A Mysterious Gene Shift in Ancient Europe?!?!

For about 200,000 years humanity has been making its way from Africa to just about every corner of this planet. The study of our past helps explain the evolution of life here on Earth. We’ve put a lot of time and effort into digging through the past and have constructed the time line of our story, all the while continually making new discoveries. So, what happens when we make a new discovery that totally contradicts what we've learned? 
Our earliest ancestors started off in Africa and since then had ample opportunities to spread across the planet over thousands of years. After decades of research scientists have been able to conclude that humans moved from Africa to the Middle East and Turkey, then some moved from there to central Europe and become the ancestors of modern day Europeans. Recently, however, that theory has been shaking in its bones. Results from a recent excavation seem to challenge the previously established theory of the European’s real origins. 
Until a few weeks ago it was thought that the older human fossils (dating back 7,500 years) told a very clear story about the migration from Africa to Europe. The established idea proposes that once agriculture was introduced as a tool, humans were able to take this new process and out live the hunter gatherers around the world. A flow from Africa to the Middle East to Europe seemed to make sense considering the data that was available. However, new data in the form of more recent fossils seem to have scientists scratching their heads. 
These newly studied fossils date back about 4,500 years and indicate a mysterious gene shift that has scientists baffled. Mitochondrial DNA from the two specimens are vastly different and pose a few questions on the origins of Europeans. Who were these people? Did the real ancestors to the Europeans perhaps travel up from the Iberian Peninsula? Did the people living in central Europe evacuate 4,500 years ago due to crop failures from a quick change in climate? Was this a pre-historic war that we have yet to find other proof for?  Regardless of what happened the point is we just don’t know and the mystery of life continues to be an interesting study. 
Even though we don’t know what the answer is, the good news is the system of science still works. Sometimes while we try to get details and answers to a question we end up asking different questions that begin a whole new branch of information. The doors are opened up on this topic and now the next generation of researchers and scientists will have their chance to answer this question. 
The answers could range from the most obvious to the bizarre. Anyone from the most seasoned archeologist to contributors for popular TV shows now have their chance to look into this amazing and fascinating mystery.
Oh and Ancient Aliens fans probably have a guess as to how the gene shift happened too...