“Life” is just chemistry and physics of a myriad of compounds. The same laws and reactions govern the interactions of “dead” matter. There really is no fundamental difference between “living” and “dead” matter.
This makes your question confusing and hard to answer – there really cannot be a clear cut answer on how A turned into B, if there is no celarly defined difference between the to begin with. I guess the answer would be “It didn’t – the chemical system just got more complicated, but it’s still not that different”.
Latest Answers