What's the difference between the following:
By the age of 45, most men had died.
By the age of 45, most men had been dead.
I was told the second is wrong but I don't know why.
What's the difference between the following:
By the age of 45, most men had died.
By the age of 45, most men had been dead.
I was told the second is wrong but I don't know why.
Had been dead wants a time-span modifier:
Had been dead for ten years....
**Had been" + adjective (or participle) establishes a span of time during which the adjective state (or ongoing action) obtains.
He had been asleep for only two minutes when the phone rang.
The terrible tot had been holding her breath when she passed out.
The phrase "by age 45" does not provide the needed time-span.
P.S. Just as the time-phrase in a present-perfect construction cannot exclude the present, because the past is perceived from the present point-of-view when using the present-perfect
*I have not seen her yesterday (correct: "did not see her yesterday")
the time-phrase in a past-perfect construction cannot exclude the more recent past, because the more distant past is perceived from the point-of-view of the more recent past in a past-perfect construction.
A phrase like "by 10PM" excludes the recent past as it cuts off the flow of time, so to speak; it locates a specific time in the past earlier than the more recent past, and ends there.
not OK He had been asleep by 10PM when the phone rang.
OK He had been asleep since 10PM when the phone rang.
Actually, both sentences can be correct, but it depends on what you are trying to say so more context is needed.
By the age of 45, most men were dead.
would be understood to mean that most men did not live past the age of 45 for whatever reason, for example war. A more usual way to phrase this might be
By the age of 45, most men had died.
To describe the results of a war one would usually say
By the age of 45, most men had been killed.
In your other phrase
By the age of 45, most men had been dead.
although awkward in phrasing could mean that by the age of 45, most men had be "broken in spirit", they had figuratively become the "walking dead" or "zombies" like something out of an Orwellian dystopia.
In an interesting news article:
A boring job really make brain dead Lack stimulation affects memory concentration later life