That's the thing. Most of the evolutionary theories about how something happened 2 or 200 million years ago are just on the level of speculation. That's one of my gripes about evolution ... the field attracts a lot of pseudoscience (such as evolutionary psychology) in the form of "explanations" for various phenomena we observe today, or how a transition happened.
The truth is no one actually knows, or can test most of the theories that seem like they MIGHT be true but could also be fanciful speculations by researchers. That something was found is a fact. How it got there is largely speculation, but I'm surprised how often these theories are taken seriously, not just by the public but by other scientists.
Real tests include statistical significance, like exploring the fossil record across continents, simultaneously corroborating the theories of continental drift and common descent. Allopatric speciation can be discovered this way. You need a bunch of data points or functions of them, that should be independent but are highly correlated. That is what supports a theory, in the Fischer sense.
Here is an example: horse fossils are found physically above t-rex fossils 99.9% of the time, and in the remaining cases, the rocks show evidence of upheaval in that area. Or, radiometric dating vs the superposition principle. If 99% of the data samples agree, that is extremely significant. That is how you prove theories.
You are mixing up proving the theory of evolution and using the theory to make speculations about the past. The speculations are only taken as seriously as the evidence they are based on. The last time you made a blog post you complained about the evolutionary psychology behind a loud female orgasm. I had to look it up for you that it is seen in other apes TODAY and since other things prove (with statistical accuracy) that we have a common descent with other apes, these speculations are viable.
Where is this supposed proof or strong evidence for the speculations? "Viable speculation" is not the standard in science for believing things to be true, and using them as a basis for conclusions.
I think the bigger mistake is to claim the invention of the baby sling caused our lengthened human gestation: it gives no selection pressure in favour of lengthening our gestation period, it merely removes a selection pressure against it.
EP is obviously not completely pseudoscience, but it has a few global problems. It's often forced to test hypotheses about things that happened long ago, which is hard and can lead to weakly supported conclusions. It also adopts the conceptual framework of cognitive psychology, which can be a bit of a grab bag in terms of falsifiability because it is so heavily reliant on "indirect observation." Finally, it frequently deals in topics which are flashpoints for controversy, which invites unusually stringent examination and rejection from people with some personal or political or religious agenda.
Yeah, it also blunders around taking the status quo as something that has more evolutionary causes than cultural ones. And thereby ignoring eg: the patriarchy as a cultural system, and looking for explanations of its effects in genes.
In this it reminds me of the science of the early 20th century that took race as a mere fact, and tried to explain it.
2.2 million years is an awful long time ago, and I didn't think we had that much evidence about humans habits and culture dating back that long ago.
Exactly what happened roughly 2.2 million years a to explain this evolutionary change?