Featured Research

from universities, journals, and other organizations

Why animals compare the present with the past

Date:
May 30, 2013
Source:
University of Bristol
Summary:
Humans, like other animals, compare things. We care not only how well off we are, but whether we are better or worse off than others around us, or than we were last year. New research shows that such comparisons can give individuals an evolutionary advantage.

The ‘contrast effect’ has been reported in a number of living things, including bees.
Credit: Daniel Prudek / Fotolia

Humans, like other animals, compare things. We care not only how well off we are, but whether we are better or worse off than others around us, or than we were last year. New research by scientists at the University of Bristol shows that such comparisons can give individuals an evolutionary advantage.

According to standard theory, the best response to current circumstances should be unaffected by what has happened in the past. But the Bristol study, published in the journal Science, shows that in a changing, unpredictable world it is important to be sensitive to past conditions.

The research team, led by Professor John McNamara in Bristol's School of Mathematics, built a mathematical model to understand how animals should behave when they are uncertain about the pattern of environmental change. They found that when animals are used to rich conditions but then conditions suddenly worsen, they should work less hard than animals exposed to poor conditions all along.

The predictions from the model closely match findings from classic laboratory experiments in the 1940s, in which rats were trained to run along a passage to gain food rewards. The rats ran more slowly for small amounts of food if they were used to getting large amounts of food, compared to control rats that were always rewarded with the smaller amount.

This so-called 'contrast effect' has also been reported in bees, starlings and a variety of mammals including newborn children, but until now it lacked a convincing explanation.

Dr Tim Fawcett, a research fellow in Bristol's School of Biological Sciences and a co-author on the study, said: "The effects in our model are driven by uncertainty. In changing environments, conditions experienced in the past can be a valuable indicator of how things will be in the future."

This, in turn, affects how animals should respond to their current situation. "An animal that is used to rich conditions thinks that the world is generally a good place," Dr Fawcett explained. "So when conditions suddenly turn bad, it interprets this as a temporary 'blip' and hunkers down, expecting that rich conditions will return soon. In contrast, an animal used to poor conditions expects those conditions to persist, and so cannot afford to rest."

The model also predicts the reverse effect, in which animals work harder for food when conditions suddenly improve, compared to animals experiencing rich conditions all along. This too has been found in laboratory experiments on a range of animals.

The Bristol study highlights unpredictable environmental fluctuations as an important evolutionary force. "Rapid changes favour individuals that are responsive and able to adjust their behaviour in the light of past experience," said Dr Fawcett. "The natural world is a dynamic and unpredictable place, but evolutionary models often neglect this. Our work suggests that models of more complex environments are important for understanding behaviour."


Story Source:

The above story is based on materials provided by University of Bristol. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. M. McNamara, T. W. Fawcett, A. I. Houston. An Adaptive Response to Uncertainty Generates Positive and Negative Contrast Effects. Science, 2013; 340 (6136): 1084 DOI: 10.1126/science.1230599

Cite This Page:

University of Bristol. "Why animals compare the present with the past." ScienceDaily. ScienceDaily, 30 May 2013. <www.sciencedaily.com/releases/2013/05/130530142003.htm>.
University of Bristol. (2013, May 30). Why animals compare the present with the past. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2013/05/130530142003.htm
University of Bristol. "Why animals compare the present with the past." ScienceDaily. www.sciencedaily.com/releases/2013/05/130530142003.htm (accessed September 2, 2014).

Share This




More Plants & Animals News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Washington Wildlife Center Goes Nuts Over Baby Squirrels

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Reuters - US Online Video (Aug. 30, 2014) An animal rescue in Washington state receives an influx of orphaned squirrels, keeping workers busy as they nurse them back to health. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Newsy (Aug. 29, 2014) In a new study, a promising experimental treatment for Ebola managed to cure a group of infected macaque monkeys. Video provided by Newsy
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins