Some of our ancestors’ brains were more apes than humans when they left Africa for the unknown wilds of Eurasia . The first human predecessors to travel north and east weren’t even of the genus Homo , and even the brain of Homo erectus was nothing like our own. Now, new research has discovered that the first humans who arrived in Eurasia between 1.7 and 1.5 million years ago still had brains more similar to those of a great ape than what we call humans, because the brain structures Modern humans emerged in African populations of the genus Homo more than 1.5 million years ago.
This means that the brain of modern humans ( Homo ) developed more than 1 million years after the genus Homo emerged, and after the first Homo erectus migrated out of Africa.
The big question: when – and where – the modern human brain evolved
The researchers, led by Christoph Zollikofer and Marcia Ponce de León from the Department of Anthropology at the University of Zurich (Switzerland) have managed to answer these questions. Using computed tomography to examine the skulls of Homo fossils that lived in Africa and Asia between 1 and 2 million years ago. They then compared the fossil data with baseline data from great apes and humans.
They compared the structure of “primitive” or “early” brains to that of a modern human brain, looking at the endocasts (casts) of the closest living relatives of humans, the great apes, including 81 chimpanzees, 27 bonobos, 43 gorillas. and 32 orangutans, along with endocasts from 110 modern humans. They then analyzed the endocasts of nearly 40 ancient human skulls, including those of Australopithecus sediba, Homo erectus, and Homo naledi, and determined how “primitive” or advanced their brains likely were by comparing them to the great ape and modern human endocasts.
The detailed endocasts revealed traces of the brain’s long-missing twists and furrows, or folds and grooves, as well as the vascular structures that surround the brain. As the team crawled through the fossil endocasts, they saw evolutionary changes unfold, like a region creeping toward the back of the brain over time.
These reconstructions yielded the appointed date, making the early evolutionary history of the genus Homo and our brains more complex than scientists thought.
“The first populations of our genus Homo had quite primitive apelike brains, like their ancestors, the australopithecines,” said Ponce de León. This includes fossils associated with Homo habilis and early Homo erectus.
The regions of the frontal lobe that are responsible for planning and executing complex patterns of thought and action, and ultimately language as well, are significantly larger areas in the human brain. According to experts, during this period (1.7-1.5 million years ago), cultures in Africa became more complex and diverse, as evidenced by the discovery of various types of stone tools. Researchers think that biological and cultural evolution are likely interdependent.
“It is probable that the first forms of human language also developed during this period” , clarifies Ponce de León.
Referencia: The primitive brain of early Homo. Marcia S. Ponce de León, Thibault Bienvenu, Assaf Marom, Silvano Engel, Paul Tafforeau, José Luis Alatorre Warren, David Lordkipanidze, Iwan Kurniawan, Delta Bayu Murti, Rusyad Adi Suriyanto, Toetik Koesbardiati and Christoph PE Zollikofer. Science (2021) .DOI: https: //doi.org/10.1126/science.aaz0032
