Final answer:
Migration during the glacial epoch was facilitated by lower sea levels that exposed land bridges, such as Beringia, and shifting climates that affected the availability of resources, ultimately influencing human movements and the adoption of agriculture.
Step-by-step explanation:
Migration would not have been possible without a glacial epoch because the Earth's changing climate had significant impacts on human movement. During the last glacial period, roughly 120,000 to 11,500 years ago, sea levels were much lower than they are today due to the large volumes of water trapped in vast ice sheets. This exposed land bridges such as Beringia, which connected Asia to North America, and enabled modern humans to migrate across the globe.
The drop in sea levels allowed humans to travel into maritime Southeast Asia and reach the Australian continent. Additionally, glacial epochs drove changes in ecosystems, animal migrations, and the availability of resources, pushing human populations to adapt and spread into new territories in search of food and favorable living conditions. As the Earth warmed up and entered the current interglacial period, humans turned to agriculture, which was spurred on by the more stable climate and end of the ice age about 12,000 years ago.
In summary, the ice ages shaped the course of human migration and played a critical role in our ancestors' ability to inhabit different regions of the world. The legacy of these migrations is still evident in the distribution of human populations today.