Brain size area in women, corresponding to spatial versus language specializations. Small studies have attempted to link brain volume with functional measures such as P300 auditory evoked potentials but finding no association. Studies attempting to related sibling differences in IQ to differences in brain volume are hampered by relatively small sample sizes and the noisy nature of such difference scores, yielding weak evidence for cross-trait cross-sib correlations. The largest brain is that of the sperm whale, weighing about , and killer whales, weighing about . An elephant's brain weighs just over and a bottlenose dolphin's . Brain size tends to vary according
Mesoplodont whale what effect this has on the population. Longman's beaked whale ("Indopacetus pacificus", also known as the Indo-Pacific beaked whale or the tropical bottlenose whale) was originally assigned to "Mesoplodon", but Joseph Curtis Moore placed it in its own genus, "Indopacetus", a taxonomic assignment which has been followed by all researchers. Two extinct species of "Mesoplodon" are known, "M. posti" and "M. slangkopi". Mesoplodont whale Mesoplodont whales are fifteen species of toothed whale in the genus Mesoplodon, making it the largest genus in the cetacean order. Two species were described as recently as 1991 (pygmy beaked whale) and 2002 (Perrin's beaked