The Similarities Between Neanderthals And Modern Humans

Home neanderthalensis (or Neanderthals) are the closest prehistoric relatives of humans (1). They were believed to have co-existed with modern humans in Europe and Asia. The physical characteristics of these Neanderthals are different from modern humans in some ways. Some experts say that this is due to evolution. There are different theories regarding their connection with the modern humans, as well as their disappearance from the face of the Earth. There is a number of Neanderthal fossils that were discovered from different parts of the world mainly in Eurasia. Two of these are the fossils found in Kebara Cave and El Sidron Cave.
Neanderthals were recognized as a distinct group of hominids after the discovery of fossils 150 years ago at
Feldhofer in Neander Valley (2). For over 500,000 years, Neanderthals have been successful in adapting to the cold weather in Pleistocene Eurasia. However, they became extinct about 32,000 years ago, which would mean that these two species have co-existed for about 18,000 years. And their disappearance may have been due to the existence of the modern humans. However, there was limited evidence to prove this. Another hypothesis is that they could have died due to extreme cold weather and adaption and evolution have become impossible for them to handle (3). The existence of Neanderthals became known to the public in 1856, but the focus of the scientists is elsewhere (4). More than 150 years later, there still are concerns with the whole concept of the existence and disappearance of Neanderthals.
Based on the fossils that were discovered these past several years, the physical appearance of the Neanderthals was compared and analyzed.
The similarities among these fossils were described and have been generalized. The physical characteristics of Neanderthals include massive limb bones, barrel chest, thick bone ridges, huge protruding face and nose, receding forehead, an absence of a well-dignified chin, bun-like bulge on the back of the skull, and slightly larger brain than humans. These physical traits suggest that Neanderthals were brutal species (4). The figure below showed the comparison between the skulls of the modern humans and
Neanderthals.

Figure 1. Comparison of the skull of modern humans and Neanderthal
Source: https://chiefio.wordpress.com/2011/11/20/neanderthal-vs-cro-magnon/
Modern human (left), Neanderthal (right)

It is said that Neanderthals vanished 10,000 years after the disappearance of the Denisovans, leaving Homo sapiens alone (5). There are two main fossil location that changed the focus to Neanderthals. The first is the discovery of a 60,000-year old Moshe in 1983. Moshe is a Neanderthal discovered inside the Kebara Cave in Mount Carmel in Israel. When it was discovered, the attention of the scientists was focused on something else. It only gathered attention when biochemists from the University of California at Berkeley in 1987 studied the DNA connection of a female who lived in Africa 200,000 years ago to all living humans. Upon the discovery of Moshe, he was lying on his back in a shallow pit, which may entail they were buried once they die. His right arm was placed across his chest and his left arm on his stomach. This habit of burying the dead lead to the discovery of several more fossils. Aside from that, this habit resembles that of humans (4).
The second set of fossil was from El Sidron and it was discovered in 1994; there was a total of 140 bones since then. The forensic team first thought that they were of Republican soldiers, but after six years of analysis, it was officially announced that it was a group of Neanderthals, who lived 43,000 years ago. It was reported that Neanderthals in El Sidron were on the run going to the central Europe and along the southern Mediterranean. Since 2000, 1,500 more bones were found and were placed in National Museum of Natural Sciences in Madrid. At least 9 Neanderthals of different age groups had cut marks that can be seen in their bones. This suggests that there were cannibals who were up against them (1).
There were several hypotheses and theories regarding the relationship between Neanderthals and modern humans and their disappearance.
Out-of-Africa theory of human evolution suggests that modern human co-existed and replaced the Neanderthals population. This can be seen in the mitochondrial DNA sequencing done by several scientists. There were analyses recently that strongly support the gene flow between Neanderthals and modern humans in Eurasia, but not in Africa (6). One of the most important parts of doing a DNA analysis is their teeth. It contains a permanent record of growth of both humans and Neanderthals. A study by the scientists using a Neanderthal tooth has found no difference between their growth pattern and that of a human. In 2006, Paabo and his colleagues had traced nearly million letters of their DNA
(1).
A version of a gene called FOXP2, which is responsible for speech and language ability, and controlling facial muscles, present in modern humans, as well as two individuals from El Sidron. Moreover, results from a DNA tracing of a 38,000-year leg of a Neanderthal suggest that they are 99.5 percent identical to modern humans. However, due to extremely cold weather of Eurasia, they were believed to have undergone evolution, changing some structures that lead to some distinction between the two (1). According to Barras, non-African descent has two to four percent of their DNA from Neanderthals (5).
There was another hypothesis that suggests that Neanderthals did not go extinct, rather, they evolved as Europeans and Middle Easterners. However, there was not enough evidence to support this hypothesis. Due to cuts found on the Neanderthal bones in El Sidron, it can be concluded that they may have been cannibalized by other species. This can affect the DNA analysis and even the dating process due to the probability of these bones being contaminated. Additionally, it scrapes flesh from the bone that can also cause the removal of the DNA. Moreover, another challenge in tracing the DNA of the Neanderthals is the possible mixture of the scientist’s DNA. Some scholars claim that the close relationship they have on humans is due to specimen contamination.
There are studies that tried to prove the relatedness of modern humans and Neanderthals. However, the tracing of the DNA of Neanderthals is controversial and challenging at the same time. Even with the numerous number of fossils that have been discovered all over Eurasia and Africa, there have been some difficulties still. This is mainly due to the contamination of the specimen, presumably by the cannibals that attacked and killed the Neanderthals. Some were saying that it is due to the scientists who may have contaminated the specimens accidentally. Considering the number of fossils that were discovered, this should account for being as enough evidence. Conversely, the evidence also caused confusions and never-ending debate of which study is most accurate. The number of evidence also results to more questions, rather than answers. Even this day, there is a number of theories and conclusion that were spreading around. In order to reach the same or similar conclusion, an additional genetic characterization of Neanderthals is needed to be able to understand the molecular diversity in their population and their relationship to modern humans. Genetic characterization consists of identifying the “variation as a result of differences in either DNA sequences or specific genes …” (7). Although scientists have already engaged in genetic characterization in the past, an additional process will be needed to carefully evaluate the DNA make up of Neanderthals, in relation to that of modern humans. The disappearance of the Neanderthals, on the other hand, present a greater challenge. Thus, doing further genetic characterization might also be helpful in answering this question.