Migrations and human demography from the origins to the 21st century
The history of man on planet Earth began about 6 million years ago, when a series of changes in genetic heritage allowed a restricted group of primates present in Africa to adopt a bipedal posture, successfully use their hands and develop a larger voluminous brain, capable of solving different survival problems.
From that very remote period, various forms of hominids developed. Some remained in Africa, while others traveled across the planet in search of better living conditions. All of these hominids disappeared over time, except for one species, Homo Sapiens, to which we belong.
The first human species to leave Africa was Homo Erectus, which appeared approximately 1.8 million years ago and survived in some subspecies until about 13,000 years ago. He was a robust hominid, with very marked eyebrow arches and in terms of knowledge, he was capable of using fire and working with stones and animal bones.
It is known for certain that Homo Erectus reached present-day Indonesia and China (Homo Erectus Erectus and Homo Erectus Pekinensis). What prompted him to emigrate from Africa and explore the immense lands of Eurasia, reaching the island of Java? Probably, the reason why he began to migrate around the planet was the need to follow herds of animals, but some scholars develop the hypothesis that, like all those belonging to the Homo species, he was curious and wanted to know the lands that surrounded him.
The debate focuses on the possibility that Homo Erectus arrived in the New World about 300 millennia ago. This is the thesis of the Brazilian archaeologist María Beltrao, who claims to have studied some sites of bones of megafauna animals worked by man, which date back to approximately 300,000 years and were found in present-day Brazil.
Possibly, the group of humans that, descending from Homo Habilis, transformed into Homo Erectus, was that of Homo Ergaster. On the other hand, in present-day Georgia the remains of Homo Georgicus were discovered, an Erectus that was probably heading east.
The debate continues over whether Homo Erectus also colonized modern-day Europe.
In the vicinity of Heidelberg, in Germany, were found the remains of a very robust hominid, weighing approximately 100 kilos and standing 1.75 meters tall. Homo Heidelbergensis, which lived between 500 and 300 millennia ago in Europe, was probably a descendant of the first Erectus that left Africa a million years ago and adapted to the harsh climate of Pleistocene Europe.
According to the latest paleo-anthropology studies, the direct descendant of Homo Heidelbergensis was Homo Neanderthal, who appeared in modern-day Spain about 230,000 years ago and survived in Europe until about 28 millennia ago.
At the same time, a descendant of Homo Erectus, with delicate and graceful characteristics, called Homo Floresiensis, who lived between 90 and 13 millennia ago, had developed on the Indonesian island of Flores.
Simultaneously with these migrations and evolutions of Homo Erectus, which dominated much of Eurasia and perhaps also some areas of the New World, a new species of humans developed in Africa, more specialized and capable of quickly adapting to climate changes and migrations of the animals. This new species, which originated from Homo Rhodesiensis 300 millennia ago, is called Archaic Homo Sapiens. Genetic studies demonstrated that all current human beings have a common origin in the so-called mitochondrial Eve, or the woman who gave rise to Archaic Homo Sapiens, approximately 200 millennia ago, in current Ethiopia.
One may wonder why the Erectus, which had already been present in Asia for millennia, did not evolve into more developed forms of humans. Furthermore, the question remains as to why the woman who gave rise to Archaic Homo Sapiens was native to Africa, just like the first hominids, and not to other areas of the Earth. For now, there is no scientific answer to this question.
The human group destined to conquer the planet originated in current Ethiopia, and after about 100 millennia of its appearance on the face of the Earth, it began several migrations that led it to colonize all areas of the world and supplant all the Erectus and their descendants.
To carry out in-depth analyzes of human migrations, paleo-anthropologists compare human remains found in different parts of the world and date them with the radiometric radiation method.
For example, remains of archaic Homo Sapiens dating back 200 millennia were found on the banks of the Omo River in Ethiopia, while remains of Homo Sapiens were found in South Africa and at the sites of Skhul and Jebel Qafzeh in Israel, whose age is 100 millennia.
Therefore, the date 100,000 years ago is considered the moment from which Archaic Homo Sapiens left Africa to conquer the planet. According to the Brazilian archaeologist Niède Guidon, a few groups of Archaic Sapiens arrived in Brazil sailing in improvised boats just 100 millennia ago, as proven by some remains of campfires dated with the thermoluminescence method, found in the Brazilian state of Piauí, in Brazil.
The situation of the human population 100 millennia ago was, therefore, the following: in eastern, southern and northern Africa (Atlas), there were archaic Homines Sapientes, which also ventured towards Brazil (very restricted groups of no more than one hundred individuals), and to the Middle East (Israel). In Europe and central Asia (up to present-day Uzbekistan) lived Neanderthal man, while Homo Erectus lived in the Far East and in present-day Indonesia (Flores Island) there was his descendant, the little man Floresiensis.
