Brown adipose tissue is present in small mammals (e.g., mice) and in newborn humans. Most of it disappears in adult humans. The cells in both types of fat are called adipocytes although they differ in origin, structure, and function in the two types of tissue.
On the left hand, index finger. It's not the index finger you wear it on. Left hand, ring finger. The finger that you would wear a wedding ring on.
ring on your thumb was a way of saying you were gay, mostly single people do this. Because gay couples generally are a round or wear a ring on their right ring finger to symbolize they have a serious relationship or commitment to someone. As far as I know things may have changed.