The life span of Elves on Tamriel. We're told several different things by conflicting sources. I'll be attempting to list the ones I'm personally aware of, and adding some commentary. I'd appreciate if other contribute evidence I will undoubtedly overlook. Even something as small as a snippet of dialogue from a game would be appreciated.
The 1,000 year lifespan argument - Some people seem to think that Elves have a very long natural lifespan. One evidence of this mindset comes from the Real Barenziah, http://www.imperial-library.info/mwbooks/realbarenziah.shtml
Based on this statement, a 1,000 year lifespan is possible for Elves but fatal trauma or disease reduces the likelihood.
Dram: http://www.imperial-library.info/intros/rg_chars.shtml This guy confuses the issue somewhat. He is stated to be over 200 years old, which would support the "Elves live a long time" argument. However he is stated to have been killed and reincarnated more than once. This contradicts later lore about the Dreamsleeve recycling souls and erasing the memories of individuals. We can deduce several possibilities about old Dram:
1 - Maybe it's a lie, or misinformation. Maybe he's not nearly that old. Or maybe he hasn't reincarnated, and when one Dram dies another Dark Elf takes his place. The mask would help with this deception.
2 - Maybe he's actually that old, and has been aided by Necromancy or other magics, and never actually died. Maybe the death/reincarnation story is a myth that he encourages to make him seem more fearful.
3 - Maybe it's actually true, and he somehow has abilities that are otherwise very rare on Tamriel. The ability to retain one's consciousness after physical death. Maybe his pact with Sithis/Mephala makes this possible in the way Umaril's pact with Meridia made it possible to be reborn in a new body.
Exceptional Individuals: We can discount these guys as evidence simply because of the fact they are exceptional and achieved their life spans through unusual methods. IMO. Others may disagree:
The Tribunal - Thousands of years old, but achieved physical immortality by tapping into the heart of Lorkhan. Their lifespans are unnaturally inflated to an extreme degree.
Divayth Fyr/Telvanni Lords - largely rumored to partake in obscure Nercomantic rituals to extend their lifespans. These magicks are unavailable to the average Dunmer and the average Dunmer would probably not participate in them due to religious belief, etc.
Mannimarco - Apparently either a Lich or an extremely well preserved mortal Altmer. In either event he's the most powerful practitioner of Necromancy in all the world, so his 1,000 year lifespan should not be attributed to his Elven lineage so much as his powers as a sorcerer.
The Psijic Order - We're lead to believe that certain individuals within this Order are very old. But for similar reasons as the above individuals, we can't seriously include them in a debate about natural Elven lifespans. They're the oldest organized magical group in all the world. They've surely figured out ways to vastly extend the limits of the flesh, not to mention they live a life of relative luxury in seclusion from the affairs of the world.
Umaril the Unfeathered - Doesn't count for several reasons. For one, the one we face is a reincarnation. That body was not thousands of years old. For another his father was an old god from a previous Kalpa. And finally he had made a pact with a Daedric Prince to preserve his soul. So we basically see a half divine/half Daedric clone of a dead old Elf king. This isn't the typical lifestyle of an Elf.
The 120-200 year lifespan argument: I should mention this is the one I subscribe to, because it's the closest we have to an official developer commentary on the lifespan of elves.
The evidence is http://www.imperial-library.info/interviews/alvur.shtml, which is not an official in game document but does appear to contain several facts about Morrowind which were later discovered to be true. I personally assume the following comments on Dark Elf lifespans are true as well:
We're told that the Dunmer are descended from Aldmer, and I'm not sure if the curse which transformed their skin also reduced their life span, but we're not explicitly told this so I don't assume it. I do know that an Altmer culture hero, Phynaster, taught the Altmer to add an additional 100 years to their life span simply by altering the way they walk. Taking shorter steps. The sources which mention this neglect to mention what the original lifespan of Altmer was before this enlightening discovery - but here's my take. For a race that already lives 1,000 years, another 100 would seem sort of insignificant, doncha think? That's a 10% increase. But if they only lived to be 120 to 200 years like the Dunmer, that's as much as a 100% increase in natural lifespan. While a 10% increase would be note worthy, Phynaster is actually considered an important enough character to be a culture hero of the Altmer. So his contribution was considered significant. Doubling the lifespan of a race of people would justify this veneration much more than adding another 10%. So I logically deduce that the natural Altmer lifespan was closer to 100 years than 1,000 years.
Thoughts? Additions? Corrections? Intelligent debate is appreciated.