It would be wonderful if we can remember all our experiences as individuals and communities, in order to improve our decisions in complex dynamic environments. But memory is costly, like the many years of education needed to transfer information, imperfectly, from one generation to the next. An interesting study with fruit flies show the cost of memory on the individual level:
“If you are forever forgetting people’s names or family birthdays, take heart. Forming permanent memories is so physiologically expensive it can result in early death – at least for fruit flies. When fruit flies form lasting memories, their neurons must make new proteins. Now Frederic Mery and Tadeusz Kawecki at the University of Fribourg in Switzerland have shown that this extra work takes its toll on the flies’ ability to survive. They trained one group of flies to associate a jolt with a bad-smelling mixture of two alcohols, while other flies were subjected either to jolts only or to jolts and odours, but not at the same time. When the flies were subsequently deprived of food and water, the group that had learned the link died an average of 4 hours, or 20 per cent, earlier than the others (Science, vol 308, p 1148).
The study suggests that there is a cost to memory and learning, raising the question of whether humans lost other qualities when they evolved superior intelligence. “We have such an extraordinary memory and learning capacity, we must have paid for it,” says Kawecki.”

From issue 2501 of New Scientist magazine, 28 May 2005, page 16