There are many groups of people the world over who are renowned for unique adaptations to their environment. These range from the tribal groups of the deep Amazon, whose hunter-gathering way of life has remained primarily unchanged for thousands of years, to the enigmatic Sherpas, whose genetics allow them to traverse the steep Himalayan slopes without suffering the effects of the thin air at those altitudes.
Similar feats are achieved almost daily by the Bajau of Southeast Asia, especially where oxygen is concerned. These “sea nomads”, as they are often called, have the unique ability to hold their breath for minutes at a time, ranking them among the world’s most unparalleled divers (and hence their unique nickname).
Some of the Bajau divers are able to operate underwater with such ease that it led to speculation as to whether they had adapted genetically over time, similar to people who thrive in higher altitudes. Last spring, evolutionary geneticist Melissa Ilardo led a study that proposed such adaptations might involve the unusually large spleens found among the Bajau, outlined in a paper published in the journal Cell. Similar adaptations have been observed in ocean-dwelling mammals, such as sperm whales which are able to hold their breaths for up to 90 minutes thanks to a substance in their bloodstream called myoglobin, which binds oxygen in their blood and becomes electrically-charged when the whales go underwater.
The Bajau perform their incredible diving feats completely naturally, although the current record for a human holding their breath underwater is held by 47-year-old Peter Colat, a diver from Zurich, Switzerland, who managed to hold his breath for an astounding 19 minutes and 21 seconds in 2010.
Colat, who was 38-year-old at the time, managed to achieve this through oxygen-assisted static apnea, where one breathes pure oxygen for 10 minutes prior to diving, according to rules set by the Guinness Book of World Records. His record ousted the previous record holder, Nicola Putignano of Italy, by just 19 seconds.
It begs the question, just how long could a person or animal survive underwater with the help of a little extra added oxygen? More specifically, what if rather than holding their breath, the mammals in question were able to breathe oxygen from the water itself?
Perhaps the earliest study looking into this goes all the way back to 1964, as reported in the journal Sea Frontiers by Johannes A. Kylstra, which discussed experiments with mice that involved such processes. The experiments were conducted in chambers partially filled with water, where the air was replaced with compressed oxygen and pressurized equivalent to that of eight atmospheres, allowing for an artificially oxygen-enriched liquid environment below it. Finally, salts which are similar to those that appear naturally in the blood of mammals were added to the water.
The study found that mice introduced into the liquid environment were actually able to “breathe for several minutes and, in some cases, hours.” Temperature was also a factor in survival, with mice surviving the longest at a temperature of 68°F. The mice, despite being within a liquid environment, were found to be “active and alert,” and “did not appear to be in severe distress” while submerged in the oxygenated water.
Most of the mice began to lose consciousness within half an hour of entering the liquid environment. Subsequent experiments involved the introduction of a chemical buffer into the water, which helped preserve a constant acidity in the liquid solution, whereafter some of the mice responded to stimuli such as shaking or tapping the outside of the tank for up to six hours while submerged.
These initial studies led to further experiments with perfluorinated hydrocarbons, which unlike the oxygenated water from the earlier studies, could more effectively remove carbon dioxide from the lungs. The most effective substance of this variety, called perflubron, has roughly double the density of water, and can also carry as much as twice the amount of oxygen as air (this substance is most often referenced as “radiopaque perfluorocarbon solution for lung lavage,” and is sold under the name “LiquiVent” in the United States and other countries, generally only for research purposes).
If all of this sounds a lot like the famous liquid breathing apparatus used by Ed Harris during the climax of the sci-fi film The Abyss, you wouldn’t be the only one who thinks so. In fact, several years ago during a revolutionary medical procedure that was used to save Adrianna Mancini–a child born five months premature–Dr. Jay Greenspan at Thomas Jefferson University Hospital and Dr. Thomas Shaffer of Temple University in Philadelphia employed the then-experimental process of liquid ventilation in order to save the child’s life, after comparing it to the liquid featured in the famous film.
“I knew that I was watching medical history being made,” Mancini later told Reader’s Digest. Shafer and Greenspan’s procedure went on to be used to save other premature infants in the years that followed.
Quite obviously, the futuristic deep-sea breathing apparatus featured in The Abyss was partially inspired by the real-life science described here (in fact, one scene in the film actually depicts a rat being submerged in a perfluorinated hydrocarbon-like liquid; an obvious a nod to the 1960s studies that introduced the idea). But what began with experiments aimed at helping mice breathe in special liquid environments did more than just inspire the world of sci-fi, and now, the real-world applications of these studies can even help save lives.