The findings and researches of various scientists found that there are only fewer connections which are connected with hairs and that also tends to the lifeless of hairs. The immune system in the body always fights against infection inside the body with the help of coordinated action of cells in the body and which has no connection with each other’s  or not even with any connection with the brain. So this clearly explains the presence or absence of nerves in the human body or any organs cannot determine the connection of a particular part of the human body directly with the brain. So if the hair is really connected with the nerves of human brain then how does it really comes to know that it has been cut and it cordially responds back by growing it again to the specific length desired by the human body and also it is not really possible and the conditions also not willing to relate with that. So it clearly shows that when once the connection of a particular part of the body connected with the brain and later or furthers the lengthening part ceases and thus the brain knows about hairs.