If there are two people, one who's behavior is confined by a strict moral code and another without any constraints are in a competitive situation where the possibility to cheat or otherwise utilize unethical or immoral means to win, the one without moral constraints, all else being equal, seems to have a clear advantage over the other since more options for pursuing victory are available to one and not the other. Generalizing from this example, it seems that morality could consistently place ethical individuals on the losing end of any competition. Life and human society being a competition of sorts in some respects, does this mean the victors and their progeny will be less moral? If not what are the advantages of morality and ethics?
When one person is unethical and everyone else is ethical, that person gains an advantage. But when everyone is unethical, everyone suffers. It's the classic "Prisoner's Dilemma".
From an evolutionary point of view (if you accept the concept of group fitness) an ethical population as a whole could outcompete an unethical population.
I don't have a citation handy, but I believe there have been studies showing that the actual distributions of unethical versus ethical behaviors in areas such as sexual fidelity do roughly correspond to theoretically optimum distributions.
First, constraint is not always an evolutionary disadvantages. Lemmings do not constrain themselves to the limits of their swimming ability, and many of them die. The same can be said of humans pursuing victory. Some social and natural constrains are actualy helpful.
Second, maybe high-functioning sociopathy is an adaptive mechanism. As another answer points out, the best for the overall group is generally cooperaton. A high-functioning sociopath benefits from the trusting nature of society. The best the high-functioning sociopath would get is what he can steal/take from others. Think of it this way if 90% of us were high-functioning sociopaths, then we would never develop technologies like computers and iPads. Thus, a socipath dominant society would probably kill itself out compared to a more cooperative model. So the genes survive best in cooperation.
The proportion of competition vs. collaboration in a society is like the one in any other species: it is part of the natural selection mechanism. Morals is to be associated with collaboration, because collaboration largely depends on morals.
Survival in all societies depends on the available resources of the environment (well, not strictly, but fairly enough for the current problem). Consider that some societies can get more resources from the same environment than others, which members don't have enough physical or mental capabilities. This implies that in order to get some resources, collaboration is required, implying that morals are mandatory.
A society which is able to collaborate in order to get more resources from the same environment is possible if and only if it has a large level of morals.
If resources are excessive for the amount of people, collaboration will decrease, competition might increase (we always want more), morals will decrease and society will be tolerant to it; resources will then quickly decrease, up to a point where society can't tolerate immoral behavior anymore. This will cause the increment of collaboration, which depends on morals, so, the loop repeats.
Such loop is the typical natural mechanism* to keep the environmental balance.
1. Collaboration, morals
2. More resources, growth
3. Less morals, competition
4. Less resources, popul. decrement
5. Back to 1
Baltimore is a clear example. A successful society that suddenly falls into catastrophy, corruption, population decrement, which now has a tendency to increment morality in order to persist.
* See the Lotka-Volterra equations, in this case, the prey is generalized as any resource.
An immoral or unethical society will eventually destroy itself. Drugs, homicide, promiscuity (sexually transmitted diseases) etc. all have bad consequences in the long run. One of them is lessening the lifespan and bringing about a gradual discontinuation of the race.
Morality makes us human, while immorality sends us to the lower level of animals who live by instincts and do not restrain their desires.
There is a higher purpose to this life, which is why some of us are compelled to try and live morally. There is an ultimate reward for those who do good in the Hereafter. They will win then, even if they don't now.
Anyway, as a side-note, isn't it amazing how God gave us the ability to think and rationalize? Can such a wonder as the human brain just evolve by itself with no Designer to work on it? Even the most amazing computer game needs an amazing creator.
"In order to think about the differences between ethics and morality, we must first resort to the etymological roots of these words. Ethics derives from the Greek word êthos, which means “character”. It was used to represent a person's ways of acting, that is, their actions and behaviors. A variant of êthos was the word éthos, which means “custom” and can be applied to a society. The Latin term that designates ethos is moris, from which we derive the word moral.
Basically, ethics is the individual and reflected behavior of a person based on a code of ethics or conduct that must have general applicability. The field of Philosophy dedicated to understanding and reflecting human actions (moral actions) and classifying them as right or wrong is called ethics. Therefore, we can say that ethics is a kind of “moral philosophy”. Morality is, in turn, the custom or habit of a people, of a society, that is, of certain peoples at certain times. Morality changes constantly, as social habits are renewed periodically and according to the place where they are observed."
Ethics is designed to assess thinking especially human's values and principe. For exemple, what is the meaning of generousity or justice? Ethics fails to assess or arbitrate behaviour. Somebody can hit the head of another one with a stick, ethics cant tell nothing from this event or fact. It's failed to tell you if this event is good or bad.
Chris Sunami's answer is great, yet it misses very important elaboration.
A major extension of Darwin's theory was emphasizing not on individual or family level competition, but obligatory requirement of competition of isolated collaborations much above family level. That makes sense, since genes mix dramatically fast with generations and an additional level of isolation is required to keep diversity.
For humans, that additional isolation was visible all the time - starting with tribes and sea/river crossing, then collaborations like Greek city-states, then modern district wars and countries borders.
Something in us unconsciously but reliably leads to "friend or foe" marking and occasionally initiates mad unprovoked "great crusade" against foes. The heavy truth is this competition was obligatory previously (during millions of years of primates development), and without it we wouldn't ever get to modern state. Unfortunately, very few keep these roots under self(us)-awareness.
With this grouping in mind, back to morality and ethics: that was correctly said that
an ethical population as a whole could outcompete an unethical population
but when we translate this to language of groups, let's say a group of 100 people:
Most of 100 act selfish, steal, deceive, scam:
= tribe-type relationship, as soon as someone gets any resources, all others focus on taking them away, and they prevent/slowdown progress/accumulation almost to none
If ~ 90/100 act moral:
= Feudal relationship: slow progress is possible, but as soon as any of 90 achieve something, that is taken away and accumulated by 10
If ~ 97/100 act moral:
= modern relationship: progress is possible, but amount of damage these 3 are creating much lager than amount they benefit; even on simple psychological level each of these 97 need to constantly think about "what if" scenario, what if they cannot trust next person
All 100 are reliable and honest: exponential increase in efficiency. Good illustration here is that you can skip wasting resources on protection, skip locking doors, hiring security staff - for example, while selling something you just place it on street with cost piece of paper and return next day for the money - no rent, no verifying, no overhead.
That is the reason why countries like Norway and Australia made enormous life quality jump recently. But also demonstrates how fragile society 4) is - even very small amount of outlaws/criminals drag such groups long distance backwards.
To finish this, morality and ethics could be extremely evolutionary advantageous on groups level when they are well established and fiercely protected against even small disturbances.