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Impli­ca­tions of a more com­plex brain

The devel­op­ment of the brain enabled hominids to make and use tools and fire, com­mu­ni­cate using lan­guage, devel­op cul­ture and soci­ety, adapt to new envi­ron­ments and, final­ly, to become self-aware and creative.

This dra­mat­ic expan­sion in the size of the human brain had an imme­di­ate effect on the lifestyle and social struc­ture of hominids. A com­bi­na­tion of a grow­ing brain case rel­a­tive to a nar­row pelvic out­let meant that moth­ers had to give birth to chil­dren ear­li­er, and that new­born babies were thus rel­a­tive­ly immature.

This meant that infants depend­ed on parental care for increas­ing­ly pro­longed peri­ods. Due to its vul­ner­a­bil­i­ty dur­ing infan­cy, a young hominid would have had a far greater chance of sur­vival if its moth­er and father remained in a monog­a­mous rela­tion­ship – a trait that was advanced through nat­ur­al selection.

What large brains mean to us today

Our large brains have saved us from extinc­tion. We have learned to shape our world to a large extent to suit our­selves and to adapt with inge­nu­ity to sit­u­a­tions beyond our control.

The evo­lu­tion of the brain has enabled us to devel­op com­plex com­put­er tech­nol­o­gy that can per­form bil­lions of cal­cu­la­tions a sec­ond, build vehi­cles that can car­ry us all over the world and even beyond it, broad­cast mes­sages to mil­lions of peo­ple simul­ta­ne­ous­ly, devel­op med­i­cines and health care that can pro­long lives, and devel­op cul­ture that enrich­es our lives dai­ly. But our mod­ern brains have also helped us to invent weapons of mass destruction …

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An inter­ac­tive dis­play at Maropeng helps you under­stand the brain

Get­ting ahead

Changes in the size and organ­i­sa­tion of the brain are thought to be impor­tant mark­ers for the devel­op­ment of human-like” behav­iour. Most sci­en­tists believe that as our ear­ly hominid ances­tors’ brains grew, so did their abil­i­ty to make and use tools, devel­op lan­guage and think symbolically.

Homo ergaster

Brain capac­i­ty: 900 cc

Aus­tralo­p­ithe­cus

Brain capac­i­ty: 450 cc

Homo habilis

Brain capac­i­ty: 600 cc

Homo nean­derthalen­sis

Brain capac­i­ty: 1500 cc

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Big brain, small beginnings

Hominid brains are rel­a­tive­ly large among the ani­mal king­dom, espe­cial­ly when com­pared to body size.

A bot­tlenose dol­phin has a sim­i­lar-sized brain to a human’s, but its body weight is more than twice as heavy as ours. A cow has a brain weight three times as small as ours and a body weight sev­en times as heavy.

But before you think our species is unique, con­sid­er the mouse: it has a brain about a third larg­er than a human’s in ratio to its body size.

Aus­tralo­p­ithe­cus, con­sid­ered a link between ape and human and appear­ing more than 4-mil­lion years ago, had an aver­age cra­nial capac­i­ty of about 450 cc to 500 cc – about the size of an orange.

The ear­li­est species of Homo named so far, Homo habilis, which appeared about 2.3-million years ago, had an aver­age cra­nial capac­i­ty of about 600 cc.

Homo ergaster, which lived from about 1.7-million to 1.4-million years ago, had a cra­nial capac­i­ty rang­ing from 800 cc to 1200 cc, with an aver­age of about 900 cc.

The species Homo sapi­ens, to which mod­ern humans belong, has an aver­age brain size of about 1400 cc.

Our brains are almost dou­ble the size of ear­ly Homo habilis and almost three times the size of ear­ly australopithecines.

Over time, some parts of our ances­tors’ brains changed rel­a­tive­ly lit­tle, while oth­ers changed so much that they became bare­ly recog­nis­able. Hominid brains show an expan­sion in the cere­bel­lum and neo­cor­tex, areas which are asso­ci­at­ed with learn­ing, con­scious thought and reasoning.

Increas­es in brain size do not nec­es­sar­i­ly cor­re­late with greater intelligence.

Nean­derthals had a brain big­ger than mod­ern humans with an aver­age of about 1500 cc, but lacked the com­plex belief sys­tems and sym­bol­ic think­ing unique to us.

Return to the Exhi­bi­tion Guide.