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The evolutionary development of life on Earth is not random but rather is based on deep causal relationships and patterns. The study of these connections helps to understand the essence of evolutionary development better and to trace the chronology of metamorphosis that occurs with life. In addition, understanding the drivers of evolution helps to predict future development and identify the most likely changes. This paper will answer three questions related to human evolutionary development in antiquity and identify the reasons for these changes.
Why Do Humans Have Such Big Brains?
It is paramount to outline what exactly is meant by the characterization of humans in this question. The traditional view of the evolution of Homo sapiens is that the modern individual did not evolve from an ape but rather from a great ape, a distant common ancestor between Homo sapiens and modern primates. The division of the genus Proconsul occurred millions of years ago, and since then, humans have evolved along their own path, parallel to modern apes, whether gorillas, orangutans, or chimpanzees (Andrews 125). Thus, when we speak of human brain enlargement, we are referring specifically to modern Homo sapiens sapiens compared to ancestral forms or other modern primates.
The enlargement of the brain compared to the size of the jaw is evident in a pairwise comparison of the facial skeleton of humans and other primates. In humans, the brain part of the skull is strongly pronounced, which balances the brain and jaw sections of the skull. In contrast, there is no such phenomenon for monkeys, so their skull is heavily skewed toward the powerful jaw part, as shown in Figure 1. One of the main reasons for the enlargement of the modern human brain is thought to be the expansion of social and creative activity, due to which there has been a slow increase in volume (Andrews and Johnson 226). Evolutionarily, humans tried to survive in a wild environment, so banding together into tribes and developing crafts was necessary for humans to have a chance to do so. Thus, the world was rapidly evolving, and increasingly new information needed to be assimilated, resulting in a biological need to expand the repository of that memory, that is, the brain. As a result of natural selection, thus, those hominids that had larger brain volumes had advantages for survival and continuation of the species, which was the probable reason for this result to be fixed.
However, this is not the only hypothesis determining the evolutionary need for a giant brain in comparison with other primates. It can be assumed that the initial increase in brain structure was accidental, but it is not so much the root cause as the fact that this trait is fixed that is attractive from the research point of view. One must understand that the brain is one of the most energy-intensive organs of the body, requiring large amounts of energy; a larger brain understandably requires more energy (Heid). In addition, the larger the individuals brain, the larger the cranium must be, which creates difficulties for comfortable delivery in the wild. Taking this into account, it is reasonable to assume that the enlargement of the brain may have been unreasonable for two reasons at once. However, human adaptability to change has engendered the consolidation of this trait. Individuals began to eat higher-calorie foods as cooking evolved, allowing more energy for brain development (Andrews and Johnson 226). In addition, women unable to give birth did not produce offspring, so this weak characteristic dropped out of the genus phenotype, maintaining an increasing trend. Thus, to summarize, it is correct to note that human brain augmentation is a complex and multidisciplinary slow process whose fixation was motivated by survival benefits.
How are Social Systems, Brain Size, and Ecology Related?
This question is a continuation of the problem raised in the previous section, so it was decided to answer it second. As has already become apparent, the human brain followed an evolutionary path of increase, which contributed to better survival and creative development. However, any biological development of man must be placed in a social context since it took place in parallel. Humans have long been biosocial animals and thus use social systems for survival and development, whether tribes, families, or groups (Coto and Traniello 2). The need for constant communication, knowledge transfer, and learning in such systems is naturally a much more complex undertaking than living outside the social framework, which influenced the increase in brain structure. Notably, social complexity as a justification for the need for brain expansion can be traced as a proven cause not only in humans but also in other socially living animals, among them ants (Coto and Traniello 4). Thus, the development of a larger brain is a response to social demands, so one would expect that the more social an animal is, the more developed its brain nervous system and, as a consequence, the larger its brain size itself.
At the same time, environmental factors that influence brain size should be considered. A critical aspect of environmental pressure should be the type of food resources used. Studies show that brain size was traditionally smaller in regions where individuals ate more vegetation (Will et al. 2). As a hypothesis, this effect is related to the effect of predation since it requires increased brain activity to catch victims for food compared to feeding on ubiquitous plants. Meanwhile, changing climatic conditions and the need to survive in a pristine environment triggered the need to learn and master experiences, which also influenced the increase of brain structures (González-Forero and Gardner 554). In other words, the ecological environment was constantly changing, so hominids needed to explore new lands in search of a better place to live, which developed the brain.
What Are The Costs And Benefits Of Infanticide? Do Humans Commit Infanticide?
Infanticide is a severe problem from the moral and legal perspectives of society but has evolutionary advantages. Many animals, including primates, rodents, and birds, commit the practice as part of a survival mechanism (Fedigan et al. 349). One of the main reasons for this behavior is population overpopulation, which translates into increased pressure for survival; fewer resources become available (Fedigan et al. 349). As a result of such overpopulation, adults kill some cubs because they see it as a salvation for the entire population. In continuation of this reason, it is reported that infanticide may be carried out by males when they feel threatened by their alpha superiority and survival (Lukas and Huchard 1). This means that infanticide helps to eliminate potential competitors and maintain leadership in the pack. Thus, the need to spend large amounts of resources on raising offspring under pressure creates a foundation for infanticide and helps the population to remain resilient.
Regarding humans, it should be understood that under the legal and moral framework of modern society, infanticide is wrongful behavior with consequences. The intentional or accidental killing of ones own children is punishable because it is inhumane and criminal. Notably, abortion generally does not fit into this framework since the killing of a fetus takes place at an earlier stage. Nevertheless, the practice of killing children persists in the socially advanced individual, the reasons for which are usually psychological deviations or personal motives (Gleeson). Such actions hardly make a profound contribution to population development and population decline but nevertheless exist as a fact.
Works Cited
Andrews, Peter. Last Common Ancestor of Apes and Humans: Morphology and Environment. Folia Primatologica, vol. 91, no. 2, 2020, pp. 122-148.
Andrews, P., and R. J. Johnson. Evolutionary Basis for the Human Diet: Consequences for Human Health. Journal of Internal Medicine, vol. 287, no. 3, 2020, pp. 226-237.
Coto, Zach N., and James FA Traniello. Brain Size, Metabolism, and Social Evolution. Frontiers in Physiology, vol. 12, 2021, pp. 1-6.
Fedigan, Linda M., et al. Costs of Male Infanticide for Female Capuchins: When Does an Adaptive Male Reproductive Strategy Become Costly for Females and Detrimental to Population Viability? American Journal of Physical Anthropology, vol. 176, no. 3, 2021, pp. 349-360.
Gleeson, Hayley. When Parents Kill. ABC, 2021, Web.
González-Forero, Mauricio, and Andy Gardner. Inference of Ecological and Social Drivers of Human Brain-Size Evolution. Nature, vol. 557, no. 7706, 2018, pp. 554-557.
Grossmann, Cesar. How do human and ape skulls compare to each other? Quora, Web.
Heid, Markham. Does Thinking Burn Calories? Heres What the Science Says. Time, Web.
Lukas, Dieter, and Elise Huchard. The Evolution of Infanticide by Females in Mammals. Philosophical Transactions of the Royal Society B, vol. 374, no. 1780, 2019, pp. 1-9.
Will, Manuel, et al. Different Environmental Variables Predict Body and Brain Size Evolution in Homo. Nature Communications, vol. 12, no. 1, 2021, pp. 1-12.
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