Brain size growth in Australopithecus. Issue 130 (May 2019)
- Record Type:
- Journal Article
- Title:
- Brain size growth in Australopithecus. Issue 130 (May 2019)
- Main Title:
- Brain size growth in Australopithecus
- Authors:
- Cofran, Zachary
- Abstract:
- Abstract: Postnatal growth is one of the proximate means by which humans attain massive adult brain size. Humans are characterized by the maintenance of prenatal brain growth rates into the first postnatal year, as well as an overall extended period of growth. The evolution of this pattern is difficult to assess due to its relatively brief duration and the underrepresentation of well-preserved fossil individuals who died during this short period. In this study, I use Monte Carlo methods to reconstruct postnatal brain growth rates in Australopithecus afarensis and Australopithecus africanus, based on estimates of neonatal brain size and of likely brain size and age at death of infant specimens (A.L. 333-105, DIK-1-1, and Taung). Neonatal brain size is reconstructed from the empirical scaling relationship among catarrhines which humans follow, and conservative estimates of fossils' chronological ages and brain sizes are drawn from the literature. Simulated distributions of these values are used to calculate average annual rates (ARs) of brain growth and proportional size change from birth (PSC), which are compared to resampled statistics from humans, chimpanzees and gorillas of known age and sex. Simulated ARs and PSCs for A. afarensis are significantly lower than those of chimpanzees and gorillas. Both ARs and PSCs for A. africanus are similar to chimpanzee and gorilla values. These results indicate that although these early hominins were derived in some aspects of brainAbstract: Postnatal growth is one of the proximate means by which humans attain massive adult brain size. Humans are characterized by the maintenance of prenatal brain growth rates into the first postnatal year, as well as an overall extended period of growth. The evolution of this pattern is difficult to assess due to its relatively brief duration and the underrepresentation of well-preserved fossil individuals who died during this short period. In this study, I use Monte Carlo methods to reconstruct postnatal brain growth rates in Australopithecus afarensis and Australopithecus africanus, based on estimates of neonatal brain size and of likely brain size and age at death of infant specimens (A.L. 333-105, DIK-1-1, and Taung). Neonatal brain size is reconstructed from the empirical scaling relationship among catarrhines which humans follow, and conservative estimates of fossils' chronological ages and brain sizes are drawn from the literature. Simulated distributions of these values are used to calculate average annual rates (ARs) of brain growth and proportional size change from birth (PSC), which are compared to resampled statistics from humans, chimpanzees and gorillas of known age and sex. Simulated ARs and PSCs for A. afarensis are significantly lower than those of chimpanzees and gorillas. Both ARs and PSCs for A. africanus are similar to chimpanzee and gorilla values. These results indicate that although these early hominins were derived in some aspects of brain anatomy, high rates of brain growth did not appear until later in human evolution. Moreover, findings also imply that brain growth rates are not a simple function of adult brain size. This study provides important new information about the evolution of brain growth, despite limitations inherent in fossil samples. … (more)
- Is Part Of:
- Journal of human evolution. Issue 130(2019)
- Journal:
- Journal of human evolution
- Issue:
- Issue 130(2019)
- Issue Display:
- Volume 130, Issue 130 (2019)
- Year:
- 2019
- Volume:
- 130
- Issue:
- 130
- Issue Sort Value:
- 2019-0130-0130-0000
- Page Start:
- 72
- Page End:
- 82
- Publication Date:
- 2019-05
- Subjects:
- Ontogeny -- Australopithecus afarensis -- Australopithecus africanus -- Life history -- Simulation
Human evolution -- Periodicals
Homme -- Évolution -- Périodiques
Human evolution
Periodicals
599.93805 - Journal URLs:
- http://www.sciencedirect.com/science/journal/00472484 ↗
http://www.elsevier.com/journals ↗ - DOI:
- 10.1016/j.jhevol.2019.02.006 ↗
- Languages:
- English
- ISSNs:
- 0047-2484
- Deposit Type:
- Legaldeposit
- View Content:
- Available online (eLD content is only available in our Reading Rooms) ↗
- Physical Locations:
- British Library DSC - 5003.415000
British Library DSC - BLDSS-3PM
British Library HMNTS - ELD Digital store - Ingest File:
- 10011.xml