From Envirowiki

culture is the sum total of beliefs, knowledge, myths and practices of a group of animals. The term usually refers to human cultures, but other animals, such as various apes, dolphins and whales, and some birds also have cultural practices - that is, ways of doing things that aren't instinctive, but are passed on from their forebears.

Human cultures vary widely, however, one culture, mostly stemming from colonial europe, currently covers most of the world, with the few exceptions of first peoples still existing outside the western system.

Cultures have both positive and negative effects. Richard Dawkins posits cultures as a mass of self-replicating memes, which evolve over time. Any meme may have a positive effect, ie a meme for "be friendly when someone offers you food" would have the effect of increasing the chances of being offered food again. Negative memes usually live for a shorter period, as they get wiped out quicker. In some situations though, negative memes may continue to spread and evolve until they change their environment to a point where their hosts either notice the impact, or wipe themselves out. Our use of oil might be considered such a case - our current meme is to constantly increase our use of oil, which is good in the sense that we have much more energy to do what we need to do, but is bad in that it's leading to peak oil and climate change - the meme may so wipe itself out, and may take it's hosts (us) with it.