10 Feb

The amphibious human

Boing Boing had this awesome link (which I can’t find to attribute) to a prof in one of my new favorite disciplines, neuro-anthropology, talking about mental and cultural adaptations to water living, specifically, free diving.

Too often, in discussions of human adaptation, we allow a flabby distinction between three basic types of adaptation: genetic, phenotypic (or physiological), and cultural (or technology). What I’ve been playing with, and will return to at the end of this piece, is the inseparability of these, especially the last two: physiology and culture. The Bajau fisherman Sulbin shows us how biology and culture are inseparable because what he does ends up shaping his body, but only because he grew up around people who knew how to manage becoming human in this distinctive amphibious way and because his adaptations play upon how his nervous system works, including some intriguing quirks.

Of interest to me, as I grew up in the Caribbean. I initially was born on land, in a house, but my family moved to a boat, right around when my earliest memories were formed (2-3?). I remember learning to swim off a dock. I remember learning how to free dive (swim deep without any breathing apparatus) from not too long after.

My first attempt to dive much deeper than 10-15 feet resulted in such crushing ear-pain that, although I snorkeled and swam constantly, I never pursued depth until I was a teen. My aunt took me scuba diving, and in the process taught me to equalize my ear drums (hold your nose tight and blow, the eardrums pop back out from being crushed by the pressure of the water). Once I’d learned that trick, I regularly began diving in the 15-30 foot range without much trouble at all.

Somewhere around 7th grade my stepdad purchased a several hundred dollar watch that had a depth meter on it. I began using that to gauge my dives.

For me it was the most zen-like experience, and I got better and better at holding my breath (though not as good as some friends also living on boats, my next door neighbor’s father boasted of 100+ free dives).

What was interesting about the article were bits like this:

Parkes argues that the central respiratory rhythm, an autonomic rhythm like the cardiac rhythm, persists during a breath hold, even though voluntary breath holding suppresses it active expression. This means that breath-holders are not so much stopping their breathing voluntarily as they are holding their chests open and resisting the respiratory rhythm. Parkes (2006: 8-9) points to a range of evidence which suggests that the respiratory rhythm intensifies during the breath hold, even causing more widespread respiratory-anticipating reactions like ‘trachial tugging’ in the lead up to the break point.

Yes, I’ve felt that! I’ve always wondered about it. Everything I’ve read about breath-holding was always weird, talking about urges you can’t fight (breathing) which, to me, always felt under habitual control once underwater. Even with your lungs burning and eighty feet under water, you were in control of those fight-to-breath urges. There were odd side effects, but it was truly one of those master moments.

My best dive was on the Wreck of the Rhone off Salt Island. It was around 80 feet at the bow (the stern is in shallower water) and very clear that day. One of the most mystical experiences I’ve ever had was getting to the bottom, and then looking back up in the crystal clear water at the surface, 80 feet overhead, like a roof capping a pale blue world, a roof that was way too far above.

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