3 ms·

Which makes me think that seaweed was staple food at some time right? We wouldn't have evolved to need more iodine than we can get in our environment otherwise.

by soco 3y ago

Which makes me think that seaweed was staple food at some time right? We wouldn't have evolved to need more iodine than we can get in our environment otherwise...

civilitty 3y ago
According to WHO estimates [1], a quarter of Africans have goiters so I think it's safe to say that archaic humans suffered from chronic iodine deficiency. Evolution works through reproduction so any condition that doesn't impact survival until sexual maturity is unlikely to face any evolutionary pressure. Since humans are tribal and took care of their offspring in group settings, survivability after procreation also has little effect. [1] https://iris.who.int/bitstream/handle/10665/43010/9241592001.pdf https://iris.who.int/bitstream/handle/10665/43010/9241592001...
- wizofaus 3y ago
  > any condition that doesn't impact survival until sexual maturity Diseases that impact even just appearance can surely make you less attractive as a mate though. And larger goiters can impede breathing or swallowing. So I'd be suspicious of the idea that we've been significantly deficient in iodine for extended periods of our evolutionary history.
  - civilitty 3y ago
    Large goiters are rare and the vast majority are not outwardly visible nor do they impact breathing. I’d be far more suspicious of applying modern standards of beauty to humans that lived hundreds of thousands of years ago.
bostonpete 3y ago
That seems like a leap -- there's other foods that can provide sufficient iodine (e.g. fish, eggs, milk)...
ssnistfajen 3y ago
Goiter is usually not immediately lethal so for most of human history, people afflicted with it just kind of lived with it which likely meant there wasn't that much selective pressure against it. Consuming thyroid glands of terrestrial animals (usually ruminants) was an effective treatment of iodine dificiency before the modern nutritional sciences discovered the relationships between goiter and iodine deficiency: https://en.wikipedia.org/wiki/Goitre#History https://en.wikipedia.org/wiki/Goitre#History Ruminants are more efficient at absorbing nutrients from plant material due their digestive system, and this is how they get iodine in non-coastal areas. All vertebrates have thyroid glands and there is a very similar organ in marine chordates: https://en.wikipedia.org/wiki/Endostyle https://en.wikipedia.org/wiki/Endostyle. So this is an organ that likely emerged when our biological ancestors still lived in a iodine-rich environment.

by soco 3y ago

Which makes me think that seaweed was staple food at some time right? We wouldn't have evolved to need more iodine than we can get in our environment otherwise...

civilitty 3y ago

According to WHO estimates [1], a quarter of Africans have goiters so I think it's safe to say that archaic humans suffered from chronic iodine deficiency. Evolution works through reproduction so any condition that doesn't impact survival until sexual maturity is unlikely to face any evolutionary pressure. Since humans are tribal and took care of their offspring in group settings, survivability after procreation also has little effect. [1] https://iris.who.int/bitstream/handle/10665/43010/9241592001.pdf https://iris.who.int/bitstream/handle/10665/43010/9241592001...

wizofaus 3y ago
> any condition that doesn't impact survival until sexual maturity Diseases that impact even just appearance can surely make you less attractive as a mate though. And larger goiters can impede breathing or swallowing. So I'd be suspicious of the idea that we've been significantly deficient in iodine for extended periods of our evolutionary history.
- civilitty 3y ago
  Large goiters are rare and the vast majority are not outwardly visible nor do they impact breathing. I’d be far more suspicious of applying modern standards of beauty to humans that lived hundreds of thousands of years ago.

bostonpete 3y ago

That seems like a leap -- there's other foods that can provide sufficient iodine (e.g. fish, eggs, milk)...

ssnistfajen 3y ago

Goiter is usually not immediately lethal so for most of human history, people afflicted with it just kind of lived with it which likely meant there wasn't that much selective pressure against it. Consuming thyroid glands of terrestrial animals (usually ruminants) was an effective treatment of iodine dificiency before the modern nutritional sciences discovered the relationships between goiter and iodine deficiency: https://en.wikipedia.org/wiki/Goitre#History https://en.wikipedia.org/wiki/Goitre#History Ruminants are more efficient at absorbing nutrients from plant material due their digestive system, and this is how they get iodine in non-coastal areas. All vertebrates have thyroid glands and there is a very similar organ in marine chordates: https://en.wikipedia.org/wiki/Endostyle https://en.wikipedia.org/wiki/Endostyle. So this is an organ that likely emerged when our biological ancestors still lived in a iodine-rich environment.