“Demonstrably so”? Science has determined when a human spirit has entered the newly genetically-unique organism? Please show us that demonstration.
You are making a religious argument based on Christianity, correct? From the Bible we can read that “God formed Adam from the dust of the ground and breathed into his nostrils the breath of life, and the man became a living being.”
Pick yer poison: http://biblehub.com/genesis/2-7.htm
Note bene that “formed” means like an artisan forming something chaotic into something orderly/beautiful (in this particular case in the “image and likeness of God” in other words in an outline of God to be filled in later)
“Dust” is an unused word meaning earth or earth materials. Both “Adam” and “man” are the same word in Hebrew.
There is order and logic in the story: “God formed Adam from the dust of the ground and breathed into his nostrils the breath of life, and the man became a living being.”
1. Adam/man is formed from preexisting earth materials
2. God breaths life (his soul?) into him.
3. Only then does Adam/man become a living being (soul).
Demonstrably, no?
Now if you want a scientific explanation I adjure to exDemmom. She’s already laid out what science knows previously, no? She seems very patient.