Perhaps it's because laying hands on life, in a plainly literal sense, connects us with our own being-in-life.
Of course, we see it when animals are brought in to help the sick and elderly : holding another living creature can heal us. There's something profoundly physical about love and belonging. For me, this is answered spiritually by my relationship with the god, within the goddess. (I see it too in older traditions of Christianity.) I can't speak with any authority on the nature of life and afterlife; I can only say that, when I lift a small flower bush towards the sun, when I cradle a baby in my arms, when I touch someone I love (or even a stranger), I feel the divinity of the body, infused with the soul of love.