Former Tukana district occupied the larger part of the north west of Kenya all within the Great East African Rift Valley bordering South Sudan and Ethiopia to the north and Uganda to the West
The area is semi-arid with extreme day temperatures and equally low temperatures at night.
 Dr Richard Leakey, a renowned Kenyan paleoanthropologist and conservationist, together with a group of paleotologists discovered  the famous “Turkana boy” the oldest and most complete skeleton of Homo erectus. 

Nariokotome Boy, or “Turkana Boy,” a Homo erectus found by Alan Walker and Richard Leakey, Lake Turkana, Kenya is the most complete Homo erectus ever found.

 The 9-12 year old boy believed to be around 1.6 million years old was an important milestone filling the gaps palaeotologists had found hard to fill back then. 
Watch a video of Dr Leakey and the Turkana boy here  

He and and his team made further discoveries. A new species of Australopithecus a bipedal species with an upright posture that dated over 4 million years ago, the earliest stages of human evolution. Human and animal remains were trapped and fossilized in the stratified sediments of the Great Rift Valley. Tectonic activity has uplifted many ancient sediments and the constant erosion of them by wind and water exposes new finds every year. The lake basin is rich in specimens of Australopithecus, the primitive “transitional” hominid with many ape-like features. Koobi Fora to the east of the lake has yielded some of the most fascinating animal fossils in the world. Different types of primitive elephants, prehistoric hippos, giraffes and ancient species of crocodiles are but a few of the fossils discovered around the lake shore.

 So Kenya and Turkana in specific has been scientifically proven to be the cradle of mankind!

further reading can be found here