Table 1.

List of individuals, axon diameter (median and the largest diameter axons) and estimated cross-brain conduction times of fibres of the corpus callosum. (Data are for the average of all corpus callosum regions sampled. All brains were removed and immersion fixed in 10% buffered formalin after variable postmortem intervals, which never exceeded 15 h.)

				axon diameter (µm)		estimated cross-brain conduction time (ms)
species	sex	age (years)	brain mass (g)	median	95th percentile	median	95th percentile
Homo sapiens	F	45	1250	0.62	2.88	37.52	8.13
Homo sapiens	M	54	1625	0.93	3.43	27.56	7.47
Gorilla gorilla	M	49	477	0.68	2.26	24.91	7.55
Pan paniscus	M	34	313	0.48	1.72	30.82	8.56
Pan troglodytes	M	31	407	0.59	1.96	27.35	8.23
Pongo pygmaeus	M	33	287	0.60	2.06	23.88	6.95
Symphalangus syndactylus	F	17	107	0.53	1.80	19.47	5.72
Cercocebus agilis	F	19	95	0.43	1.41	22.86	7.06
Colobus guereza	F	15	84	0.52	2.16	18.45	4.42
Macaca nemestrina	F	7	86	0.44	1.38	21.70	6.96
Papio hamadryas	F	31	140	0.53	1.78	21.36	6.34
Alouatta caraya	M	21	56	0.62	1.80	13.38	4.61
Pithecia pithecia	F	1	30	0.52	1.92	12.96	3.53
Saguinus geoffroyi	M	15	11	0.43	1.74	11.18	2.74
Saimiri sciureus	F	27	19	0.43	1.20	13.63	4.86