Just How Big Is the Human Brain in Size

Just How Big Is the Human Brain in Size Theories Biological Psychology Print The Size of the Human Brain The size of the brain may not always indicate a measure of intelligence By Kendra Cherry facebook twitter Kendra Cherry, MS, is an author, educational consultant, and speaker focused on helping students learn about psychology. Learn about our editorial policy Kendra Cherry Updated on October 06, 2019 Matt Cardy / Getty Images More in Theories Biological Psychology Behavioral Psychology Cognitive Psychology Developmental Psychology Personality Psychology Social Psychology Psychosocial Psychology The human brain is an amazing organ, capable of surprising feats of memory, susceptible to damage, and yet remarkably adaptable to change. It does so much but what is the actual size of the brain? While the human brain has a structure similar to that of other mammals, what makes it so very different is its size in relation to body size. Compared to the size of our bodies, human beings have much larger brains than many other mammals. The Size of the Human Brain In terms of weight, the average adult human brain weighs in at 1300 to 1400 grams or around 3 pounds.In terms of length, the average brain is around 15 centimeters long.For comparison, a newborn human babys brain weighs approximately 350 to 400 grams or three-quarters of a pound.Men tend to have bigger brains than women. After taking overall body weight into account, mens brains tend to be approximately 100 grams larger than womens.In women, parts of the frontal lobe and limbic cortex (areas associated with problem-solving and emotional regulation, tend to be bigger than those of men.In men, the parietal cortex (associated with the perception of space) and amygdala (linked to social and sexual behavior) tend to be larger than those in women.Neurons are the structures that serve as building blocks of the brain and nervous system. They transmit and carry information, allowing different parts of the brain to communicate with one another as well as allowing the brain to communicate with various parts of the body. Researchers estimate that there are around 100 billion neurons in the human brain. Does Brain Size Matter? Obviously, not all people have the same size brain. Some are larger, and some are smaller. You might find yourself wondering if brain size might be linked to characteristics such as disability or intelligence. Researchers have found that in some cases brain size can be linked to certain diseases or developmental conditions. For example, autistic children tend to have bigger brains (and earlier disproportionate brain growth) than non-autistic children. The hippocampus tends to be smaller in elderly adults suffering from Alzheimers disease. This area of the brain is strongly associated with memory. What about intelligence? The answer to that question depends largely upon who you ask. According to one  analysis of many studies that looked at this issue by Michael McDaniel of Virginia Commonwealth University, bigger brains were correlated with higher intelligence. Not all researchers necessarily agree with McDaniels conclusions. Such studies also raise important questions about how we define and measure intelligence, whether we should account for relative body size when making such correlations, and what parts of the brain we should be looking at when making such determinations. It is also important to note that when looking at individual differences among people, brain size variations are relatively small. Other factors that may influence or play a pivotal role include the density of neurons in the brain, social and cultural factors, and other structural differences inside the brain. Genetic and Environmental Factors Influence Intelligence