The proto-Hive portrayed in the Books of Sorrow are said to have short lifespans of a mere ten years, but ten years to a proto-Hive may be much longer than it is to a human. In Earth years, it's possible proto-Hive lifespans could be as short as 120 years or as long as a whopping 1,650 years. Allow me to explain my thought process regarding this assertion:
Consider that we have different frames of reference. As humans, we measure a year by the time it takes the Earth to transit the Sun, but the proto-Hive would measure a year by the time it takes Fundament to transit the Sun. We know that the lifespan of the proto-Hive must be considered within their frame of reference and not our own because the Books of Sorrow are written by Oryx and thus within his frame of reference. Already, this must mean that a year to Oryx means a different amount of time than it does to a human, but how much time does it mean in Earth years?
It is impossible for us to say for sure how long it takes Fundament to transit its star in Earth years, but if we consider the gas giants of our own Sol System, we can hazard a few guesses. If Fundament orbits its own star at a distance similar to Jupiter's distance from our Sun, its orbit would take roughly twelve Earth years to do so. Thus, if we multiply the proto-Hive lifespan by Earth years, we arrive at a lifespan of roughly 120 years. Doing the same maths in regard to a Neptune year yields a result of 1,650 years.
However, I believe that it is likely that the proto-Hive lifespans were closer to the 120 years. We ultimately know nothing of the nature of Fundament's star, and thus we can only guess at how long a Fundament year is. When considering the narrative of the proto-Hive, I believe that it is safer to err on the side of a shorter lifespan simply because Oryx puts so much focus on the brevity of their lives in his writing. No matter how you cut it, 120 Earth years is a hell of a lot shorter than 1,650.
If anyone else would like to weigh in, I am curious what you think.
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I have not read the book of sorrows so I may be missing important details about Fundament. I think it should be assumed that when the cards says years, it is referring to Earth years. However, Relativity may play a part in the age of the "Proto-Hive" in a time conversion viewpoint.