How did climate affect the spread of early humans

Ok, so say like you were in Africa. According to a website, it says that "the first wave of humans might have left Africa as much as 65,000 years." But the question is: Why? because it's not just global warming that's affecting all of us. It may be because of environmental differences. For instance, during the Arabian Peninsula period, there were "heavier rainfalls, more bodies of water, and vegetation."

Hope this makes sense to you! :-) 

 Peoples of the earliest homo-genus migrated out of Africa some 1.8 million years ago and took a route out of North Africa, along the Levantine Corridor (the narrow, fertile strip of land bordering the eastern Mediterranean) and into Europe. 

The precursor for this migration appears to have been the development of communication including rudimentary language. 

A second migration followed some 800,000 years ago and another migration some 600,000 years ago. It was this latter migration of ‘Heidelberg Man’ who are the ancestors of today’s Homo Sapiens. 

This migration would have been made possible by climatic changes in the Greater Saharan Region, something commonly referred to as the Saharan Pump. During periods when the Pump is active there is far greater rainfall in north Africa than there is now, seasonal monsoons bring heavy rainfall and plants and animals flourish, lakes form and many rivers flow. Today all that remains are the dried up remnants. 

This availability of food, firewood, shelter and basic tools would have enabled Homo erectus to migrate northwards. The pump failed 1.8 million years ago and the migration ceased for the next million years until once again, north Africa became fertile. 

Once the early peoples had navigated beyond the Levantine Corridor they were able to spread out and move north, west and eastwards. Over the next half million years they spread into many parts of Europe and Asia. 

Migration into America didn’t happen until much later, quite when it happened it the subject of much debate but all parties agree it was between 14,000 and 30,000 years ago and that Beringia would have provided the route. 

Beringia is the name of the land bridge that forms across the Bering Straits and links the American continent to the Asian continent. 

It is believed that as the last glacial maximum (ice-age) came close to it’s peak, about 20,000 years ago, the human population in northwestern Asia was broken up by the formation of large tracts of glacial ice. One group, of a few thousand, became isolated on the eastern side of the glacial ice and migrated eastward across Beringia to arrive in what today is Alaska. 

Over the next 10,000 years the glaciers retreated and the humans migrated southwards and eastwards into Canada and America. 

At times of glacial maxima vast amounts of water are locked up in the glaciers and this causes global sea-levels to fall. During the last glacial maximum sea-levels were some 120 metres (400 feet) lower than they are today, this would have created land-bridges across which people could have easily migrated. Examples include the Doggerland bridge that linked the UK to the rest of Europe and the Sinai bridge linking Africa to Eurasia (this still exists as the Sinai region of Egypt).

Iwould like a photo instead of all this and you can’t just go out asking for a paragraph thinking someone will be like oh yeah here it is