Saturday Citations: The Dark Energy Survey; the origins of colorblindness; the evolution of heads

The Dark Energy Survey took an entire decade to produce a value for the cosmological constant—and it’s smaller than you might think! There were other stories as well, including one about primeval black holes, and because I am inescapably drawn by the relentless gravity of black hole news, it’s included below, along with two other stories related in one way or another to heads.

This article is brought to you by Phys.Org.