Looking at the description:
This is the first time that we tell Drethnor specifically that each turn is lasting 100 years. Time in the early game passes quickly and 100 years is standard, later as things speed up turns could last a lot less time!
However the important bit is that this is a classic example of actions not working out the way that you intend. Drethnor made his actions to address the problems of malnutrition, accidents and disease wiping out so many of his people. He gave them spears to fight off wild animals he thought were causing the accidents, and helped them hunt down more food in the form of killing animals with the spears and with domesticated vultures.
Sure eating fresh kills did cut down on disease, and accidents did eventually go down but . . . the initial trial and error of hunting caused the accidents to go UP at first, and an all meat diet has actually increased the problem with malnutrition. So population has decreased and the big change is in his peoples attitude, almost by accident Drethnor is starting to develop a warrior culture.
It's not actually a bad move and a more experienced player could have done the same thing on purpose, but here it illistrates that you don't always get exactly what you expect. Fortunately the player doesn't seem too upset at what happened. He's just determined to address the real problem NOW!