According to the eminent scholar A. J. Coale, the demographic consistency of humanity 100 millennia ago (including, therefore, all species of Homo), was no more than 30,000 individuals. We can estimate that approximately 20,000 were Archaic Sapient Homines, while the rest were Neanderthal, Erectus or Floresiensis.
It remains to be clarified what the expansion guidelines of the archaic Sapiens were and why they imposed themselves so easily over the other hominids that had already colonized Eurasia.
According to some researchers, Sapiens left Africa through the Sinai isthmus, heading east. There are several explanations for why they adapted to particular ecological niches.
Above all, they were capable of manufacturing much more specific and effective instruments than those of their predecessors. Not only did they efficiently work stone, obtaining real weapons that were used to cut, pierce, hit and penetrate prey, but they could also make sophisticated instruments by molding animal bones and ivory, thus obtaining harpoons, nets and ropes for fishing, and bows, arrows, spears and slingshots for hunting.
This remarkable adaptation to the difficult living conditions during the very long Würm glaciation (from 130 to 11.5 millennia ago) led Homo Sapiens to establish itself as the most formidable hunter on the planet and, therefore, to expand demographically. It is possible that there were never bloody confrontations between Sapiens and Erectus, but simply that the number of Erectus fell precisely because it was difficult for them to compete for food with the new ones.
According to the latest paleo-anthropology studies, Homo Sapiens arrived in Australia around 50 millennia ago. About 40 millennia ago it prevailed over the Neanderthals of Europe and reached the New World in considerable flows, both through the Pacific routes and through the Beringian grasslands.
According to demographer A. J. Coale, the number of humanity 70 millennia ago was only 60,000 individuals, while 40 millennia ago the world population reached 800,000 people. Starting around 40 millennia, Homo Sapiens began artistic and spiritual manifestations. It probably began with the cult of the soul and life after death. In the tombs found all over the world and dating back to this period, various ornaments and objects can be seen that were placed next to the corpse, in order to accompany the deceased on the eternal journey.
The first cave paintings (and petroglyphs) date back to this period, for example those discovered in the Chauvet cave (France), and the first zoomorphic ivory statuettes (Vogelherd). Music also made its appearance with wind and percussion instruments such as the flute and drums. In addition, trade began to take place between the various communities. While the Neanderthals and Erectus lived on self-consumption and did not have frequent barter with other ethnic groups, the Sapiens exchanged their products, such as obsidian utensils, jade, precious shells such as Spondylus and semi-precious stones. It is even thought that precisely around 40 millennia ago the first embryos of modern languages were born.
According to the latest archeology studies, the first civilization, that is, an organized, hierarchical society, based on agriculture, where there is a system that enforces the rules and where some groups of people dedicate themselves to the arts, whether plastic or pictorial or concerning ceramics, emerged on the coasts in front of the current state of Gujarat, in India, around 7500 BC (Khambat civilization).
The scholar Coale also believes that around that period the world population was 8 million people.
During the sixth millennium BC, Sapiens became sedentary, with the improvement of agricultural techniques. In addition, they had begun to use metals, using copper for ornamental objects and defense instruments.
In 3000 BC, when the great historical civilizations of the Indus Valley, the Blue River in China, the Sumerians in modern-day Iraq, the Egyptians and Caral in central Peru emerged, the world population already amounted to 40 million people. In 500 BC, while Solon was promulgating his laws in the agora of Athens, and while Siddhartha Gautama Buddha was preaching his doctrine of the four noble truths, the world population already reached 125 million people. At the birth of Jesus, humans numbered 160 million, while 1800 years later, in the midst of the Napoleonic era, the inhabitants of the planet reached one billion. Only two hundred years later, in 2000, the world population exceeded 6 billion while today, a few months after 2010, it reaches almost 7 billion.
The exponential increase in the human population is also due to the increase in life expectancy, but more than anything to the very high birth rates in African and Asian countries. If future prospects are confirmed, by 2050 the world population could exceed 9 billion. It is an alarming fact, especially considering that a good part of this immense human mass does not have access to free drinking water, does not have adequate medical care and does not receive a basic education, while the minority adopts a lifestyle characterized by excessive consumerism and little respect for the environment and energy resources.
Today, after approximately 100 millennia since Homo Sapiens began the conquest of the planet, taking over, in effect, the world, man continues to emigrate incessantly. The majority of those who leave their homeland do so to find better living conditions or simply because they are looking for work. Rich countries receive migratory flows, and those see immigrants as a threat to their cultural and economic integrity.
It is expected that a global debate will be opened on 21st century migration, which takes into account the incredible economic and social disparities that currently exist on the planet, for example, between a citizen of Australia or Canada (30,000 euros per year per capita income) and a citizen of Bangladesh or Ethiopia (330 euros per year per capita), so that the people who still live in desperate conditions today are transferred to almost uninhabited areas of the Earth rich in resources, so that they can be given hope for a better future.
YURI LEVERATTO
