This is such a strange thread. It didn't start out strange. Everchangingworld posed an entirely reasonable question and received some very straight and cogent answers.
Then, by the second page, it went off at a tangent, as posters came in asking questions such as asking at what point in human evolution did humans acquire a soul?
Bit of an odd question, that! Not intrinsically odd; it's perfectly reasonable to wonder about that, if one is so inclined, though it becomes somewhat more odd when one realises that the poser of that question is a many times self-professed atheist, who de facto does not believe in the existence of a soul, leading the reader to wonder, logically, why she would pose the question in the first place, that being the case. One might almost suppose the questioner might be laying a trap for the unwary, but no! Surely not? Perish the thought!
Anyway, odd or not, it's an unreasonable question to pose here, since the likelihood of any poster being able to give an accurate answer is infinitesimal. It's a little like asking me how a television signal actually manages to travel simultaneously all over Britain and land inside my TV set just at the moment I want to watch it, and be there at the same time in a TV set of a viewer in, say, northern Scotland. I know this happens. (I also know it would be easier to prove than any answer to the question about the soul, but still...) But ask me to explain the whys and wherefores of a TV signal and why the air isn't jam packed with flying pictures all over the place, and I'm stumped. My guess is most of you are the same, though it's possible there's a TV engineer or scientist out there on this board who could do it. But answer about the soul and when it arrived inside a human? I haven't a clue. Truly, realistically, have you?
The reason I haven't a clue about that, and I bet nobody else does either, is first and foremost because it isn't answerable. It's a non-question, formed in the assumption that the soul has a definable physical quality that somehow gets injected or posted into a body. It just doesn't work like that. A soul just isn't like that.
Then the thread acquires further questions of this nature, and becomes further derailed, moving away from the simplicity of the OP.
Everchangingworld, this is your thread. To me, whose deep underlying faith in God managed to withstand all the harm that the Watchtower could inflict, it seems a strange question, because, for me, and for most people in Britain, there is no division at all between faith and science.
I wonder if this thread below might help by answering the question for you? Because I'm on my iPad I can't make it clickable but I'll see if I can do so in an edit. Hopefully it'll throw a lot of light on it for you.
http://www.jehovahs-witness.net/watchtower/beliefs/243003/1/The-Teaching-of-Evolution-in-UK-Schools-Mandatory