In general, it is procreation that makes humans think about the long term. The truth is, no matter what you do, you will be dead in a hundred years. Wanting to leave the world a better place for your children and grand-children is a much more powerful motivator than abstract philosophical principle.
I certainly think in terms of leaving the world better for all living things rather than for my children (although I guess they would benefit).
I personally feel shame that I am a part of the destruction of this world which in turn motivates me to want to make it better.
This is something that has grown as I have aged, I feel now that I'm older I can see things in the longer term and I can see how long it takes to make change and make it stick.
Parents who don't care whether the children are theirs biologically will have a greater tendency to raise children regardless of biological relationship. That means they are more likely to expend their finite resources on other people's children. That increases the likelihood that other lineages will prosper and expand, and decreases the likelihood that their own will.
Therefore we should expect that, with the passage of generations, the desire to have one's own biological progeny will spread and come to dominate the population.
That is, if such inclinations are heritable--or if a heritable desire to have one's own children appears in the population at some point.
Yeah, but this will only happen over the course of millions of years... not in 2050... Not to mention this is already the dominant desire...