Early human beings lived on trees and in caves.

Early humans were nomads who moved from place to place in search of food and shelter. They did not have permanent settlements like modern humans. They lived in different types of habitats depending on the availability of resources.

Living on Trees:
- Early human beings lived on trees mainly to protect themselves from predators and other dangers on the ground.
- They also used trees as a source of food, eating fruits and nuts that grew on them.
- Living on trees also allowed them to observe their surroundings and spot potential dangers, such as other animals or rival tribes.

Living in Caves:
- Early human beings also lived in caves, which provided shelter from the elements and protection from predators.
- Caves also provided a place to store food and tools.
- Early humans used fire to keep warm and cook food, and caves provided a safe place to build fires.

Advantages of living on trees and in caves:
- Protection from predators and other dangers.
- Shelter from the elements.
- Access to food and water sources.
- Ability to observe surroundings and spot potential dangers.
- Ability to build fires for warmth and cooking.

In conclusion, early human beings lived on trees and in caves because it provided them with the necessary protection and resources needed for survival. As they evolved, they developed more sophisticated ways of living, such as building houses and settlements.