Even three years after it emerged, there's still no consensus on the origin of the virus that shut down the world. Last week, the US Department of Energy said that its conclusion (albeit with "low confidence") was that the virus escaped from a lab. Three days later new genetic research pointed to the presence of the virus in racoon dogs found in Wuhan at the time the virus began to spread.So chalk up another data point for each side, and still we're searching for answers. What does the new evidence tell us about each theory? How has this debate become politicized? Will we ever know where the virus truly came from? And if we did, what would it change ... if anything?GUEST: Umair Irfan, correspondent at Vox writing about climate change, Covid-19, and energy policy. (Read Umair's latest piece on Covid's origins here.)