Hard. Sometimes viciously. Mother nature has already shown us that dog-eat-dog is the best way to adapt, survive, and even thrive. The business world is the same way. Take your kum-buy-yah bullshit and go sell it to someone else. I have work to do so my company can kick your company's ass and put them out of business.
Not all species, nay, not even all human cultures and periods of history follow this rule. If you look across the continuum of group sizes, that's not even true at all levels in even the most competitive society. It's rather unfortunate (and rather telling of how immature we as a culture are) that so many aspects of our lives are ruled by cutthroat competition, where 0.9 + 0.95 + 1 = ~1 rather than something closer to 2.85.
We've figured out that at the smaller sizes, cooperation is superior. After all, small teams of people get more done than a whole bunch of individuals who are each working towards their own ends, especially if you tell the individuals that they have to expend some of their effort to fend off attacks from others and attack in kind. We still struggle at the sizes involved at the corporate level, where some companies unify vision and goals rather than pit each department against one another.
When there's some external stimulus (usually some common threat), people figure out real quick that it's better to work together. Perhaps one day, we will evolve to the point where people don't need prodding to stop the bullshit and put their resources to work towards common ends, or at least not spend so much effort opposing one another.