The armadillo shown below belongs to the vertebrate class Mammalia, as does this panther. Mammals can be distinguished from the other vertebrates on the basis of several characteristics. All mammals have hair that functions (to some degree) for insulation, three bones in their inner ear that increasing hearing sensitivity, and mammary glands for milk production, and internal fertilization. Most mammals develop in the maternal uterus and are nourished by nutrients diffusing from mother to child across an organ called the placenta. Young marsupial mammals complete their development in a maternal pouch; marsupials include kangaroos, opossum, and Tasmanian Devils. A few animals (e.g., the echidna and the platypus) are monotremes, which are mammals that lay eggs and lack nipples.
Animals III Part 3 VoiceThread Transcript
Humans are vertebrates, and we are subject to the same evolutionary principles that govern all life on the planet. However, we are a relatively new species. Although our genus Homo first arose almost 2.5 million years ago, modern humans, Homo sapiens (those that learned agriculture and demonstrated tool use and complex social structure) date back to a mere 150,000 to 200,000 years ago. While this may sound like a long time ago, consider that this represents only 5000 generations. This is not long on an evolutionary scale. The figure above shows the major migration paths prior to 10,000 years ago, and all of us can trace our own ancestry back to one or more of these migrations.