Washington, April 9 2021: Scientists have been trying to solve a mystery for as long as our origin story has been known: Exactly when and where did the brain evolve into something that made us human?
Research has revealed that modern brains may be a result of evolution as early as 1.5millions years ago, sometime after humans started walking on two feet. Studies of skull fossils unearthed in Africa, Georgia and Indonesian Java reveal the modern brain evolved more recently than originally thought. A team of scientists including paleoanthropologist Christoph Zollikofer, and Marcia Ponce de Leon examined these skulls and the marks the brains have left in them.
Since brains themselves are not preserved as fossils, scientists created virtual endocasts of what had filled the skulls long ago. In humans, part of the frontal lobe linked to speech production, is much bigger than the corresponding zone in other great apes. The expansion of an area results in the shifting of everything behind it.
The study reveals that the oldest brains (1.7million years old) actually had a frontal lobe characteristic. This means the genus Homo “started with bipedalism,” or walking on two legs, were just terrestrial bipeds, with ape-like brains.
And the younger African fossils, dating back 1.5 million years, showed characteristics of modern human brains. This signified that the evolution of the brain took place between the two dates, in Africa, according to the study. The conclusion is backed up by the fact that more complex tools appeared during this same period, called Acheulean tools, which have two symmetrical faces.
The discovery of primitive brains in Georgia skull fossils also means people without big modern brains migrated away from Africa, not just ones with modern brains as previously thought.
Meanwhile, fossils from Java, the youngest specimens in the study, showed modern brain characteristics. The researchers therefore believe that there was a second migration out of Africa after the first migration involving primitive brains. Researchers say these results are conclusive since they are based on real fossil evidence.
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