Here's a breakdown:
Hominid:
* Old definition: Used to refer to all members of the family Hominidae, which included humans, chimpanzees, gorillas, and orangutans.
* New definition: In modern scientific usage, the term "hominid" is often used more narrowly to refer specifically to members of the tribe Hominini, which includes humans, *Australopithecus*, and other extinct human ancestors.
Key Features of Hominids:
* Bipedalism: Hominids are distinguished by their ability to walk upright on two legs.
* Large Brains: Hominids have relatively large brains compared to other primates.
* Tool Use: Many hominids have shown evidence of tool use.
* Complex Social Structures: Hominids often live in complex social groups.
Examples of Hominids:
* Humans (Homo sapiens)
* Australopithecus afarensis (Lucy)
* Homo habilis
* Homo erectus
* Neanderthals
Why the shift in definition?
The shift in the definition of "hominid" came about due to advances in genetic and fossil evidence. It was discovered that chimpanzees and gorillas are more closely related to each other than they are to humans. This led to a reclassification of the family Hominidae, with humans and their extinct ancestors forming their own tribe, the Hominini.
Important note: The terms "hominid" and "hominin" are often used interchangeably, but they have distinct meanings. Always be aware of the context to ensure you are using the correct term.