
Read our June issue
This month we cover desalination, land restoration, air pollution, procurement incentives for electric vehicles, monitoring global development aid and more.
This month we cover desalination, land restoration, air pollution, procurement incentives for electric vehicles, monitoring global development aid and more.
The cause of the sudden increase in the complexity of prehistoric societies 4,000–6,000 years ago is unknown. Pig diet and millet-field manuring studies indicate that an intensive millet–pig system developed approximately 5,500 years ago in North China, which provided food for the growing populations of the emerging complex societies.