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There are several oddities about humans that seem to indicate that we were semi-aquatic at one time: webbed fingers and toes, hairlessness (compared to other pr

There are several oddities about humans that seem to indicate that we were semi-aquatic at one time: webbed fingers and toes, hairlessness (compared to other primates and hominids, we are the "naked ape"), our big beak noses that help keep water out of our nasal passages (some people can voluntarily seal their nostrils), our babies float and instinctively hold their breath, the fine hairs on our backs are slanted towards our spine (rather than away like all other primates) improving flow, our fingerprints that swell and wrinkle when wet making it easier to grip things, our eyes have a special "underwater mode", etc.

thatwasunusual 5y ago
> our babies float and instinctively hold their breath This is just partly true, however, and I assume you don't mean that babies are natural born swimmers. :) Ref. Wikipedia; "Babies are not old enough to hold their breath intentionally or strong enough to keep their head above water, and cannot swim unassisted. Most infants, though not all, will reflexively hold their breath when submerged to protect their airway and are able to survive immersion in water for short periods of time." [0] [0] https://en.wikipedia.org/wiki/Infant_swimming https://en.wikipedia.org/wiki/Infant_swimming
- abfan1127 5y ago
  We put all 3 of our kids through ISR (Infant Swim Resource). they started at 9 months (based on summer relative to their birthdays). Its pretty incredible to see a 6-9 month old baby float indefinitely. At a year, they teach them to "swim, float, swim". The swim phase is targeted to 5-7 sec of holding their breath while swimming. https://www.youtube.com/watch?v=jeY9zYkNf7M https://www.youtube.com/watch?v=jeY9zYkNf7M
Bayart 5y ago
Isn't the hair stuff mostly explained by running on two legs and thermal regulation ?
- Scaevolus 5y ago
  Yes. Also, most every mammals other than whales _still_ have fur (seals, sea lions, otters, etc), so it's not clear that hairlessness has strong selection pressure.
  - scotty79 5y ago
    When thinking about what water humans had a contact with at one time you should rather think of hippos not otters. Shalow, warm, maybe even not salty water? It must have been significant food source if we have very specific adaptation to gipping something in water.
    - Scaevolus 5y ago
      Pruney fingers are a general primate adaptation, and likely have more to do with not slipping from trees when it rains than any serious aquatic phase.
      - scotty79 5y ago
        Not that general. The only other species I can find mentioned to have pruney fingers are macaque monkeys. And we are unsure if that's a remnant of common ancestor or a parallel evolution.
jvanderbot 5y ago
I think that has a lot more to do with enabling us to walk, jog, and work long hours by sweating to keep cool. More water lost, but huge competitive advantage in endurance. Since we're literally oozing water, I'm guessing all those water-adaptive advantages start to make more sense for landlubbers.
drewmol 5y ago
Interesting. I happened to be one of those natural born swimmers (not as newborn) as an infant as I could float, move around by wiggling like a fish and close nasal passages instinctively (w/o exhaling) at 8 months. Always perplexed me that some people will hold their nose closed or have to exhale through it while under water.
francisofascii 5y ago
Also, humans enjoy being near large bodies of water. (oceans, lakes, etc.)
- mongol 5y ago
  Yes. The price of seafront property is a strong indicator or our aquatic past.
  - sparker72678 5y ago
    I would definitely read a paper with this as the premise, regardless of the quality of the research.
warent 5y ago
Voluntarily sealing your nostrils is something I never knew about until I was complaining about some city odor to a girlfriend who said "Just plug your nose." I said I didn't just want to walk around pinching my nose, and she gave me the most incredulous look. She was like "No, just do it without touching your face..." This definitely shocked me. May as well ask me to sprout wings and fly!
- carlosf 5y ago
  Wait, what? People can do that? That's the coolest thing since a friend showed me he could move his ears.
  - skohan 5y ago
    You can't? Have you tried it?
    - Majestic121 5y ago
      I'm not sure how to start trying it. I can move my nostrils a bit, but it's more to expand them : I don't have any muscle 'plugging' them it seems Or are you supposed to plug from the inside, with your tongue blocking the top of the mouth kind of ?
      - checkyoursudo 5y ago
        I don’t know about others but I don’t use my tongue. I can block my nasal passage and breathe through my mouth. I can have my mouth wide open and do this. It must be controlled by some muscle but I don’t know what.
        robofanatic 5y ago
        you can either breath through nose or mouth not simultaneously. I thought this is normal ..
pvaldes 5y ago
Yep, the semi-aquatic simian theory to explain bipedalism. If I remember correctly, It was disproven yet when we studied it in anthropology course.
iancmceachern 5y ago
My cousin can do it with his upper lip, he just moves it up like a flap and it covers both nostrils!

