Our morals aren't as strong as they used to be, but some are still there, which is why you don't see any 12 year old crack whores. Also, this happens when you throw education in the picture as well, so let's keep that out for now, we'll throw it in later on in the discussion.
Sarge: I represent the past, where things cost less and people knew the value of a hard day's work, but they only lived to be 28 years old.
Simmons: And I am the future, where people have no morals and no emotions, but we have a bunch of kick-ass gadgets.
Grif: And I'm the future, which sucks; we have nothing cool, and also no morals.
Thomas Hobbes:
Everyone is self-interested. Prior to forming society, we exist in a "state of nature," where all individuals are at war with all other individuals over scarce resources such as food, water, and shelter. Anything goes. However, being reasonable people, we realize that, if we are self-interested, we can achieve more as individuals if our right to life is guaranteed; thus, we enter into a social contract with everyone else and invest all our rights into one leader, the Leviathan, who guarantees our safety from others.
John Locke:
Everyone is self-interested, but in the "state of nature," people have fundamental rights: life, property, self-defense, punishment, and reparation. As with Hobbesian SoN, we compete over scarce resources, although we generally exist in a peaceful state (because there are not too many people such that competition causes war). Being reasonable people, we realize that, as self-interested individuals, we can achieve more as individuals if we work together. By giving up their rights to be judge, jury, and executioner should they be wronged by someone else, everyone retains all their own other rights and invest in a minimalist government that protects them.
Both of these are very much simplified.
I tend to subscribe to Locke.