> It's fascinating to me that the complexity of life always goes up. This isn't true- many things evolved to be simpler over time. For example, some viruses ar

> It's fascinating to me that the complexity of life always goes up. This isn't true- many things evolved to be simpler over time. For example, some viruses are beleived to have evolved from parasitic bacteria, which themselves evolved from free living bacteria. Many other parasites have simplified and lost the ability to survive without a host. You also have examples like many cave and underground animals losing eye sight and pigmentation. Also consider things like marine mammals losing limbs land mammals had, and many sedentary/fixed marine invertebrates evolving from free swimming ones. There are costs to complexity, and so organisms evolve it when needed, and lose it quickly when it isn't giving an advantage... there is not an "arrow of complexity" that only moves one direction.