Brain size associated with longevity

Jul 15, 2010
© Daniel Sol

Mammals with larger brains in relation to body size tend to live longer. This is the conclusion reached by researchers at the Centre for Ecological Research and Forestry Applications (CREAF), affiliated to Universitat Autňnoma de Barcelona, after having analysed almost 500 mammal species and obtaining new data on the relation between brain size and lifespan.

The of some is larger than expected for their body size. This is the case of large primates, such as chimpanzees and gorilla, and of whales, dolphins and elephants. Scientists have spent years investigating why sometimes nature favours the development of large brains given that they require much more time to reach functional maturity and use up so much energy. One of the classical explanations is the Cognitive Buffer Hypothesis (CBH). This hypothesis suggests that a larger brain provides more flexibility in behaviour when facing changes in the environment and makes learning easier, aspects which allow species to overcome ecological challenges successfully.

CREAF researchers César González-Lagos and Daniel Sol, together with Simon Reader (University McGill, Canada), offer new data supporting this hypothesis in an article published recently in Journal of Evolutionary Biology. Using statistical methods, the authors analysed data from 493 mammal species - from rodents and bats to cetaceans, felines, ungulates and marsupials - and have reached the conclusion that having a larger brain entails having a longer life, and this represents a new advantage.

In addition to generating more opportunities to adapt to changes and therefore improving survival, a larger brain size also permits animals to live longer and thus have more chances to reproduce, which is beneficial to each individual member. This is the compensation for a longer embryonic development needed to generate a larger brain. Species with larger brains have also shown to take longer in reaching sexual maturity, which is in part compensated by a longer reproductive life.

The study includes an extended taxonomic range in comparison to previous studies and takes into account phylogenetic relations between species analysed. Researchers analysed a series of other variables which could be related to higher longevity, such as metabolic rates - the amount of energy expended while at rest - diet or habitat, and concluded that none of these can be significantly associated with . Connections are made however not only with a larger brain size, but also with a larger body size, given that large animals are known to live longer. Nevertheless, CREAF researchers confirm that the size of the brain affects lifespan regardless of the size of the body. Hyenas, for example, have a larger brain than giraffes in proportion to and on average live longer, although they are smaller than these herbivores.

The statistical model used by researchers also took into account whether age registers of the almost 500 species analysed were carried out with animals living in the wild or in captivity. The latter were shown to have more chances of living longer.

The authors of the study emphasise that the relation between a large and a longer life is not always one of cause and effect. "CBH points to this fact, that a larger encephalon favours a longer lifespan, but it is equally possible that a longer life favours the development of larger brains", researchers assure. Thus, it is possible that a longer life works in favour of a delay in reproductive cycles and this would in turn allow progenitors to invest more resources and time in caring for their offspring. This also leads to the formation of stable social groups whose members, according to the Social Intelligence Hypothesis (SIH), must deal with more cognitive demands than animals living alone, and this would be the reason for larger brains. "Our results", researchers add, "do not demonstrate which of the two options is correct, although we think that the two complement each other and go hand in hand".

Explore further: Seeing the (UV) light: Previously undetected difference in human mutation rate unique to Europeans

More information: C. González-Lagos, D. Sol, S. M. Reader (2010) "Large-brained mammals live longer". Journal of Evolutionary Biology, 23 (5), 1064-1074. DOI: 10.1111/j.1420-9101.2010.01976.x

Provided by Universitat Autonoma de Barcelona

5 /5 (7 votes)
add to favorites email to friend print save as pdf

Related Stories

Big-brained birds survive better in nature

Jan 10, 2007

Birds with brains that are large in relation to their body size have a lower mortality rate than those with smaller brains, according to new research published in the journal Proceedings of the Royal Society B: Biological Sc ...

Migratory behavior affects the size of brains in birds

Apr 29, 2010

Researchers at Centre for Ecological Research and Forestry Applications (CREAF, a Universitat Autonoma de Barcelona, Spain) shed new light on the evolution of brain size in birds. Scientists have known for some time that ...

Why newborn babies can't walk

Dec 18, 2009

( -- The first steps of an infant is a real milestone in the development of all mammals including humans, but little is known about why some animals can walk soon after birth, while others need ...

Male deer are born to live fast, die young

Aug 31, 2007

In the September issue of The American Naturalist, Juan Carranza (Biology and Ethology Unit, University of Extremadura, Spain) and Javier Pérez-Barbería (Macaulay Institute, United Kingdom) offer a new ...

Monkeys' grooming habits provide clues to how we socialise

Sep 30, 2009

( -- A study of female monkeys' grooming habits provides new clues about the way humans socialise. New research reveals a link between the size of the neocortex in the brain, responsible for higher-level ...

Recommended for you

Dairy farms asked to consider breeding no-horn cows

Mar 28, 2015

Food manufacturers and restaurants are taking the dairy industry by the horns on an animal welfare issue that's long bothered activists but is little known to consumers: the painful removal of budding horn ...

Italian olive tree disease stumps EU

Mar 27, 2015

EU member states are divided on how to stop the spread of a disease affecting olive trees in Italy that could result in around a million being cut down, officials said Friday.

China starts relocating endangered porpoises: Xinhua

Mar 27, 2015

Chinese authorities on Friday began relocating the country's rare finless porpoise population in a bid to revive a species threatened by pollution, overfishing and heavy traffic in their Yangtze River habitat, ...

A long-standing mystery in membrane traffic solved

Mar 27, 2015

In 2013, James E. Rothman, Randy W. Schekman, and Thomas C. Südhof won the Nobel Prize in Physiology or Medicine for their discoveries of molecular machineries for vesicle trafficking, a major transport ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jul 16, 2010
A bit late this. The paper was out in May. Journal of Evolutionary Biology has moved on several issues. Perhaps better than details of papers that have yet to appear even in amongst a journal's advanced publication.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.