New evidence suggests that the collapse of Egypt’s old kingdom some 4,000 years ago was caused by environmental catastrophe rather than internal social upheaval.
Conclusion
The collapse of Egypt's Old Kingdom was caused by an environmental catastrophe rather than internal social upheaval.
Evidence
Ocean sediments reveal a period of global cooling at the time, a condition generally associated with extended droughts. The author acknowledges that while there were serious social problems in Egypt at the time, they resulted from a severe dry spell.
Evaluate
Since we have a causal conclusion, we can use our Explain Curious Fact template.
CURIOUS FACT: what caused the collapse of Egypt's Old Kingdom?
EXPLANATION: an environmental catastrophe (specifically a long drought) caused the collapse.
Goal
To strengthen the argument, we want to rule out an Alternate Explanation for the collapse (such as social issues) or boost the plausibility of the author's explanation that it was related to environmental reasons such as drought.