The understanding the evolution of the human brain must be done based on an in-depth study of the reconstruction of early human evolution or early humans to modern humans. This reconstruction is done based on the records contained in the fossils found on the sites of ancient human civilizations. One component used as an evolutionary study material is the volume of the human brain.
The human brain is a soft component that is almost impossible to be a fossil, but the study of the volume of the skull (cranium) becomes an interesting evolutionary thing to learn more. The fossil record can explain evolution because it shows that past organisms are different from today's organisms and that many extinct species can be guided in viewing evolutionary changes that occur over time in different groups of organisms.
The most commonly observed fossil during the study of brain evolution is the cranium. This headshell reflects the size and morphology of the brain and surrounding tissue. In addition to fossil shell head can also pay attention to the mould endocranial or also called "endocast".
This 3-year-old child's skull is the first early human skull ever discovered in Africa. It was found in 1924, but it took over 20 years after that before scientists accepted the importance of Africa as a major source of human evolution. Want to know how we know how old Taung Child is and how the child died? [1]
These vertebrates from the individual spine of Australopithecus africanus show that he walks upright in a manner very similar to that of modern humans. The unique curve of your lower back absorbs the shock as you walk. This early human spine has the same curve. [2]
Sometimes endocasts can occur naturally when the shell is filled with sediment, one of which is found in Australopithecus africanus named Taung.
Scientists were initially reluctant to accept that the Taung Child and the new genus Australopithecus were ancestral to modern humans. In the issue of Nature immediately following the one in which Dart's paper was published, several authorities in British paleoanthropology criticized Dart's conclusion.Three of the four scholars were members of the Piltdown Man committee: Sir Arthur Keith, Grafton Elliot Smith, and Sir Arthur Smith Woodward.They were much more sceptical about this fossil's place in evolutionary history and believed it deserved to be categorized as a chimp or gorilla rather than an Australopithecus. However, Dart still had the hesitant support of W.H.L Duckworth, but he still asked for more information on the brain to support this claim. [3]
Endocasts can also be made artificially using molding materials such as liquid latex to the internal headshellMore recently, endocast-making techniques have been developed using the latest technology called 'virtual endocast' based on tomography (CT) scans of head bones that are then reconstructed in computers.
These endocasts approximate outer brain morphology because the brain, meninges, and cranial bones interact in an integrated and highly coordinated way during early development. Present-day modern humans have globular brains and globular endocasts with steep frontal, bulging parietal, and enlarged, rounded cerebellar areas. Together with small and retracted faces, this globularity characterizes the modern human skull. In contrast, Neandertals and other archaic Homo individuals have anterior-posteriorly elongated endocasts. [4]
The Homo fossil endocast shows the importance of brain size in the evolution towards Homo sapiens. The morphological changes associated with a number of important capacities in the hominids are a remarkable increase in brain volume.
During hominid evolution, there is generally an increase in the size or volume of the brain in an absolute and relatively observable state although in some relatively static periods and in some periods of visible brain expansion.
Brain Volume on Body Mass In The Evolution of the Human Brain
The increase in brain volume is very important in human evolution. There is a tendency to increase the primate mammalian brain in the process of evolution that occurred during this time.
The observation that absolute brain size increased over the past 2 million years is one of the few uncontested facts of hominid evolution. There is, however, less agreement about how the size of the brain evolved relative to that of the body. Relative brain size has proven to be difficult to quantify because fossil hominid crania that offer the endocranial measurements, and postcrania that generally provide the body-mass estimates, can only rarely be attributed to the same individual. If it could be established that some aspect of the cranium is strongly correlated with body mass, then relative brain size could be calculated for each fossil hominid cranium that has a measured endocranial volume. This paper investigates one such cranial feature, the area of the orbital aperture, and its correlation with body mass in a large sample of extant primates. [5]
The greater the brain volume the more progressive the species. For decades there have been many studies of brain measurements and it is almost impossible to explain them all. However, The volumetric data they get can only roughly calculate the brain's organ volume. But it is from the data they have gained over the years that can help uncover the evolutionary centre of brain evolution.
