Any species that can recognize another of their kind over time and remember a kind deed will reciprocate.  Even vampire bats are altruistic.  Humans inherently assume "what goes around comes around."

Mutual aid is a function of self-preservation, reciprocity and empathy. Self-preservation is gene preservation. Gene preservation extends to progeny, siblings and their progeny as they to each other throughout the family tree. The less the genetic distance, the more energy will be expended and risks taken to preserve the gene carrier. This is a genetic trait of all animals and some plants.

Reciprocity extends mutual aid to non-progeny gene carriers as a function of the likelihood that protecting someone in a community will be reciprocated by someone in the community. As with self-preservation, unrelated children are protected with greater energy and risk than elderly adults as a function of procration ability.

Ethics is generalized or abstracted reciprocity. A hand-shake seals a contract, not only because of "tit-for-tat," but also because dishonesty feels bad as revealed in fMRI studies that a primative part of the human brain activates negative emotions when the actor engages in fraud, likely due to reprocussions suffered by human ancestors. Honesty is genetic.

If humans own themselves, the essence of morality is ethical behavior, i.e. no fraud or trespass, and any property value loss resulting therefrom is reversed or compensated.  Extending morality to encompass universal reciprocity makes no sense due to the genetic distance issue. Extending morality to encompass nudity or covering the mouth or nose during a cough or sneeze for example, only makes sense with regard to the trespass of diseases.

If honesty is genetic, then why is peer pressure required to extend ethics to larger communities as a function of communication within the community. Why do mutual aide and ethics decline in reverse proportion to  the size of a community, i.e. the more distant its members, the less likely good deeds will be reciprocated? This is evident in rural communities where doors are often left open or unlocked as opposed to large cities where everything must be thoroughly secured. Something else is at work.