Nobody knows what came first, the chicken or the egg. I often wonder who was the first person to ever eat an egg and did this person just think, ‘hmm let me try that white thing popping out of this bird’s butt.’ Humans started out as being hunter-gatherers, so they would forage for food everywhere, and they would taste everything that didn’t smell foul, and they probably saw a snake or some other creature consuming an egg one day and that is where they got the idea to try it. Primitive people, barely standing up right and scrounging around for scraps in the dirt probably wouldn’t have looked at much of anything as unappealing. An egg probably looked pretty darn good to them. Eggs are high in protein, and they can be found in trees and they are sometimes left unguarded. They are a natural prey for any curious primate with grasping fingers.
Chickens do lay eggs out of their anus, as the egg, their poop and urine all exits out of the same hole. The orifice through which the egg leaves the hen is called the vent and, the valve called the cloaca separates the oviduct from the intestine. When an egg comes out, the chicken’s Cloaca is turned inside out so that the egg does not come into contact with their intestines, thus fecal matter and all that nastiness does not contaminate the egg.
Hens can lay no more than one egg per day, as the process of laying an egg is governed by the presence of sunlight. The lack of natural light during the winter months means that even fewer eggs are laid during this time of the year. Humans use tricks to keep chickens laying eggs by adding artificial light to the coop. The laying process starts when light entering the hen’s eye activates a photosensitive gland (the pineal gland) positioned nearby. Once stimulated, this gland triggers a process that leads to the release of an egg, or oocyte, from the hen’s ovary. An egg can still be laid whether or not it has been fertilized by a male (roster), but only fertilized eggs can develop into chicks.
A pullet (a young hen, especially one less than one year old) starts life with two ovaries, but as she matures, the right ovary remains undeveloped and only the left one becomes fully functional. The functioning ovary contains all the undeveloped yolks, or ova, the pullet started out with. When a pullet reaches laying age, or a hen comes back into lay after a break, one by one the yolks mature, so at any given time her body contains yolks at various stages of development. Approximately every 25 hours, one yolk is mature enough to be released into the funnel of the oviduct, a process called ovulation, which usually occurs within an hour after the previous egg was laid.
Normally the hen approaches the nest in a very hesitant way, and she sits quiet for a long time, often for half an hour or more, then when she gets more exited, the hen will raise her tail and spreads the feathers of her bottom. Under her tail, between the feathers, is a small opening called the vent which is in the form of a horizontal slit, that is about an inch wide and this is surrounded by a ribbed rim, with skin and feathers further outside. The hen will stand up with her feet wide apart, tail raised, bottom feathers spread out, and back feathers upright, as her vent opens. Then the hen lowers her bottom, her vent widens rapidly and the rim is stretched further. Once the vent is wide open and the ribbed rim has become narrow and far stretched, the egg appears. The hen may strain at various intervals of the laying process, but as this continues the egg comes out a little further. As it does, the membrane opens to form a red collar around the wider, middle portion of the egg. The membrane will protrude a little ways from the ribbed rim.
The moist egg pops out and sometimes it will come out blunt end first, sometimes pointed end first. For a few seconds after the egg is laid, a small red cone still remains outside, but it is retracted almost immediately and the vent is closed again. The bird stands high above the egg and rests, beak open and panting after the heavy work. The entire process (from rising to dropping the egg) is quite fast and is finished within half a minute, which makes it hard to observe. After a while, the hen looks back, inspects the egg with her beak and leaves the nest under loud cackles. The hen then eats and drinks and goes her usual ways, almost as if she has forgotten her egg completely.