The origin of humans has been explained in various ways. The fossil records evidence of human evolution has been proposed to be the most accurate for of tracing human ancestry. Other fields of study such as biology have described human origin through molecular and anatomical analyses. This work focuses on providing a detailed report of human fossil records.
Physical characteristics
Cultural characteristics
Australopithecus anamensis
Lived approximately 4 million years ago.
The species was discovered in Kenya and Ethiopia.
Male were around 5 feet tall while females were around 4'3”. The weight of the males was around 110 lbs. while that of the females was around 70 lbs.
The brain size of the species is unknown due to the limited material that can be used to ascertain cranial capacity (Monroe, & Wicander, 2011).
The upper end of the tibia had a bone that assembles the human ankle joint. The feature indicate that the species was bipedal. Additionally, they had long forearms and the features of the wrist bones suggests that the A. anamensis climbed trees.
The species had teeth that are similar to those of apes. They had large canines and parallel tooth rows (Monroe, & Wicander, 2011).
There is no evidence showing that the species used fire or had modified any tools. They used unmodified stones and sticks to obtain food.
Also, they had limited language ability.
Further, no evidence suggest that the species had developed any form of art, had personal items or had a form of religion (Monroe, & Wicander, 2011).
Australopithecus afarensis
The hominin existed between 3.9 and 2.9 million years ago and was discovered in East Africa. Major remains of the species were found in Hadar, Afar Region of Ethiopia. Other areas with the remains of A. afarensis include Koobi Fora and Lothagam in Kenya (Monroe, & Wicander, 2011).
The species lived in a wide range of environments such as sparse woodlands, or in denser forests.
The Hominin had relatively reduced canines and molars as compared to the modern and extinct apes. However, they are relatively larger to those of modern humans.
A. afarensis had a small brain size of about 380-430 cm3.
The fossil also had a face with forward-projecting jaws.
There have been debates on whether the A. afarensis was bipedal or arboreal. The anatomy of the hands, shoulders and feet favor the latter interpretation. The curvature of the fingers and the phalanges is almost similar to that of the modern day apes and suggest the ability of the hominin to grasp tree branches (Monroe, & Wicander, 2011).
There is also enough evidence to support the fact that the hominin was bipedal. A. afarensis had a pelvis that is similar to that of humans, short iliac blades and a wide sacrum. The species was an efficient bipedal walker over short distances.
They exhibited sexual dimorphism. Female’s weight and height were around 66 pounds and 3’5” respectively. Males on the other hand weighed between 99 and 150 pounds and had a height of around 5 feet.
The species used simple tools such as sticks and stones. There is no evidence that explains that the tools were shaped in a specific manner.
Evidence suggests that the species had no language or speech abilities (Gurche, 2013).
There is no evidence that suggest that the species used fire, had any form of religion or developed any kinds of art (Monroe, & Wicander, 2011).
Homo erectus
The species existed about 1.8 million years ago and was discovered on Dmanisi, Georgia.
Had a cranial capacity of around 850cm3, had a face that is more orthognatic, with large brow-ridges, a broad flat nose. and less prominent check bones with a thick and large jaw. The face was large with a low, slopping forehead, and lacked a pointed chin (Monroe, & Wicander, 2011).
They also had shorter arms and longer legs and walked upright.
The males were about 25% larger in height and weight than the females.
Their weight ranged from 88-150 lbs. and heights ranged between 4 feet and 9 feet.
They used fire to cook and made hand axes out of stone. Research also identifies that the Asian H. erectus used rafts to travel over water bodies. Also, it was found that the species used flakes and choppers. Flakes and choppers are small, flat and thin pieces of wood or stone that are broken away from a larger piece. They are usually irregular in shape (Monroe, & Wicander, 2011).
Evidence also suggests that the species had developed language abilities that enhanced their social organization. They could make simple gestures, grunting sounds and could utter simple words (Gurche, 2013).
The H. erectus created art. There is evidence showing the Zigzag etchings made on a shell found in Indonesia. However, they did not paint or carve.
The species did not have a religion.
Homo heidelbergensis
The species existed about 700,000 and 300,000 years ago in southern Africa, East Africa and Europe.
The H. heidelbergensis had a cranial volume of approximately 1,250cm3.
Male H. heidelbergensis averaged about 5’9” tall and 136 lb. while females averaged 5’2” and 112 lb.
Their faces were relatively flat, and had no pointed chins. They also had an orbital constriction, a short, sloping forehead and a double arched brow ridge (Monroe, & Wicander, 2011).
The teeth were smaller than those of earlier species and were arranged in a way that they formed a parabolic shape. However, they were larger than those of modern humans.
They had stone hand axes and wooden spears.
They used fire as a source of warmth and for cooking (Gurche, 2013).
The species also had developed simple languages that facilitated communication.
There is limited material suggesting the religious life or the art work done by the H. heidelbergensis.
Homo neanderthalensis
The species lived in Europe, Asia and some parts of Africa from about 400,000 to 40,000 years ago.
The Neanderthals were stockier, had shorter legs and bigger bodies as compared to modern humans. Additionally, they had a reduced chin, sloping forehead, and a large nose.
