Final answer:
The success of 'Out of Africa 2' migrations was driven by climate changes that made Africa drier, necessity for survival due to resource scarcity and generational knowledge transfer on the benefits of migration, as well as the opportunities presented by lower sea levels during the glaciation period that allowed for human expansion into new territories.
Step-by-step explanation:
Possible reasons for the success of "Out of Africa 2" migrations involve a combination of environmental, survival, and exploration factors. The climate changes in Africa around this time caused regions to become drier, resulting in a scarcity of plants and animals that were crucial for the humans' hunter-gatherer way of life. This scarcity likely pushed Homo sapiens to migrate in search of more abundant resources. They employed strategies of hunting and gathering during their migrations, allowing them to adapt to new environments.
Another factor for successful migrations could be the learning and teaching aspects of early Homo sapiens. In very early generations of the species, individuals who found that migration improved their chances of survival would teach their young to carry on the behavior, passing on crucial survival strategies to future generations.
Lastly, the glaciation period and the low sea levels it brought enabled human expansion into new territories. For example, humans could move into maritime Southeast Asia and Japan, and reach Australia. Another significant migration occurred when humans entered North America from Siberia via a land bridge exposed by the low sea levels.