Human evolution was a convoluted process in which many paths and traits died out. However, the traits we do have are able to be traced back through fossil evidence (Human Evolution by The Smithsonian Institution's Human Origins Program)
Ardipithecus ramidus
- Most documented early hominid and is dated back to 4.4 million years ago (see figure 4.1)
- Had a bowl shaped pelvis, indicating bipedalism. Further to this the foramen magnum position is also consistent with the hypothesis that they were bipedal
- Had a grasping big toe which leads to the conclusion that they climbed trees
- Around 4 million years ago, the Australopithecus genus formed
- Found to have small brains and large teeth
- The two most known of this genus are Australopithecus afarensis and Australopithecus africanus.
- Lucy is an Australopithecus afarensis fossil that was found in 1974. She demonstrates a pelvis, leg structure and big toe alignment that suggests bipedalism. This genus’s arms are still longer in proportion to Homo sapiens.
- Small brained, however it is larger than that of the Ardipithecus genus, demonstrating developments in cognitive function
- Showed sexual dimorphism
- There molars appeared more prominent compared to Ardipithecus, suggesting a more plant diet
- Branches from Australopithecus
- Small body
- Large skull, large jaws and molars
- Small brained
- Prominent brow ridge
- Bipedal due to foramen magnum position
- Prominent sagital crest suggesting strong jaw muscles
Homo Genus
- First appeared 2.4 million years ago in Africa (Pontzer, H. (n.d.)
- Share similar bone structure to the Australopithecus genus, however, they had smaller teeth and bigger brains
- Dated back to 2.4 million years ago
- Known as the first tool makers
- Exhibited shortened fingers and a precision grip
- Fossils found within Africa and Eurasia region dating back to around 2 million years ago
- The first emigrants
- Larger brain than Homo habilis, allowing the species to thrive in varying geographical regions as they had an increased cognitive function.
- Shorter front forelimbs compared to the Australopithecus genus
Homo floresiensis
- Named ‘the hobbit’ for its stunted growth as they had small statures
- Small brains
- Date back to 95,000 years ago but only inhabited the island of Flores in Indonesia
- Their position in the evolutionary timeline is still vastly unknown as it is difficult to determine their ancestors as they have differing characteristics to many species, due to their isolation
- Dated back to around 700,000 years ago.
- Suggested that Homo sapiens and Homo neanderthalensis both evolved from heidelbergensis, however in different geological regions
- Discovered the use of fire
- Larger brain
- Brow ridge
- Sloping forehead
- Shorter jaw, resulting in less projection
- Smaller teeth than earlier species, yet still larger than Homo sapiens
- Existed in the fossil record in Europe and the Middle East
- Found to have a larger brain then Homo sapiens, inferring complex thought processes
- Died out between 40,000 and 35,000 years ago
- Inhabited Earth at the same time as Homo sapiens, hence, they are not an ancestor of the modern human
- Proposed that they evolved from Homo heidelbergensis
- Evolved around 200,000 years ago in Africa
- It is suggested that they evolved from Homo heidelbergensis
- Larger cerebral cortex, allowing a greater capacity to learn and teach through speech
- Increased cognitive processes, allowing us to outcompete all other species once we migrated from Africa 70,000 years ago
- Recently discovered and from South Africa
- Had a brain the size of an orange but despite this small size, they these early hominins performed burial rituals
- Possessed a mixture of characteristics such as feet developed for walking on land but hands built for life in the trees
- It is unknown where this species fits into the human lineage
- Stood about five feet tall at 45 kg
- Small teeth and slender jaw
- Shoulder structure similar to apes
- Depending on its age, it could be a direct ancestor of Homo sapiens
- More testing needs to be performed to determine its linkage to Homo sapien evolution
The recent discovery of Homo naledi proves that Homo sapien heritage is extremely vast and still up to interpretation as their it is continually proven that there is more out there to be discovered
As shown through the comparisons of Figure 4.1 and 4.2, there are varying interpretations of the data that is collected through fossil records and DNA evidence, however, both can be viewed as correct as neither has been proven wrong. As there are gaps within the fossil record and large geological times that it is predicted that individual species inhabited Earth, it is difficult to conclude with absolute certainty whether certain models and evolutionary links are correct.