Navigation Links
Biologists Question Animal Brain Size Theory

Social behavior hypothesis contradicted in research paper

FRIDAY, May 29 (HealthDay News) -- Animals -- carnivores in particular -- that follow a social order do not necessarily develop bigger brains, say two biologists whose findings contradict the so-called Social Brain Hypothesis followed by many evolutionists.

In a report published online May 27 in the Proceedings of the National Academy of Sciences Early Edition, John Finarelli of the University of Michigan and John Flynn of the American Museum of Natural History said their detailed analysis of meat-eating animals -- living and extinct -- shows changes in the size of the animal's brain relative to itself were influenced by more than just sociality within the species.

"This is a sophisticated and powerful analysis that integrates fossils with extant species of carnivores," Flynn, dean of the Richard Gilder Graduate School at the American Museum of Natural History, said in a museum news release. "If you only analyze living forms, you often don't correctly reconstruct the evolutionary transformations. Our research shows another example of this, and indicates that the Social Brain Hypothesis does not hold for all Carnivora."

Past studies have linked sociality, such as the pack structure in wild dogs, to the relative increase in brain size to body size for several classifications of mammals. Finarelli and Flynn said their analysis of brain size to body mass in 289 carnivores -- roughly half of which were fossil species -- showed a story far more complex.

The study found at least six distinct changes in brain sizes for carnivores -- which included bears, dogs, cats and weasels -- and the changes were not universal or uniform. While brain size stayed relatively unchanged in some (for example, most cats), it steadily decreased in the extinct bear-dogs called Amphicyonidae. Meanwhile, for dogs, brain size only recently showed an increase in size despite modern-types of dogs having been around for 10 million years.

The hypothesis further broke down when they looked at relatively large-brained carnivores, such as bears, small cats and weasels. The Social Brain Hypothesis would hold that these animals would have social orders, but in actuality, they don't, the authors said.

More information

The Alzheimer's Association has more about how the brain works.

-- Kevin McKeever

SOURCE: American Museum of Natural History, news release, May 25, 2009

Copyright©2009 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Where tumor cells boldly go: Weill Cornell cancer biologists shed light on the metastatic niche
2. Cell biologists identify new tumor suppressor for lung cancer
3. Microbiologists receive top Canadian recognition
4. Boston College biologists build a better mouse model for cancer research
5. Biologists Discover How Dengue Virus Matures
6. New From the Heinz Family Philanthropies: 10 New Questions Families Should Ask Before Choosing Long-Term Care
7. Study questions whether Ontarios primary health care reforms serve the sick and poor
8. Rarely Used Closed Doors Slammed Again in U.S. Senate Health Care Reform; Sen. Max Baucus Must Publicly Answer 10 Questions About Mandatory Purchase of Health Insurance
9. Heinz Family Philanthropies ( Release Questions Families Should Ask About Long-Term Care - 10 Questions to Answer...(
10. Ted Karkus Admits to Financial Relationship With Dr. Richard A. Rosenbloom; Demonstrates Pattern of Improper Influence, Unethical Behavior, Falsification and Distortion; Company Questions What Else Karkus May Be Hiding From Shareholders
11. Sen. Max Baucus: Answer 10 Questions About Mandatory Purchase of Health Insurance Including Why the Public Was Excluded From Todays Committee Meeting
Post Your Comments:
Related Image:
Biologists Question Animal Brain Size Theory 
(Date:11/27/2015)... ... , ... According to an article published November 6th by The ... of British Columbia suggested that laws requiring bicyclists to wear helmets may not actually ... the reason for the controversial conclusion is that, while helmets have certainly prevented a ...
(Date:11/27/2015)... ... November 27, 2015 , ... ... toilets were," said an inventor from Hillside, N.J. "Many people catch diseases simply ... so that individuals will always be protected from germs." , He developed the ...
(Date:11/27/2015)... , ... November 27, 2015 , ... ... of progress through sharing, the 2016 Building Better Radiology Marketing Programs ... will begin on Sunday, March 6, 2016, at Caesars Palace in Las Vegas ...
(Date:11/27/2015)... ... November 27, 2015 , ... CBD College is proud to ... Programs (CAAHEP) awarded accreditation to its Diagnostic Medical Sonography program. CBD College is honored ... one of twelve colleges and universities in the state of California make the cut. ...
(Date:11/26/2015)... ... November 26, 2015 , ... Patients at Serenity ... have come together on Thanksgiving Day to share the things that they are ... the Serenity Point YouTube channel, patients displayed what they wrote on index cards, ...
Breaking Medicine News(10 mins):
(Date:11/26/2015)... , November 26, 2015 3D bioprinting ... 2022, according to a new report by Grand View Research ... Disease (CKD) which demands kidney transplantation is expected to boost ... effective substitute for organ transplantation. --> 3D bioprinting ... 2022, according to a new report by Grand View Research ...
(Date:11/26/2015)... 2015 --> ... potential att använda SyMRI för att hitta ... patienter med multipel skleros (MS) eller hjärntumörmetastaser ... AB för att kunna använda SyMRI Research ... SyMRI kan man generera flera konstrastbilder från ...
(Date:11/26/2015)... DUBLIN , Nov. 26, 2015 ... the addition of the "2016 Future Horizons ... Monitoring (TDM) Market: Supplier Shares, Country Segment Forecasts, ... offering. --> ... comprehensive analysis of the Italian therapeutic drug monitoring ...
Breaking Medicine Technology: