What is the point of a chicken laying an unfertilised egg

Isn't it a lot of energy wasted to create the egg, if it serves no evolutionary purpose?

What is the purpose of the eggs that are laid that are unfertilised?

What else do you know about hens eggs?

Thank you, I am just really confused over what the human equivalant would be - mensturation?

None. But in the wild, almost all eggs are fertilized in birds... Chickens are jungle birds originally. Man domesticated them. Now they are warehoused in huge buildings, their reproductive system hijacked for your morning breakfast.

Many live their whole lives in cages, never touching the ground.

Human equivalent, yes probably menstruation. During most of human history, the average woman had 13 pregnancies, and 9 live births in her life time. She was lucky to raise two to teenagers. This is still the case in areas of no "imported" medicine, such as the bush of Africa, or the rain forests of the world.

Modern medicine in First world countries now saves most babies, and most mothers.

You're right, it does seem like a waste of energy for a chicken to lay an unfertilized egg. Sometimes, for various reasons, a chicken's egg is simply not fertilized during development. A hen can store sperm for several days, but vitality drops after about ten days. Domestic chickens have been selectively bred for good egg laying --- meaning, they will lay nearly every day when in prime condition, whether there is a rooster or not. See? Domestic chickens have already scored big with the whole "survival of the fittest" - like other domesticated animals the species is highly desired by man. Dogs, cats, cattle, pigs, etc. are in the same boat. I would think that since the wild jungle fowl (relative to the domestic chicken) is a gregarious bird, the eggs they lay are usually always fertile, plus they do not lay as often as a domesticated chicken.