I've started thinking about differences between Neanderthal culture and modern human culture and I discovered that there is a genre called "prehistoric fiction". One of the famous examples of prehistoric fiction is Jean Auel's The Clan of the Cave Bear, which I've never read. In the decades since people such as Auel began speculating about Neanderthal culture, the paleontological evidence has continued to accumulate and we even have results from genetic studies of Neanderthals. It is fun to imagine that during the entire evolution of our species there could have been Observers who watched and recorded all the twists and turns of the human family tree.
One possibility is that there was a time (about 100,000 years ago) when, to objective Observers, Neanderthals might have seemed the most important members of the genus Homo. If so, some Neanderthals might have been taken off of Earth and allowed to develop under artificial conditions. For The Start of Eternity, I assume that Gohrlay was a descendant of just such a group of Neanderthals. While I suspect that Neanderthals were behaviorally very similar to us, it is fun to imagine the existence of a few behavioral differences that might go along with known physical differences such as greater physical strength and greater sexual dimorphism in body size.
The Bonobo and the Common Chimpanzee might provide a useful example of the kind of behavioral differences that can exist between sister primate species. Bonobos and Common Chimpanzees might have diverged about a million years ago, while our common ancestor with Neanderthal might have been about half a million years ago. It has been suggested that Bonobo females band together, allowing them to dominate over males in a way that is not observed for the Common Chimpanzee (particularly in relation to feeding behavior, it has been suggested that Common Chimps show the opposite pattern). It is fun to imagine that in a technologically advanced Neanderthal culture the females might have been dominant.