Neanderthals, once thought to have smaller brains, actually match the 1,350 cubic centimeters average of modern humans, researchers report. In contrast, chimpanzees average only 400 cubic centimeters, highlighting a vast species gap.

The study compares brain volumes across primates, noting that total brain size best predicts cognitive abilities when comparing species. Within a species, smaller variations hold little behavioral significance.

Early hominins like Australopithecus afarensis had 500 cubic centimeters, suggesting a cognitive profile closer to chimpanzees. Today’s Neanderthals, however, align cognitively with contemporary Homo sapiens.

These findings clarify the evolutionary trajectory of brain development and underscore that human intelligence is more a function of overall brain size than fine‑grained interspecies differences.