Farm vs. factory farm eggs

I tend to be suspicious of claims about food. For instance, I understand that high-fructose corn syrup is not a good thing to be pumping our bodies full of, but I am skeptical of drinks and snacks that claim "no HFCS! Real Sugar!" like that in and of itself is a health claim. If it has 45 grams of sugar, HFCS or cane sugar, it still isn't good for you. I am also a bit dubious about if organic food actually has more nutrients like some sources say. I figured the benefit was more that it didn't have pesticides.

I was also pretty suspicious about eggs. That is, people say that eggs not grown on a factory farm have much yellower yolks. I was like "pff, I think they are exaggerating."

Nope, that particular claim is true, it turns out.

Factory farm eggs on the left, eggs from my aunt's chickens on the right.

I would say they are noticeable different colors...

Actually there is some science behind this. To paraphrase what I learned in developmental biology, chickens make "white" (I think it is actually pale yellow) and orange yolk. They make layers of the white yolk while it is day time, or while it is light out. They make layers of the orange yolk at night, when it is dark. Because factory-farmed chickens live in buildings with perpetual artificial day, very little of the orange is made.

Is it weird that I think about developmental biology almost every time I crack open an egg? Probably.

The real reason why I try to get eggs from farms is because I am trying to be ethically and environmentally responsible, but the farm eggs are quite pretty.