Technology has always been closely linked to the ways in which people have lived. Before the development of civilization, humans lived for many millennia with tools and techniques that allowed them to live successfully in a wide variety of environments. From primitive stone implements to fairly sophisticated and specialized tools, prehistoric humans developed technologies that allowed them to increase their control over the natural world. In return, the tools that they used increasingly changed their way of life.
Not hypothesis, observation
A primary source. A primary sources are first hand accounts like diaries, autobiographies, etc.
A chimpanzee is homo sapiens sapiens, humans, closest relative. Both species share a common ancestor.
Because he was assassinated by Serbian rebels. Most of Europe was allied with someone, a tangle of alliances. Serbia was allied Russia. Austria-Hungary didn't like Serbia. Well when the Archduke decided to visit Sarajevo, he was assassinated by a Serbian assassin. Because of that, Austria-Hungary wanted to punish Serbia and declared war. Well Austria-Hungary was allied with Germany and Italy. And Serbia was allied with Russia. Well Russia attacked Austria-Hungary and Russia was allied with both Great Britain and France.... So it triggered a chain reaction like that.