INDONESIAN EYE, LONDON – The human brain weighs about 1.4 kilograms. The most complex organ in the human body consists of billions of cells called neurons. In connection with evolution, it turns out that the size of the brain decreased about 3,000 years ago.
According to SciTechDailyexperts study ants as a model to illustrate why brain size may increase or decrease.
The researchers have a hypothesis. That brain shrinkage is in line with the expansion of collective intelligence in social life. Studying and understanding the causes and consequences of brain evolution helps us to understand human nature.
The size of the human brain has indeed increased over the course of evolutionary history. However, its size has also decreased since the Pleistocene epoch. When and why this change occurred is never known with certainty.
“The surprising fact about humans today is that our brains are smaller than the brains of our Pleistocene ancestors. Why our brains shrink is a big mystery to anthropologists,” said Dr. Jeremy DeSilva of Dartmouth College to SciTechDaily.
A team of researchers from various academic fields came together to study patterns in the evolutionary history of the human brain. This study has been published in the journal Frontiers in Ecology and Evolution by title When and Why Did Human Brains Decrease in Size? A New Change-Point Analysis and Insights From Brain Evolution in Ants pada 22 Oktober 2021.
In this study the researchers applied analysis to a dataset of 985 ancient and modern human skull fossils. They found that the size of the human brain increased by 2.1 million years. And 1.5 million years ago or during the Pleistocene. However, the size of the human brain shrank about 3,000 years ago (Holocene). “Most people realize that humans have extraordinarily large brains. Much bigger than expected considering our body size. In our deep evolutionary history, the size of the human brain has increased dramatically. The reduction in the size of the human brain 3,000 years ago was unexpected,” said Dr. James Traniello, one of the experts on the study from Boston University.
The timing of the increase in brain size coincides with what was previously said about early human evolution.
This leads to better diet and nutrition. As well as larger social groups. While regarding the shrinkage of brain size, the research team proposed a new hypothesis. And they found clues from the social life of the ants.
Launching from Daily Mail, scientists studied computational models and brain size patterns of worker ants. Structure and energy use in some groups of ants. For example weaver ants, leaf cutter ants or ordinary garden ants. They demonstrated that cognition and division of labor can be selected for variations in adaptive brain size.
“The social lives of ants and humans are very different and have followed different paths in social evolution,” said Dr James Traniello.
Even so, ants also have similarities with humans in aspects of social life. Such as decision making in groups, division of labor, and food production (agriculture). These broad similarities can tell us about the factors that can influence changes in human brain size.
The researchers explain that a smaller brain uses less energy. And because early humans began sharing knowledge 3,000 years ago, their brains required less energy to store a lot of information, resulting in shrinking in size.
Reporter : Alyaa
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