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[Home]
[Prog summaries - [Ice World]
[The Earth was Born] [Out
of Eden] [In perspective]]
[Out of chaos - [Introduction]
[Divine guidance] [Tools
of knowledge] [Religious conflict]
[Search goes on]]
[Survival - [Introduction] [Exodus]
[New Technology] [Moving
on]]
[The Globe - [Introduction]
[Star Dust] [Water
of life]]
[Find out more]
[Credits]
[Full site with images]
Genetic evidence shows only one successful exodus from Africa. This was some 80,000 years ago when the ice caps were advancing again, freezing up the moisture turning land to dust. Sea levels dropped as the world's seas became locked in ice. As the game began to disappear, our hunter-gatherers became fishermen and beachcombers, developing tools, such as hand axes with a sharp end made of chipped stone.
As the sea levels continued to fall, the Red Sea became more cut off from the Indian Ocean, resulting in the sea becoming saltier and probably killing most of the seafood.
To survive, small groups of families moved through Eritrea towards the green inviting hills of the Yemen. This same small group has populated the whole world, diversifying to fit their environment. After travelling 6,000 miles and 6,000 years from Africa they reached the tropical rain forest of South East Asia.
Wherever they settled their bodies adapted to their new homes, the climate dictating body shape. The colder the environment, the shorter and stockier we became to retain warmth. Tall and slender shapes deal better with the heat.
Height also relates to diet. In the rain forest conditions of Asia, stature became slightly reduced through lack of meat as humans survived first on fish and small game, fruit and roots and more recently on rice as the staple food. The population is growing taller again as meat returns to the menu.
Skin colour also varies, depending on environmental conditions. Folate is crucial for embryonic development and too much ultra violet radiation from the sun destroys it. So our ancestors in tropical Africa needed to be dark to protect their survival. But too little ultra violet prevents the formation of vitamin D, causing rickets, which can kill. As they migrated to the sunless north they had to grow paler to survive.