On a hot summer day, in Uberdia, an ancient site in northern Israel, it is surrounded by endless hay. On the distant horizon, Jordan's mountains sparkle in the haze.
Time goes back about 1.5 million years, and if you walked among the thorny bushes on the slopes of Uberdia, you would have seen something completely different than you do now.
At that time, there was a large lake here that stretched all the way to Mount Jordan.
It is densely wooded with wild oak, olive and pistachio trees. At the lake' edge, you might catch a glimpse of some of the ancient ancestors of modern humans, a group of Homo erectus who used sharp stone axes to dismember the carcasses of deer or hippos.
Uberdia is one of the earliest known sites settled by Homo erectus (sometimes referred to as Homo sapiens) on their way out of Africa. The ancient site, named after a nearby Palestinian Arab village and discovered in 1959, may be the key to answering the question of why Homo erectus migrated from Africa.
<h1 class="pgc-h-arrow-right" data-track="15" what exactly is > the reason why Homo erectus is forced out of Africa? </h1>
Is it innate curiosity? Or is the climate changing dramatically? Or is it some other reason?
Through the study of fossils from about 2 million years ago, we believe that Homo erectus was the first "humanoid" species.
Over a period of about 1.75 million years, they expanded to West Asia and then to East Asia, including present-day China and Indonesia.
Homo erectus is one of the most successful human species ever made, and the sheer number of tools and fossils found in East Africa has led most scholars to believe that Homo erectus originally evolved in the rift valleys of the region.
But a 2.04 million-year-old skull found in South African herring suggests that these people began migrating 2 million years ago. The range of homo erectus migration within and outside Africa was astounding, and they occupied most of the world.
On their way from Africa to Europe and Asia, Homo erectus crossed the Levantine Corridor. It was a long strip of land stretching from the Mediterranean Sea in the west to the desert in the east, including present-day Syria, Lebanon, Israel, Palestine and Jordan. The ruins of Uberdia, where Homo erectus arrived between 1.2 million and 1.6 million years ago, are a halfway point through the Levant.
For years, scholars have supported the "Savannahstan" hypothesis to explain the journey of humans out of Africa. According to this view, Homo erectus arrived from East Africa and dispersed there about 2 million years ago due to the expansion of the East African steppes towards the southern Levant due to climate change.
Homo erectus was likely to be trapped near water sources, lakes, and rivers during their long journeys. As scavengers, they may scrape flesh from animal carcasses, especially those killed by saber-toothed tigers. Essentially, the primitive Savannah Stan hypothesis suggests that these hominids were very adapted to open grasslands and the occasional small patch of forest, and that they eventually decided to move out of Africa as the climate changed environment.
But the discovery in Uberdia complicates the inference that Homo erectus passively followed the spread of the savannah, because Uberdia is not a savannah at all: it is a woodland, covered with trees.
Thousands of fossilized animal bones have been found, including the teeth and bones of rhinos, hippos, crocodiles, bears, pigs, camels and saber-toothed tigers.
The horns come from an extinct buffalo species that once lived in "Uberdia".
Most of the ungulate mammals found in Uberdia are Eurasian species, such as deer and elk, suggesting that it did not become the ecology of the African savannah.
In addition, the composition of carnivorous fossils dating back to the Early Pleistocene (2.6 million years ago to about 770,000 years ago) is taken from Uberdia and four other Eurasian paleoanthropological sites. She identified both the Homo erectus sites—de Manisi in the country of Georgia and the northern Piro of Italy—that are inhabited by a diversity of animal species, including coyotes and dog breeds, favoring open, long-distance running environments, meaning these sites may be shrubs or meadows. Meanwhile, three others — Uberdia, Ventamisena in Spain, and Akhaal karachi in Georgia — featured a wider variety of ambush hunters, such as felines, who relied more on trees, indicating that these sites were covered by forest.
In addition, comparing the composition of carnivores fossils from Uberdia and four other Eurasian human sites, it is inferred that the Homo erectus habitat here is inhabited by a wide variety of animals, including hyenas and dogs, who prefer an open long-distance running environment, meaning that these sites may be shrubs or meadows.
Meanwhile, three other countries — Uberdia in Spain, Venta Michena and Akhalcaraki in Georgia — have more types of ambush hunters, such as felines, which rely more on trees, suggesting that these sites were once forests.
Based on this, scientists have proposed a different theory of migration: Homo erectus adapted to diverse environments before the population left Africa, hunting antelopes on open plains and foraging in forests.
This space not only provides a place for humans to forage and avoid predators, but the challenges of these unfamiliar environments also enable individuals who are born with the ability to adapt to survive and survive, promoting the gradual evolution of humans.
An analysis of the skulls of Homo erectus ancestors at the 1.77-million-year-old Dmani site in Georgia shows that the bones came from a man who had no teeth for a time before his death. It is inferred that in the circumstances of the time, this person was fortunate to have the news that there were other people to take care of him and help him gather things, and also inferred that people at that time would already process food, such as meat and plant rhizomes, because in this way, it could be eaten by a person who had no teeth and could not chew.
These ideas fundamentally reimagine the capabilities of ancient humans. Homo erectus is not a passive creature, so their migration is not to go with the flow, but to actively choose and adapt.
Of course, human beings have experienced periods of high climate change, which has also inspired human adaptation and evolution of the environment.
In times of rapid and continuous climate change, only individuals with certain characteristics can survive, thrive, and raise children, who can carry these beneficial traits and shape human evolution.
Out of Africa, to Europe or East Asia. This is just a modern definition of the Homo erectus migration path.
Homo erectus did not have a map, and they did not know that they had gone out of Africa. They may have migrated just to see what they could eat in the ravine ahead or in the woods.
And it is this little bit of exploration psychology, step by step forward, through millions of years, their descendants scattered on all continents of the world.