Modern humans are fundamentally different from our closest living relatives, the great apes. The first populations of homo sapiens appeared in Africa about 2.5 million years ago. They were able to walk upright, but their brains were half the size of modern human brains. These earliest homo sapiens populations in Africa had ape-like brains — like their extinct ancestors — the Australopithecus subfamily. So, when and where did the typical human brain evolve?
An international team led by Christoph Zollikofer and Marcia Ponce de León from the Department of Anthropology at the University of Zurich (UZH) has now successfully answered these questions. "Our analysis shows that modern human brain structures only emerged in African Homo sapiens populations between 1.5 million and 1.7 million years ago," Zollikofer said. The researchers used computed tomography to examine the skulls of fossil Homo sapiens who lived in Africa and Asia between 1 million and 2 million years ago. They then compared the fossil data with reference data from great apes and humans.
In addition to size, the human brain is different from the brain of the great ape, especially in the location and organization of the various brain regions. Study first author Marcia Ponce de León notes: "The typical feature of humans is primarily those areas of the frontal lobe, which are responsible for planning and executing complex patterns of thought and action and, ultimately, language. "Because these regions are significantly larger in the human brain, adjacent brain regions are displaced backwards.
The first homo sapiens population outside Africa, in what is now Demanissi, Georgia, had brains as primitive as those of their African relatives. Thus, it follows that the brains of early humans did not become particularly large or modern until 1.7 million years ago. However, these early humans had considerable capacity to manufacture numerous tools, adapt to the new environmental conditions of Eurasia, develop animal food sources, and care for group members in need.
During this period, African cultures became more complex and diverse, as evidenced by the discovery of various stone tools. Researchers believe that the evolution of organisms and cultures may be interdependent. Anthropologist Ponce de León said: "It is likely that the earliest forms of human language also developed during this period. "Fossils found on the island of Java provide evidence that the new population was very successful. Soon after their first appearance in Africa, they migrated to Southeast Asia.
Previous theories offer little support due to the lack of reliable data. "The problem is that the brains of our ancestors have not been preserved as fossils. Their brain structure can only be inferred by dissolving the imprints left by folds and ravines on the inner surface of the stone bone. Research leader Zollikofer said. Because these imprints vary from person to person, until now it was not possible to tell definitively whether the brain of a fossil Homo sapiens was more like an ape or more human. Through computed tomography analysis of a series of skull fossils, researchers have now been able to fill this gap for the first time.