
Yes morality is a distinction between right and wrong, but i believe the problem is not in the defining of morality, but the definitions of right and wrong.
Interestingly enough, co-operation is not just required to form at the animal stage, but was required for the evolution from unicellular to multicellular life, so we have evidence of it in the fact that we are actually here at all. There has been research done into the evolution of co-operation, and the evolution of multi cellularity that actually looks at cheating affecting the system as well. to illustrate using the research example that is used as a case study in biological evolution (cant remember names at moment, so generalising bacteria instead of actual species.:
Consider a sterile beaker, filled with pure nutrient broth, and a species of bacteria. this original bacteria free floats in the broth (so called floater), and requires sunlight to digest its food. It tends to live as a true individual. Over time, a new subspecies forms, which is covered in fuzz, and produces a gluish substance ( called fuzzies), which due to the fuzz and the glue making it less dense, resides at the surface. the glue and fuzz cause these fuzzies to stick together, and form a raft, preventing a large portion of light from reaching into the water. eventually, this advantage causes the fuzzies to be pretty much the only bacteria left. Now, sometimes, a new form occurs, which has a wrinkly skin which allows it to increase nutrient intake, and allow the glue and fuzz of other bacteria to stick to it. these were called cheaters. now, these would quickly reproduce as reduced energy expenditure plus increased energy intake allowed faster breeding. eventually, the raft either rips, dropping the cheaters and surroundings to the bottom, or the whole raft would sink. Once sunk, the bacteria would die, leaving any surviving floaters to start the cycle over again.
Now, the scientists found that in the samples shaken to prevent the fluzzy colonies and cheaters from forming, the population density and diversity remained low, compared to the fuzzies and cheaters. the mats that only ripped as opposed to sinking fully had even higher diversity and density to the population.
So, the altruistic behaviour was found to be useful at the individual cell level, and that while it didnt allow for cheaters, individualitic systems also fared very poorly. the altruistic systems had the co-operators performing individually worse than cheaters, but better than the floaters, and the sinking of the mats ensures that a high level of cheaters cant occur in a population, forcing co-operation to be further selected for.
As evolution is now pressing towards maintaining the mat, something interesting happens. slowly, evoulutionary pressusre becomes less on the individual to do well, due to the consequences to the system, so evolution begins to act on the system as a whole, singular individual. essentially, this mat is now a very basic multicellular being.
This scenario is considered one of the likely causes of multicellularity arising, and progressing.
Now, while the conflict between cheaters and altruistic beings doesnt really disappear, the sacrifice made in being altruistic in altruistic societies is more than offset by the advantages of belonging in an altruistic population, regardless of the presence of any cheaters or not. So the genes for altruism are promoted more than the genes for selfishness, and altruism wins out in populations that continue to survive.
Continue this pattern of evolution favouring altruism through increasing levels of individual and societal complexity, and eventually you reach the ideas of morals, as the expressed ideas of altruism versus cheating the system.
So say thanks to altruism and sacrifice for allowing multicellullarity to exist.

Ps. sorry for the wall of text. you think that was bad, that was just the summary of the first weeks lectures. the second week covered co-operation and the evolution of sex, and the third week was co-operation and the evolution of culture and language.
PeterZ wrote:All this is to say, that biology does not select for moral behaviors as we understand such behaviors. Compulsion is hardly a moral trait. Biology would select against traits leading to altruism and sacrifice.
Further responses as time permits.