Drying pushed the Sahara's fishers aside and made herders the winners

Drier conditions in the later seventh and sixth millennia BCE moved the advantage away from the communities living off the Saharan waterways and toward Nilo-Saharan speakers who had built their living on dry land. Through the proto-Northern Sudanic, proto-Saharo-Sahelian and proto-Sahelian periods of the eighth and seventh millennia, those peoples of the southern and eastern Sahara began by protecting cattle and by the close of the seventh millennium were herding cattle outright, along with the sheep and goats that had recently arrived. They had started as collectors of wild grain. By the later eighth millennium the vocabulary they left behind, and the granaries archaeologists find, indicate they were cultivating sorghum and probably pearl millet as well. Nobody here was waiting for the climate to decide. What emerged was an economy pairing herds with grain that would carry across the whole Sahel within two millennia, and the pastoral societies of Sudan and the Fulani of West Africa descend from it.

Trinidad stayed joined to the South American mainland until the Holocene, and the consequences are still visible in what lives there. Its plants and animals are continental in range, and the island holds a long list of species that never reached the rest of the Antilles. It covers about four thousand eight hundred square kilometres, which makes it the sixth largest in the chain. Most of it is low hills and badly drained lowland, with a rough northern coast as the exception. That combination of position and biological range is why archaeologists routinely call Trinidad the gateway to the Caribbean. It is worth being precise about what the label means. Anything moving out of the Orinoco country and into the island chain had to come this way, so the settlement history of every island downstream begins with what people were doing here. A Caribbean that starts in 1492 skips the door and describes only the room.

From 6000 BCE the peoples of the middle Nile shared far more than an economy. A body of common ideas and ritual practice took hold from south of the Nile confluence all the way north into the country where the Old Kingdom would later be founded. The people involved did not speak one language. As far north as the latitude of Aswan they spoke Eastern Sahelian tongues, a branch of Nilo-Saharan. From Aswan down to El-Badari in Middle Egypt they spoke dialects of what would become ancient Egyptian. The convergence went straight across that boundary and produced shared pottery styles, shared ceremonies and shared assumptions about the world on both sides of it. So the culture area was bilingual from the start, and the civilisation that grew out of it carried both inheritances. Egypt spoke an Afrasian language and practised a great deal that had come upriver from Nilo-Saharan speakers over three thousand years of contact.

In northeastern Africa, among peoples speaking Cushitic languages, a third kind of clan religious figure goes back at least to the sixth millennium BCE. In some Soomaali-speaking parts of the Horn the waab or waaber is also called rooble, possessor of rain, which indicates plainly what people believed he could do. Holders of the office never became political rulers. They commanded reverence, and their views carried great weight whenever a community had a decision to make. That makes three inherited traditions of authority, all traceable to the sixth millennium BCE or earlier, in three different language families. The Nilo-Saharan sacral king fused spiritual and temporal power. The Niger-Congo kumo mediated between the living and the ancestors inside a matrilineal clan. The Cushitic rain possessor held religious standing that gave his voice weight without ever hardening into rule. Political authority has more than one origin story, and Africa preserves at least three of them.