Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hey
Speaker 1: brain Stuff, Lauren Vogel Bomb. Here, we humans have done
Speaker 1: pretty well for ourselves evolutionarily speaking, with our winning combo
Speaker 1: of dexterity, intellect, endurance and a scrappy can do attitude.
Speaker 1: But although humans are physiologically tricked out in a lot
Speaker 1: of ways, other animals have evolved capabilities that we don't have,
Speaker 1: sniffing out water sources, for example. That ability seems like
Speaker 1: it would have been of great evolutionary advantage to us,
Speaker 1: considering that relative to most other animals, humans have exceptionally
Speaker 1: high water intake requirements, and so if dogs, elephants, and
Speaker 1: vultures seem to be able to smell water, why can't we?
Speaker 1: Before we get too far down this rabbit hole, let's
Speaker 1: be clear about two things. First, science has always characterized
Speaker 1: the human olfactory senses being just so. So, though recent
Speaker 1: research suggests that we might be able to differentiate between
Speaker 1: around a trillion different odors, modern humans don't interface with
Speaker 1: the world through our shnaz is as much as some
Speaker 1: other animals do. Also, water is odorless. This chemical element
Speaker 1: is a total non negotiable requirement for almost every organism
Speaker 1: on Earth. But it's just a couple of hydrogen atoms
Speaker 1: stuck with covalent bonds onto an oxygen atom. There's nothing
Speaker 1: smelly going on there. So it seems that American environmentalist
Speaker 1: Edward Abbey was onto something when he wrote in his
Speaker 1: memoir Desert Solitaire, a season in the Wilderness in quote
Speaker 1: long enough in the desert, a man, like other animals,
Speaker 1: can learn to smell water, can learn at least the
Speaker 1: smell of things associated with water. The unique and heartening
Speaker 1: odor of the cottonwood tree, for example, which in the
Speaker 1: canyon lands is the tree of life. Because although plane
Speaker 1: H two has no scent, chemically pure water are also
Speaker 1: basically never occurs in nature. You've got to make that
Speaker 1: stuff in a lab. So when other animals sniff out
Speaker 1: a water source, it isn't the water itself they're smelling.
Speaker 1: It might be a water loving cottonwood tree, or other
Speaker 1: stuff in or around or otherwise associated with the presence
Speaker 1: of fresh water, chemicals, bacteria, algae, plant matter, or minerals.
Speaker 1: For the article, this episode is based on How Stuff Work.
Speaker 1: Spoke with Dr Kara Hoover, and anthropology professor at the
Speaker 1: University of Alaska, Fairbanks. Doctor Hoover specializes in the evolution
Speaker 1: of human smell. She said, humans, like all terrestrial animals,
Speaker 1: smell volatile or airborne compounds. Our class one olfactory receptor
Speaker 1: genes that detect water born odors are switched off, so
Speaker 1: we can smell water via other compounds in it that
Speaker 1: get released into the air through a variety of physical processes.
Speaker 1: According to Hoover, people have evolved to take pretty detailed
Speaker 1: visual and auditory inventor worries of their surroundings, and though
Speaker 1: our olfactory assessments aren't often as thorough as those of
Speaker 1: some other animals, we are perfectly capable of detecting a
Speaker 1: nearby swimming pool when we smell chlorine, and we can
Speaker 1: pick up on the sulfuric odor of a hot spring,
Speaker 1: or that mineral rich dead fish thing that the ocean's
Speaker 1: got going on. Like Edward Abbey said, we might be
Speaker 1: able to teach ourselves to detect water sources if we
Speaker 1: applied ourselves to learning the smells that go along with it.
Speaker 1: Another reason humans don't smell sources of water as well
Speaker 1: as other animals maybe precisely because we need a lot
Speaker 1: of it. Our bodies require extravagant amounts of the stuff
Speaker 1: due to the way that we sweat. According to Hoover,
Speaker 1: walking exclusively on two feet came with some physiological shifts
Speaker 1: that drastically raised our water requirements. Hooever said, one major
Speaker 1: shift is our ratio of echerne to apocrine glands. Modern
Speaker 1: humans have more echerne glands than any other mammal. These
Speaker 1: glands release water and to a lesser extent, sodium from
Speaker 1: our bodies when we sweat a Shedding water through ecrine
Speaker 1: glands is less energetically costly than shedding nutrients through apocrine glands,
Speaker 1: which is why humans will always beat a horse in
Speaker 1: a long distance race as long as there's water available.
Speaker 1: Hoover suggests that between four and seven million years ago,
Speaker 1: when our ancestors became bipetle, they became tied to sources
Speaker 1: of water, meaning they couldn't afford to sniff around. They
Speaker 1: needed to know where to find reliable sources of water
Speaker 1: in their home territories or long regularly traveled roots. Hoover said,
Speaker 1: but we have no way of knowing, but most likely
Speaker 1: our original home ranges included water sources that were cognitively mapped.
Speaker 1: As ranges expanded and new sources would be located, and
Speaker 1: maybe that next watering hole could be found by just
Speaker 1: following an elephant around for a while. Who needs a
Speaker 1: good nose when you've got brains. Today's episode is based
Speaker 1: on the article why didn't evolution give us the ability
Speaker 1: to smell fresh water? On house toff works dot com
Speaker 1: written by Jesslyn Shields. The brain Stuff is production of
Speaker 1: Our Heart Radio and partnership with hous toff works dot com,
Speaker 1: and it's produced by Tyler Playing the four more podcasts
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