Final answer:
Our Hominin ancestors separated from the Chimpanzee/Gorilla branch around 6 million years ago, with the genus Homo evolving around 2.8 million years ago. Homo sapiens, with a lineage including species like Homo habilis and Homo erectus, exhibited evolutionary features such as bipedalism and increased brain size.
Step-by-step explanation:
Our Hominin ancestors separated from the Chimpanzee/Gorilla branch around 6 million years ago. This key event marked the divergence from a common hominoid ancestor, leading to species that are more closely related to humans rather than chimpanzees. Thus, the term hominin refers to those species that evolved after this significant split.
Among the many species that came from the evolutionary branch that includes humans, Homo sapiens is the sole survivor. Marker features such as bipedalism, increased brain size, and a fully opposable thumb distinguish humans from other hominoids. Early species like Homo habilis and Homo erectus were fully bipedal with brain sizes larger than those of chimpanzees, providing a baseline for evolutionary advancement towards modern humans.
A fundamental milestone was the evolution of the genus Homo around 2.8 million years ago. These species had adapted efficiently to bipedal movement but retained smaller brains and distinct anatomical differences from modern humans. Notably, the species Sahelanthropus tchadensis, living about 7 million years ago, is contended by some to be the last common ancestor shared by humans and chimpanzees, existing near the estimated time of divergence based on genetic studies.