This section will describe what I think will occur in the future of the human species after we establish self-sufficient space colonies. Of course, it assumes we are successful in establishing self-sufficient space colonies before an extinction event occurs in our biosphere.
After survival, our next main issue and responsibility will be creating an ethical artificial general intelligence which will effectively become our descendant.
Along the way, we may engage in transhumanism. Exactly what is meant by "transhumanism" is up for debate. We will surely be developing biotechnologies to extend our life spans, enhance the performance of our brains, be able to control mechanical items by connecting them directly to our nervous system (cyborgs), and connect additional sensors to our nervous system likewise. There is actually a lot of work and some early successes in these areas already.
By isolating laboratories in space, we create some security by isolating biological experiments which can go bad.
However, what will transcend all of this will be "The Singularity" which occurs when artificial general intelligence reaches the point where it can self-improve. (It will also self-replicate very quickly.)
Of course, none of the above will happen if we try to develop these technologies on Earth. Creating manmade viruses which will make humans extinct is far easier and will come much sooner than advanced things like transhumanism, life extension, etc. Indeed, many of the things we are tinkering with, such as life extension, cell repair, rejuvenation, and curing diseases at the cellular level, are largely genetic programming issues, which is a double edged sword.
However, the purpose of this page is to state that even assuming that we create space colonies whereby the human species survives the great Earth extinction, even with these big space colonies and space industrialization, I do not believe that humans will populate the galaxy, or even our own solar system very much. The vast majority of what I hear and read in the current literature about the future assumes that humans will continue to think pretty much as they do today.
It totally misses the revolutionary and imminent event of The Singularity.
These issues are covered in my website www.GAINextinction.com on biotechnology and nanotechnology human extinction, or The Singularity. (GAIN = Genetics, Artificial Intelligence, and Nanotechnology.)