Altruism, from an evolutionary perspective, is a higher-order trait that develops in animal species with a high enough intellect, Homo Sapiens obviously included. It is a behavior that is beneficial to the species as a whole, while at times may be detrimental to the individual displaying the altruism. However, most times, helping another altruistically will not harm the altruist and will provide a boost of positive emotion instead, which may be beneficial for the altruist's own survival in the immediate aftermath of the altruistic exchange.
On a social scale, though, altruism takes on a whole new level of meaning. Now we can ask: are we a selfish society, or an altruistic one? And the answer lies in averages and social norms, and fads and other such things, but a selfish society will always collapse, while one based on pure altruism also seems to work poorly, from small communes of late 1800 and early 1900 both in the US and worldwide.
Larger scale experiments with Socialism have failed miserably in the past, killing millions in the process.
So what's the answer? We need a combination of both. One Communist society has not failed - China. And that is because they have allowed elements of consumerism and capitalism into their system, which made it stronger and more resistant to revolution or collapse. And it has brought prosperity.
On the other hand, we have the US, which is a purely non-altruistic society, as only the deeply religious pay tithe, and welfare and such are at a minimum. Does this work? Also no. We are collapsing because the non-altruistic nature of pure capitalism has turned us into overweight, under-educated, consumerist zombies who cannot control their own democratic republic, due to materialist-related corruption within the political class.
We need a middle road solution. A mixed system of altruism and capitalism with a generous but FAIR social service undernetting. With mechanisms built in for helping those that have lost their way and fallen back up and on their way.
But to base a society PURELY on altruism is a foolish endeavor, as the Universe is a harsh, lethal place that will kill you the first chance it gets. It is chiseling, winnowing species (including our own) to be strong, ample survivors. And survivors survive due to their own efforts, and not due to efforts of other 'altruistic' members of their species, with rare exceptions, as the altruist too needs to spend a vast majority of his/her time to survive.