The African elephants (Loxodonta africana), Asian elephants (Elephas maximus) and Woolly Mammoths (Mammuthus primigenius) diverged approximately 4-6 million years ago. The exact relationship amongst them has always remained controversial. Morphological studies have suggested a Mammuthus-Elephas clade while several others have supported Loxodonta-Mammuthus clade. Recently, phylogenetic trees based on mitochondrial DNA (mtDNA) and nuclear DNA sequences of respective elephants, also refuted each other. This has left the phylogenetic relationship between these elephants, unresolved.
The domestic dog is a ubiquitous species having frequent encounters with humans; in the U.S. over 4 million of these result in a dog bite. These injuries might be reduced by improving human-canine communication. Canine responses to alterations of human facial expressions were recorded. The dogs' responses to the presence of a human experimenter were subsequently analyzed against survey data collected by the shelter on the individual animals (time in shelter, age, sex, reason surrendered). Staring at a dog induced more arousal than other human facial expressions (i.e., Averting Eyes, Grinning, or Yawning).