[Hilarious. It seems it makes you get side tracked -- even when
you're a fruit fly]
http://www.newscientist.com/news/news.jsp?id=ns99994200
Cleverness may carry survival costs
13:50 24 September 03
NewScientist.com news service
Being smart is not always a good thing in the evolutionary race,
suggests a new study by Swiss researchers
If intelligence were always a positive attribute, it would always be
selected for by natural selection. But it is not - people and animals
have their dolts as well as their Einsteins.
To evolutionary biologists, that diversity means that theoretically,
there must be some cost to being smart. Now for the first time,
researchers have shown that in fruit flies at least, it doesn't always
pay to be clever.
When Frederic Mery and colleagues at the University of Fribourg,
pitted fast-learning fruit fly larvae against their more dimwitted
cousins in scarce food conditions - the slower fruit flies came out on
top.
"This shows that just having a better ability to learn involves a
cost, even when you aren't using it," Mery told New Scientist.
Sabotaged flavour
The team first bred a group of fast-learning flies. They allowed fruit
flies to lay eggs on gels flavoured with either orange or pineapple
juice. But one or the other was also spiked with bitter quinine. The
next time round the flies were given the juice only - but some
remembered which had previously been laced with quinine and laid their
eggs on the other flavour.
The scientists collected those eggs to breed the next generation of
flies, gave those flies the same opportunity to learn, and bred the
next generation from those that made the "right" choice.
After 20 generations, most flies from the selected line could learn
the task in one go. They were not just better at tasting different
juices or more averse to quinine, as ordinary flies could eventually
learn to avoid the sabotaged flavour too, but it took them three to
five sessions.
When the ordinary flies did learn, they also forgot faster than the
selected flies. "That shows we selected a gene that improves both
memory and the speed of learning, or two genes that are tightly
linked," says Mery.
Neuronal connections
However, when the larvae of the more astute flies were made to compete
with ordinary larvae for scarce food, fewer of them survived.
"They are slower at feeding," says Mery. He speculates that the flies
may have to invest more energy in making or re-arranging connections
between neurons in their brains, leaving them with less energy to
forage when calories are limited.
He cautions that the work measures the ability of fruit flies to learn
only a particular task, though the group is testing whether their
smart flies are also better at learning other things. "But this should
open up the evolutionary question," he says. In principle, it should
be possible to look for the costs of intelligence even in primates.
The group is now collaborating with molecular geneticists to try and
tease out which genetic changes have made their fruitflies so smart.
Journal reference: Proceedings of the Royal Society of London B (DOI
10.1098/rspb.2003.2548)
Debora MacKenzie