Saturday Citations: Color vision created demand for colorful animals; observing black hole light echoes; deadlines!

This week, researchers hypothesized that human culture is distinguished from cultures of other species like whales by unique open-endedness—the ability to communicate and understand an infinite number of possibilities. An ancient unicellular organism provided evidence that embryonic development evolved before actual animals. And researchers reported that the Earth experienced a massive, rapid melting period following the last ice age. Additionally, we reported on the sociological implications of blowing deadlines, a method to calculate the mass and spin of a black hole, and the evolution of species coloration.