Einstein developed special relativity at age 26 in 1905. Newton invented physics and played role in calculus development. Mozart started composing music at age 5, wrote hundreds until 35
Grey matter contains neuronal cell bodies, neuropil, glial cells, synapses, and capillaries. It appears light grey with yellowish or pinkish hues from blood vessels. Distinguished from white matter by its lack of myelinated axons
Domestic cat brain measures 5 cm long and weighs 25-30 g. Cat brain has surface folding similar to human brains. Contains 203 million cortical neurons and 83 cm2 cerebral cortex. Brain is divided into interconnected hub-and-spoke network
Brain size can be measured by weight, volume via MRI or skull measurements. Human brain weighs about 1.5 kg, with volume around 1260 cm³ in men. Brain size varies between species and within individuals. Brain-to-body mass ratio follows power law with exponent of 0.75
Sex differences result from different chromosome complements and hormone exposure. Females have XX chromosomes, males have XY chromosomes. X-chromosome inactivation enables equal gene expression in females
Cerebellum divided into vermal, paravermal, lateral zones and flocculonodular lobe. Vermal zone maintains balance through muscle tone regulation. Paravermal zone controls skilled movements via interposed nuclei. Lateral zones regulate whole body motor activity. Flocculonodular lobe coordinates balance and eye movements