A recent study conducted by researchers at the University of Reading and the University of Durham has revealed that the increase in relative brain size, known as encephalization, during the seven million years of human evolution was a result of incremental changes within individual species.
Modern humans, Neanderthals, and other recent relatives on the human family tree evolved large brains much more rapidly than earlier species. Image credit: SINC / Jose Antonio Peñas.
“One of the most striking evolutionary changes in human evolution, closely linked to the unique cognitive and behavioral characteristics of humans, is the increase in brain size,” explained lead author Thomas Puschel and his colleagues.
“The question of encephalization in human evolution has been a topic of debate, with various studies comparing the brain capacities of different hominin species and exploring adaptive mechanisms that might have influenced differences in brain size among hominins. Our research proposes
“Some argue for a gradual growth pattern over time, while others suggest a pattern of rapid increases followed by periods of stagnation.”
“Certain studies support a combination of both models, while others claim that they are indistinguishable.”
In their recent study, the authors compiled the largest dataset of ancient human fossils spanning seven million years and utilized advanced computational and statistical methods to identify gaps in the fossil record.
These innovative approaches have provided the most comprehensive understanding to date of the evolution of brain size over time.
“This study has completely altered our perception of how the human brain evolved,” noted study co-author Professor Chris Venditti.
“Previously, it was believed that brain size varied significantly between species, like upgrading to newer computer models.”
“However, our study reveals a pattern of steady, incremental ‘software updates’ occurring within each species over millions of years.”
This study challenges the traditional notion that certain species, such as Neanderthals, remained unchanged and were unable to adapt, suggesting instead that the increase in brain size was a gradual and continuous driving force in evolution. It underscores the significance of changes.
“Major evolutionary shifts do not always require dramatic events,” Pushel stated.
“They can result from making small incremental improvements over time, akin to the learning and adaptation processes observed today.”
The researchers also identified a notable pattern: larger-bodied species tend to have larger brains, but the variation observed within individual species does not consistently correlate with body size.
Hence, the evolution of brain size over long evolutionary timescales spanning millions of years has been influenced by factors distinct from those observed within individual species, underscoring the complexities of evolutionary pressures on brain size. It’s remarkable.
“The reasons behind the evolution of large brains in humans are a key aspect of human evolution,” added study co-author Dr. Joanna Baker.
“Through analyzing the brain and body sizes of various species over millions of years, we have demonstrated that the characteristic large brains of humans primarily emerged through gradual changes within individual species. This became evident.”of study On November 26, 2024, Proceedings of the National Academy of Sciences.
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Thomas A. Puschel others. 2024. The increase in human brain size was revealed by intraspecific encephalization. PNAS 121 (49): e2409542121;doi: 10.1073/pnas.2409542121
Source: www.sci.news
