Short answers, pulled from the story.
The onion has been cultivated since at least 2000 BC, with ancient cuneiform tablets from Mesopotamia recording recipes that describe a cuisine of striking richness and sophistication. This pungent bulb, scientifically known as Allium cepa, has been cultivated since at least 2000 BC, with ancient cuneiform tablets from Mesopotamia recording recipes that describe a cuisine of striking richness and sophistication.
The stinging sensation that causes uncontrollable tears when cutting an onion is the result of a complex chain of chemical reactions designed to protect the plant from predators. When cells are damaged by a knife, enzymes called alliinases break down amino acid sulfoxides to generate sulfenic acids, which are then rapidly acted upon by a second enzyme known as the lacrimatory factor synthase to produce syn-propanethial-S-oxide.
In 2008, the New Zealand Institute for Crop and Food Research created no tears onions by genetically modifying the plant to prevent the synthesis of this specific enzyme. By early 2018, Bayer released the first commercially available LFS-silenced onions under the name Sunions, the product of 30 years of cross-breeding without genetic modification.
China leads global onion production which accounted for 17% of the total, with global production reaching 5.0 million tonnes in 2022. The top global producers include India, the United States, and Turkey, with Mali, Angola, and Japan serving as secondary producers.
Ancient Egyptians revered the onion's concentric rings as a symbol of eternal life, placing them in the eye sockets of pharaohs like Ramesses IV to ensure their vision in the afterlife. The plant's journey from the wild grasses of Central Asia to the dinner plates of the modern world is a story of human ingenuity and biological adaptation.
While onions are a staple food for humans, they are toxic to animals including dogs, cats, and guinea pigs, causing damage to their red blood cells and leading to anemia. The plant can also accumulate heavy metals such as cadmium and lead, particularly when cultivated in contaminated soils, leading to regulatory limits set by the European Union.