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.
The ring is more noticeable on the right hand due to the traditional shaking of right hands in greeting. Several traditions exist in traditional Jewish wedding ceremonies: most commonly today, the ring is placed on the index finger; but other traditions record placing it on the middle finger or the thumb.