About 2.6 million years ago, when the ancestors of Homo habilis (skilled man) began to make stone tools by chipping, the Earth entered a period of glacial cycles. Geologists refer to this period by the term “Pleistocene”. Every time the glaciers started moving from the poles, the sea level around the world dropped by about 120 meters. During this period, Sardinia and Corsica were a single land mass, and Corsica was separated from the Italian mainland by no more than ten kilometers of sea.
Therefore, it is not surprising that hominids (probably Neanderthals) inhabited Sardinia long before modern man came out of Africa, which happened about 170,000 years ago (that is, two ice ages earlier), and also around the time when the so-called mitochondrial eve (an African woman from the genus Homo sapiens, from which every living person inherited their mitochondrial DNA) produced their fateful offspring. By the time modern humans arrived in Sardinia (perhaps 20,000 years ago, most definitely 13,000 years ago), the pygmy hippos, elephants, and pigs that once roamed the island were long extinct (perhaps due to active hunting), as were the hominids that hunted them. However, the new inhabitants of the island found a lot of shellfish, deer and now extinct giant hares. The sea level gradually rose, covering the way back to Corsica and the mainland with water, and isolated the inhabitants of Sardinia in the middle of the Mediterranean sea. These stone age pioneers provided the primary genetic material that malaria would later develop. But for many millennia they lived without this disease.
Plasmodium falciparum has been introduced into the human body in the recent past. Wherever this parasite spread, people developed different ways to counter it. Such a wide variety of forms of protection suggests that P. falciparum first infected humans after we left Africa. According to this view, if we had had this infection before we left our native land, all people would have inherited similar forms of protection.
Other indirect evidence supports the recent introduction of P. falciparum into the human body. Since the last ice age, adapted mosquitoes that carry P. falciparum have developed rapidly on the sub-Saharan African continent. Perhaps this indicates a more favorable climate for mosquitoes, as well as that people lived in conditions of greater crowding.
In addition, certain clues are in the DNA of the parasite itself.
Several decades ago, in keeping with our long-standing habit of blaming parasites on domestic animals, scientists mistakenly considered chickens to be the source of P. falciparum. However, genetic analysis has determined that the body of chimpanzees is home to a more related species of Plasmodium. In subsequent studies was established more than a close relative of the parasite that lives in the gorillas. Thus, at the moment, the history of getting a human parasite P. falciparum looks like this: at some point over the past 10,000 years, a mosquito that had just received a portion of the blood of an infected gorilla somewhere in Central Africa bit a person who was nearby. At this point, malarial eve colonized Homo sapiens. This parasite took over the human body in a short time in Africa, and then in the Middle East and other regions.
Exactly when P. falciparum arrived in Sardinia remains unclear. In all likelihood, the parasite colonized the Eastern Mediterranean before arriving in the Western regions. References to annual epidemics associated with the flooding of the Nile began to appear in Egyptian texts 5,000 years ago. The first direct evidence was Plasmodium DNA extracted from a 4,000-year-old Egyptian mummy. However, anemia caused by adaptation to malaria (in particular, thalassemia) was already well known in Ancient Greece and Anatolia, which indicates a much longer period of human co-existence with this parasite. Deformed bones found in an 8,100-year-old settlement now submerged in the sea off the coast of Israel show clear signs of thalassemia . And the Sardinian navigators, who regularly traded and raided the Eastern Mediterranean during the bronze age, encountered this parasite and probably brought it home.
However, despite much evidence of long-term early contact with malarial regions, historians usually blame the Carthaginians for bringing P. falciparum to Sardinia from North Africa about 2,600 years ago. In any case, upon arrival on the island, this parasite found extremely favorable conditions there. The swampy area provided a lot of stagnant water-ideal habitat for mosquitoes. Like other peoples in the Mediterranean region and beyond, the Sardinians also unintentionally made the environment more conducive to mosquitoes. They cut down trees to get wood or to create pastures, increasing the number of sunlit ponds. Since at least the Roman Empire, the island has developed a reputation for high epidemiological risk.
Since then, for many centuries, representatives of foreign authorities came by sea, settled coastal areas, ruled, cursed the malarial fever and longed for home, while the Sardinians themselves went inland. Unlike Sicily, with its more mountainous terrain and relatively low prevalence of malaria, whose people assimilated wave after wave of settlers (Phoenicians, Greeks, Romans, vandals, Arabs, and Norman crusaders), the Sardinian genome never received fresh blood.
The results of comparative genetic studies indicate that the Sardinian branch of a larger regional family tree separated quite early and remained separate. Europeans living on the continent have a closer relationship with the Italians than the Sardinians. In some coastal cities, such as the ancient Catalan city of Alghero, scientists find traces of external genetic influence, but in General, whatever genes were subjected to constant, relentless sharpening by malaria in Sardinia, they remained undiluted.
And modernity was already knocking at the door.