WEBVTT - Why Didn't We Evolve to Smell Water?

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<v Speaker 1>Welcome to brain Stuff production of I Heart Radio. Hey

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<v Speaker 1>brain Stuff, Lauren Vogel Bomb. Here, we humans have done

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<v Speaker 1>pretty well for ourselves evolutionarily speaking, with our winning combo

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<v Speaker 1>of dexterity, intellect, endurance and a scrappy can do attitude.

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<v Speaker 1>But although humans are physiologically tricked out in a lot

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<v Speaker 1>of ways, other animals have evolved capabilities that we don't have,

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<v Speaker 1>sniffing out water sources, for example. That ability seems like

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<v Speaker 1>it would have been of great evolutionary advantage to us,

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<v Speaker 1>considering that relative to most other animals, humans have exceptionally

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<v Speaker 1>high water intake requirements, and so if dogs, elephants, and

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<v Speaker 1>vultures seem to be able to smell water, why can't we?

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<v Speaker 1>Before we get too far down this rabbit hole, let's

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<v Speaker 1>be clear about two things. First, science has always characterized

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<v Speaker 1>the human olfactory senses being just so. So, though recent

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<v Speaker 1>research suggests that we might be able to differentiate between

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<v Speaker 1>around a trillion different odors, modern humans don't interface with

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<v Speaker 1>the world through our shnaz is as much as some

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<v Speaker 1>other animals do. Also, water is odorless. This chemical element

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<v Speaker 1>is a total non negotiable requirement for almost every organism

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<v Speaker 1>on Earth. But it's just a couple of hydrogen atoms

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<v Speaker 1>stuck with covalent bonds onto an oxygen atom. There's nothing

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<v Speaker 1>smelly going on there. So it seems that American environmentalist

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<v Speaker 1>Edward Abbey was onto something when he wrote in his

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<v Speaker 1>memoir Desert Solitaire, a season in the Wilderness in quote

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<v Speaker 1>long enough in the desert, a man, like other animals,

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<v Speaker 1>can learn to smell water, can learn at least the

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<v Speaker 1>smell of things associated with water. The unique and heartening

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<v Speaker 1>odor of the cottonwood tree, for example, which in the

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<v Speaker 1>canyon lands is the tree of life. Because although plane

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<v Speaker 1>H two has no scent, chemically pure water are also

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<v Speaker 1>basically never occurs in nature. You've got to make that

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<v Speaker 1>stuff in a lab. So when other animals sniff out

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<v Speaker 1>a water source, it isn't the water itself they're smelling.

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<v Speaker 1>It might be a water loving cottonwood tree, or other

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<v Speaker 1>stuff in or around or otherwise associated with the presence

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<v Speaker 1>of fresh water, chemicals, bacteria, algae, plant matter, or minerals.

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<v Speaker 1>For the article, this episode is based on How Stuff Work.

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<v Speaker 1>Spoke with Dr Kara Hoover, and anthropology professor at the

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<v Speaker 1>University of Alaska, Fairbanks. Doctor Hoover specializes in the evolution

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<v Speaker 1>of human smell. She said, humans, like all terrestrial animals,

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<v Speaker 1>smell volatile or airborne compounds. Our class one olfactory receptor

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<v Speaker 1>genes that detect water born odors are switched off, so

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<v Speaker 1>we can smell water via other compounds in it that

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<v Speaker 1>get released into the air through a variety of physical processes.

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<v Speaker 1>According to Hoover, people have evolved to take pretty detailed

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<v Speaker 1>visual and auditory inventor worries of their surroundings, and though

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<v Speaker 1>our olfactory assessments aren't often as thorough as those of

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<v Speaker 1>some other animals, we are perfectly capable of detecting a

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<v Speaker 1>nearby swimming pool when we smell chlorine, and we can

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<v Speaker 1>pick up on the sulfuric odor of a hot spring,

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<v Speaker 1>or that mineral rich dead fish thing that the ocean's

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<v Speaker 1>got going on. Like Edward Abbey said, we might be

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<v Speaker 1>able to teach ourselves to detect water sources if we

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<v Speaker 1>applied ourselves to learning the smells that go along with it.

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<v Speaker 1>Another reason humans don't smell sources of water as well

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<v Speaker 1>as other animals maybe precisely because we need a lot

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<v Speaker 1>of it. Our bodies require extravagant amounts of the stuff

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<v Speaker 1>due to the way that we sweat. According to Hoover,

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<v Speaker 1>walking exclusively on two feet came with some physiological shifts

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<v Speaker 1>that drastically raised our water requirements. Hooever said, one major

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<v Speaker 1>shift is our ratio of echerne to apocrine glands. Modern

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<v Speaker 1>humans have more echerne glands than any other mammal. These

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<v Speaker 1>glands release water and to a lesser extent, sodium from

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<v Speaker 1>our bodies when we sweat a Shedding water through ecrine

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<v Speaker 1>glands is less energetically costly than shedding nutrients through apocrine glands,

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<v Speaker 1>which is why humans will always beat a horse in

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<v Speaker 1>a long distance race as long as there's water available.

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<v Speaker 1>Hoover suggests that between four and seven million years ago,

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<v Speaker 1>when our ancestors became bipetle, they became tied to sources

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<v Speaker 1>of water, meaning they couldn't afford to sniff around. They

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<v Speaker 1>needed to know where to find reliable sources of water

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<v Speaker 1>in their home territories or long regularly traveled roots. Hoover said,

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<v Speaker 1>but we have no way of knowing, but most likely

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<v Speaker 1>our original home ranges included water sources that were cognitively mapped.

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<v Speaker 1>As ranges expanded and new sources would be located, and

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<v Speaker 1>maybe that next watering hole could be found by just

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<v Speaker 1>following an elephant around for a while. Who needs a

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<v Speaker 1>good nose when you've got brains. Today's episode is based

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<v Speaker 1>on the article why didn't evolution give us the ability

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<v Speaker 1>to smell fresh water? On house toff works dot com

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<v Speaker 1>written by Jesslyn Shields. The brain Stuff is production of

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<v Speaker 1>Our Heart Radio and partnership with hous toff works dot com,

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<v Speaker 1>and it's produced by Tyler Playing the four more podcasts

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