Question

The first organisms on Earth appeared approximately 3.8 billion years ago and were all unicellular. Multicellular organisms have only existed for about one billion years.

What evolutionary milestone made it possible for more complex, multicellular organisms to exist?

Answer 1

The development of specialized cells and cellular cooperation made it possible for more complex, multicellular organisms to exist.

Step-by-step explanation:

The evolutionary milestone that made it possible for more complex, multicellular organisms to exist was the development of specialized cells and cellular cooperation. As cells started to live together in colonies, some cells began to specialize in performing different functions, making the colony more efficient. This specialization allowed the cells to remain small while still carrying out specialized tasks, leading to the evolution of multicellular organisms. These organisms were bigger, more efficient, and capable of performing more complex functions than single-celled organisms.