Summary
An article published in the New York Times titled narrower skulls, oblong brains: How Neanderthal DNA still shapes us, by Carl Zimmer asserts that Neanderthal DNA continues to affect not only the shape of the human skull but also the brain size. Zimmer (2018) initially starts by recognizing the fact that individuals usually sign up for genetic testing in various companies such as 23andMe. He reports that individuals whose ancestry lies outside Africa usually record a similarity rate of between one and two percent. The article focused on a recent research that affirmed that a particular form of Neanderthal DNA influences the shape of human brains (Zimmer, 2018). The study offered insight on how genetic changes are impacting the evolution of the human brain.
Through the analysis of the volume inside the Neanderthal skulls, biological anthropologists have established that Neanderthal brains were as big if not more bigger than the modern human brains. However, the article quotes, Phillip Gunz, a paleoanthropologist at Nax Planck Institute for Evolutionary Anthropology in Germany who states, “We have roundish brains while all other human species have elongated braincases” (Zimmer, 2018). The article asserts that oldest human skulls dating as far back as 300 centuries ago illustrated elongated brains that corresponded more with the Neanderthal skulls than the brain shape of a modern human being. Skulls from 120,000 years ago demonstrated that the brain shape was somewhat roundish, but it was yet to mimic the current ranges. Skulls from 36,000 years ago illustrate the distinctive roundness of the brains of modern humans as reported by Dr.Gunz and his colleagues (Zimmer, 2018).
The researchers hypothesized that the human brain adopted a round shape due to change in the size of some areas of the brain such as the back of the brain, the cerebellum, which has expanded throughout the development of human mind. Dr.Gunz and his colleagues attributed the change to the interbreeding of modern humans and Neanderthals almost 60 centuries ago, which also explains the persistence of Neanderthal DNA in modern generations of individuals of non-African descent (Zimmer, 2018).
According to Zimmer (2018), while the effect of Neanderthal genes on the brain is subtle, through studying the DNA and genes of more than 4,600 individuals compared with more than 50,000 common genetic markers of ancient Neanderthals, the research conducted by Dr.Gunz concluded individuals who have Neanderthal genes have unusual patterns of gene activity in their brains. One marker was in a gene known as PHLPP1 which is unusually active in individuals with the Neanderthal genes. The gene is active in the production of an insulating sleeve known as myelin, which wraps around neurons. Myelin is important in long-range communication in the brain. Another marker identified is the UBR4 gene, which is less active in putamen brain region in individuals that carry the Neanderthal genes. UBR4 gene is used in helping neurons divided in children’s brain.
The article concludes that PHLPP1 and UBR4 genes evolved to work differently in modern humans since the version of PHLPP1 gene in modern humans produce extra insulation in the cerebellum while the UBR4 gene leads to faster growth of neurons in the putamen region of the brain. These changes are attributed to modern humans’ high sophistication in language and the ability to develop tools which are hugely dependent on motor circuitry (Zimmer, 2018). Activities such as articulation and using tools require the brain to send fast and clear commands to specific muscles in the brain. Both the cerebellum and putamen are essential in motor circuitry in areas that were crucial in the overall change of the human brain.
Despite the conclusions of the research, the article asserts that it is difficult to quantify what the results mean for individuals that carry the Neanderthal genes since it is a daunting task to correlate human behavior to genes not to mention the precision it requires to account for what a few Neanderthal genes mean.
Relevance
Scholars and researchers continue to dedicate resources to studying anthropology particularly biological anthropology since it explains the functionality of modern human beings. The article assertion that Neanderthal DNA continues to impact the functionality of the modern human illustrate that the similarity between Neanderthal and modern humans may be more significant than previously thought. (Zimmer, 2018). The article demonstrates that there are distinctive differences between the Neanderthal and the modern human brains. However, it also shows there are evident effects of the Neanderthal genes in modern humans who are carriers of the DNA.
