Why did human civilizations develop along the east-west axis rather than along the north-south axis?

Human civilizations develop along the East-West axis rather than along the North-South axis because of its environment. The crop and livestock species can spread more in this latitude (East-West axis). The people who are using technologies and social behaviors associated to those species are most likely to spread in this region. Here, they experience constant day length and seasonality and usually they experience similar diseases. The humans did not prefer the North-South axis because of its changing day lengths and seasonality. If they were to live there, humans would be experiencing different weather and climate including different diseases the environment can give.