The emergence of Homo sapiens
Specific genes made the modern man. And modern science has made it possible not only to identify these very genes, but also to determine the time – when these very genes became part of the human genome. So, let’s get to the bottom of this.
So, the oldest Homo sapiens skulls were discovered in Jebel Irhoud (Morocco. Northwest Africa, the shore of the Atlantic Ocean, near the Strait of Gibraltar between Europe and Africa). Initially, the age of the finds was estimated at 160 thousand years ago. However, in our time, the finds have become older, today they are dated at 315 thousand years (and this is absolutely contrary to the genetic data). The most ancient cultural center of Homo sapiens was found in Blombos Cave (South Africa), here were found engraved stones, shell jewelry and paint (ochre), dated 70,000 – 100,000 years ago. That is, judging by these dates and facts – the movement of Homo sapiens went from north to south towards South Africa, where ancient hominids already lived and no other way! However, academic historians argue exactly the opposite – that man of the modern type appeared in South Africa and from there began his dispersal towards the north.
In southern China, Homo sapiens teeth have been discovered in Fuyan Cave in Hunan Province. There were 47 teeth found in the cave, which probably belonged to at least 13 individuals. Dating revealed that the teeth are between 80,000 and 120,000 years old. They do not have archaic features that are common to Neanderthals or other species of the genus Homo, such as Denisovans. These teeth are similar to later finds of Homo sapiens from other parts of Asia, Europe and Africa. Southern China during this period was quite favorable for habitation, with a mild climate and available resources. Other hominid species such as Neanderthals and Denisovans inhabited Asia at this time. Despite the age of the find, there is no evidence of long-term habitation of Homo sapiens in this region for the next tens of thousands of years, which may indicate a temporary settlement or extinction of the population (Apparently this is due to the extinction of mankind a period – 74 – 70 thousand years ago). The age of the find was determined using the uranium-thorium method of dating the sediments in which the teeth were found, as well as analyzing the fauna found in the same layers.
(Recall that according to academic historians, man of the modern type originated in Africa and then began to disperse beyond its borders about 60,000 years ago.)
Modern humans, Cro-Magnons (early representatives of Homo sapiens), appeared and lived in Europe and Western Asia about 45,000 to 10,000 years ago. Cro-Magnons are not a separate species, but represent the European population of modern humans in the late Pleistocene. At the same time, they still differed from modern humans – with a larger and stronger skeleton and a more voluminous skull.
Specific genes made the modern man. And modern science has made it possible not only to identify these very genes, but also to determine the time – when these genes became part of the human genome. So, let’s get to the bottom of this.
Genetic modification of ancient hominids 2.5 million years ago.
Changes in the genome of Homo habilis and Homo erectus:
ARHGAP11B gene. The gene is directly related to the development of the cerebral cortex, including its size and complexity. During this period, Homo habilis and Homo erectus began to show signs of more complex behavior, including the use of tools and a more developed social structure.
SRGAP2 gene. This is a gene that was elongated in the ancestors of Homo sapiens, which contributed to improved cognitive function, including the ability to think abstractly and plan. This improved connections between neurons and was an important step in the evolution of human intelligence.
TLR4 gene. This gene is involved in recognizing bacterial pathogens, particularly bacterial lipopolysaccharides.
PAX3 gene. This gene is involved in the development of facial structures and also affects the development of the teeth and jaw. It is important for the normal formation of the facial part of the skull and can influence features such as the shape of the nose and chin.
Genes associated with tooth development. The MSX1 gene is involved in the formation of tooth rudiments, and the RUNX2 gene plays a role in the development of the jaw bones and teeth.
MC1R (Melanocortin 1 receptor) gene. The gene plays a key role in determining skin, hair, and eye color in humans, as well as the response to sunlight. About 2 million years ago, the first changes occurred that resulted in lighter skin in some ancient hominids, which was due to adaptation to different levels of solar radiation in different geographical areas.
The hand of the ancient hominid became adapted to making tools, with gradual improvements in motor skills and hand anatomy, especially in species of the genus Homo, such as Homo habilis and Homo erectus.
Genetic modification of humans 200,000 years ago.
So, 200 thousand years ago, there were cardinal changes in the hominid genome that led to the emergence of Homo sapiens, the modern type:
The FOXP2 gene. This gene is linked to the development of speech and language and plays a key role in the development of motor skills, including the control of movements needed to articulate sounds. According to genetic evidence, changes in the FOXP2 gene that are specific to humans occurred about 200,000 years ago. This is likely related to the development of the ability for complex speech communication in the ancestors of modern humans. This included changes in the structure of the larynx, the development of vocal cords, and an increase in brain volume, especially in the area responsible for speech processing (e.g., the broca center).
