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When human’s very ancient ancestors took their first steps out of Africa, some 3 million years ago, their brains looked more like those of great apes. A new study says our big brains developed only some 400,000 years later.
Using CT technology to scan what
skull fossils remain from our earliest ancestors, researchers at the University
of Zurich have turned conventional scientific thinking on its head, saying that
our modern brains began to evolve in Africa only about 1.7 million years ago.
Prior to the Swiss research,
conventional scientific thinking was that our hominid lineage arose some 2.8
million years ago, and our predecessors spread out of Africa around 2.1 million
years ago.
The researchers, who published
their study in the current edition of the journal Science used CT
scans to analyze replicas of the brain’s outer surface re-created from the
oldest known fossils of early human skulls. The 1.77-million to
1.85-million-year-old fossils are from the Dmanisi archaeological site in
Georgia and were compared by the researchers with bones roughly two million to
70,000 years old from sites in Africa and Southeast Asia.
For their research, the Swiss scientists focused on the frontal lobes – the areas of the human brain linked with complex mental tasks such as toolmaking and language. Early hominids from Dmanisi and Africa were found to have retained a great-ape-like organization of their frontal lobe some 1.8 million years ago – long after they began moving away from Africa.
“According to our analyzes, modern human
brain structures only emerged 1.5 to 1.7 million years ago – in African
homogenous populations,” said study author Christoph Zollikofer, a paleoanthropologist at
the University of Zurich.
The findings reveal early humans may have
possessed relatively primitive brains even after they first began dispersing
from Africa. Speaking of their findings, the researchers pointed out to Science News that these more primitive populations
were nonetheless capable of producing a variety of tools, as well as using
animals and caring for their elders.
Their study, meanwhile, notes that the
development of the more modern brain “largely coincides” with
the earliest evidence of more complex “technocultural performance” in
Africa, prompting the team to hypothesize that the biological and cultural
changes were mutually dependent.
“It was during this period that the
earliest forms of human language developed,” said Marcia Ponce de León,
anthropologist and study co-author.
The researchers say that hominids with
modern human-like brains appeared in Southeast Asia shortly after 1.5 million
years ago, suggesting additional dispersals from Africa separate from the
earlier first migration.
The study said further research was needed
to say with certainty whether this second wave merged with or replaced the
earlier groups.
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