Do microorganisms have a presence of mentality?
Buddhists often say: "All beings want to be happy"
But "want" and 'happy" can refer to a lot of different levels of experience, and these levels do not require a human brain, or any process that we may be directly familiar with. So, you swat at a house fly and it quickly dodges to avoid being killed. A moth, on the other hand, is attracted by an open flame and may burn itself up. Both , in their own way "want" to be 'happy".
Insects have a type of brain too. And you can go further down, smaller and smaller. Even sperm swim eagerly to an egg. They may not possess anything that we would regard as "consciousness" and being only one cell, have no brain. But there is a level of "awareness" in small creatures which responds to the environment, which leads them to sources of warmth or food or proteins or whatever, and by "awareness" I don't mean they are contemplating their actions, but that they are responding, even automatically, to changing conditions, because doing so should
produce a favorable result. This of course, is not always the case, either for moths or for humans. So, it may be stretching the definitions of "want" and 'happy" but it is a principle which is being applied.
I read something a while back that said that a large percentage of what we consider to be the composition of our bodies (by weight, for example) is actually a lot of non-human things such as bacteria and other living organisms. Since Humans are composed entirely of cells that reproduce on their own, doing all sorts of things such as fighting infectious intruders and whatever, is each of us actually a city on legs?
Evolution differs from "Creation" because it acknowledges the interconnectedness of species development. Yet, there is still the tendency to freeze any given species in time, saying "this is a frog" or "this is a Homo Sapien" as though it is a separately existing thing (the creationist view). I think Buddhist teachings go a little further: "Yeah, homo sapiens for now
but wait 24 hours and you get homo sapiens version 2.0" because we regard everything as no "thing" but as continuous, interconnected transformation.
That changes any discussion of evolution
a little bit.