If it doesn't all fit in the subject line, put what you're asking for in the first sentence. This makes the purpose of your email immediately clear, and if the recipient is interested in the details they can read the next four lines. A busy person will appreciate you getting to the point and not beating around the bush.
The message body should stand on its own, even if it means repeating information from the subject line. I hate long, rambling subjects only to find something like "So how about it?" in the message itself. Like the contents, the subject line should be short, concise and to the point, only moreso. This is especially important if I'm reading the email on my phone, where a long subject will be mercilessly truncated.
I have a hard time sympathizing with those pining for the days of high infant mortality and periodic semi-starvation. While I don't argue that many people now are unhappy and working too hard, if you're privileged enough to be reading hacker news in your free time you have a shot at a significantly better outcome.
e.g. I went to a public school, worked for 2.5 years out of college, then saved enough to pay off debts and take a year and a half off to go travel. I'm in great health, I have a beautiful wife that I love dearly, my house is never cooler than 65 degrees, and when it rains I don't have to get wet. You can keep your hunting and gathering.
Just because most people now are suckers doesn't mean you have to be one. Smart fiscal and dietary choices open a world of possibilities totally inaccessible to pre-agrarian (or even pre-industrial) humans.
