Final answer:
Viruses exhibit complex characteristics that indicate they are living things, despite not being classified as such. They have genetic material, can evolve, and some of them contain more genes than certain cellular life forms.
Step-by-step explanation:
Viruses are not classified as living things, but they do exhibit several complex characteristics. First, viruses have genetic material like all cells do, and they can undergo mutations, contributing to their ability to evolve.
Second, some viruses have been discovered to contain more genes than certain cellular life forms, suggesting they may have once been able to reproduce without a host cell. Third, studies of viral proteins have provided strong evidence that viruses are living things.