Methuselah's Children by Robert A. Heinlein

Again, this is one of my favorite Heinlein novels, possibly because it sets up a later novel, Time Enough for Love. I wonder if he was consciously preparing to write a story about the man who would never die, Lazarus Long, here, or if it was just a chance name selection, or if it had more to do with the idea that Lazarus had "died" as far as the authorities were concerned, several times by the time of the story, in order to conceal his longevity.

The story is about a group of people on Earth called the Howard Families. Ira Howard, a very wealthy man, found himself dying of old age very early, and endowed a foundation to study and encourage human longevity. The directors of the foundation chose to do this by a selective breeding program, taking young adults whose grandparents had lived into their 90s and 100s (a somewhat rare event at the beginning of the 20th century) and giving them financial incentives to marry and bear many children. By the time of the story set in 2125, most of its members are living to be well in excess of a century.

They have kept their existence secret for two centuries, but have decided that mankind has become enlightened enough to accept them and not persecute them for being different. Oops. When a select group of the Families reveal their existence, the public and the government become convinced that they are hiding the secret for nefarious reasons, rather than being merely born with the proper genes, and the administration in power decides to suspend their civil rights and arrest them for interrogation.

Coincidentally? the first colony ship for extrasolar exploration has just been completed, and Lazarus Long, known as The Senior for being the oldest known member of the Families, and his buddies manage to hoodwink and hornswoggle the reiging powers and "borrow" the ship to get all 100,000 or so of the Howards off planet.

They visit a couple of different alien races on the voyage, both so advanced in comparison to humans as to be godlike in their powers. The first attempt to domesticate the humans, and the second merely to assimilate them into their communal mind. Either way, Lazarus - and Heinlein - have other ideas about the true nature and destiny of Man. Fun stuff.