Chickens have been bread for other things like meat, eggs.etc .
Game chickens can and do fly well . They are very similar to the wild Jungle Fowl that modern chickens were bread from .
Physiologically, wild birds have all dark meat due to the extensive blood/oxygen supply needed to sustain the muscles -- esp the beating of the wings. For domestic chickens -- it all has to do with marketing white meat.
Domestic chickens (meat providers) are bred for white (breast) and dark meat (legs). Breast muscles greatly lack blood supply -- that's what makes them "white". Little blood supply makes for weaker muscle development. Add to that, domestics are bred for mass and they have shorter wings -- a heavy, weak bird can't get off the ground.
On the other hand, a laying hen is streamlined. They can fly for short distances then glide to a landing. A more normal arrangement for the Galliaformes order that includes peacocks, quail, grouse, turkey, and other "chicken-like' fowl. In general, the entire order prefer to run rather then fly.
BTW, domestic turkeys bred for huge breast meat also can't fly.
Vault is right. Some chickens can fly a short distance.
https://www.google.com/?gws_rd=ssl#q=chi...
Well they can, for very very very short periods of time, it's hardly flying but I know what you mean and the answer is simple, their wings cannot hold up their body mass and they do not have enough strength to flap for such long periods of time especially against air resistance and gravity, etc.
Because they're overweight, they gravity is stronger than their ability of flying.
I just passed your question along to my flock. If they ever stop laughing, they will answer you. In the meantime, I will just say that it varies with the breed. Leghorns, very popular as egg-layers, are especially flighty.
I've never really thought about it before, I've always just accepted it as a fact. But, why is it that chickens can't fly?