The most important thing is not the overall magnitude but the ratio of the parts in it and its ratio to the total body mass. Because if only based on the large volume of the brain, the human brain is much smaller than the whale's brain, but in fact, humans are much more developed in terms of thinking by using the brain compared with whales.
During brain evolution, the cerebral cortex undergoes many changes. Especially in sophisticated and complicated behavioural mammals are associated with the relative size of the cerebral cortex and there is a curvature that increases the surface area.
As mammalian orders are monophyletic and originated at approximately the same time (Meredith et al., 2011), we examined the range of EQs found in each order. This allowed us to examine broadly phylogenetic patterns while also exploring variations in EQ (Fig. 2). Primates (F593 = 176.7, P < 0.001, Levene’s test) and Cetartiodactyla (F552 = 265.0, P < 0.001, Levene’s test) had a significantly larger variance in EQ when compared to other mammals. When taking phylogeny into consideration, Primates and Cetartiodactyla continued to have a significantly larger variance in EQ (Fig. S3). EQ values within these highly encephalized taxa ranged from 0.90 to 5.72 in Primates and 0.14–4.43 in Cetartiodactyla. Other clades had considerably less variation in EQ, and the next two most variable orders were Rodentia (0.25–2.26) and Eulipotyphla (0.39–2.92). [6]
Primates and cetaceans (whales and dolphins) also have an extraordinarily complex and large cerebral cortex. But in reality the cerebral whale cortex is second, still cannot defeat humans in terms of its surface area (comparison relative to body size).
Animals exhibit extreme variation in brain size, with the sperm whale’s brain weighing up to 9 kg (1), whereas the brain of the desert ant weighs only 0.00028 g (2). Although body mass is the single best predictor of brain size (1, 3), some species have much larger brains than expected given their body size (e.g., humans and dusky dolphins), whereas other species have much smaller brains than expected (e.g., hippopotamus and blue whale) (1). Brain tissue is energetically costly (4–6), and therefore, large brains are presumed to have been favored by natural selection, because they confer advantages associated with enhanced cognition (3). However, despite great interest in the determinants of brain size, it remains controversial whether brain size truly reflects an animal’s cognitive abilities (7–9). [7]
The comparative relationship between brain size and body size is very important to be studied primarily in mammals.
The relationship between brain size and mammalian body mass size. In further evolution, the brain gets bigger, relatively faster with body size. This enlargement is accompanied by the separation between existing regions with functional changes, resulting in mammals causing a very strong relationship between brain volume and the number of different regions in the cortical region
The discussion of the evolution of the human brain is structurally derived from the formation of neural tubes with heads that have sense receptors and are free to evolve.
The brain begins with an enlarged end area of this nerve tube, which in the next phase develops into three parts: the forebrain, the midbrain, and the back (hindbrain). Each of these sections is related to a particular sensing. The front for kissing, the middle for viewing, and the back for balance and vibration. It is from this basic building that all vertebrate brains are built. Next, there is an increase in the size and number of nerves.
The front becomes a cerebrum, which consists of the frontal area (telencephalon) and the back (thalamencephalon); the midbrain develops into an optic tectum and the back of the brain to be cerebellum.
In mammals, including primates and humans, telencephalon develops extraordinarily and many times into cerebral hemispheres, and its cortex consists of several layers of neuronal cells. The largest expansion occurred in the neocortex area, especially the expansion of the area. This enlargement suppresses the growth of the old cortical regions into the interior of the brain structure, bending and becoming the hippocampus (hippocampus).
