Human evolution brain capacity

Endocasts of Homo erectus, (left) and Homo sapiens (right)Bigger Brains: Complex Brains for a Complex World

Endocasts of Homo erectus (left) and Homo sapiens (right) illustrate rapid increase in brain size. As early humans faced new environmental challenges and evolved bigger bodies, they evolved larger and more complex brains.

Large, complex brains can process and store a lot of information. That was a big advantage to early humans in their social interactions and encounters with unfamiliar habitats.

Over the course of human evolution, brain size tripled. The modern human brain is the largest and most complex of any living primate.

Brain size increases slowly

Graphs showing changes in climate and changes in braincase volume.From 6–2 million years ago

During this time period, early humans began to walk upright and make simple tools. Brain size increased, but only slightly.

Brain and body size increase

From 2 million–800, 000 years ago

During this time period early humans spread around the globe, encountering many new environments on different continents. These challenges, along with an increase in body size, led to an increase in brain size.

Brain size increases rapidly

From 800, 000–200, 000 years ago

Human brain size evolved most rapidly during a time of dramatic climate change. Larger, more complex brains enabled early humans of this time period to interact with each other and with their surroundings in new and different ways. As the environment became more unpredictable, bigger brains helped our ancestors survive.

chart of Chimpanzee brain growth rapidly before birth.Why the sudden increase in brain size?

Graphs showing changes in climate and changes in braincase volume. Courtesty of Karen Carr Studios The top graph shows how Earth’s climate has fluctuated over the past 3 million years. Notice how much the fluctuations increased between 800, 000 and 200, 000 years ago. To construct this graph, scientists studied fossils of tiny organisms found in ocean sediment cores.

The bottom graph shows how brain size increased over the past 3 million years—especially between 800, 000 and 200, 000 years ago. A large brain capable of processing new information was a big advantage during times of dramatic climate change. To construct this graph, scientists measured the brain cavities of more than 160 early human skulls.

Evidence of ancient brains

Endocasts are replicas of the insides of early and modern human braincases. They represent the size and shape of the brains that once occupied the braincases.

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Q&A

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What is the capacity of the human brain in gigabytes?

The capacity of the human brain cannot be defined in binary computer units, as the brain does not use binary addressing. As knowledge, feelings, and memories do not have a standard format, it would be impossible to determine how much space it would take to place this data in binary form.

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What is the capacity of a human brain

The memory capacity of the brain was between 1 and10 terabytes, with a likely value of 3 terabytes.The human brain contains about 50 billion to 200 billion neurons.

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