Egg

Humans and other hominids have eaten eggs for millions of years, and the most widely consumed eggs today are those of fowl, especially chickens, first harvested for food in Southeast Asia around 1500 BCE. Eggs of other birds, such as ducks and ostriches, are also eaten, though far less commonly than chicken eggs, and people sometimes eat the eggs of reptiles, amphibians and fish, the latter known as roe or caviar. Hens and other egg laying creatures are raised throughout the world, and the mass production of chicken eggs is a global industry: in 2009 an estimated 62.1 million metric tons of eggs were produced worldwide from a laying flock of about 6.4 billion hens. Regional variation in demand and expectation, along with debate over mass production methods, has shaped the industry, and in 2012 the European Union banned the battery cage housing of laying hens.