Final answer:
From 4000 to 3000 BCE, as the climate grew drier, irrigation systems grew in importance, leading to the creation of canals, the invention of plows, and the domestication of cattle, which all supported the growth of civilizations.
Step-by-step explanation:
Settlements and Agricultural Breakthroughs in Early Civilizations
During the period from 4000 to 3000 BCE, as the climate became drier with less rainfall, irrigation systems became vital for the growth of settlements. This challenge lead to significant breakthroughs in the ancient world, among them the creation of canals, the invention of plows, and the domestication of animals such as cattle, which were integral to the development of agriculture. These innovations allowed for the emerging civilizations along river valleys like the Tigris and Euphrates, to not only survive but to thrive.
The Sumerian civilization, which emerged in southern Mesopotamia, is a prime example of these advances. It was in these urban centers that agricultural practices such as crop rotation and metal plows were discovered and improved over the years, greatly increasing crop yields and supporting larger populations.
The domestication of cattle was an important step in this agricultural evolution, providing manpower for plowing fields and transportation for both goods and people, facilitating trade and spreading cultures.