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Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey

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Speaker 1: brain Stuff, Lauren Vogel Bomb. Here, we humans have done

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Speaker 1: pretty well for ourselves evolutionarily speaking, with our winning combo

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Speaker 1: of dexterity, intellect, endurance and a scrappy can do attitude.

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Speaker 1: But although humans are physiologically tricked out in a lot

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Speaker 1: of ways, other animals have evolved capabilities that we don't have,

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Speaker 1: sniffing out water sources, for example. That ability seems like

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Speaker 1: it would have been of great evolutionary advantage to us,

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Speaker 1: considering that relative to most other animals, humans have exceptionally

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Speaker 1: high water intake requirements, and so if dogs, elephants, and

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

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Speaker 1: Before we get too far down this rabbit hole, let's

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Speaker 1: be clear about two things. First, science has always characterized

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Speaker 1: the human olfactory senses being just so. So, though recent

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Speaker 1: research suggests that we might be able to differentiate between

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Speaker 1: around a trillion different odors, modern humans don't interface with

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Speaker 1: the world through our shnaz is as much as some

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Speaker 1: other animals do. Also, water is odorless. This chemical element

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Speaker 1: is a total non negotiable requirement for almost every organism

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Speaker 1: on Earth. But it's just a couple of hydrogen atoms

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Speaker 1: stuck with covalent bonds onto an oxygen atom. There's nothing

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Speaker 1: smelly going on there. So it seems that American environmentalist

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Speaker 1: Edward Abbey was onto something when he wrote in his

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Speaker 1: memoir Desert Solitaire, a season in the Wilderness in quote

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Speaker 1: long enough in the desert, a man, like other animals,

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Speaker 1: can learn to smell water, can learn at least the

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Speaker 1: smell of things associated with water. The unique and heartening

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Speaker 1: odor of the cottonwood tree, for example, which in the

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Speaker 1: canyon lands is the tree of life. Because although plane

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Speaker 1: H two has no scent, chemically pure water are also

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Speaker 1: basically never occurs in nature. You've got to make that

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Speaker 1: stuff in a lab. So when other animals sniff out

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

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Speaker 1: It might be a water loving cottonwood tree, or other

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Speaker 1: stuff in or around or otherwise associated with the presence

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Speaker 1: of fresh water, chemicals, bacteria, algae, plant matter, or minerals.

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Speaker 1: For the article, this episode is based on How Stuff Work.

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Speaker 1: Spoke with Dr Kara Hoover, and anthropology professor at the

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Speaker 1: University of Alaska, Fairbanks. Doctor Hoover specializes in the evolution

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Speaker 1: of human smell. She said, humans, like all terrestrial animals,

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Speaker 1: smell volatile or airborne compounds. Our class one olfactory receptor

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Speaker 1: genes that detect water born odors are switched off, so

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Speaker 1: we can smell water via other compounds in it that

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Speaker 1: get released into the air through a variety of physical processes.

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Speaker 1: According to Hoover, people have evolved to take pretty detailed

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Speaker 1: visual and auditory inventor worries of their surroundings, and though

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Speaker 1: our olfactory assessments aren't often as thorough as those of

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Speaker 1: some other animals, we are perfectly capable of detecting a

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Speaker 1: nearby swimming pool when we smell chlorine, and we can

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Speaker 1: pick up on the sulfuric odor of a hot spring,

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Speaker 1: or that mineral rich dead fish thing that the ocean's

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Speaker 1: got going on. Like Edward Abbey said, we might be

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Speaker 1: able to teach ourselves to detect water sources if we

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Speaker 1: applied ourselves to learning the smells that go along with it.

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Speaker 1: Another reason humans don't smell sources of water as well

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Speaker 1: as other animals maybe precisely because we need a lot

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Speaker 1: of it. Our bodies require extravagant amounts of the stuff

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Speaker 1: due to the way that we sweat. According to Hoover,

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Speaker 1: walking exclusively on two feet came with some physiological shifts

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Speaker 1: that drastically raised our water requirements. Hooever said, one major

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Speaker 1: shift is our ratio of echerne to apocrine glands. Modern

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Speaker 1: humans have more echerne glands than any other mammal. These

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Speaker 1: glands release water and to a lesser extent, sodium from

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Speaker 1: our bodies when we sweat a Shedding water through ecrine

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Speaker 1: glands is less energetically costly than shedding nutrients through apocrine glands,

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Speaker 1: which is why humans will always beat a horse in

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Speaker 1: a long distance race as long as there's water available.

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Speaker 1: Hoover suggests that between four and seven million years ago,

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Speaker 1: when our ancestors became bipetle, they became tied to sources

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

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Speaker 1: needed to know where to find reliable sources of water

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Speaker 1: in their home territories or long regularly traveled roots. Hoover said,

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Speaker 1: but we have no way of knowing, but most likely

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Speaker 1: our original home ranges included water sources that were cognitively mapped.

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Speaker 1: As ranges expanded and new sources would be located, and

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Speaker 1: maybe that next watering hole could be found by just

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Speaker 1: following an elephant around for a while. Who needs a

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

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Speaker 1: on the article why didn't evolution give us the ability

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Speaker 1: to smell fresh water? On house toff works dot com

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Speaker 1: written by Jesslyn Shields. The brain Stuff is production of

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Speaker 1: Our Heart Radio and partnership with hous toff works dot com,

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Speaker 1: and it's produced by Tyler Playing the four more podcasts

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