Males and females had cranial capacities of between 1600cm3 and 1300cm3 respectively. The height of the males was around 165cm while that of females was around 154cm.
The Neanderthals used fire and made stone tools. They used tools known as the Mousterian. It is a techno-complex of flint lithic tools. The tools included small hand axes and spears which they used for hunting.
They created art and used adornments. They also made cave paintings.
They buried the dead. However, their specific form of religion is not clear (Monroe, & Wicander, 2011).
The species had a language ability that is similar to that of modern humans.
The Sequence of the Selected Fossil Forms.
1. Australopithecus anamensis. Existed approximately 4 million years ago.
2. Australopithecus afarensis. Existed between 3.9 and 2.9 million years ago.
3. Homo erectus. Existed about 1.8 million years ago.
4. Homo heidelbergensis. Existed about 700,000 and 300,000 years ago.
5. Homo neanderthalensis. Existed about 400,000 to 40,000 years ago.
From the selected fossil forms, the modern human species can trace their ancestry to the Australopithecus anamensis. The species evolved into the Australopithecus afarensis, Homo erectus, Homo heidelbergensis, Homo neanderthalensis and finally into the modern human. However, the evolution of the Homo neanderthalensis did not directly give rise to humans as there are other species such as the Homo floresiensis
and the Homo sapiens that existed between them.
The term mosaic evolution describes that the changes that occur gradually among species take place in some body parts or systems without changes occurring in other parts during the same time. For instance, the early development of bipedalism in Australopithecus happened before there were any significant changes in brain or skull size (McKee, Poirier, & Mcgraw, 2015). Among the Homos, evidence shows a significant increase in brain capacity while there are no major changes in the limbs or body size.
Of the selected species, there is no more than one kind of hominin that lived on earth at the same time. Any of the hominins existed for a certain period before they became extinct. Upon their extinction, they were replaced by an evolved species. The cycle continued until the development of the modern day human (McKee et al., 2015). For instance, the A. anamensis lived approximately 4 million years ago. The species was wiped out by A. afarensis which existed between 3.9 and 2.9 million years ago. Currently, there are no other species of the human present on the planet. However, this has not always been the case in the past. For instance, the Neanderthals existed and interbred with the Homo sapiens.
Kenyanthropus platyops relates to the human fossil records according to paleontologists. The species existed about 3.5 to 2.2 million years ago. The remains were found in Lake Turkana, Kenya. There have been debates surrounding the existence and the classification of the species. Some researchers have suggested that the species represents an entirely new hominin species and genus while others have identified that it is a separate species of the Australopithecus (Gurche, 2013). The species is distinct since it had a flat, non-prognathic face, a stepped nasal cavity entrance, and a thin palate roof. The unique features have led to debates on the classification of the species in the Australopithecus family.
Scientists have also established that human evolution can be explained by analyzing the anatomy and embryology of different species. An assessment of the physical features of species explains that organisms can share a common ancestry if they have homologous features. A perfect example is that of the forelimbs of whales, humans, birds, and dogs (Lyons, 2012). The limbs may look different from the outside due to the difference in their adaptation, but they have a similar bone structure. The similarities explain a common ancestry. Also, scientists have linked organisms to a common descent especially if they have vestigial structures. An example is that of the human tailbone. The tail has reduced over time due to lack of use. Further, scientists have explained evolution through analogous features among species. Analogous structures usually have different evolutionary ancestries but perform the same function such as the wings of a fly and a bird. Scientists have classified this type of development as convergent evolution (Lyons, 2012). Finally, researchers have identified that species have exhibited similar ancestries through observing their embryos. Observations have shown that vertebrates develop similarly and have a common ancestor.
It is essential that there are multiple or independent lines of evidence of human evolution. The different theories help incorporate the various schools of thought in explaining human development. The strategy diversifies the description of the origin of humans.
In conclusion, human evolution continues to be a significant field of study in the present day. Evidence suggests that the important patterns in physical traits include an increase in brain capacity, reduced prolonged jaw, reduced body hair and changes in limbs so that they are more adapted to walking and running. Differences in cultural characteristics over time included the development of art, language and religion, the use of fire, and tools. The hominins changed over time, mainly due to the need to adapt to changing environmental conditions. The discoveries and changes in the manner in which we interpret phylogenies to demonstrate the development of the scientific method of explaining human evolution. The findings establish that the scientific techniques of human evolution are more dominant in explaining human origins. However, discoveries have led to the development of debates and controversies surrounding human evolution. I find that more research needs to be conducted to find the missing information necessary in defining the physical and cultural traits of different species.
References
Gurche, J. (2013). Shaping Humanity: How Science, Art, and Imagination Help Us Understand Our Origins. Yale University Press.
Lyons, S. (2012). Evolution: The Basics. Routledge.
McKee, J. K., Poirier, F. E., & Mcgraw, W. S. (2015). Understanding human evolution. Routledge.
Monroe, J. S., & Wicander, R. (2011). The changing earth: exploring geology and evolution. Cengage Learning.
