Answer:
In general, they were able to find out what his last meal was in his stomach, since he was so well preserved. In fact, he's the oldest and most well preserved mummy to be discovered.
They also learned he was killed by a blow to the head, perhaps by an enemy tribesman. They also gained knowledge of his burial rituals and a clear view on everyday life during the prehistoric age.
They've also been able to extract blood from him, the oldest blood sample ever retrieved. It sheds new light on his death and may change the way police study blood found in modern crime scenes.
