Short answers, pulled from the story.
People in Southeast Asia began harvesting chicken eggs for food by 1500 BCE. The chicken was most likely domesticated for its eggs from jungle fowl before 7500 BCE. Humans and other hominids have eaten eggs for millions of years.
In 2023, world hen egg production reached 91 million tonnes, a 77 percent increase from 2000. In 2017, world production of chicken eggs was 80.1 million tonnes, led by China at 31.3 million tonnes, followed by the United States, India, Mexico, Japan, Brazil, and Russia.
Joseph Coyle invented the egg carton in 1911 in Smithers, British Columbia. He created it to settle a dispute over broken eggs between a farmer in Bulkley Valley and the owner of the Aldermere Hotel. Early egg cartons were made of paper.
Eggshell color comes from pigment deposited during egg formation in the oviduct. The brown pigment is protoporphyrin IX, a precursor of heme, and the blue pigment is biliverdin, a product of heme breakdown. Chicken breeds with white ear lobes generally lay white eggs, and those with red ear lobes lay brown eggs.
The U.S. Department of Agriculture grades eggs by interior quality and the appearance of the shell, with grades of AA, A, and B. A very fresh egg has a small air cell and receives a grade of AA, and the grade drops as the air cell grows and quality decreases. Grade A is the quality most often sold in stores.
A century egg is preserved by coating an egg in a mixture of clay, wood ash, salt, lime, and rice straw for several weeks to several months. Its alkaline material gradually raises the egg's pH from about 9 to 12 or more, turning the yolk into a dark green cream and the white into a dark brown jelly with a strong odor of sulfur and ammonia.
As of June 2023, the killing of male chicks has been banned in Germany, France, Luxembourg, and Italy. Some egg producers use in-ovo sexing to determine a chick's sex before it hatches and remove male eggs from incubation. As of April 2025, in-ovo sexing was used for 28 percent of the European layer population.