Research conducted in Kenya and Ireland shows how cattle domestication evolved in Africa and points to seagoing trade thousands of years ago, writes Dick Ahlstrom.
Scientists working in Nairobi and Dublin suggest that seagoing trade links had opened up between the Far East and Africa more than 3,000 years ago.
The claims are based on studies of the genetic background of cattle herds found in Africa. The genetic mix in today's cattle points to a major influx of cattle from India many centuries ago; animals that joined herds along much of Africa's east coast as far south as Madagascar.
The scientists have helped to unravel some of the mystery surrounding when cattle in Africa were first domesticated. The history of livestock herding in Africa is a tale of tribal migrations, seaborne trade with Arabs and India and cattle exchange with Europe, explains Dr Dan Bradley of the Department of Genetics at Trinity College, Dublin.
The study, published this month in the journal Science, was done by the International Livestock Research Institute in Kenya and Trinity College, with the Institute leading the research, Dr Bradley says. It compared genes found in Africa's modern cattle breeds as a way to discover their origins, interrelatedness and subsequent cross breeding. "Pastoralism is a very important feature of the economies of many parts of Africa," he says.
The research team decided to study the genetic makeup of 50 breeds across the African continent as a way of understanding how cattle herding evolved over the past 9,000 years. "The population events that happen to ancestors can often be seen as signatures in the patterns of genetic variation," Dr Bradley explains. "We plotted the genetic diversity on a map. We have a landscape of genetic diversity over the whole of Africa.
"It is most likely that the cattle we have here in Europe, humpless cattle, originated in north-east Africa," perhaps 9,000 years ago. "At that stage, the Sahara was fertile."
Domestication was no easy matter, as the cattle from which modern breeds emerged were fearsome. The techniques involved in taming and herding cattle spread, along with the animals themselves, gradually westward across Africa and much later southwards, Dr Bradley says.
It took until about 400 AD for this cattle breed, Bos taurus, to reach South Africa. Domestication techniques and herd dispersal are likely to have followed migration patterns of tribes such as the Fluani in the north and Masai in the south. There were secondary migrations, with exchange between Africa and Europe via Gibraltar and the Middle East via Sinai.
Perhaps more significantly, there are clear signs of exchange with India and the introduction of zebu or hump-backed cattle, Bos indicus. Their arrival affected the genetic mix in a dramatic way, he says, and suggests this was likely to have been a seaborne trade. The genetic diversity map for the zebu genetic contribution is concentrated in the Horn of Africa and along the east coast as far south as Madagascar. The influence is particularly strong in modern Madagascan animals.
THE zebu emphasis on the east coast suggests they arrived not by land but by sea. "It points towards a long-distance Indian Ocean trade," Dr Bradley says. There were other Asian imports emerging at this time including chickens and camels and African exports to Asia included agricultural products such as sorghum and finger millet.
While genetic data is not as solid as archaeological evidence, it is indicative of what happened, believes Dr Bradley. "We can make some inferences about migrations."
It also raises the likelihood that ocean-going vessels were already traversing the Indian Ocean in pursuit of trade. This implies both considerable ship-building skills as well as the ability to navigate safely.