Short answers, pulled from the story.
Systematic cultivation of rye began around 13,000 years ago at the Epipalaeolithic site of Tell Abu Hureyra in northern Syria. Archaeologists uncovered rye grains at this location though critics argue that radiocarbon dates show inconsistencies.
The current best candidate for the ancestral species is Secale segetale. Small quantities of domesticated rye appear at Neolithic sites in Asia Minor including Pre-Pottery Neolithic B Can Hasan III near Çatalhöyük.
Rye plants produce antifreeze polypeptides by their leaves during subzero environments. This mechanism allows them to survive snow cover that would kill winter wheat and enables rapid growth in spring.
World production of rye reached 12.7 million tonnes in 2023 with Germany leading global output at 25% of the total. Poland and Russia served as major secondary producers while Europe produces around half of the world's rye.
Like wheat and barley rye contains glutens and related prolamines which make it unsuitable for people with gluten-related disorders such as celiac disease. Some wheat allergy patients can tolerate rye or barley however.