However, scientists believe that more complex forms of language, such as grammar and abstract concepts, developed later, about 50,000-80,000 years ago, when more complex social structures and forms of communication emerged.
(In human predecessors, such as Homo erectus or earlier species, this gene existed in a different form. As Homo sapiens evolved, the gene changed to allow for more precise and controlled movement of vocal cords and facial muscles, as well as language processing in the brain. However, in Neanderthals, the form of this gene was similar to the modern form).
DISC1 gene. This gene plays a role in the formation of synaptic connections and in the regulation of neuronal growth. Changes in this gene have affected brain development and cognitive function as well as mental disorders. Changes in the gene have been shown to improve social interactions and abstraction ability.
MMP9 (Matrix Metalloproteinase-9) genes. These genes play an important role in regulating processes such as tissue development, matrix remodeling, and immune response. And also play an important role in processes related to tissue growth, development and repair. These genes are also important for the immune system by participating in inflammatory responses. In addition, play a role in the body’s adaptation to changing environmental conditions, including changes in physical development, which may include brain and bone development.
TLR7, TLR8, and TLR9 genes. These genes are responsible for recognizing viruses and bacterial DNA. These genes have undergone changes in the last 200,000 to 100,000 years as Homo sapiens began to encounter more complex viruses and bacterial infections.
EDAR gene. This gene is associated with hair development and also plays a role in tooth and jaw formation. Changes in this gene that affect the teeth and jaw, as well as hair levels, are associated with adaptations to different climatic conditions.
PAX3, MSX1 and RUNX2 genes. New changes in these genes, played a key role in the formation of modern face and tooth shape, including the reduction in tooth size due to dietary changes and tool use.
MC1R (Melanocortin 1 receptor) gene. The gene plays a key role in determining skin, hair, and eye color in humans, as well as the response to sunlight. It regulates the synthesis of pigments such as eumelanin (responsible for dark color) and pheomelanin (responsible for light color). Changes in this gene have led to the appearance of different skin, hair and eye shades in humans, which is associated with adaptation to different climatic conditions.
Genetic modification of modern man 12,000 years ago.
The final genetic change that resulted in modern humans:
The EDAR gene. This gene is associated with physical features such as the shape of hair, teeth, and skin. In East Asians (e.g., Chinese and Japanese), changes in the EDAR gene resulted in more pronounced thickening of hair and a distinctive tooth structure. In Europeans and Africans, changes in this gene were less pronounced, and hair shape tends to be more straight. (Presumably, changes in this gene could have occurred much earlier than 20-30 thousand years ago).
LCT (lactase persistence) gene. This gene plays an important role in the ability of humans to digest milk sugar (lactose) in adulthood. Changes in these genes have been an important step in human evolution, especially in the context of agriculture and animal domestication. We would add that changes in this gene have been associated with human groups in Europe, Asia Minor and Central Asia, the Middle East, and in some African tribes.
Amylase gene (AMY1). There was an increase in copies of the amylase gene, this improved starch digestion. Human ancestors had about 2-3 copies of the AMY1 gene. However, with the shift to agriculture and more consumption of starchy foods, the number of copies of the amylase gene increased to 5-9 copies of the AMY1 gene. This increase allows them to digest starch more efficiently.
SLC24A5 gene. This gene plays a key role in skin pigmentation by regulating levels of the pigment eumelanin, which gives the skin a lighter shade. The changes were associated with adaptation to low sunlight conditions, which presumably led to the appearance of lighter skin in northern populations of Homo sapiens. These changes were important for optimizing vitamin D absorption in low sunlight conditions. (There is reason to believe that changes in this gene occurred much earlier).
HERC2 gene. A mutation in this gene directly affected the activity of another gene called OCA2. Thus, a mutation in HERC2 reduces melanin production in the iris, resulting in light, blue eye color. (There is reason to believe that changes in this gene occurred much earlier).
MC1R gene. Presumably, a new mutation in this gene led to the appearance of light-colored hair at first (due to decreased levels of the pigment melanin), and later to the appearance of red hair.
So, the genetic evolution of Homo sapiens involved many changes that range from brain development and cognitive abilities to adaptations to the environment and changes in physical anatomy. These changes combined to produce humans of the modern species, capable of complex speech, social interactions, abstract thinking, and adaptation to a variety of environments.