Final answer:
Homo erectus had small jaws and teeth, a distinctive sagittal keel on the skull, and were bipedal with humanlike feet. They had large brains, with diminished sexual dimorphism in size compared to earlier hominins. Homo erectus also used fire, made sophisticated stone tools, and may have shown cooperative behavior and care for the sick and elderly.
Step-by-step explanation:
The morphological characteristics of Homo erectus, an early human ancestor, include several features akin to those seen in modern humans. Notable physical traits were small jaws and teeth, a larger third molar compared to other molars, and a skull shape that resembled that of Homo erectus or Homo habilis. One distinct feature of their skull is the presence of a sagittal keel, which is a slightly raised ridge on top of the skull. Additionally, their adaptation to bipedalism was advanced, as they walked with a humanlike gait and had humanlike feet with arches and well-formed ankles. Homo erectus emerged roughly 1.8 million years ago and is considered the first hominin species to have migrated out of Africa. They achieved heights up to 1.85 meters, with a weight range of up to 65 kilograms, comparable to modern humans. Their brain size was larger than earlier species, ranging from 775 to 1,100 cubic centimeters, and featured a nose with downward-facing nostrils, suited for warming cold air. Homo erectus was also adept at using fire, hunting, and creating home bases, suggesting a high level of adaptability and social cooperation. By further examining the evolution of Homo erectus, we see a progressive increase in brain size over time and evidence of skills such as the use of fire and cooking meat. A nutritious diet including cooked food may have driven the reduction in the size of their teeth and allowed for the expansion of the brain. Moreover, with longer legs and a taller stature, Homo erectus was well-equipped for endurance running, a trait that made them efficient hunters.