Question

What is the earliest species that we are confident is a hominin? When and where did it exist? What type of environment did it live in? What is so special about 'Ardi'? How does the position of the foramen magnum in Ardipithecus ramidus allow us to infer that it was a hominin? What is the evidence that Ardi also spent considerable amounts of time in the trees? How did it move in the trees? How did it move on the ground? What features of its teeth were human-like and what do these features suggest about male-female relationships in this species? Based on the dental evidence, how intense was intrasexual selection on Ardipithecus ramidus males? What is the evidence that Ardipithecus ramidus represents a very early stage in hominin evolution

Answer 1

The earliest confirmed hominin is Ardipithecus ramidus, which lived about 4.4 MYA in heavily forested environments in Ethiopia. The foramen magnum and limb morphology indicate bipedal and arboreal locomotion, while reduced canines suggest changes in male-female relationships and social structure. Ardipithecus ramidus is crucial for understanding the early stages of hominin evolution and the development of bipedality.

Step-by-step explanation:

The earliest species that we are confident is a hominin is Ardipithecus ramidus. It existed about 4.4 million years ago (MYA) and was discovered in Ethiopia. Ardipithecus ramidus lived in heavily forested environments during the Pliocene era. A key feature that suggests its bipedality is the forward position of the foramen magnum, indicating that it could walk upright. The evidence of an opposable big toe and the arm bones suggest that Ardi was also adapted for arboreal locomotion, being quadrupedal in trees. On the ground, Ardipithecus ramidus likely moved bipedally, as seen in the structure of its legs and pelvis.

When considering dental morphology, Ardipithecus ramidus had reduced canine teeth compared to other primates, implying less aggressive male behavior and perhaps more monogamy, as huge canines are usually a sign of intrasexual competition. This reduction in canine size could also suggest female preference for males with milder temperaments, contributing to changes in male-female relationships. The lack of extreme canine sexual dimorphism in Ardipithecus ramidus was nearly human-like and suggests lower intrasexual selection pressure on males than in some other primates.

The discovery of Ardipithecus ramidus is important because it represents a very early stage in hominin evolution. This species illustrates the evolutionary transition to bipedality while retaining several primitive traits for tree-climbing. Its features mark significant developments in our understanding of how hominins evolved and the environmental pressures that shaped their morphology and behavior.