Companionship, friendship, love and affection are very much biological needs. In study after study, we know that people of all ages live longer and in better health when they have companionship and affection. Babies who are deprived of care and nurturing don't thrive at all, and adults are not all that different. It is very much a biological need, most likely driven by evolution. Companionship, since it's a boon to our health and longevity, increases our chances of successfully passing our genes on to another generation.