And something else. I grew up on a farm, we raised cattle. We bred them to work out the bad, and increase the good. Same with humans. They could easily breed out a giant race. Humans tend to focus on what is beauty. Some guy 9 feet tall is going to stick out like some guy 9 feet tall in a crowd.
Back to our beginnings, being different tends to get you noticed. Not a good thing if you are the 9 foot tall guy with a bunch of 5 footers that some lion spots.
Maybe for basketball but not good for avoiding the lunch crowd. And so humanity breeds them or their condition out, as between the obvious easy prey bit, they are not what we consider the norm.
Kind of. Things are bit more complicated though.
See, the thing is that while we humans adapt to our environment over time, some of that adaptation is self-imposed - we are already selectively breeding ourselves, and not always for obvious reasons. Consider what most humans consider desirable in other humans when seeking a mate, and the one trait that keeps popping up is symmetry. Why would we be programmed to find symmetry attractive? Simple. Symmetry implies proper growth, which suggests good health and good DNA - exactly the sort of person that you'd want to have children with from an evolutionary standpoint.
But what about blue eyes? That's a very old mutation that's been artificially reinforced over many thousands of years. Blue eyes are a rarity in most mammals and there's a good reason for this: they don't function as well as brown eyes do. True story! Brown is a better color from a technical standpoint, which is why it's such a common eye color among mammals. Granted, the difference is small and having blue eyes as a caveman is not a death sentence, but it's a rare mutation that we've selectively reinforced over time, even though (from the point of view of the rest of the natural world, including potential predators) it places us at a disadvantage. So why did we encourage it? We don't know and can't know why our ancestors favored it, but the simple theory holds that it was unusual enough to be desirable without contradicting any pre-existing "programming" in our minds and was not an obvious disadvantage, so early people actively sought out mates with blue eyes. (Red and blonde hair might be in the same boat.)
Would being massively tall place someone at a disadvantage against predators? I don't think so. I don't know much about Old World lion attacks and they're often not documented well, but New World predatory cat attacks (in this case, from our good friend the cougar) are much better recorded and easily found. I'm not convinced that enough of them have occurred to be statistically significant, but this is all we have, so this is what we work with. You'll notice some definite trends when you read over them. The victims are always one of three types:
1. A jogger, skier, or bicyclist. Fast motions tend to trigger predatory instincts in cats. You can even fool some house cats into pursuing (and possibly mock attacking) an adult human in this way.
2. Small children.
3. The elderly.
Discounting #1, we see another trend that's nearly universal among the predators of the natural world: predators look for dinner, not fights. A fight with a prey animal may very well wind up killing you. Instead, you pick out the weakest and/or most isolated animal and you go for the easy meal. These predators (in particular cats) actively avoid the largest target. Do you think that a person significantly taller (and thus probably faster, and possibly stronger as well) would be at a disadvantage against predators? Or would the person that's shorter and skinnier than the rest be in trouble?
But it gets more complicated than that, because in the industrialized world, predators are not a problem. Heart disease and cancer are the problems. Some of the food allergies that are common today would have guaranteed that you would not have survived childhood two centuries ago. Modern medicine has removed those evolutionary pressures, and in the span of even a few generations, health issues that didn't really exist before are now becoming common. And that's the thing with evolution - it happens surprisingly quickly.
So why not people that are 9 feet tall today? It's not because of lions. It never was.
Why are mainstream historians so reluctant to change their views on history? They're not, really. Most people thought that Columbus was the first to the New World until the L'anse aux Meadows excavation. The result of that was not a government coverup or riots in the streets. Instead, the historians said, "Well, it is what it is. Time to rewrite the history books."
This is why forensic evidence trumps theories, and why I disapprove of using questionable evidence and/or cherry picking evidence to try to force a theory. The theory should be created to explain the evidence, not vice versa.
Also, this post got away from me in terms of length. Sorry about that, but human evolution fascinates me. I'd tell you that I typed this up on an iPad mini but I don't think that anyone would believe me.
