Final answer:
Homo erectus first adapted to open savannas. Their adaptations included efficient long-distance walking and running, anatomical changes for better vision and mobility, behavioral adaptations like cooperative hunting and the use of fire, and the ability to create tools.
Step-by-step explanation:
The eco-niche that Homo erectus first adapted to was open savannas. To be successful in this eco-niche, Homo erectus developed several adaptations. First, they had efficient long-distance walking and running abilities, allowing them to cover large distances on the savanna in search of food and water.
Second, their anatomical adaptations included a tall and upright posture, which helped them see prey and predators over the tall grass. They also had a narrower pelvis compared to their ancestors, which allowed for more efficient walking and running.
Third, Homo erectus exhibited behavioral adaptations such as cooperative hunting, where they worked together in groups to bring down large game. They also likely used fire for warmth, protection, and cooking, which provided them with a significant advantage on the savanna.
Lastly, Homo erectus had the cognitive ability to make and use tools. They crafted stone tools that allowed them to process and consume a wider range of foods, increasing their chances of survival in the open savanna environment.