Does intelligence depend only on brain size?

Human intelligence is one of the greatest mysteries of science, and a recurring question is whether brain size has a direct relationship with intellectual capacity. For a long time, brain size was considered a key factor in determining the level of intelligence of a living being; However, recent studies reveal that intelligence depends on multiple factors, and that brain size is just one piece in a much more complex puzzle.

Brain Size and Intelligence: An Ancient Myth

Since the 19th century, brain size has been the subject of scientific speculation. It was believed that a larger brain implied greater intelligence, an idea that influenced the perception of human intelligence compared to other species. Although there is a general correlation between brain size and the complexity of certain behaviors, modern science has shown that this relationship is not so direct or conclusive.

For example, animals such as elephants and whales have much larger brains than humans, but they do not have the same level of intellectual development or advanced cognitive abilities. This leads to the fundamental question: what makes the human brain so special?

What Really Influences Intelligence?

Intelligence is a multifactorial phenomenon. Brain structure and organization, neuronal density, connectivity between regions, and neurotransmitters play a key role in cognitive function and the ability to process information in complex ways.

1. Neuronal Density and Connectivity: One of the most important factors is the density of neurons and the quality of the connections between them. The human brain has approximately 86 billion neuronsbut the most surprising thing is the network of synaptic connections, which allows rapid and efficient communication between different areas of the brain.

2. Brain Plasticity: The brain’s ability to adapt and reorganize is essential for learning and the development of intelligence. Brain plasticity allows the brain to create new synaptic connections and reorganize existing ones, which facilitates learning and problem solving.

3. Prefrontal Cortex: In humans, the prefrontal cortex (associated with functions such as decision making, abstract thinking, and planning) is larger and more complex compared to other species. This area of ​​the brain plays a central role in intelligence.

4. Processing Speed ​​and Working Memory: The speed with which the brain processes information and its short-term memory capacity (working memory) are also important determinants. These abilities are linked to neuronal efficiency and the transmission of electrical signals in the brain.

Brain Size and Encephalization Coefficient: Relative Factors

To better understand the relationship between brain size and intelligence, scientists use a metric called encephalization coefficient (EC). This coefficient compares brain size to the body size of a species. A higher EQ suggests that the brain is large relative to the body, which, in some cases, is associated with greater cognitive abilities.

Humans have a higher encephalization coefficient than any other species. However, some primates, dolphins and other marine mammals also have a high EQ. This suggests that, although relative brain size can provide clues about a species’ cognitive abilities, it is not the only determinant of intelligence.

Intelligence in Different Species: Surprising Examples

There are many examples that show that the intelligence of a species is not necessarily linked to the size of its brain:

1. Dolphins and Whales: Dolphins have large brains compared to their bodies and demonstrate complex skills, such as tool use and advanced communication. Their brains have a specific structure that allows for strong social communication, a key characteristic for intelligence in dolphins.

2. Crows and Parrots: Despite having small brains, some birds, such as crows, have demonstrated a remarkable ability to solve problems, remember events, and use tools. This indicates that intelligence is also influenced by neuronal organization and neuron density in specific regions, such as the pallium, which in birds serves a similar function to the cortex in mammals.

3. Octopuses: Octopuses are invertebrate animals with impressive problem-solving abilities. Despite having small brains compared to mammals, octopuses display remarkable intelligence, as they can open jars, navigate mazes, and exhibit adaptive behaviors.

What Does Science Say About the Human Brain?

The human brain is particularly efficient in terms of energy consumption and the organization of neuronal connections. The large number of neurons in the cerebral cortex and the complex network of connections between them allow an unprecedented capacity for information processing, creativity and introspection.

Furthermore, recent studies have shown that the neural synchronization between different areas of the brain plays a crucial role in intelligence. The speed and precision with which signals are transmitted between different regions allows for efficient cognitive coordination, which is essential for solving complex problems.

What Is the Role of the Environment in Intelligence?

Environment and experience play a fundamental role in the development of intelligence. Learning, cognitive stimulation and access to enriching experiences enhance intellectual capacity. Even in humans, intelligence is not determined solely by biological factors, but also depends on environment, learning and education.