It Really Was a Planet of the Apes Two Million Years Ago

New genetic research shows early humans’ brains were “much more ape-like” than what is measured in modern humans. What this means is that the first waves of human ancestors to migrate out of Africa were perhaps much more primitive than previously considered.

Until now it was greatly assumed that when modern humans and our ancestors first dispersed from Africa they had large brains, more akin to modern people than apes. However, using computed tomography and virtual reconstructions a team of archaeological researchers have determined the internal brain case structures of early  Homo skulls discovered at Dmanisi, Georgia, “were much more like apes.”

Researchers mount a cranium from Dmanisi, Georgia, for synchrotron tomography at the European Synchrotron Radiation Facility in Grenoble, France. (Paul Tafforeau, ESRF)

Researchers mount a cranium from Dmanisi, Georgia, for synchrotron tomography at the European Synchrotron Radiation Facility in Grenoble, France. ( Paul Tafforeau, ESRF )

Discovering the Early  Homo Brain was Ape-like

In a study published today in  Science by University of Zurich paleoanthropologists Marcia Ponce de León and Christoph Zollikofer, the fossilized skulls of hominins were studied, including five individuals who lived in Western Asia more than 1.7 million years ago. The paper explains that these brains were about “half the size of modern brains” and that they were organized more like the brains of modern great apes.  The new research, unexpectedly, shows “the brain of  Homo to be ape-like.”

An earlier  study published last year by Dr. Marcia Ponce de León and her coauthors demonstrated that an older human ancestor, Australopithecus afarensis  (Lucy), had an ape-like brain. Now it is understood that at the early stages of hominid evolution, Homo also had “ape-like-appearing cerebral cortices,” according to the most recent paper. When then did our brains begin to evolve into the powerhouses we wield today? The new research suggests the emergence of a more complex frontal lobe occurred from 1.7–1.5 million years ago. This finding, according to Dr. Marcia Ponce de León, “is shockingly recent . . . and it’s convincing.”

New research shows brains of early humans (illustrated in blue) may have evolved from a more ape-like version (left) seen in a specimen from Dmanisi, Georgia, to the more modern humanlike one (right) from Sangiran, Indonesia, between 1.7 million and 1.5 million years ago. (M.S. Ponce de León and C.P.E. Zollikofer/University of Zurich)

New research shows brains of early humans (illustrated in blue) may have evolved from a more ape-like version (left) seen in a specimen from Dmanisi, Georgia, to the more modern humanlike one (right) from Sangiran, Indonesia, between 1.7 million and 1.5 million years ago. ( M.S. Ponce de León and C.P.E. Zollikofer/University of Zurich )

A Study Encompassing All “Two Legs”

The fossils presented in the study date from 1.8 million years ago and they belong to some of the first  Homo individuals to leave what is today Africa. The researchers also studied “endocasts” from fossilized remains of hominins ranging from 2.03 million to 70,000 years old from Africa, Europe, and other parts of Asia. Just in case you are like me, and didn’t know, an “endocast” is the internal cast of a hollow object, often referring to the cranial vault in the study of brain development in humans and other organisms. Furthermore, the team studied the skulls of modern humans, chimpanzees, bonobos, gorillas, and orangutans.

Virtual fillings of the braincases of early Homo from Dmanisi, Georgia, are shown in turquoise. Their structures provide new insights into human brain evolution 1.8 million years ago. (M. Ponce de León and Ch. Zollikofer/University of Zurich)

Virtual fillings of the braincases of early Homo from Dmanisi, Georgia, are shown in turquoise. Their structures provide new insights into human brain evolution 1.8 million years ago. ( M. Ponce de León and Ch. Zollikofer/University of Zurich )

Over the years Professors Marcia Ponce de León and Christoph Zollikofer have developed new techniques to analyze the inner surface of skulls. Today, many of their traditional processes have been replaced by technology and the brain structures of fossilized hominins are now being mapped with computed tomography and MRI. The researchers explain in their paper how their research “evaluates the imprint,” which they call an “endocast,” that brains leave on the internal cranial vault. In this new study the scientists analyzed the endocasts of five  Homo erectus  fossils found in Dmanisi, Georgia, in Western Asia, and this is the first time this process has ever been undertaken.

An Ape Aspiring to be Human

In an article in The Scientist Dr. Christoph Zollikofer concluded that the earliest representatives of the genus  Homo – both from Africa and the samples from Dmanisi that are older than 1.7 million years – had brains were much more similar to those of the “ australopithecines,” such as Lucy, “or to modern great apes, in terms of size and organization.”

However, even if you have kind of an ancestral brain, added Dr. Zollikofer, “that doesn’t mean that you are incapable of doing interesting things like venturing out of Africa, caring for elderly people, exploiting meat resources, et cetera.” This is all put into context when we consider all Southeast Asian  H. erectus  remains and Homo specimens younger than 1.5 million years from Africa are between 70,000 to 1.49 million years old, and they all had “more human-like brains,” according to the study.

Top image: New research shows that early human brains were more ape-like than modern. Source: M. Ponce de León and Ch. Zollikofer/University of Zurich

By Ashley Cowie

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