If we take the view that humans are descended from lower order animals, then how can this be true? In the animal kingdom, the only rule is survival of the fittest. Animals kill other animals, steal from other animals, take the mates of other animals because that is their instinctively driven behavior. If we are descended from those same animals, then how can it be in our very nature to not do these things?
Perhaps you would not be able to figure out that rape, murder, stealing, lying are wrong, without some authority telling you they are, but truly moral people do not need to be told they are wrong.
Then how did those people learn to do it? And how did the people who taught those who taught these moral people learn? Where did what we consider to be good behavior come from?
What you are implying is that rape, murder, stealing, and lying are only wrong because God said so. If He said they were OK, would they be?
I am not implying it, I am explicitly saying it. Look at the Islamic faith as an example for how morality is derived from religion. In this faith, the holy book states very clearly that it is perfectly OK to kill nonbelievers, that it is perfectly OK to lie to advance the cause of Islam and that it is perfectly OK to have sex with minor girls. Many followers of Islam who agree with these tenets do so because Allah told them it was OK.
Likewise, societies that base their morality, and ultimately their laws upon laws listed in the Bible do so because we believe that God told is this was the right thing to do.
“If we take the view that humans are descended from lower order animals ...”
I do not take that view. (Do you?) Since the rest of your post is based on that false assumption I’ll only add this:
Please tell me where in the Bible the principles of the calculus are found. If they aren’t there, how could men possibly know them. Why do you think if men, using their ability to reason could discover the principles of calculus they could not discover the principles of ethics.
Hank
Contrary to what many educated people seem to believe, ignoring the visceral and emotional component to morality does not produce better decisions and more moral people. Quite the opposite, it produces monsters. We can know this because psychopaths, who are often otherwise quite intelligent and rational, lack the visceral empathic component and it allows them to behave in monstrous ways toward others. This is why psychopaths are often described as not having a conscience or even being simply being evil (you can find a good introduction to psychopaths here).
So to a degree, Hank is largely right and a significant amount of morality is is an element of human nature in normal people, though psychopaths (perhaps 4% of the population) don't have that visceral moral conscience as part of their nature and narcissists (a much larger portion of the population who do have a visceral moral conscience, though it is it impaired). In fact, similar moral principles can be observed in chimpanzees and other social animals (you can find a good overview of some of the similarities as well as differences in this program). The research with chimpanzees point to another important element of moral behavior, which is impulse control.
That said, culture and religion also play a role in human morality and behavior by playing with the visceral and rational components of morality and their relative dominance. To make a long story short, it's possible to encourage normal people to behave like psychopaths by emotionally distancing them from the victims of their moral decisions (the classic dehumanization of the enemy), encouraging people to generally be emotionally aloof and even to ignore their visceral emotional reactions as wrong (I believe this is what's been happening in modern academia and with self-styled intellectuals), and by making immoral behavior seem normal, since humans also naturally validate their moral decisions against those of the people around them. Thus you can take a normal person who has a healthy visceral emotional conscience and get them to behave like a psychopath without a conscience.
While it's possible to argue that morality is necessary for human survival, the reality is that some percentage of human beings survive without it (psychopaths) or with impaired morality (narcissists) Further, entire societies have existed for quite a while while downplaying or even doing their best to eradicate the moral conscience of their citizens. For example, the way Spartans conditioned their citizens was essentially designed to turn people into psychopaths by beating the moral conscience out of their children. In addition, individuals balance their morality against their needs and consequences and that balance of interests will often lead people to make decisions that they know are immoral because the value the benefits is high to them and the consequences of behaving immorally are acceptably low. This is why people will do things they know are wrong and feel guilty about when they know they can get away with it. This is also where impulse control comes in handy.
The bottom line here is that most people do have an innate sense of morality that will encourage them to be behave morally but it can be suppressed by the culture around them and they can and often will freely ignore their moral conscience when the consequences of behaving immorally are low or inconsequential. So why normal people don't need to be told, per se, that rape, murder, stealing, lying, and so on are wrong, they may need to be taught to view those they might rape, murder, or steal from with empathy rather than as sub-human resources to be pillaged, they may readily ignore that moral understanding if the benefits are sufficiently high and the costs sufficiently low, and may have their moral conscience suppressed or even erased by a culture that dehumanizes others or tells them to ignore their visceral emotional responses in favor of their rational utilitarian thoughts that focus solely on costs, wants, and needs.
That's where religion comes in and, in particular, where some particular elements of Judeo-Christian religion comes into play.
Religion, in general, tells us that not only is there a supernatural always watching us even if we don't get caught behaving immorally by another human being but it also generally tells us that how we lead our lives will determine how eternity judges us, again, even if there is no earthy punishment for our wrongs.
To illustrate, I once asked an atheist friend (and member of Mensa) who was puzzled about why religious people assume that atheists are morally lacking, "Why is it wrong to kill someone?" He started giving me the normal utilitarian argument about how we don't kill people because we hope they won't kill us, at which point I stopped him and said, "Suppose you knew you could get away with it and nobody would ever punish you?" There is no shortage of despots who died peacefully in their sleep having never suffered earthy punishment for their sins. He looked and me and didn't have an answer. In fact, it's even worse. "What if you don't care if you get caught and punished?" There are plenty of examples of that, too. Here the absence of religion (or the belief in a cold and utilitarian religion that offers moral judgment can work the same way) weakens the visceral moral conscience. To put it another way, removing God as the center of the universe makes the individual the center of their own universe.
Where the Judeo-Christian (and even Muslim) perspective goes even a step further is that it argues that all humans are children of God and are morally equivalent. This, in theory, encourages people to treat all humans (even their enemies) with a minimum set of humanity, which one doesn't find in many pagan cultures, who treat outsiders as less than human. Where it breaks down with radical Muslims, as it has with many militant Christians, is when one uses a lack of belief as an excuse to treat others as less than human. I don't want to get into a larger debate about the particular views of each of those religions and their multitude of sects but I do think that the general idea that humans were created in God's image has been critical to the sort of global morality that's the norm in Western Christian civilization and it's why the Western Christians were critical in the elimination of the slave trade, among other things.
So to wrap this all up, most humans are born with an innate sense of morality commonly referred to as a "conscience". Some percentage of people aren't born with or never develop a "conscience" and a very large percentage of them behave like monsters, not necessarily murdering those around them but often leaving a trail of destruction in their wake as they use and abuse those around them. For those born with a conscience, the environment and their beliefs will play a huge role on whether they listen to the visceral emotional component of their moral decision making process (their "conscience") or whether they'll ignore it and act according to baser needs, utilitarian motives, or the orders of others. Religions that extend moral judgement to eternity, hold people responsible for their moral deeds even when not watched by others, and encourage people to view all humans as morally valuable children of God (as do Judaism and Christianity) tend to strengthen and vitalize a person's conscience and encourage them to behave morally even when there are no consequences to behaving immorally. An absence of religion offers no such strengthening and can actually undermine the visceral emotional component of morality because it can be written off as irrational and worthy of being ignored. And that's exactly why one sees so much immorality being promoted by academics and why it seems that the more people intellectualize a problem, the more immoral the solutions they are wiling to consider become.
The truth is that there is no rational reason to be moral, a point that this philosophy paper lays out in great detail. While it's possible to explain why people have a conscience in evolutionary or psychological terms, it doesn't provide an individual with a finite life any particular reason to care. Why should an atheist care if the human race survives or dies off in a matter of years once they are in the ground pushing up daisies? And once people stop caring, they can stop listening to that little moral voice in their heads called a "conscience" and the results of doing so are rarely good.