Academics And Dogs

In Poul Anderson's There Will Be Time, how do Jack Havig and Leonce recruit thousands of time travelers from all over the world and throughout its history? It takes more than ten years of their lifespans but why not the rest of their lives or longer? On Robert Anderson's advice and by his introductions, they take into their confidence a number of twentieth century academics who advise them on anthropology and semantics - and keep quiet. There must be a lot more to it than that but I have scoured the extremely condensed text to find these nuggets. In Anderson's The Boat Of A Million Years, Hanno confides in just one guy who tries to research immortality.

Meanwhile, I have learned that:

"Domesticating the dog had been one of the things that triggered the original human revolt against the Empire of Shadow; they could sense disembodied nightwalkers, too, even when they were impalpable and invisible as far as men were concerned."
-SM Stirling, Shadows Of Falling Night (New York, 2014), CHAPTER THREE, pp. 39-40.

So was history inhabited by time travelers, immortals or Shadowspawn? None of the above. We did it all ourselves. As one of James Blish's demons said of another mythological figure:

"WE WILL DO WITHOUT THE ANTICHRIST. HE WAS NEVER NECESSARY. MEN HAVE ALWAYS LED THEMSELVES UNTO ME."
-James Blish, Black Easter (New York, 1977), XVIII, p. 163.