International Encyclopedia of Biological Anthropology, 2018

2011

http://brain.oxfordjournals.org/ Downloaded from and the return to the original one for additional detailed observations will certainly be compulsory'.

PubMed, 2019

This article is the second of two that addresses the development of the human brain. Last month's article, "The Evolution of Human Capabilities and Abilities," focused on neurons, the basic information-processing units of the nervous system. This month's article examines the evolution of the neocortex, a part of the cerebral cortex concerned with sight and hearing in mammals, regarded as the most developed part of the cortex.

WordPress, 2022

Our modern civilisation may be the most advanced to ever exist on Earth, but around 100 generations ago, our ancestors had brains that were larger than our own. Human ancestors had bigger brains than we have. Several thousand years ago, humans reached a milestone in their history – the first known complex civilisations began to emerge. The people walking around and meeting in the world's earliest cities would have been familiar in many ways to modern urbanites today. But since then, human brains have actually shrunk slightly. The lost volume, on average, would be roughly equivalent to that of four ping pong balls, says Jeremy DeSilva, an anthropologist at Dartmouth College in the US. And according to an analysis of cranial fossils, which he and colleagues published last year, the shrinkage started just 3,000 years ago. "This is much more recent than we anticipated," says DeSilva. "We were expecting something closer to 30,000 years ago." Agriculture emerged between 10,000 and 5,000 years ago, although there is some evidence that plant cultivation may have started as early as 23,000 years ago. Sprawling civilisations, full of architecture and machinery, soon followed. The first writing appeared at roughly the same time. Why, during this age of extraordinary technological development, did human brains start to dwindle in size?

The Journal of Pediatrics, 2014

Objectives To examine brain volumes and cortical surface area and thickness and to relate these brain measures to cognitive function in young adults born small for gestational age (SGA) at term compared with non-SGA control patients.

Intelligence, 1991

It is widely believed that human brain size and intelligence are only weakly related to each other. Using magnetic resonance imaging, we show that larger brain size (corrected for body size) is associated with higher IQ in 40 college students equally divided by high versus average IQ, and by sex. These results suggest that differences in human brain size are relevant to explaining differences in intelligence test performance. Studies have shown positive but modest relations between external head size and psychometric intelligence (e.g., Van Valen, 1974, for a review of earlier research; Susanne, 1979). An assumption in much of that work was that head and brain size were fungible, and if head size were not powerfully predictive of intelligence, brain size would not do much better (Gould, 1981). Large betweenperson variation in average skull thickness compromises extrapolations of external cranial measurements to predict cranial capacity, however (Rogers, 1984). The evolution of brain size, sex differences, and intelligence have been classic questions (Jerison, 1973). Postmortem evidence brought to bear in the 19th and early 20th centuries was deficient in sampling and methodology: Sex, age, body size, brain-fixation procedures, weighing before or after fixation, inclusion or exclusion of meninges, and cause of death were often inadequately controlled. Elderly personages with small brains were said to illustrate the irrelevance of brain size in high achievement, and large-brained personages were thought to

Neurosurgery, 2003

"IS IT SUFFICIENT GLORY to don a white apron and swing a carbolized knife and is therein a sufficient indication to let daylight into a deformed cranium and on top of a hopelessly defective brain, and to proclaim success because the victim consented not to die of the assault? Such rash feats of indiscriminate surgery, if continued, moreover in the presence of fourteen deaths in thirty-three cases, are stains on your hands and sins on your souls. No ocean of soap and water will cleanse those hands, no power of corrosive sublimate will disinfect the souls." These passionate words, delivered by Abraham Jacobi, the father of American pediatrics, at the International Congress in Rome in 1893, and later in the article "Non nocere" (42), epitomize the growing antagonism to the attempts by many prominent surgeons to improve the gloomy fate of severely retarded, microcephalic children by "liberating" their brains from their presumed bony chains by "linear craniotomy." This article portrays how the fallacious 19th-century concepts of the relationship between the capacity of the cranial cavity and intelligence, backed by "scientific racism" together with the changing attitude toward retarded and malformed children, generated a surgical solution for microcephalic idiocy. It describes how hopeful surgeons, neurologists, and pediatricians, encouraged by the advances in anesthesia and asepsis, lost their judgment and disregarded logic and evidence. They generated a wave of enthusiasm and hope that soared from the United States and France through the British Isles, Europe, and as far as Ceylon and Australia to end in a ripple of bitter disgrace under caustic criticism, leaving a scar on the recently budding field of neurological surgery.

David S. Webster (1999) How Does Brain Size Matter?. Psycoloquy: 10(030) Brain Expertise (5) Volume: 10 (next, prev) Issue: 030 (next, prev) Article: 5 (next prev first) Alternate versions: ASCII Summary Topic: Brain expertise View Topic Article: 5) Webster 10(030) How Does Brain Size Matter?

Biology Letters, 2005

Many studies assume that an increase in brain size is beneficial. However, the costs of producing and maintaining a brain are high, and we argue that brain size should be secondarily reduced by natural selection whenever the costs outweigh the benefits. Our results confirm this by showing that brain size is subject to bidirectional selection. Relative to the ancestral state, brain size in bats has been reduced in fast flyers, while it has increased in manoeuvrable flyers adapted to flight in complex habitats. This study emphasizes that brain reduction and enlargement are equally important, and they should both be considered when investigating brain size evolution.

Neuropsychologia, 2004

This multifactorial study investigates the interrelationships between head circumference (HC) and intellectual quotient (IQ), learning, nutritional status and brain development in Chilean school-age children graduating from high school, of both sexes and with high and low IQ and socioeconomic strata (SES). The sample consisted of 96 right-handed healthy students (mean age 18.0 ± 0.9 years) born at term. HC was measured both in the children and their parents and was expressed as Z-score (Z-HC). In children, IQ was determined by means of the Wechsler Intelligence Scale for Adults-Revised (WAIS-R), scholastic achievement (SA) through the standard Spanish language and mathematics tests and the academic aptitude test (AAT) score, nutritional status was assessed through anthropometric indicators, brain development was determined by magnetic resonance imaging (MRI) and SES applying the Graffar modified method. Results showed that microcephalic children (Z-HC ≤ 2 S.D.) had significantly lower values mainly for brain volume (BV), parental Z-HC, IQ, SA, AAT, birth length (BL) and a significantly higher incidence of undernutrition in the first year of life compared with their macrocephalic peers (Z-HC > 2 S.D.). Multiple regression analysis revealed that BV, parental Z-HC and BL were the independent variables with the greatest explanatory power for child's Z-HC variance (r 2 = 0.727). These findings confirm the hypothesis formulated in this study: (1) independently of age, sex and SES, brain parameters, parental HC and prenatal nutritional indicators are the most important independent variables that determine HC and (2) microcephalic children present multiple disorders not only related to BV but also to IQ, SA and nutritional background.