Scientists have known for several years that modern humans emerged from sub-Saharan Africa within the past 100,000 years. (…) After emerging into the Arabian peninsula, some of our ancestors took sea routes along the south Asian coast to reach Australia 50,000 years ago. Only later, about 40,000 years ago, did we enter Europe - its cold and its Neanderthals making it far less hospitable - while one group of Asians headed farther east over the land bridge that then connected their continent to America.