Final answer:
Modern apes evolved from a common ancestor with monkeys and are distinguished by their larger brains, absence of a tail, and brachiation. Relationships within the Hominidae family show humans and chimpanzees share a common ancestor. Hominins, like Australopithecus and Homo species, are characterized by bipedalism, increased brain size, and opposable thumbs.
Step-by-step explanation:
Evolutionary Relationships and Features of Modern Apes
The evolutionary history of modern apes involves a divergence from a common ancestor with monkeys approximately 25 million years ago. Modern apes include the families Hylobatidae (lesser apes) and Hominidae (great apes and humans), and are characterized by their larger brain size, lack of a tail, and their ability for brachiation or knuckle-walking. Notably, the DNA evidence supports that humans and chimpanzees have a shared ancestry, tracing back about six million years ago. The term hominin refers to species that evolved after this split, which includes ancestral species like Australopithecus, Homo habilis, and Homo erectus, as well as modern humans. Hominins are distinguished by features such as bipedalism, larger brain sizes relative to body mass, and opposable thumbs.
Distinguishing Features of Hominins
Early hominins like Australopithecus exhibited bipedalism similar to modern humans, evidenced by footprints found in Laetoli, Tanzania. However, they also retained some ape-like characteristics such as a smaller brain size relative to body mass and more pronounced sexual dimorphism. These features and environmental pressures contributed to the hominin evolution towards the species we see today, including modern humans. One crucial development in this lineage has been the increase in brain size and the capacity for language and culture.