I'm not talking about influenza, or SARS, or AIDs, or whatever. I'm talking about a real plague. And not like the Bubonic one, because we can fix that now. No, we need a disease which:
-Is a virus. This will make things a lot easier because viruses are harder to fight.
-Has a gestation time of several years in which there are no real symptoms, ensuring it reaches everywhere on earth.
-When it stops gestating, a person dies quickly and relatively painlessly. Basically, if you get symptoms, you're dead. That way
-Spreads really easily, through breathing the same air or touching the same surfaces; lives for a long time outside the body (like 24 hours or more), and is resistant to disinfectants.
-Reduces the population by 65% worldwide and renders an addition 15% impotent. 20% means a little less than 1 billion people left.
-Attacks the elderly and the severely ill (cancer-weakened immune system, AIDS, etc) most of all. Not that I don't like old people, but if we're slicing up the population of the planet it's probably best that we not have more of them than we have people to care for them.
-Affects people less if they get good health care but still have a strong immune system-- so a person who was raised on antibacterials isn't safe, but the people who played in dirt as kids have a bit more protection. That's pretty much a given, a strong immune system always means more resistance and good health care too. This can't make us go extinct, and honestly, as terrible as it seems, the world would be better off if a little bit more of the deaths were coming from third-world nations that can't support their massive populations anyway.
-Has a lesser impact on Native Americans, gypsies, aborigines and other such underrepresented races; it still needs to affect them, just at a decreased rate so they aren't obliterated. Affects the Chinese and Indians a bit more, but not by much. Absolutely can't affect Caucasians differently from Africans, though, that would be disastrous politically. Also, Ashkenazi Jews will have high resistance, because I'm so sick of Ashkenazi Jews always being the highest-risk group for everything. Plus Ryter's Ashkenazi and it would be nice if he didn't die.
-The bodies have to still carry enough traces of the virus after death to warrant cremation just to be sure. Otherwise, the world would be a cemetery.
-Can't have any affect on non-humans.
-After a few years, scientists need to find a vaccine that can be mass-produced inexpensively and administered to new children, so the outbreak doesn't happen again.
What's my reasoning for the need for this plague? Well, think about it. The world never comes together as well as it does while recovering from tragedy. So there would be looting and panic, and then afterwards people would start to band together on account of not having anything left.
There would be more food and first-world nations would probably give their massive amounts of excess the first couple years to the third-world nations, with the alternative being to let it rot. After a season or two they'd stop producing as much, sure, but the land in third-world nations can often support 20% of it's current human population.
It would be centuries before we'd have to seriously worry about population again.
Countries would throw money into sciences, trying to ensure we were prepared for another such outbreak.
Huge tracts of land would be left unused. Eventually nature would reclaim it. People would start to clump, especially from towns and cities that lost huge amounts of their population; they'd probably head to a few key areas in each country and build new lives there. Like in this country, suburbanites would move towards the coastal cities. That would offer even more land that would be reclaimed.
Also, it would be several generations before people would return to ideas of real war, because their armies would be so reduced.
Maybe this wouldn't all happen, but that's how I see it going down. I don't know, a worldwide plague, maybe not one with this many deaths but a big one, might do us a lot of good.