Empathy and Reciprocity are the roots of moral behavior, but human morality adds an important layer : a shared system of norms and values several members of a group can tap into and which functions as a sort of operating system for a specific community.
Empathy and Reciprocity are already active and present in chimps, but apes do not have morality, since they lack the mental capacity to create inter-subjective systems of norms which acquire a sort of "objectivity" when adopted and believed by many individuals.
After a person has adopted a specific moral norm, it becomes part of his/her identity, sometimes to an extent that people will give their life to defend this moral norm or these moral values, considering them sacred (whether they are just tribal or universal, like "human rights" ).
Empathy seems like the root of it, but there I believe there are more than one type of morality depending on different situations.
I think ethic is based on rules/laws. Some of the oldest existing writings are laws such as the Code of Hammarby
Empathy and reciprocity are non-cognative and amount to rah/boo ethics, which have no rational ground
A conception of what is or is not just seems to be common to societies. While it is argued that our conception of justic is normative and varies from socity to society, I believe there are certain laws that transcend normative values: such as the law against unwarranted killing.
Chimps don't have courts of law, only death penlties...
The deeply felt morality that you speak of might have social value within a particular group, but in some circumstances that kind of morality might be a handicap. If there is war a person might have to put aside his moral sentiments. Maybe it’s a valuable thing to be able to see morality as purely subjective and relative rather than as ones sacred identity. The alternative might lead to insanity, or to defeat.
A soldier can still empathize with the enemy, but he needs the ability to perform his duty without emotional baggage.
Neuropsychologists believe there are two types of empathy: emotional and cognitive. Emotional empathy generates group identity, and is mediated in part by the hormone oxytocin. This hormone is released in the mother when the newborn suckles, enabling the formation of a strong emotional bond. Emotional empathy is the ying-yang of empathy in that it is the basis of in-group/out-group identity. Donald Trump is great at promoting emotional empathy, and generating antipathy between groups. Cognitive empathy transcends group identity, allowing one to logically assess his fellow human's position. This type of empathy doesn't develop in the human until young adulthood.
I don't think those who study the difference between humans and chimpanzees would agree with your assessment on the difference between humans and apes. Michael Tomasello's research has shown that chimps and human children have similar IQs. Where we differ is in our social skills. Humans seem to have a greater capacity to form empathetic bonds than do chimps. A great book to read is Tomasello's "The Cultural Origins of Human Cognition." He summarizes years of research on the differences between humans and chimpanzees. Many now believe that the primary role of the frontal lobes is not to enhance cognitive abilities, but rather to enable us to navigate our social world. Lesions in many areas of the frontal lobes result in the individual being unable to navigate social norms.
@Matias I haven't read the Tomasello book on morality yet, but I don't think he distinguishes emotional and cognitive empathy in his work. The key paper on this distinction is a 2009 paper by Shamay-Tsoory and colleagues, "Two systems of empathy..." I think that the development of morality is contingent on the development of cognitive empathy. I think we can enhance the development of cognitive empathy in secondary education through the use of the narrative. In fact, I think this should be the primary goal of secondary education. If we develop cognitive empathy in our students, then they can use this in a variety of ways, including their own personal development of morality. Personally, I view the US election of Donald Trump as a manifestation of our failure in secondary education.
Is empathy a response to morality as a baseline social preference or an internal driver? Certainly moral/ethical rules have different grounds depending on their culture, therefore ethical rules are not universal. Responses to the ethical rules of another culture are informed by one's own cultural, ethical norm and so can be responded to with curiosity at best and horror further along the scale, depending upon the deviation from personal practice if coming from an ethnocentric standpoint.
If empathy is cross-cultural then it transcends societal norms. If it is inter-social it is an aspect of social construction. An argument could be that empathy can be trans-cultural due to the observable empathy many individuals have for different species regardless of the culture within which they are innate.
I think it began as a transaction which was not just an agreement to support each other in need, but also as an investment in the future in the sense of insurance against need. If so, that's a hell of a concept for a cave-dweller to ideate. It's astonishing to think how that idea, which I think is akin to barter, reached its apotheosis over time in the Christian notion of a man-god investing in his own death to buy himself a better position in heaven and support and save all mankind in the process.
Moral behaviors, group accepted norms, are possibly a gift to us from deep time and most likely a product of developing empathy coupled to survival needs. This is evidenced by the general consistency among disparate/isolated groups. The novel I just began assembling research for deals with this subject in a far flung future human colony on a planet slightly larger than Mars orbiting Alpha Centauri B sometime around Earth year 3160.
Empathy can be very important, but science shows that people who are or have psychopathic tendencies can have a strong moral code. Yes, serial killers are usually psychopaths, but psychopaths are not all serial killers. So, something other than empathy can guide a human to being moral. Would that be reasoning? Maybe.
@Matias first, you make some very valid points. As far as my guess of reasoning, I would say I was thinking about people like Hitchens and his ilk. No doubt sime of the "most moral" people have been and still are butchers. I used to teach Les Miserable and always pinpoint when the Nun, a religious figure, lies to the police, Javert, to save a good man, Jean. And then the teens when can it be a moral right to lie, etc. I ever had one student who said the Nun was wrong to sin. I am not sure what he would say today at 36 and a Lutheran minister, who bought me lunch a couple months ago and admitted he has given out 12 keys to his church to not legal immigrants. As I said somewhere else here, I can find a reason that would make breaking the 10 commandments, etc for a more moral cause.