Early inhabitants of the East African Rift Valley enjoyed a reliable environment for thousands of years as there was a large number of freshwater lakes, and reach grasslands were favored by large herbivores.
However, the situation changed more than 320,000 years ago, as the environment started to be unpredictable, forcing early humans to adapt. Tests performed on drill cores that cover more than 1 million years of history reveal that an evolving ecosystem was one of the primary factors which encouraged human evolution.
Studies that focused on artifacts that were recovered from a well-known archaeological site revealed that early humans had used more the same tools for more than 700,000 years, and their lifestyles were quite stable within this timeframe as no notable changes had been observed.
The situation changed dramatically as Middle Stone Age started, as people started to create weapons and tools which were smaller, easier to use and more accurate in some cases. Trades have also started to become more popular at this point in time, as resources were exchanged, and symbolic communication is reinforced by the use of coloring materials.
While some have argued that climate change was the primary factor behind the advancements, it seems that other changes have also played an important role. New geological faults and changes in vegetation and fauna reshaped the landscape, forcing the use of new tools and trades to ensure survival.
Some of the innovations that appeared have also paved the way for additional changes in the fauna, including the use of projectile weapons. The disappearance of large-scale grassland led to forced big herbivores to die out. Humans managed to follow the changes in the ecosystem with relative ease, adapting fast enough to prevent negative consequences.
Adaptability has saved humanity a lot of times, and it will remain essential as the environment continues to change due to anthropogenic influences.