Navigation Links
Big brains arose twice in higher primates
Date:7/9/2008

After taking a fresh look at an old fossil, John Flynn, Frick Curator of Paleontology at the American Museum of Natural History, and colleagues determined that the brains of the ancestors of modern Neotropical primates were as small as those of their early fossil simian counterparts in the Old World. This means one of the hallmarks of primate biology, increased brain size, arose independently in isolated groupsthe platyrrhines of the Americas and the catarrhines of Africa and Eurasia.

"Primatologists have long suspected that increased encephalization may have arisen at different points in the primate evolutionary tree, but this is the first clear demonstration of independent brain size increase in New and Old World anthropoids," says Flynn of the paper that appeared in the Museum's publication Novitates this June. Encephalization is the increase in brain size relative to body size. Animals with large encephalization quotients (E.Q.'s) are those with bigger brains relative to their body size in comparison to the average for an entire group. Most primates and dolphins have high E.Q.'s relative to other mammals, although some primates (especially apes and humans) have higher E.Q.'s than others.

At the heart of the new paper is the development of more accurate equations for estimating body size in platyrrhines, or New World "monkeys." Most fossils are fragments of skulls or teeth so, to help in estimating their body size (and then E.Q.), Flynn and colleagues collected 80 measurements of the skulls, jaws, and teeth of 17 different species of living New World monkeys that ranged across the full spectrum of body sizes. This study is one of the first to estimate body size with platyrrhines instead of their better-studied counterparts from the Old World, and this detailed analysis uses new statistical approaches to tease out which characteristics correlate best with body size. The goal is to apply this equation to fossilized specimens.

Chilecebus, found high in the Andes and described by Flynn and collaborators in 1995 in Nature, is one such fossil. The skull dates to 20 million years ago and is the oldest and most complete well-dated primate skull from the New World. In the Novitates paper, Flynn and colleagues more accurately estimate that Chilecebus weighed about 583 grams and had an E.Q. of only 1.11a much smaller relative brain size than any living New or Old World anthropoid, which have E.Q.'s ranging from 1.39-2.44 (and even higher for humans).

"The result is clear: early fossil members of both the New World and Old World anthropoid lineages had small brain sizes, thus the larger brain sizes seen in both groups today must have arisen independently," says Flynn. "Documenting that large brains evolved separately several times within Primates will enhance understanding of the timing and pathways of brain expansion and its effects on skull growth and shape, and may lead to new insights into the genetic controls on encephalization."

Eric Delson, the Chair of Anthropology at Lehman College, City University of New York and a Research Associate at the Museum, concurs. "This work confirms that brain size increase may be one of the common characteristics of all primates," he says. "The relatively small brain of Chilecebus contrasts with that of the slightly younger (16.5 million years ago), larger brained fossil Killikaike found in Argentina and described two years ago. It is probable that brain size also increased independently in the lemurs of Madagascar, as well as in the apes (of which humans are the extreme case) and the cercopithecid monkeys of Africa and Asia."


'/>"/>

Contact: Kristin Phillips
kphillips@amnh.org
212-496-3419
American Museum of Natural History
Source:Eurekalert  

Related biology news :

1. Doctors learn to control their own brains pain responses to better treat patients
2. From brains to behavior: Cold Spring Harbor Protocols features methods for neuroscience research
3. Brains R Us: Neuroscience and education town hall
4. Girls who begin dieting twice as likely to start smoking
5. Risk of common vaginal infection linked to preterm birth appears higher for blacks
6. Improved e-jet printing provides higher resolution and more versatility
7. Low vitamin D linked to higher risk of hip fracture
8. Engineers study brain folding in higher mammals
9. Less Arctic ice means higher risks, experts warn
10. Obesity-related hormone is higher in children with Down syndrome
11. Insects take a bigger bite out of plants in a higher CO2 world
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Big brains arose twice in higher primates
(Date:4/11/2017)... NXT-ID, Inc. (NASDAQ:   NXTD ) ("NXT-ID" or ... independent Directors Mr. Robin D. Richards and Mr. ... the company,s corporate governance and expertise. ... Gino Pereira , Chief Executive Officer said," ... and benefiting from their considerable expertise as we move forward ...
(Date:4/5/2017)...  The Allen Institute for Cell Science today announces ... portal and dynamic digital window into the human cell. ... application of deep learning to create predictive models of ... a growing suite of powerful tools. The Allen Cell ... publicly available resources created and shared by the Allen ...
(Date:4/5/2017)... , April 4, 2017 KEY FINDINGS ... to expand at a CAGR of 25.76% during the ... is the primary factor for the growth of the ... https://www.reportbuyer.com/product/4807905/ MARKET INSIGHTS The global stem ... technology, application, and geography. The stem cell market of ...
Breaking Biology News(10 mins):
(Date:6/22/2017)... ... June 22, 2017 , ... ... specialists DST Diagnostische Systeme & Technologien GmbH, thereby expanding its product portfolio to ... from hay fever, urticaria, asthma, atopic eczema or a food allergy. Allergies are ...
(Date:6/22/2017)... (PRWEB) , ... June 22, 2017 , ... The first ... took 20 years until the first data on cross-contamination of human cell lines with ... been an increasing issue in cell culture labs and is associated with dramatic consequences ...
(Date:6/20/2017)... , ... June 20, 2017 , ... Biologist Dawn Maslar ... While researching her latest book, Men Chase, Women Choose: The Neuroscience of Meeting, Dating, ... has a physiological effect on men. ”The logical next step, in my estimation, was ...
(Date:6/20/2017)... ... June 20, 2017 , ... Do More with OHAUS , With the launch ... supplier in the weighing industry, to extending its expertise across the entire laboratory to ... hybridizations and more, allowing for its customers to 'Do More' in the ...
Breaking Biology Technology: