WT literature even up 70s or 80s refers to evolution as a tool of Satan. But since the latest literature accepts the so-called "microevolution", that begs the question (for j-dubs): If microevolution is true, then it is a part of Creation, i.e. a tool of Jehovah. How can microevolution be a tool of Jehovah, and macroevolution a tool of Satan, since it's the same process, just in different time scales?
Even from Russell days, evolution was thought anti-biblical (it is, of course; it's just that Genesis happens to be a total myth). The Bible Students were just a mixing of Adventist and other fundamentalist US-based Christian groups; all those groups had always been creationists and anti-science in general.
Side note: the 49,000 years theology of JWs does not differ that much from the literal 7-day theology of young-earth creationists. In the scope of geological time (4.6 billion years), 49,000 years and 7 days are roughly the same, the same absurd, at least. And, basically, the WTS hasn't dropped officially the 49,000 years theology, even to this day (last time I checked). An average thinking person can surmise just from that what kind of loony teachings we're talking about.