Earth Science News  





. Aging Boosts Chances That A Family Line Will Be Long-Lived

it's all there in the palm of your hands...
by Staff Writers
Seattle WA (SPX) Mar 14, 2007
Scientists have puzzled over just why organisms evolved aging as a strategy, and now there appears to be an answer. Allowing one individual to carry all the cellular damage inflicted over time, rather than dividing it between two organisms during reproduction, increases the chances that the individual's line will continue to reproduce for many generations to come, a new study indicates.

The earliest organisms, single-celled creatures called prokaryotes, which include bacteria, probably did not age but rather divided damaged material equally among new cells. There was not a parent cell, but rather the original cell divided into two siblings that were, in effect, the same age and shared the damage from the original cell equally.

Somewhere along the way, that strategy changed so that a parent cell retained most of the damage from aging and the offspring started with a mostly clean slate.

"The idea is that the damage has a constant effect on the fitness of the offspring, but if the damage is concentrated in one individual then a lot of damage will be eliminated from the lineage when that individual dies," said Carl Bergstrom, a University of Washington associate professor of biology who participated in the work.

Aging is essentially a decline in reproductive rate and an increase in mortality over time, based on changes in tissues, cells and cellular structures. Those changes can include damage to DNA or damage to cellular material or even organs.

In what is called symmetric reproduction, a cell divides in two and splits the damage equally among the succeeding generation of cells. In asymmetric reproduction, the parent retains the damage associated with aging.

Symmetric reproduction favors a longer life for an individual, but eventually the damage is likely to be so great that a particular line will no longer be able to reproduce. Asymmetric reproduction likely means a shorter life for an individual in exchange for the likely greater longevity of the line.

"If you divide asymmetrically, the survivor is likely to be the undamaged one, which will then be in a better position to produce surviving offspring," Bergstrom said.

The mechanisms that favor asymmetrical aging over symmetry are so general that they are expected to operate in a wide range of organisms, the researchers say. The new work suggests that aging has evolved in most - perhaps even all - types of organisms.

The research is described in a paper in the April edition of the journal Aging Cell. The lead author is Martin Ackermann of the Institute for Integrative Biology in Zurich, Switzerland. Besides Bergstrom, co-authors are Lin Chao of the University of California, San Diego, and Michael Doebeli of the University of British Columbia in Vancouver.

The researchers used mathematical models and computer simulations to examine the likely evolution of aging by distributing damage asymmetrically during reproduction. They also studied the investment an organism makes in a mechanism to repair damage. From their findings, the scientists concluded that reproduction in which damage was distributed asymmetrically would be favored.

The models were altered to allow cells to repair some of their damage, and asymmetric reproduction still was favored. Not only that, but once asymmetric division became the dominant reproduction method the models indicate that evolution will eventually reduce the investment in repair, Bergstrom said.

The implication is that evolution favors individuals aging as a means of allowing their lineage to persist longer.

"A lineage is more likely to survive in the long run if one individual falls on the grenade of its own cellular damage," Bergstrom said.

Email This Article

Related Links
University of Washington
All About Human Beings and How We Got To Be Here

Getting On Your Nerves And Repairing Them
Bethesda MD (SPX) Mar 12, 2007
Here is some news that will certainly get on people's nerves: In a study to be published in the March 2007 issue of The FASEB Journal, scientists from East Carolina University report that a key molecular mechanism, RNA interference (RNAi), plays a role in the regeneration and repair of periphery nerves, which are the nerves located outside of the brain and spinal column.

.
Get Our Free Newsletters Via Email
  



  • Indonesia Allots One Billion Dollars To Prevent Floods
  • Relief Flows Into Indonesia Quake Area As Death Toll Revised Down
  • Global Disaster Bill Declines In 2006 Says Swiss Re
  • Death And Destruction After Powerful Indonesia Quake

  • Climate Shifts And The Probability Of Randomness
  • EU Summit Seeks Unity On Tackling Global Warming
  • Banning New Coal Power Plants Will Slow Warming
  • The U.N.'s War On Global Warming

  • CryoSat-2 On The Road To Recovery
  • Space Scientists To Take The Pulse Of Planet Earth
  • Climate Change View Clearer With New Oceans Satellite
  • Satellite Scientists Set To Descend On Hobart

  • New Lithium-Ion Battery Technology Created
  • Unlocking The Secrets Of High-Temperature Superconductors
  • China Bans New Small Coal-Based Power Generators
  • Progress Made in Biomass-to-Biofuels Conversion Process

  • Genome Sequence Shows What Makes Bacteria Dangerous For Troops In Iraq
  • A Year Of Added Life More Valuable For The Young
  • Researchers Reconstruct Spread Of Bird Flu From China
  • Troubling Trends In AIDS Cases

  • Remote Sheep Population Resists Genetic Drift
  • Social Tolerance Allows Bonobos To Outperform Chimpanzees On A Cooperative Task
  • Why Do Birds Migrate
  • Some Corals Might Be Able To Fight The Heat

  • Bacterium Could Treat PCBs Without The Need For Dredging
  • Asian Pollution Linked To Stronger Pacific Storm System
  • Canada's Oil Sands To Keep Polluting
  • As An Economy Blossoms An Ancient Capital Suffocates

  • Getting On Your Nerves And Repairing Them
  • Human Rights In Darfur
  • Aging Boosts Chances That A Family Line Will Be Long-Lived
  • These Legs Were Made for Fighting Not Just Climbing Over You

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement