Question from Amanda:
Where did atheists believe humans came from before Charles Darwin’s theory of evolution existed?
Answer by SmartLX:
There’s some information on this here. There were theories of what would come to be called evolution long before Darwin, though none that fit the evidence nearly so well. Among some biologists there were inklings of the basic concept of common descent, for instance the idea that humans and apes were related, but without the strength of Darwinian theory this opinion was highly controversial and one risked one’s reputation by airing it.
So for the lay atheist minority worldwide, our best answer to your question was that they just didn’t know. Since they didn’t think a god existed, let alone created humanity, they reasoned that there must have been a natural mechanism to allow modern life forms to develop some time after the birth of the planet. With what they knew then, they were unable to take it any further.
This basically meant that evolution in that period was in the same position abiogenesis (the initial emergence of simple life from non-life) is in now. No mechanism was clear despite various conjectures, but if a god didn’t seem likely to you then this inspired confidence that a mechanism existed and might eventually be found. Darwin came through for his field, but we’re still waiting for “the Darwin of abiogenesis”. While we wait (and while some of us work at it), we have to content ourselves with not knowing, because to demand an answer when information is lacking is to open ourselves to a wrong answer.