First of all, we should never trust the results of any experiment until it's been reproduced by independent researchers because most research is poorly designed and very poorly analyzed - few researchers actually understand statistical methods and merely apply them rote-fashion, leading to hilariously incorrect conclusions. Secondly, we lack adequate understanding of other primates' vocalizations so we can't compare those of humans to other primates and say ours are more complex. Thirdly, no one with any notion of how evolution works would ever claim that humans aren't still evolving.