First, the article affirms the conclusions of different researchers who maintained that the brain size of Neanderthals concerning volume was the same size if not more substantial than that of modern humans. Moreover, it proceeds to illustrate that there is a distinctive difference in the brain shape of Neanderthals and modern humans. Modern humans have a roundish brain, unlike Neanderthals who had an elongated brain. It is important to note that analysis of skulls dated 300,000 years ago indicated that humans in that particular age had elongated brains that resemble that of Neanderthals. A similar analysis on a fossil dated 120,000 indicated that humans were slowing evolving to adapt the current brain shape since the brain was more roundish than elongated in shape. (Zimmer, 2018) The most recent analysis of a skull from 36 centuries ago concurred with the ranges of the humans in the current society.
The article provides evidence and explanations for the gradual change in the shape of the human brain. One reason is the mating between Neanderthals and modern humans around 60,000 years ago (Zimmer, 2018). In their bid to explore resources across the globe, modern humans left Africa, encountered Neanderthals and mated with them producing children who inherited the chromosomes from each parent. Undeniably, this particular explanation provides insight on why there is evidence of one or two percent match between the genes of a modern human of a non-African descent and the DNA of Neanderthals.
Another explanation for the gradual change in the shape of the human brain is grounded on the fact that humans continued to develop over the centuries. Aspects such as speech articulation and the use of tools require a level of brain activity that Neanderthals were unlikely to possess. Researchers and academics are unable to describe the level of sophistication the Neanderthals had. For instance, while there is evidence they used simple tools such as spears; scientists are unable to tell if they used any languages or symbols for communication (Zimmer, 2018). The development of languages and improvement in technology increased the motor activities of the brain. As mentioned, tasks such as speech articulation and using tools necessitate the brain to make quick and precise commands to different muscles. Therefore, the human brain had to develop to account for these changes and demand for the modern society.
Indeed, the research which article references conducted an analysis that compared the brains of humans who are carriers to over 50,000 common genetic markers associated with ancient Neanderthals. In comparison, two Neanderthal genes were found that associated the brain activity of the modern humans and those of the Neanderthals. The two markers were PHLPP1 and UBR4 genes. Unlike individuals who are not carriers of the Neanderthal gene, PHLPP1gene is unusually active in the cerebellum of the carriers. PHLPP1 gene is responsible for the production of myelin that is used for long-range communication in the brain. The UBR4 gene, on the other hand, is less active in the putamen part of the brain in individuals who are carriers of the gene. The core function of UBR4 gene is to assist in the division of the neurons in the brains of children (Zimmer, 2018). Therefore, the findings indicate that PHILIPPI and UBR4 genes changed in some ways in modern human brains. Mainly, PHLPP1 gene produces increased myelin in the cerebellum, and the UBR4 gene in modern humans may facilitate a faster rate of division of neurons in the Putamen sector of the brain as such influencing the roundness and the difference in sophistication of advanced human beings and Neanderthals.
Moreover, the question of how Neanderthals, who had similar or larger brain capacities than the modern human beings, went extinct while humans thrived has often puzzled many scholars. The article provides insight into the distinct differences between humans and Neanderthals. Unlike previous research that concentrated on quantifying the size of the brain through measuring the volume inside the skulls, the study illustrates how the human brain developed and changed in shape to adapt to the demands of the society particularly as technology progressed.
While it is evident Neanderthal genes still affect the brain shape and functionality of the brain, it is difficult to conclude what this association means for individuals who carry the genes (Zimmer, 2018). While genetics is used to analyze several aspects of an individual from physical appearance to emotional capacity and psychological functionality, there are limits to what genetics reveals. Indeed, despite evident progress in the field of biological anthropology, it is hard to predict how genes influence psychology and subsequently behavior accurately. Undeniably, it is a more complex task to try and account for how a few Neanderthal genes differentiate carriers and non-carriers whether physically or behaviorally. Primarily, the article indicates that although it has been centuries since the extinction of Neanderthals, their genes continue to influence the activities of the modern man. Acknowledging the influence of genetics in physical appearance, emotional responses, psychology and by extension behavior, investigating how Neanderthal genes remain relevant in contemporary society is beneficial.
References
Zimmer, C. (2018, December 13). Narrower skulls, oblong brains: How Neanderthal DNA still shapes us. Retrieved January 27, 2019, from The New York Times: https://www.nytimes.com/2018/12/13/science/neanderthals-humans-brains-skulls.html?rref=collection%2Ftimestopic%2FArchaeology%20and%20Anthropology
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