A couple of quick thoughts:
1. There is NO "representative democracy." Whether or not it's a good or credible idea, it does not exist. What's called "representative democracy" is, in practice, plutocracy—governments where "elected" official are sponsored by wealthy corporations and ultra-wealthy individuals.
2. Nature DOES seem to contribute more to human behavior than nurture. That said, human beings are capable of overcoming some of their tendencies. For example, when people get angry they strike out violently only a small percentage of the time. The same holds for sex. While there are way too many sexual assaults, I bet the reader (YOU) can recall many, many occasions when you felt sexually aroused and yet did not commit rape. We are influenced, but NOT CONTROLLED by our biology.
I am of the opinion that, although communism and capitalism and representative democracy have proven to be deeply flawed—at best—in practice, WE as a species can do much better. In fact, we must.
I am not ready to declare defeat in advance. I believe in making a sincere and concerted effort. If we fail—well, that's that. But not trying is unforgivable.
The group The Saners is committed to preventing climate collapse and building a more humane and sustainable society. WE are trying. YOU can join, if you wish.
See WeAreSaners.org and consider signing up for the email list at WeAreSaners.org/join.