Neanderthal vs. Human Brain: Unraveling the Differences
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Chapter 1: The Neuron Count Discrepancy
Research indicates that Homo sapiens have a higher number of neurons in the frontal cortex compared to Neanderthals. This difference stems from a single amino acid alteration in a protein that is activated during prenatal brain development.
[Artist: John GurchePhotographer: Chip Clark, CC0, via Wikimedia Commons] Is it a given that modern humans possess the largest brains in the genus Homo? While contemporary Homo sapiens average a brain volume of 1,350 cc, this is not the largest recorded within the genus.
Neanderthals may have had larger brains historically. In 1978, early Neanderthal remains were unearthed in Germany, including fragments of a skull estimated to be 200,000 years old. Researchers utilized a silicon mold of the skull to gauge its volume, submerging it in water to observe displacement. According to Dimitra Papagiani and Michael A. Moore in their work Neanderthal Rediscovered, various tests eventually determined an average capacity of 1,430 milliliters, marking it as the largest brain from that era discovered globally. Subsequent Neanderthal specimens likely had even larger brains, potentially reaching capacities of up to 1,700 cc.
Neanderthal skull — [Photo: AquilaGib, CC BY-SA 3.0, via Wikimedia Commons]
Section 1.1: Importance Beyond Size
When evaluating cognitive potential, brain volume is just one factor; the structure of the brain and the number of neurons, especially in the more recently evolved areas like the frontal cortex, are crucial. Notably, there are marked differences in neuron counts between modern humans and Neanderthals. A study published in the esteemed journal Science utilized "minimal brains"—lab-grown organoids that allow for early-stage organ development analysis.
Subsection 1.1.1: The Role of Amino Acids
The focus of the research was on the TKTL 1 (transketolase-like 1) protein, which is particularly active in the frontal cortex during fetal development. This protein is found in precursor cells that eventually develop into neurons. Remarkably, the TKTL 1 protein differs structurally between humans and Neanderthals. In Homo sapiens, arginine is present, while Neanderthals have lysine in its place. This seemingly minor distinction has significant implications for each species.
Homo neanderthalensis skeleton — [Photo: Archaeomoonwalker, CC0, via Wikimedia Commons]
Section 1.2: Experimental Insights
Scientists initially conducted experiments using mouse embryos. By injecting a human version of the TKTL 1 protein into some of the mice, they observed that those with the human variant developed a greater number of precursor cells and, consequently, a higher neuron count.
In subsequent experiments, researchers utilized organoids—miniature lab-grown brains of Homo sapiens. They modified the human TKTL 1 protein by substituting arginine with lysine. The results indicated that those with the "Neanderthal" protein variant produced fewer precursor cells, leading to a decrease in neuron production.
Anneline Pinson, the lead researcher, stated, “While we cannot determine the exact neuron count in Neanderthal brains, it is reasonable to infer that modern humans possess a greater number in the frontal cortex, where the TKTL 1 protein is most active.” Wieland Huttner, a neurologist and biochemist associated with the study, added, “This difference may have played a crucial role in the evolution of cognitive abilities linked to the frontal cortex.”
Chapter 2: Insights from Webb's Telescope
Thanks to the capabilities of Webb’s telescope, the first-ever photograph of an exoplanet has been captured, showcasing the incredible advancements in astronomical research.
The first video illustrates the distinctions between human and Neanderthal brains, diving into the implications of their structural differences.
The second video discusses how Neanderthal brains developed differently, providing insights into the evolutionary pathways of both species.
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