system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do multiple eggs from the one birds nest know to hatch at the same time? Having had chickens I know the eggs aren't all laid on the same day, yet they tend to hatch within hours.

I've seen some posts mention "They communicate with each other" but how??? They're in an egg? And does that mean some of the chicks are premature or underdeveloped because the older egg chose when to hatch or something?
gpt
The hen does not begin to incubate the eggs until the whole clutch is laid. When a hen does this it's called 'Broodiness' and is a behavior a lot of chicken ranchers use to recognize when to separate the hen from the rest of the flock to prevent infighting.