In today's society, cynicism prevails. The common wisdom holds that everyone is looking out for their own individual self-interest first. People say, "It's a dog-eat-dog world."
In a complicated world of competing interests and agendas, why not simply look out for number one? Isn't everyone else doing that?
Besides, it's a world dictated by the survival of the fittest, isn't it? Taking the effort to help someone else, sacrificing something you have to accomplish an end greater than yourself; what's the point in that, in a world where the strongest survive, and the weak perish? Altruism in this context appears to be futile and hopelessly naive.
This is a fundamental foundation of modern thought. But it is incomplete. Yes, the science of evolution demonstrates that those who are best equipped to survive, will prevail. However, there are a broad number of instances where altruism (the act of doing something that does not benefit one's self or is harmful to one's self, but that does benefit others) can be observed to be an essential part of the greater order of the universe.
The instinct to help others in ingrained in the human psyche. There are countless examples of other animal species who also act "altruistically". Ants form colonies to ensure the survival of all, lions are organized into prides, primates such as chimpanzees live in social communites devoted to taking care of one another. Even slime molds display a form of altruism.
Myxomycetes (plasmodial slime molds) have a life cycle that involves two feeding stages. The first stage consists of single-celled amoebae. The second stage consists of the plasmodium. To form the plasmodium, the single-celled amoebae merge together to form the multi-cellular plasmodium structure. "Under favorable conditions, the plasmodium gives rise to one or more fruiting bodies containing spores. The spores of myxomycetes are for most species apparently wind-dispersed and complete the life cycle by germinating to produce the uninucleate amoeboflagellate cells" (http://www.discoverlife.org/20/q?search=Eumycetozoa).
Even in our own bodies, the law of altruism is clearly demonstrated. "Apoptosis, or programmed cell death, is a normal component of the development and health of multicellular organisms. Cells die in response to a variety of stimuli and during apoptosis they do so in a controlled, regulated fashion...Apoptosis...is a process in which cells play an active role in their own death" (http://www.sgul.ac.uk/depts/immunology/~dash/apoptosis/). Some cells die, when they have surpassed their usefulness, so that an entire organism can continue living.
Sacrifice is an important concept in any proper understanding of society. As natural rights philosopher John Locke stated, humans sacrifice their unlimited freedom to use certain rights that they are born with in order to live in an ordered society that protects those rights from being infringed upon by other people.
In a world where life can be "nasty, brutish and short" (Hobbes, Leviathan), a community centered around individuals sacrificing their own energies and time and resources to achieve common ends may be the most efficient and practical way to ensure the well-being of human beings. Altruism remains the best and most effective method of survival.
Because after all, it's not really a dog-eat-dog world out there. It's more like a pack-eat-dog kind of world.