Answer:
From simple to complex.
Step-by-step explanation:
The development of life on Earth occurs from simple to complex type of organisms. At first organisms are simple body and cellular structure but with the passage of time simple organisms are evolved and turn into complex organisms. The first life that was appeared in the Earth's oceans about 3.8-billion years ago was prokaryotic organisms. For example, Bacteria are the first organism that has simple body structure and appearance but with the passage of time various different types of bacterial species are formed that have complex body structure.