The main symptoms of the HIV-AIDS infection are due to the fact that patient’s body can no longer fight off many minor infections and hence becomes the reason of the patient’s ultimate death. This happens because

This is due to the HIV affecting/ weakening your immune system. By attacking and taking over T-Cells. When it has gone to a point where it destroys a majority of your cells it is considered AIDS. Hence HIV/AIDS

Explanation:

the fossil record provides evidence of a common ancestor to many species.