatic animals. This development was mostly for vocalization purposes, but it also provided other benefits—namely the ability to close the trachea while diving and facilitate massive surfacing breaths after a long period of submersion. So the next time you're sucking wind like a vacuum after a two-wave hold-down, thank your larynx.
05. Infantile Swimming Reflexes
Maybe you weren't really born to surf, but in a sense, you were born to swim. Newborns come screaming into this world with several swimming reflexes. When an infant is submerged, it will instinctively hold its breath and open its eyes. And, until about 6 months old, infants placed on their stomachs in water will naturally move their arms and legs in a swimming fashion. The fear many people have of water, or the ocean, doesn't develop until long after birth. After all, birth is kind of like making your first barrel. And that's the only time it's cool to claim by crying.