In the Central East Africa, there lived three major types of human ancestors – H. habilis, H. rudolfensis, and P. boisei, which differed from each other due to the climatic conditions and their direct ancestors. In fact, many research studies have proved some ideas regarding the necessity of distinguishing the identified species. On the other hand, the researchers have not found any firm ground for differences because these species, particularly H. rudolfensis and H. habilis have almost no tangible differences. However, further investigations have revealed biological and gender differences between those species found 2 million years ago. A closer consideration of all three species will help identified differences in terms of size of brain, teeth and other parts of the body. In this respect, H. rudofensis and H. habilis seem to be identical in terms of biological features, whereas P. boisei differs in terms of brain size, tooth, and other physical characteristics, but all three have direct relation to the current appearances of modern humans.
The major critical feature of H. rudolfensis of KMN-ER 1470 includes the braincase size, which constitutes 775 cubic centimeters, which is above larger as compared to H. habilis. At least one braincase from similar region demonstrates a significant cranial capacity. Originally, H. rudofenslis reffered to H. habilities, but the differences consists in the large braincase size of the former. Larger molar, longer face, and premolar teeth are among the major differences between the identified species. Due to the identified features, some researchers are still interested in whether this species could belong to Australopithecus, although it has a large brain.
When it comes to the contrastive characteristics between H. habilis and P. boisei, the emphasis has been placed to the analysis of dietary habits. As such, Smith, Benazzi, Ledogar, Tamvada, Pryor Smith, and Strait have introduced their analysis of australopithecines, among which P. boisei is considered to be the robust form, revealing traits aimed to produce high bite forces and strengthened face in terms of dietary habits. At the same time, recent mechanical analysis implies that the species is not considered to be an effective producer of the bite force because morphology of primates is not strong. The researchers have resorted to the engineering method of finite element evaluation to demonstrate that the facial skeleton of the identified species is strong and shows a specific pattern, which differs from chimpanzees, along with Australopithecus africanus. It also efficiently develops high level of bit force. It has been stated that P. boisei consumed grass and sedge pith. At the same time, the topography of this and other species assumes that the australopithecines adjust to eat hard food, such as sedge seeds and grass. The evolution trends in the dietary habits and feeding mechanisms shows that food processing patterns in the identified species were disrupted because of the environmental and climate change, which contributed to the evolution of Paranthropus and Homo.
The ancestors of Homo Sapiens include the members of Australopithecines who were intermediate chains between apes and humans. Both humans and australopithecines are similar in biological ways and share important features of human generation. At the same time, Australopithecines have certain features of chimpanzees, gorillas and bonobos. For the last decades, there have been a large number of discoveries in Africa which have provided certain explanation to the transitional processes of apes to humans. The creatures lived right after from the emergence of the modern hominid ancestor with bonobos and chimpanzees during the early Pliocene Epochs and Miocene. Over 2 million years ago, there were two major evolutionary lines of hominines. The first line was adapted to the food resources in grassland environments near lake; they do not have a vegan diet and included much meat. These were species, which started making stone tools. The second line lived in mixed environment, similar to early human ancestors and preferred eating vegetarian food. This line was more conservative and died by 1 million ago. It is similar to early hominids, which supplemented protein rich termites, like chimpanzees used doing today.
The food patterns among the identified hominids had a potent influence on the teeth size development. The diversity in molar tooth size among humans and hominines has strongly affected out outlook on human evolution. The shift in overall size and decrease in molar size have presented for over a century and is associated with the reduced selection for dentitions due to the shift in dietary habits and food processing mechanisms. The size variation in tooth has been presented as morphogenetic gradient in mammals and more specifically among hominines. At the same time, the tool size variations have been understand insufficiently, with the existence of diverse hypotheses ranging from morphogenetic fields and close theory. In the study, the emphasis has been placed on such questions such as tooth size evolution, activator-inhibitor mechanisms influencing tooth size in mammals, and default patterns of tooth size. At the same time, the identified species, along with the modern humans reveal a close correlation between tooth proportions and general tooth size, such as single developmental parameter which can explain absolute and relative sizes of teeth. With reliance on the correlation of inhibitory pattern sizes, it is possible to use the size for predicting the size of the postcannie teeth. The research study also introduces expectations for exploring the evolution of the genuine proportions of human teeth.
The contrastive analysis of the above-identified species can provide a vivid explanation of the ways and transitions which occur on the ways to formation of modern humans. As such Kimbel and Villmoare have asserted that transition from Australopithecus to modern humans is commonly an issue of a rapid transformation, the fossil record which takes roots from the earliest evolution of Homo Sapiens, but it is not officially accepted or documented. Therefore, the poles and borders of transition are associated to taxation, in which substantial differences have accumulated over specific spans of evolution. These comparisons are adaptively diverse and remote species are aimed at defining the transition to the fact that the ground should be considered to be monophyletic clades and unified grades. At the same time, when the problem is not evident in terms of lineages, the adaptive issue is not still the answer to the identified question because of the evident lapses in describing the evolution and transition issues. The patterns and novel features, therefore, should be discussed at different levels and provide the transitive patterns which are not known to the modern scientific findings. The absence of evidence does not provide sufficient information to further exploration. Generalized species and adaptive descriptions could be presented as amplifications and extensions of the old hominine trends.
With reliance on the findings and research explorations, it could still be stressed that brain size, dietary habits, and skull form are among the major criteria according to which it is possible to judge which species stand the closest to the current image of Homo Sapiens. It also explains the gradual transition from apes to humans. However, the existence of different forms of hominines 2 million years ago also proves that not all species participated in the modern form of Australopithecus. Hence, the assumption that australopithecines could be presented as the ancestors of apes allows to admit that that paranthropus could be the ancestors of gorillas, dividing the Australopithecus into two branches of development – humans and chimpanzees. Hence, some of the lines, which derived from one species, have been split due to the unknown reasons. What is more important is that much of the evidence do not support the logic of the composed family tree and there are many other theories of how a modern human evolved. Nonetheless, the fact that there were different types of transitions and similar features of the proposed tree provides a sufficient ground for further analysis and clarification of how these species evolved and what further steps to be taken to highlight those transitions.
In conclusion, it should be stressed that the difference between the identified species lie on the size of braincase, tooth size, and dietary habits, which explained the emergence of the modern humans. It has been reported that there are a number of similarities between H. habilis and H. rudoflensis, although the former has larger braincase. Apparently, H. habilis seems to stand at a higher ladder of development as compared to other identified species. Dietary habits also provide certain explanations because of the emergence of new food processing mechanisms. To enlarge on the issue, P. boisei were less inventive in terms of food processing and, therefore, they were able to consume hard food. Other species at issue were more adoptive and closer to the modern human. Despite the close connection between hominines and humans, there is still a large gap between those due to the absence of documented evidence. Instead, there are a number of hypotheses, which are logical and lack sufficient evidence to support further investigation. As soon as the hypotheses exist, it is still possible to construct new theories and frameworks, which could lead to the genuine explanation of the human evolution. However, the in-depth exploration have still revealed similar and diverse features between the identified species which could help the researchers reach the final results and provide new transitions and evidence. In my opinion, H. rudoflensis and H. habilis seem to be closer to the evolutionary chain of modern humans because of the similar features and biological characteristics.