While the hunter-gatherer had been romanticized, basing your data on currently living groups is also flawed. They have all been in contact with modern society, which probably has influenced them in multiple ways. From taking over customs to limiting the area they can move in to the impact on the climate from factories, which all might be factors influencing their entire way of living. So the only way to actually study then is through archeological records from before the birth of cities, which are unfortunately limited in what they can say.