Rachel Feltman of The Washington Post joins us for a roundup of her top science stories this week: A Science study from December that looked at how short conversations could change the voters’ minds on big questions was retracted by one of the authors; researchers dug up a 3.3 million-year-old stone tool in Kenya; plus, scientists investigated microbiome of pandas.

Then, Megan Palmer, a bioengineer-turned-security policy researcher, joins us to talk about the potential good—and bad—of engineering yeast that can brew up compounds like opiate drugs.