thatwasunusual 5y ago

> our babies float and instinctively hold their breath This is just partly true, however, and I assume you don't mean that babies are natural born swimmers. :) Ref. Wikipedia; "Babies are not old enough to hold their breath intentionally or strong enough to keep their head above water, and cannot swim unassisted. Most infants, though not all, will reflexively hold their breath when submerged to protect their airway and are able to survive immersion in water for short periods of time." [0] [0] https://en.wikipedia.org/wiki/Infant_swimming https://en.wikipedia.org/wiki/Infant_swimming

abfan1127 5y ago
We put all 3 of our kids through ISR (Infant Swim Resource). they started at 9 months (based on summer relative to their birthdays). Its pretty incredible to see a 6-9 month old baby float indefinitely. At a year, they teach them to "swim, float, swim". The swim phase is targeted to 5-7 sec of holding their breath while swimming. https://www.youtube.com/watch?v=jeY9zYkNf7M https://www.youtube.com/watch?v=jeY9zYkNf7M

Bayart 5y ago

Isn't the hair stuff mostly explained by running on two legs and thermal regulation ?

Scaevolus 5y ago
Yes. Also, most every mammals other than whales _still_ have fur (seals, sea lions, otters, etc), so it's not clear that hairlessness has strong selection pressure.
- scotty79 5y ago
  When thinking about what water humans had a contact with at one time you should rather think of hippos not otters. Shalow, warm, maybe even not salty water? It must have been significant food source if we have very specific adaptation to gipping something in water.
  - Scaevolus 5y ago
    Pruney fingers are a general primate adaptation, and likely have more to do with not slipping from trees when it rains than any serious aquatic phase.
    - scotty79 5y ago
      Not that general. The only other species I can find mentioned to have pruney fingers are macaque monkeys. And we are unsure if that's a remnant of common ancestor or a parallel evolution.

jvanderbot 5y ago

I think that has a lot more to do with enabling us to walk, jog, and work long hours by sweating to keep cool. More water lost, but huge competitive advantage in endurance. Since we're literally oozing water, I'm guessing all those water-adaptive advantages start to make more sense for landlubbers.

drewmol 5y ago

Interesting. I happened to be one of those natural born swimmers (not as newborn) as an infant as I could float, move around by wiggling like a fish and close nasal passages instinctively (w/o exhaling) at 8 months. Always perplexed me that some people will hold their nose closed or have to exhale through it while under water.

francisofascii 5y ago

Also, humans enjoy being near large bodies of water. (oceans, lakes, etc.)

mongol 5y ago
Yes. The price of seafront property is a strong indicator or our aquatic past.
- sparker72678 5y ago
  I would definitely read a paper with this as the premise, regardless of the quality of the research.

warent 5y ago

Voluntarily sealing your nostrils is something I never knew about until I was complaining about some city odor to a girlfriend who said "Just plug your nose." I said I didn't just want to walk around pinching my nose, and she gave me the most incredulous look. She was like "No, just do it without touching your face..." This definitely shocked me. May as well ask me to sprout wings and fly!

carlosf 5y ago
Wait, what? People can do that? That's the coolest thing since a friend showed me he could move his ears.
- skohan 5y ago
  You can't? Have you tried it?
  - Majestic121 5y ago
    I'm not sure how to start trying it. I can move my nostrils a bit, but it's more to expand them : I don't have any muscle 'plugging' them it seems Or are you supposed to plug from the inside, with your tongue blocking the top of the mouth kind of ?
    - checkyoursudo 5y ago
      I don’t know about others but I don’t use my tongue. I can block my nasal passage and breathe through my mouth. I can have my mouth wide open and do this. It must be controlled by some muscle but I don’t know what.
      - robofanatic 5y ago
        you can either breath through nose or mouth not simultaneously. I thought this is normal ..

pvaldes 5y ago

Yep, the semi-aquatic simian theory to explain bipedalism. If I remember correctly, It was disproven yet when we studied it in anthropology course.

iancmceachern 5y ago

My cousin can do it with his upper lip, he just moves it up like a flap and it covers both nostrils!