This oneness has been proven wrong recently in a personality study. Of course, the goal of the study is not to disprove the body-soul theory but to disprove that the personality changes with age.
Doctoral student and original author Christopher Nave infers from his personality study that "we remain recognizably the same person". Personality implies person and the person is recognizably the same from early childhood till death thus vindicating the 5000 year old knowledge contained within the Gita that the person is changeless whereas the body changes ultimately implying that we are not the body but something other than the body.
The research will be published in an issue of social psychology and personality science. I found this article on Yahoo - link
However, what is interesting is at the end the author states that personality is part of us, part of our biology. He equates personality with biology as one. That means biology is also constant and unchanging. But this cannot be true as we constantly experience biological changes taking place in our body, how then, can an unchanging personality be equated with a changing biology?
This obvious contradiction exposes the fallacy of modern day thought and the hypocrisy associated with it - all in the name of knowledge & evidence!