Is monogamy natural ?

Do they really? Or do we just tell ourselves that so that we feel better about our insignificant spot in the universe?

We tell ourselves that we have morals so that we don't do stupid things that can affect humans in a bad way. We already know that at the end of the day, we're just small insignificant living beings. It's not what we are, but how we deal with it.

But everything that a person does is in some way detrimental to the planet which is detrimental to the rest of the human race, albeit in an extremely minor fashion.

Everything starts from you, yourself, and you. It doesn't matter what other people do, what matters is what YOU do. That is when you know you have hope to cling on.

What you do may influence your mates, and they may or may not follow your principles, and so on.

My answer may not be a satisfactory one for you, but what I can tell is to have hope. From here on, if you decide not to have one, then be it. I tried.

This. I'd also put it down to personal preference. Most people are taught that monogamy is the right way to go through upbringing and education, but this doesn't necessarily mean that everyone follows it, much like anything in this world.

I am not sure about my recollection of ancient civilization, but I believe there were no constraints at that time as far as reproduction is concerned, due to absence of a definite social order like religion and laws that will restrict them from having multiple sex partners. We are also animals but with higher intelligence than other creatures who are able to "reason out" and develop our own social norms and standards.

It is possible that monogamy was developed because of the following reasons: in order to reduce the growth of human population in a particular area (e.g. more people means increase in demand of resources), it helps to minimize problems on social responsibilities (e.g. child negligence, infidelity that might lead to disputes (depending on the norms and morals of the people in the society).

Anyway, we should just go with the flow of modern civilization for the purpose of promoting social order and having a good relationship with other people. Monogamy that is.

Polygamy is still accepted, just like in the case of the religion "Islam". It is still a civilized act and accepted as something moral because the people in the society believe so. In any case, it still undergoes a process which I don't know, so I would not comment too much about that.