New research shows that although the human brain’s size has changed throughout history, its size fell approximately 3,000 years ago because of social networks.    

American researchers examined 985 fossilized brains from modern humans and found that there was an increase in size between 2.1 million and 1.5 million years ago. But, a decrease was discovered during the Holocene era which was around 12,000 years.

Ancient humans formed social circles during this period where they could share their knowledge or were experts at certain tasks. This made the brain more efficient and decreased in size.

Boston University’s Dr James Traniello, co-author of the study, stated that it was due to increased reliance of collective intelligence. This idea that a group of people are smarter than the one who is the smartest, is sometimes called the “wisdom of crowds”.

Scroll down to see the video 

American researchers analyzed 985 fossilized and modern human brains and observed a size increase 2.1 million years ago and again 1.5 million years ago, but a decrease was identified during the Holocene era

American researchers examined 985 fossilized brains from modern humans and found that there was an increase in size 2.1 million years and 1.5 million years respectively. However, a decrease during the Holocene period revealed that it had decreased.

Despite this recent decrease, the human brain has nearly quadrupled in size over the last 6 million years ‘since Homo last shared a common ancestor with chimpanzees, but human brains are thought to have decreased in volume since the end of the last Ice Age,’ the authors wrote in the study published in Frontiers in Ecology and Evolution.

Researchers used a change point analysis to discover the cause of brain changes. They found that size increases that occurred millions years ago coincided both with the early evolution of Homo sapiens and technological advances.

Dartmouth College’s Dr. Jeremy DeSilva was co-author of this study. He stated in a statement that “A surprising fact about humans today” is that our brains are smaller than those of our Pleistocene ancestors.

Anthropologists have struggled to understand why our brains have shrunk in size.

During this time, ancient humans began to form social circles where knowledge was shared or individuals were specialists at certain tasks, which led to the brain adapting to become more efficient, such as decreasing in size

This is when ancient humans started to form social circles that allowed knowledge to be shared and individuals who were experts at certain tasks to be shared. This enabled the brain to adapt to become more efficient, like shrinking in size.

To unravel this mystery, the team analyzed historical patterns in human brain evolution and compared them with what is known about ant societies to gain broad insights.

Traniello stated that Traniello had met with a biological anthropologist, an evolutionary neurobiologist, and a behavioral economist to discuss brain evolution. Traniello suggested that bridging research between humans and ants could help determine what is possible in natural systems.

Studying computational models and patterns in worker ant brain structure, size, and energy use in various ant clades such as the Oecophylla weaver and Atta leafcutter, or the common garden, ant Formica showed that group-level cognition may allow for adaptive brain size variation.  

The researchers explain that smaller brains use less energy and because ancient humans began sharing knowledge 3,000 years ago, their brains needed less energy to store loads of information - thus resulting in a decrease in size

Researchers explained that smaller brains use less energy. Because ancient humans began sharing their knowledge 3,000 year ago, their brains required less energy to store large amounts of information. This led to a decrease in size

Traniello stated that “Ant and human societies” are very different and have taken different paths in social evolution. 

“But, ants share important aspects of social and cultural life with humans, such as group decision making and the division of labor as well as the production of their food (agriculture). 

“These similarities can help us to understand the factors that could influence changes in brain size.”

Researchers explained that smaller brains use less energy. Because ancient humans started sharing knowledge 3,000 year ago, their brains required less energy for storage of large amounts information. This led to a decrease on the size.

Traniello stated that the decrease in intelligence was due to an increased reliance on collective intelligence. This belief holds that a group of people can be smarter than one person, and is often called the wisdom of the masses’.

Our larger brains mean that humans develop motor skills faster than other primates. 2020 study 

Great apes like these bonobos have big brains like humans and can therefore learn very skilful dexterity

These bonobos are great apes and have brains as big as humans. They can also learn very skilled dexterity.

Biologists from Switzerland reported that humans develop fine motor skills more slowly than other primates, due to having larger brains that take longer for development.  

Although “a big brain equals great agility”, humans need to wait longer before they can use their full dexterity to tie shoes, hold a pen, and use cutlery.   

Researchers at the University of Zurich analyzed more than 30 primate species in seven years.  

While species of great apes – including homo sapiens – have big brains and can therefore learn very skilful dexterity, they take longer to fully develop, they found.

Comparatively, squirrel-like Tamarins reach their full potential in mastering objects faster, but lack the skills of more advanced primates. 

Despite humans taking longer time to reach our peak skill potential, scientists claim to have found a common pattern in all primate species. 

They claim that the complex motor skills required to manipulate food or tools are developed in distinct stages. This is consistent across all primate species. 

‘It is no coincidence that we humans are so good at using our hands and using tools, our large brains made it possible,’ said Dr Sandra Heldstab, an evolutionary biologist in the Department of Anthropology at the University of Zurich, Switzerland.  

‘Our results show that the neural development follows extremely rigid patterns – even in primate species that differ greatly in other respects.’ 

More: Motor skills develop later in humans than in primates