Sun dogs are either caused by the refraction of light on plate-shaped hexagonal ice crystals in high and cold cirrus or cirrostratus clouds or drifting in the air at low levels like in these pictures.
Millions of years ago, a very important change — or mistake — in our ancestors’ DNA occurred, and it may explain why we’re all here.
Single-celled organisms swimming through a primordial sea was what life consisted of long ago. But at some point, cells started coming together to create entities with two, ten and eventually millions, of cells. This led to the rise of organisms containing different kinds of cells, which paved the way for the creation of tissues and organs, and eventually life as we know it.
Now, researchers from the University of Oregon say they’ve traced the steps of evolution backward through the phylogenetic tree and pinpointed a singlemutation that they believe ushered in the transition from unicellular to multicellular organisms.