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The Comparative Anatomy of the Thyroid andAdrenal Glands in Wild Animals

Fascinating thyroid facts and figures - amazing what is out there. Even more amazing if you ever have any reason to know any of this!

The Comparative Anatomy of the Thyroid and

Adrenal Glands in Wild Animals


In the wild state, the adrenal glands are larger than the

thyroid gland, with a ratio as high as twenty-three to one in

certain small rodents. In a human, the thyroid gland is larger

than the adrenal glands, the ratio being two to one.


According to our data, a larger size of the thyroid

gland in relation to the adrenal glands would seem to be a

characteristic of the human being only.

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Well, that makes sense, given that wild animals have to be constantly on the alert, for fight or flight.


Also might be relevant that humans and guinea pigs need to consume vitamin C. (Hmm - but that wouldn't explain why humans only have the ratio the other way around.)


When my last dog was just a young puppy she got caught up in some fence wire in the local park and ended up hanging upside-down by her legs. She screamed in distress, and I rushed to release her. While I was trying to release her she started biting me in absolute panic and terror. (She was uninjured apart from a tiny cut a couple of millimetres long.)

I later found out that if she had been a member of a pack of dogs she could have expected to be attacked and killed by other members of the pack because she had screamed. By screaming she could have alerted the local predators to the presence of the pack and brought danger to them all. So killing members of the pack that are screaming or bleeding is self-preservation, and perhaps my initial attempts to help my dog were interpreted by her as an attack.

The same behaviour can be expected in many different species. So animals may need to have such huge adrenal glands because they have to protect themselves against their own species as well as against predator species.

Humans, on the other hand, have developed to be more co-operative with each other for the good of the tribe, and an injury doesn't make other members of the tribe attack the injured member, so perhaps that is why humans don't need to be on the alert as much as a dog.

The above is just idle speculation. :)


Interesting. I didn't know any of that.


hb you are just plain awesome ;)


Thank you! ;) I didn't expect that reaction to my odd ramblings! :D


Bit late in the day but you've saved my, 'learn something new as each day passes' resolve. Bravo !

Mind, I'm a diva and I'm always screaming... :D


I'm fine at learning at least one new thing every day. But how many do I forget?

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