Pain and loneliness

This book says pain and loneliness are associated with the same piece of our brain. So I was wondering, if I can cut that piece off, then am I going to be fearless? My friend laughed at me after he heard it, "pig head, if you cannot feel pain, you even don't know how your arm get cut off". Yeah, I was stupid.. and this book also mentioned that this loneliness gene is developed as an alert to us, since being alone is more dangerous than within a group. Especially for children, they are more vulnerable, so they will feel more pain than adults when left alone. I guess this applies to the weaker people as well, no offence, but it seems that weaker people are more sensitive about loneliness.