This area in humans plays a central role in spatial memory, learning and emotion. In Homo species, there is a characteristic feature in the evolution of the neocortex that there is a widespread widening of the neocortex and functional differentiation. The rise of this neocortex makes humans capable of performing cognitive operations more efficiently than other species:
The large warning capacity, faster learning, faster perceptual activities, inferences on the basis of careful and careful consideration, and capable of long-term travel
A central insight of evolutionary developmental biology (evo-devo; e.g., West-Eberhard 2003) is that many, if not most, significant evolutionary changes result from changes in ontogenetic timing. That is, if an adaptation emerges earlier or later in ontogeny, or takes shorter or longer to develop, in a modern population as compared with an ancestral population, the result can be huge changes in the phenotype because of the interaction of this change with existing developmental pathways. [8]
The results of brain evolution make today's human beings have a greater brain volume than other primates and provide biological benefits to humans. The development of this brain that causes mental development. The Comparative studies of the ontogenic development of cognitive skills of children and chimpanzees suggest that humans have many cognitive skills not possessed of their nearest primates.
The volume of the brain enlarges and causes changes in the axis and the position of the brain against the spine. It also encourages modern bipedalism. Bipedal change from quadrupedal causes hip to receive heavier loads. The increase in brain volume causes the foramen magnum to connect between the spine and the occipital into a straight line that causes the human body to become more and more robust.
The upright of the body will change the shape of the spine that originally had only one hollow into two holes, causing the capacity of the chest cavity and abdominal cavity to become wider. All of this enables bipedal hominids to thrive by not only being skilled at walking on two legs,
In addition, bipedalism also affects the vocal tract due to the formation of space between the spine and the oral cavity at the larynx as a result of spinal infusion in the foramen magnum, called the inferior laryngeus.
The impact on these vocal channels leads to the variety of vowels that can be mentioned so that humans can speak because they can recognize a wider variety of vowels. The wide spread variety of vowels has an impact on the language system. Language is a complex system of communication and is one of the elements of culture.
Many people believe that between Australopithecus and Homo (modern man) have experienced the development of communication systems in relation to language. In ancient times known as proto-language with a small number of words. So the development of this language is also not separated from the evolution of the brain.
The development of brain volume causes an impact on the vocal tract so that the spoken word can be more numerous due to the wider variety of vowels. In addition, due to the evolution of the brain causes the development of speech centres in the brain.
The developing brain allows humans to take advantage of their environment. Humans have been using the environment in the past, either by cultivating, cultivating, nurturing or destructive for their sake. The consequences of human activity give rise to shades and shapes for the environment which are reflected in archaeological evidence that exists in the form of artefacts, ekofak and features.
It is through this evidence that can show human life in the past that can be used to see evidence of a human culture that helps in reconstructing cultural evolution as well as seeing the relationship of cultural evolution with the evolution of the brain.
The Stone artefacts have been found during the Pleistocene. At this time the volume of the hominid brain has increased rapidly and shows that they have adapted to the environment by making tools of stone.
Conclusion
In a study tracing the evolution of the human brain is known that the human brain has three times the growth compared to early humans. During the process of evolution, the human brain experiences relatively faster enlargement of body size leading to the separation of existing regions with functional changes. This increase is what causes humans to increase the capacity of memorial and learning process.
The evolution of the brain also affects the body shape and vocal tract. The occurrence of changes in body axis and the position of the brain against the spine, encouraging the occurrence of modern bipedalism. Bipedalism has an impact on the release of the upper arm in humans so as to create simple to complex tools.
The changes in the vocal tract cause the widespread vowel variety resulting in the development of primitive languages into more complex languages. It is these changes that drive the development of a culture that leads to cultural evolution.
Therefore it can be concluded that in the development of the evolution of the human brain also has an impact on the development of cultural evolution supported by evidence in the form of artefacts and findings related to human civilization is growing from time to time.
REFERENCE
EndNote:
1. Taung Child Wikipedia Source
2. Human Fossils Species Australopithecus Africanus Source
3. Taung Child Wikipedia source
4. These Endocasts Approximate Outer Brain Morphology Source
5. The Observation That Absolute Brain Size Increased source
6. As Mammalian Orders are Monophyletic Source
7. Animals Exhibit Extreme Variation in Brain Size Source
8. Ontogenetic Source
