Brain Size and Fat
Aveiro/Coimbra - The plumpness of the human newborn has long been recognized as a trait in need of explanation among researchers. Using a linear regression analysis, scientists from the Universities of Coimbra and Aveiro in Portugal found that head circumference is significantly and positively associated with BMI (body mass index) at birth. After gestational age and birthlength were controlled for, in a sample of 1,069 healthy liveborn routinely delivered at the University Hospital of Coimbra (Am. J. Hum. Biol. 16:24-30, 2004).
This significant association is consistent with the idea that newborn fatness is related to the higher need of lipids in newborn humans as an energetic and plastic substrate during its accelerated brain growth period. As birth weight and birth head size are associated with head size and cognitive abilities in childhood and adult life, it could be postulated that these cognitive abilities could have acted as selective pressure responsible for the newborn fatness increase in the human lineage.