Science is most fun when it throws up completely bizarre surprises. Like these study results ...
Learning and longevity | Critical thinking | Economist.com
...After repeating the experiment for 30 generations, the offspring of the learned flies were compared with normal flies. The researchers report in a forthcoming edition of Evolution that although learning ability could be bred into a population of fruit flies, it shortened their lives by 15%. When the researchers compared their learned flies to colonies selectively bred to live long lives, they found even greater differences. Whereas learned flies had reduced life spans, the long-lived flies learned less well than even average flies.
The authors suggest that evolving an improved learning ability may require a greater investment in the nervous system which diverts resources away from processes that stave off ageing. However, Dr Kawecki thinks the effect could also be a by-product of greater brain activity increasing the production of reactive oxygen particles, which can increase oxidation in the body and damage health.
No one knows whether the phenomenon holds true for other animals. So biologists, at least, still have a lot to learn...
As far as we can tell, humans are the only technological species that ever lived on planet earth. (See, however, Stephen Baxter's Evolution for a wonderful imaging of a pre-technological sentience.)
We've come along fairly late in the planet's history.
Why did it take so long to produce an extinction-event class species ? What was there about intelligence that was so hard?
The flies might be giving us some clues ...
 Anyone studying the fossil records will see evidence of worldwide mass extinction beginning early in our evolutionary career. Species that can cause that kind of mass extinction are in a class of their own, albeit a short-lived class.
The learning process, purely intellectual learning, taxes the nerve sense system in the growing child. When that self same process is adapted to be an artistic, creative process, a process created as the vehicle, the basis, or foundation for the learning process, the nerve sense system is not unduly taxed.
I can see that the self same principle applied to fruit flies would hold true. I suspect that because the life cycle of the fruit fly is so extremely short, as apposed to the humans, that the application of such experimentation would be greatly magnified and result in the outcomes described.
“What was there about intelligence that was so hard?”
I suspect that the nerve sense system when fully utilized by learning, reacts to brain activity and results is a degenerative process. As the metabolic process metabolizes the reactive oxygen particles, thereby increasing oxidation in the body, the damage is reflected in a sort of dying, death process of the nerve system. The nerve sense system is regenerative but only to a certain threshold. Once that threshold is passed damage is irreversible.
The described experimentation applied a process to fruit flies that under normal conditions would not have been evident. Therein lays the challenge. The problem with science is that much of it is hypothesis! The scattering of results from non normal conditions applied to test subjects are hard to read or make sense of.
The fact that long lived flies learned less well, I can only presume tongue in cheek of course, that I also have trouble learning now that I am almost a senior citizen and senior fruit flies are probably no better off!
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