So this is a very early Robert A Heinlein novel, but one that I also really liked. So apparently it was first serialized in 1941, but this full edition probably went through a lot of editing and rewrites for its publication in 1958. It takes places a few hundred years in the future, and we find ourselves situated within a commune of humans that through selective breeding have extended human life expectancy to one and a half to two and half times the natural lifespan. Given this nature, their leadership at any given time (though they are split into clans — laughably structured like Scottish clans to the point where some of them wear kilts and Sgian-dubh and all that.
In a meeting discussing the state of things, specifically the real possibility that the rest of humanity has figured them all out, they are made aware of Lazarus Long (real name: Woodrow Wilson Smith) who is significantly older than the other meetings. He advises to layback and see what happens, but not commit to actions. But things being a democracy, this all goes under discussion. In the meantime, he becomes friends with Mary Sperling, the next oldest member, and because of their genetic fixing their physical age at about 35, this connection buds into an attraction. Of course, this group of long-livers is found out and this forces their hand as they have to look for a permanent place in the galaxy to settle.
The novel begins as a kind of sci-fi political novel, moves onto an adventure tale, and turns into a space exploration story….all wrapped up in a 200 page package. It also begins a series of novels that will comprise about 2000 or more pages and several more decades.