My take only... chickens eat what they know is good for them... i mean how did chickens survive and multiply before humans controlled their diet? Seems to me chickens are a lot smarter than we give them credit for being.
LOL
Too true for some of us
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I need to add though that dumb chickens died while the smart ones lived long enough to pass on their knowledge to their young. Just like pretty much any naturally living creature.
I've kept hundreds and hundreds of birds of many different species over the years and they are all very intelligent in their own way. I think we humans are the ones that lack intelligence. Our egotistical minds blind us to the natural intelligence of higher life forms....... such as chickens:cd ......and trees .....and worms.