The two words of “climate change” have only been used around the world in relatively recent times but, when I worked in Africa in the 1950s, I had extensive dealings with a prominent scientist who believed — and proved — that climate change was a cyclic occurrence and was responsible for the exodus of the origins of we human beings from that continent.

The scientist in question was Professor Louis Leakey, a Kenya-born blood brother of the Mukanda tribe and world renowned paleoanthropologist and archaeologist. His life’s work of historic discovery in Africa was devoted to his many detailed first finds that Africa was the original cradle for the evolution of all members of the human family.

I first met this highly committed scientist when, as a foreign correspondent, I interviewed him at length for a series of articles and broadcasts published over 60 years ago.

Known as “The Man of Olduvai Gorge” in Tanganyika, my Cambridge University educated friend and scientific explorer into our original beginnings lived a rugged life in tents for most of his working life as he and his then wife, Mary, fossicked for more and more evidence on the origins of humankind.

Between them, they used stones and bones found in their many diggings to prove the now generally accepted scientific theory that the first ancient humans evolved from the once lush forests of Middle Africa. Until their eventual deaths, Louis and Mary both received numerous world scientific acclamations and awards for unearthing, for instance, the early footsteps of our kind when they started to walk upright as homo erectus over three million years ago.

Before the Leakey’s started their archaeological work in Africa, science at the time held firmly to the ‘fact’ that the original humans had actually migrated to Africa after evolving in Europe and Asia. But, with the Leakeys’ irrefutable material evidence, science was forced to officially and finally accept that Africa was the original birthplace of our first humans.

Working as they tirelessly did in the now most important fossil locations on our planet, the Leakey man and wife team also unearthed the skull of a 1,750,000-year-old man they fondly called “Dear Boy.” This discovery also started the first official era of scientific research into human evolution and growth.

My big question to Professor Leakey was always, of course, “Why did the first humans leave Africa in the first place?”

Armed with a great deal of palaeontological evidence, my informant would explain why early man left his original leafy homelands near to what is now believed to be Northern Botswana, a landlocked country in Middle Africa.

His scientific DNA evidence and fossil analysis was that our original ancestors were forced to leave their birthplaces about 180,000 years ago due to severe periodic cyclic climate changes and the destruction of their forest habitat through persistent droughts and encroaching desert conditions.

In Louis Leakey’s own words, homo erectus were forced to become wanderers, seeking better pastures for food and shelter. Over millennia, they travelled north up Africa and crossed the Middle East before spreading throughout Europe, Asia and finally Australasia about 60,000 years ago. He believed that, so many years ago, ancient man suffered major rainfall changes, failing ecosystems, violent weather events and broken biodiversity, making life impossible for existence in Middle Africa.

The great African exodus of our original forebears apparently followed several different routes north via the Great Rift Valley in East Africa and the Nile River in Central Africa, together with other green corridors offering an escape.

Professor Leakey was also the first scientist to establish that a minority of early humans fled south from the original homeland and were forced through bad weather patterns to live in the encroaching deserts, thus becoming the now well-known isolated bushmen of the Kalahari sand dunes.

As the original scientific champion of our human origins in Africa, Louis Leakey was the academic sponsor of the well-known English chimpanzee researcher, Jane Goodall, who I met in his company on a couple of occasions before trekking with her to her mountainous research station and her famous chimp family. As Jane was wont to say, “Louis Leakey is history’s homo scientificus.”