Weight and Size of Brain

Although the weight and size of brain differ from person to person, anthropologists and physicians estimate that the average weight of an adult male is 1,400 grams (1.4 kg), or 49.9 ounces, while the female brain weight is 1,300 grams, or 45 ounces. The average weight of the newborn is 400 grams, or 14.1 ounces, which is doubled at the end of the first and tripled at the end of the fourth year. However, in advanced senescence (old age) and in alcoholics, the cerebrum starts losing considerably weight, due to demyelinization, which means loss of myelin sheath in the cerebral fasciculi (bundles). This is because of a bad or toxic nerve cell respiration (production of ATP).

Body weight and cranial shape also affect the weight of the brain; for example, the cerebrum of people with a brachycephalic cranium weighs more than those with a dolichocephalic one. Finally, the weight of Homo sapiens brain also depends on the diet and lifestyle; eating meat, eggs, and saturated fat and spending time learning, studying and working out favor greatly the healthy development of the myelin sheath and the cerebral bundles.

Size and dimension

The average sagittal (occipitofrontal) diameter of the brain of an adult, male human being ranges from 16 to 17 cm (6.4 to 6.8 inches), while the maximum width in the parietal region averages 14 cm (5.6 inches). The maximum height can reach to 12.5 cm (5 inches). The cerebrum of dolicocephalic people is longer, but individuals with a mesocephalic and brachycephalic crania have wider brain than dolicocephalics, especially in the parietal region.

The average volume of  today's Homo sapiens' brain is 1,425 cm3 (cubic centimeters), with the volume being the space it occupies in a three-dimensional aspect. However, the primitive hunter brain volume averaged bigger than today's, with 1,600 cm3 for Homo sapiens neanderthalensis and 1,500 cm3 for Cro-magnon hunters. It says a lot about the diet and the motor and temporospatial functions stimulation that implied living in a harsh environment and having to fight for survival.