Check out "Sketch for a Historical Picture of the Progress of the Human Mind", by Marquis de Condorcet, 1794. The last chapter, The Tenth epoch/The future progress of the human mind. There he lays out unlimited advance of knowledge, unlimited lifespan for humans, improvement of physical faculties, and then finally improvement of the intellectual and moral faculties.

And this was not some obscure author, but leading figure in the French Enlightenment. Thomas Malthus wrote his essay on population as counterargument.