structural:scholar_edition, structural:summarization, information:extraction, stylistic:style_transfer
Biodiversity and climate

As crucial as rivers and marshlands were to the rise of civilization in the Fertile Crescent, they were not the only factor. The area is geographically important as the "bridge" between North Africa and Eurasia, which has allowed it to retain a greater amount of biodiversity than either Europe or North Africa, where climate changes during the Ice Age led to repeated extinction events when ecosystems became squeezed against the waters of the Mediterranean Sea. The Saharan pump theory posits that this Middle Eastern land bridge was extremely important to the modern distribution of Old World flora and fauna, including the spread of humanity.

The area has borne the brunt of the tectonic divergence between the African and Arabian plates and the converging Arabian and Eurasian plates, which has made the region a very diverse zone of high snow-covered mountains.

The Fertile Crescent had many diverse climates, and major climatic changes encouraged the evolution of many "r" type annual plants, which produce more edible seeds than "K" type perennial plants. The region's dramatic variety in elevation gave rise to many species of edible plants for early experiments in cultivation. Most importantly, the Fertile Crescent was home to the eight Neolithic founder crops important in early agriculture (i.e., wild progenitors to emmer wheat, einkorn, barley, flax, chick pea, pea, lentil, bitter vetch), and four of the five most important species of domesticated animals— cows, goats, sheep, and pigs; the fifth species, the horse, lived nearby. The Fertile Crescent flora comprises a high percentage of plants that can self-pollinate, but may also be cross-pollinated. These plants, called " selfers ", were one of the geographical advantages of the area because they did not depend on other plants for reproduction.