Fish use logic to size up rivals-study

[Lisachromis]

From http://news.yahoo.com/s/nm/20070124/od_uk_nm/oukoe_uk_fish_logic_1

Wed Jan 24, 1:08 PM ET

LONDON (Reuters) - Male fish, like humans, use a sophisticated form of logical reasoning to assess potential rivals, scientists said on Wednesday.

By watching how other males perform in battles over territory, tiny African fish called cichlids decide which opponent they should take on and are likely to defeat to improve their social standing.

The type of reasoning, known as transitive inference, is learnt by young children. It has also been shown in primates and rats but scientists at Stanford University in California are the first to demonstrate it in fish.

"These results show fish do, in fact, use transitive inference to figure out where they rank in the social order," said Russell Fernald, a professor of biological sciences at the university.

"I was amazed that they could do this through vicarious experience, just by watching other males fight."

Male cichlids climb the social ladder by picking fights and defeating their opponents. Fish who are constantly defeated slump in the pecking order.

Fernald and his team, who reported their findings in the journal Nature, demonstrated transitive inference in fish by staging a series of experiments in an aquarium in which eight bystander fish watched others in battles.

They used a species of cichlid called Astatotilapia burtoni which displays a black stripe, or eyebar, on its face. If a fish is defeated in a battle it is easy to spot the loser because the eyebar disappears temporarily as it swims away from its victorious opponent.

When all the fighting was finished and the fish recovered from their losses, the researchers filmed the bystanders as they chose their potential opponent. They also recorded the amount of time they spent near them, which indicates their preference.

Nearly all the bystander fish selected the weakest fish.

"Our experiment shows that male cichlids can actually figure out their odds of success by observation alone. From an evolutionary standpoint, transitive inference saves them time and energy," Fernald said.

[Dan Woodland]

Pretty cool, I found this link...

http://www.msnbc.msn.com/id/16796139/

Now people will know what we've known all along!

Dan

[Darrell Ullisch]

I would like to see the actual report from the study before assuming that those fish were sizing up the others ONLY by observing fights. There's no mention in that news report of aCONTROL group; of course, that's because they're just looking for the "exciting" parts.

In this instance, you need a group of fish that did NOT observe the fighting, and then record which fish THEY go after. If they go for the same fish without having observed the fights, then there is another factor involved, and the logical inference they are claiming is incorrect. However, if the control group reacts differently than the experimental group, THEN you may infer that they observed the differences during the fights and made a logical choice.

A true study requires a control group, so many these days seem to forget that. I've been guilty of making assumptions from my observations without running a controlled experiment. But I'm not writing papers on it.

[michi tobler]

Hi,

the study is actually very well done (that's why it was published in Nature) and the authors made the necessary controls. Cool stuff!

Cheers, M

[Darrell Ullisch]

That's why I hate to read about such things in the "popular" news outlets. They leave out so many important facts.

I went to see if I could get the article, they want $30 for just the one article. A subscription to Nature magazine is $199 per year; I can't even afford the article, much less a subscription!

[bantamweight1911]

I would like to see the actual report from the study before assuming that those fish were sizing up the others ONLY by observing fights. There's no mention in that news report of aCONTROL group; of course, that's because they're just looking for the "exciting" parts.

In this instance, you need a group of fish that did NOT observe the fighting, and then record which fish THEY go after. If they go for the same fish without having observed the fights, then there is another factor involved, and the logical inference they are claiming is incorrect. However, if the control group reacts differently than the experimental group, THEN you may infer that they observed the differences during the fights and made a logical choice.

Absolutely.

Of course, if 2 fish fight, the most likely winner is the one that has a physical advantage, size, or speed, or both. The 'bystanders' would be able to judge this, and it may just be that the biggest fish won the fight, and the bystanders chose to take on the smaller fish, which by no co-incidence was also the loser.
Also, if a fish has recently lost a fight, it will be acting less aggresive, and so any other males in the area would be likely to single him out as vulnerable regardless of if they have seen him fight and lose.

In addition, most animals choose to display and judge their opponents before engaging. This prevents uneccessary fights between uneven matched opponents.

None the less, its an interesting report.

[michi tobler]

Hi,

just send me an email, I'll send the study to you.

Cheers, m

[Darrell Ullisch]

Someone from a mailing list that I'm on sent me a copy of the article; in fact, two people sent it to me! Good folks on that Anubiasdesign list.

I read it, and they did not have blind controls of the sort I described. They did use a reversal of heirarchy, so that half of the subject group saw one male as Alpha, while the other half saw them reversed by artificially giving the least dominant male the Alpha position. While that seems to be an adequate control, I would have added to the study by running the dominance fights, then placing non-observer males in the center to see if he can infer position without observing the actual fights. Many color and pattern clues could exist that we don't see, but that the fish does.

Still, it is an interesting study.