What are indications of long life or short life in natal charts

[retinoid]

I guess the main focus is the 1st, 4th, 6th, 8th and 12th houses?

I know Saturn in the eighth is supposed to give long life but that isn't true necessarily w/ a lot of people with this placement. Uranus in the eighth can bring a 'sudden' death. Uranus always brings good and bad things 'suddenly' or unpredictably. Beneficial planets in the 1st house bring health. The 6th house of health is a little ambiguous (I have sun, mars, mercury, pluto in the sixth). I know mars is supposed to give you recuperative powers and pluto can do that too but can also bring health problems.

[Olivia]

A strong hyleg, unafflicted alcocoden, trip rulers of the ascendant inclined to life, trip rulers of the sect light angular and unafflicted.

You'd want to look at primary directions as well to see what nastiness may arise (a bunch of really bad PDs along with a nasty profection or solar return during the same time could cut life short), but the stronger the chart generally - planets in dignity, few afflictions, and the above-mentioned, are indicators of long life.

[Lost_spirit]

That's a hard question to answer,but since it's one of the things I like to study a lot I can only tell you some things I've realized.It's really hard to determine the length of life since I've seen charts with harmonious aspects and the people died young,while many charts with afflicted planets and grand squares lived a very long life.The ancient astrologers took into account things besides the chart,like the environment someone lives.For example a prince who gets all the medical atttention can live very long,even with an afflicted chart,while a child born in a starving country may die young even with a very good chart.
Provided that someone is somewhere between the two situations I mentioned above,a strong Ascendant ruler is a good start for a long life.A strong Ascendant ruler means not in its fall or detriment and prefferably in an angular house(1,4,7,10) and also not under the Sun's beams.Having the Sun or Moon in a hylegical house(1,7,9,10,11) is also good.It's also a good thing when the Sun,Moon,Ascendant and Ascendant ruler are not in bad aspect to Mars or Saturn.In General the three vital points of the chart are the Sun,Moon or Ascendant and depending on their placement usually one of them is the most important.
If you search about the hyleg you will find some methods to calculate the length of life.I can't say if they are accurate or not.There is a huge database of charts available online in a site(I don't know if I'm allowed to mention the name)if you want to do your research,with categories that include short and long life.I'm as interested in this subject as you are.