Final answer:
Dramatic climatic shifts, environmental characteristics, natural events, and changes in diet and caloric requirements have contributed to changes seen in pre-modern day human fossils.
Step-by-step explanation:
The changes seen in pre-modern day human fossils can be attributed to several characteristics. Firstly, dramatic climatic shifts over several million years forced periods of rapid biological and cultural adaptation, resulting in the emergence of new hominin species and developments in skills like language and toolmaking. Secondly, environmental characteristics have played a role in shaping religious beliefs, gender relations, food-getting strategies, and political systems. Additionally, natural events like volcanic eruptions and droughts have triggered mass migrations and the collapse of empires. Lastly, changes in diet and caloric requirements in response to a colder climate have influenced the evolution of bipedalism and the growth of the human brain.