The core difference between Science and Theology is how they deal with statements of "truth" without evidence.
Theology starts with "it's true because I said so"
Science starts with "it's true because I can demonstrate it"
That humans were complex in the past is a good hypothesis. It needs evidence before it can be accepted as fact, or even necessarily expect respect from others. The lack of recent skull changes would seem to be a good start.
If someone believes the hypothesis to be true, they will go explore and find evidence to back their claims. If there was a complex society in the English Channel, it's likely well preserved, just waiting to be found!
To believe this is to cut yourself off from an unfathomably rich collection of human knowledge, and it is sad to see someone committed to it.
God speaks to someone. That someone says "It's true because God told me so."
I have read religious works, I'm not cut off from them. It's impossible to be cut off from theology in the USA. However, they all start with "it is true because I (the author) say so".
I think at least some of the people in this thread would argue against that, seeing as how it is about the idea of advanced or at least extant cities in the distant past. That would be exactly one of the points being argued on.
Similarly to biological evolution, on any sufficiently long time scale the descendents aren't more advanced, simply better adapted to different conditions. Our ancestors' societies reflected wildly different contraints and path dependence, not primitiveness.
I understand what you mean, yet I refuse to call concepts like universal human rights, rule of law and the unacceptability of war crimes as simply different adaptations, as opposed to being strictly more advanced than the predecessor ideas.
This is a long but highly informative presentation by Sander van der Leeuw from 2012:
https://yewtu.be/watch?v=pOyQqPi28ug
Relevant segment begins at about 8m30s.
1. sophistication is driven by specialization
2. the ability to specialize is driven by access to surplus energy
3. before the advent of agriculture bands of humans simply did not have the excess calories available to them to support a priesthood and philosophers and bureaucrats, etc.
The people in Mesopotamia (and in other similar areas which were slowly turning into a desert) didn't really have a choice. Building and maintaining irrigation systems takes a lot of people and coordination. Since most would probably prefer to be the ones handling 'coordination' aspect rather than digging trenches in the mud priests and philosopher classes had to appear to maintain social cohesion. It's much easier to convince peasants to give X% their harvest to the local strongman when they know that he's an divinely appointed king or maybe even a living god himself.
Sophisticated technology is driven that way for sure, Sophisticated culture, I would argue, does not have those preconditions.
My understanding is that there is no evidence for pre-historic human societies that had advanced technologies. We have hard data in our genetics for the timeframes of human existence (statistical rate of random genetic drift vs nearest ancestors) in addition to the fossil record, we have good information from ice cores about when/what of particulates were in the atmosphere, we know general rates of tectonic movements , and it's easy to observe what's under kilometers of strata with drilling cores if anyone has a good hypothesis as to where to drill.