Evolution is actually caused by genetic variation, mostly through gene duplications and mutations. These mutation rates are fairly consistent and therefore we are still evolving at the molecular level. I do however, believe that some lineages of the human species are evolving tword a weaker more dependant being. I don't think that the rise of the natural human body temperature is a sign of evolution, it's more like our biological systems are trying to adapt to new environmental conditions. We can not change the genetic info. that we pass on to our offspring due to enviornmental conditions.