I realize this isn't the perfect place to ask but this question started bothering me due to content in Skyrim and i'm hoping you guys can clarify this for me. Orc cheiftens are replaced by their sons when they're too old, but being elves of a kind (Orsimer) wouldn't they have the 1000 year span allotted to Mer, so does this seem a little odd to anyone?

No If the life-span is the same for an Orc then they would be killed by there sons at when the Orc chief grows to be around 900 i suppose.

which is what sounds weird, so i just wonder what exactly is their life span or is it some weird Darwinian thing that when they hit say 400-500 the son kills them maybe? But i don't know?

Okay a few things are relevant here.

1. We don't know the average life span for elves, some speculate a thousand but a dev interview once said Dunmer live on average about 150 years with up to a 1000 for nobles. So a lot depends on the life style

2. Many Dunmer we meet in Skyrim are at least 200 more years old, so that getting confusing.

3. We have no idea how long Altmer live

4. Orcs, Dunmer, Bosmer, Altmer all come from the same source. Aldmer.

5. They are all different in ways including life span

6. The Patron god of Orcs (Malacath) is pretty corrupted from what he used to be, the Orcs became corrupted with them. So while technically they started out as elves, they are no longer really the same as their distant cousins the Dunmer, Bosmer and Altmer of this world.

So in conclusion the average life span of Orcs and indeed all elves does not have to be related to that of other elves, it seems to be different depending on a lot of things. Including life style. Orcs just have incredibly short life spans, especially for elves. But part of this probably also comes from culture and their way of life.

60 is considered a very advanced age for orsimer after Shor moved a curse of short life off the nords onto the orcs.

Altmer definitely live towards the 1000 years if i recall correctly, there's a book about them learning to walk the right way r some weird thing i think, but i just would have thought that Orc's would've at least had a 200 year span

Yeah im pretty sure i read somehwere that they live less than humans, about 60 years. Plus they like to pop off before they get old, rather than get frail and die. Go see Old Orc.

lol but it svcks that they die at like 60 coz i love Orcs they're just so cool, and what about that ancient Orc in Winterhold?

He's a librarian likely no older then 50.

A good Orc mage however could last several life tims, but there is no evidence that the guy you mentioned is one.

lol well if he can have you torn apart by angry antronach's i think he'd be a pretty good mage

As others have already said, 60 is considered very old for an orc.

Shame i expected so much more of a life for my Orcish freedom fighter, he didn't even get to use molotov's