So how do you rationalize the fact that the world was far more brutal and "cold" before capitalism? Capitalism did not create this condition, rather it was formed to respond to it. It was born from an era where people were abused, died and horribly mistreated because of a family name or some connection to a mythical deity gave the monopoly of violence to some random jack ass. The fact is, and this is something even Marx admitted to--capitalism raised the standard of living in nearly every country it was implemented in. There were radical improvements in almost every metric of quality of life.
This rise in quality, in fact, is needed in order to reach Marx's utopia. This is another thing he readily admits to. The only way to form a good socialist base (Which can evolve into communism) is the higher productivity and social equality in Capitalism (Note I said higher--because as bad as capitalism's social equality can be, it's leaps and bounds better than the systems before it.)
Capitalism didn't "bury" our true nature. It merely understood our true naturewhenwe have to deal withresource scarcity. When there isn't enough to go around, we tend to be very terrible, we are brutal, cold and will disenfranchise the weak in order to reduce scarcity for the strong. Capitalism accepted that as a truth and channeled it into higher productivity by created a political-economic system that offered abstracted reward structure that controlled the normal violent byproducts of that nature and allowed for innovation and a far more fluid social mobility (Though, it's obviously got major flaws--but it IS vastly superior to systems before).
If anything, Capitalism brought us one step closer to your view of human nature--and again, even Marx admits this (Capitalism is a step on his progression to Communism). However, it's only a step because as long as there is scarcity, people will be this way. That's not something Capitalism is forcing on us, it's always be present. That's why the Romans had slaves, it's why the feudal lords were assholes and why the Mongols took everyone's stuff--because people, at their core, are brutal when they need stuff (Or, as I think Dumar is saying, when they THINK they need more--which is a flaw of modern capitalism).
The fact is though, that said brutal nature due to scarcity? That's a driving force of evolution. It's buried in us. Capitalism isn't keeping down our happy place, it's instead putting a restraint on that brutal nature by placating it with stuff. (I believe what Dumar is referring to is how we've achieved a very high level of production and the desire for more now is not natural, but instead synthetic based on capitalism's need for growth. And that's fair, it's a fatal flaw in Capitalist economics--that productivity becomes self serving, Supply Side economics is the fruition of that. Haven't caught up completely on the thread though.)