referred to as communal or cooperative breeding,would benefit benefit survival if they were not born into such a handy and from an energy-fueled brain,including its role in the development intelligent species. of language(14).It is too easy to emphasize a baby's deficient Given the large literature dedicated to the territory covered motor skills,and thus to forget how intelligent and unlike other here,Piantadosi and Kidd's powerful scenario(1)is probably too primates they are from the very earliest moments of life.Al- simple to depict the complex evolutionary processes that brought though they are relatively small,neonatal human brains are the us big brains,intelligence,and costly babies.Regardless,their absolute largest for primates,as previously stated.So,if brain research underscores the importance of child-rearing in the size is linked to intelligence in adults,why not in babies? evolution of humankind,an importance that is often overlooked. Through gaze,facial expressions,gestures,and more,human Likewise,the work that goes into raising children is woefully infants and young children manipulate parents and other care- undervalued both socially and economically in the United States givers into investing so carefully and intensely (2).Perhaps It is unlikely that an evolutionary appreciation for childcare will hominin babies have cleverly manipulated their intelligent care- lead to massive culture and societal change,but such change givers into relaxing selection on many of the traits that would may arise by a slow and gradual process. 1 Piantadosi ST,Kidd C(2016)Extraordinary intelligence and the care of infants.Proc Natl Acad Sci USA 113:6874-6879. 2 Hrdy S(2009)Mothers and Others (Harvard Univ Press,Cambridge,MA) 3 Trevathan W,Rosenberg K,eds(2016)Costly and Cute:Helpless Infants and Human Evolution(School for Advanced Research Press,Santa Fe,NM). 4 Bogin B,Bragg J,Kuzawa C(2016)Childhood,biocultural reproduction,and human lifetime reproductive effort.Childhood:Origins,Evolution and Implications, eds Meehan CL,Crittenden AN (School for Advanced Research Press,Santa Fe,NM). 5Dunsworth HM,Warener AG,Deacon T,Ellison PT,Pontzer H(2012)Metabolic hypothesis for human altriciality.Proc Natl Acad Sci USA 109(38):15212-15216. 6 DeSilva JM(2011)A shift toward birthing relatively large infants early in human evolution.Proc Natl Acad Sci USA 108(3):1022-1027. 7 Pontzer H,et al.(2016)Metabolic acceleration and the evolution of human brain size and life history.Nature 533:390-392 8 Leigh SR(2004)Brain growth,life history,and cognition in primate and human evolution.Am J Primatol 62(3):139-164. 9Kennedy GE(2005)From the ape's dilemma to the weanling's dilemma:Early weaning and its evolutionary context.JHum Evol 48(2):123-145. 10 Humphrey LT (2010)Weaning behaviour in human evolution.Semin Cell Dev Biol 21(4):453-461. 11 Zink KD,Lieberman DE (2016)Impact of meat and Lower Palaeolithic food processing techniques on chewing in humans.Nature 531(7595):500-503. 12 Ferraro JV,et al.(2013)Earliest archaeological evidence of persistent hominin carnivory.PLoS One 8(4):e62174. 13 Groopman EE,Carmody RN.Wrangham RW(2015)Cooking increases net energy gain from a lipid-rich food.Am JPhys Anthropol 156(1):11-18. 14 Falk D(2016)Evolution of brain and culture:The neurological and cognitive joumey from Australopithecus to Albert Einstein.J Anthropol Sci 94:1-14. 6818 I www.pnas.org/cgi/doi/10.1073/pnas.1606596113 Dunsworthreferred to as communal or cooperative breeding, would benefit from an energy-fueled brain, including its role in the development of language (14). It is too easy to emphasize a baby’s deficient motor skills, and thus to forget how intelligent and unlike other primates they are from the very earliest moments of life. Al￾though they are relatively small, neonatal human brains are the absolute largest for primates, as previously stated. So, if brain size is linked to intelligence in adults, why not in babies? Through gaze, facial expressions, gestures, and more, human infants and young children manipulate parents and other care￾givers into investing so carefully and intensely (2). Perhaps hominin babies have cleverly manipulated their intelligent care￾givers into relaxing selection on many of the traits that would benefit survival if they were not born into such a handy and intelligent species. Given the large literature dedicated to the territory covered here, Piantadosi and Kidd’s powerful scenario (1) is probably too simple to depict the complex evolutionary processes that brought us big brains, intelligence, and costly babies. Regardless, their research underscores the importance of child-rearing in the evolution of humankind, an importance that is often overlooked. Likewise, the work that goes into raising children is woefully undervalued both socially and economically in the United States. It is unlikely that an evolutionary appreciation for childcare will lead to massive culture and societal change, but such change may arise by a slow and gradual process. 1 Piantadosi ST, Kidd C (2016) Extraordinary intelligence and the care of infants. Proc Natl Acad Sci USA 113:6874–6879. 2 Hrdy S (2009) Mothers and Others (Harvard Univ Press, Cambridge, MA). 3 Trevathan W, Rosenberg K, eds (2016) Costly and Cute: Helpless Infants and Human Evolution (School for Advanced Research Press, Santa Fe, NM). 4 Bogin B, Bragg J, Kuzawa C (2016) Childhood, biocultural reproduction, and human lifetime reproductive effort. Childhood: Origins, Evolution and Implications, eds Meehan CL, Crittenden AN (School for Advanced Research Press, Santa Fe, NM). 5 Dunsworth HM, Warrener AG, Deacon T, Ellison PT, Pontzer H (2012) Metabolic hypothesis for human altriciality. Proc Natl Acad Sci USA 109(38):15212–15216. 6 DeSilva JM (2011) A shift toward birthing relatively large infants early in human evolution. Proc Natl Acad Sci USA 108(3):1022–1027. 7 Pontzer H, et al. (2016) Metabolic acceleration and the evolution of human brain size and life history. Nature 533:390–392. 8 Leigh SR (2004) Brain growth, life history, and cognition in primate and human evolution. Am J Primatol 62(3):139–164. 9 Kennedy GE (2005) From the ape’s dilemma to the weanling’s dilemma: Early weaning and its evolutionary context. J Hum Evol 48(2):123–145. 10 Humphrey LT (2010) Weaning behaviour in human evolution. Semin Cell Dev Biol 21(4):453–461. 11 Zink KD, Lieberman DE (2016) Impact of meat and Lower Palaeolithic food processing techniques on chewing in humans. Nature 531(7595):500–503. 12 Ferraro JV, et al. (2013) Earliest archaeological evidence of persistent hominin carnivory. PLoS One 8(4):e62174. 13 Groopman EE, Carmody RN, Wrangham RW (2015) Cooking increases net energy gain from a lipid-rich food. Am J Phys Anthropol 156(1):11–18. 14 Falk D (2016) Evolution of brain and culture: The neurological and cognitive journey from Australopithecus to Albert Einstein. J Anthropol Sci 94:1–14. 6818 | www.pnas.org/cgi/doi/10.1073/pnas.1606596113 Dunsworth