SCIENCE NEWS September 06, 2007
It's No Delusion: Evolution May Favor Schizophrenia Genes
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marked by hallucinations, multiple personalities and cognitive disorganization, affects roughly 1 percent of the U.S. population. Many of those afflicted, however, also have reduced reproductive fitness, which means they are less likely to pass a genetic profile associated with the condition onto their offspring. "It's sort of a genetic paradox," explains Steve Dorus, an evolutionary geneticist at the University of Bath in England. "Why is this disease found at such a high prevalence?"
Dorus co-authored a report, appearing in this week's Proceedings of the Royal Society B, about the evolution of genes linked to schizophrenia. After analyzing human DNA from several populations around the world and examining primate genomes dating back to the shared ancestor of both humans and chimpanzees, researchers reached a striking conclusion that several gene variants linked to schizophrenia were actually positively selected and remained largely unchanged over time, suggesting that there was some advantage to having them.
"Schizophrenia can be explained by a lot of individual alleles (variations of genes)," Dorus notes. "There are many different loci that impact the actual manifestation of the disease." Over the past decade, several dozen genes have been identified as potential culprits, and scientists believe that several genes cause disruptions in protein formations predisposing a person to schizophrenia.
For this study, the team, which also included Bernard Crespi, an evolutionary biology professor at Simon Fraser University in British Columbia, and East Carolina University evolution professor Kyle Summers, focused on 76 gene variations most strongly related to schizophrenia. By comparing these combinations with the evolution of other genes known to affect neuronal processes, the researchers determined that 28 of the schizophrenia-associated genes have been evolutionarily preferred in recent years by either Caucasian, Asian or African populations.
"Because it's a such a complex genetic trait … you actually expect there to be some variability from population to population, in terms of what genes are playing a role in the disorder," Dorus says. He notes that he was surprised that the study turned up a positive selection for some of the genes most closely associated to the disease, including DISC1 (disrupted in schizophrenia 1), which is involved in the transport of proteins along the relatively lengthy cell bodies of neurons, among them. "The most important thing is we don't really know what the basis of the selection has been," he says. "It could be due to an entire range of neurodevelopmental processes."
Co-author Crespi says that a number of theories have been floating around regarding the persistence of schizophrenia's genetic underpinnings. One holds that schizophrenia is a "disorder of language" and that the illness is an unfortunate consequence of the development of human speech, expression and creativity. "Whenever you get strong selection, it's like a big plus, and you can drag along a lot of minuses," he says. "You can think of schizophrenics as paying the price of all the cognitive and language skills that humans have—they have too many of the alleles that taken individually…might have positive effect, but together they are bad."
Dorus says the team will now home in on the 28 genes fingered in positive selection in the hope of finding new treatments for the mysterious disorder.
Norman Geras, an old Socialist, puts things so well. We would all, left, right and liberal be better off to at last take in some of what he says. Like all writers, philosophers or critics, there will always be disagreements, but it is time the American Left began to do some research on why they think and behave as they do. Why the Ameican Left hates American so much. I give you all just a tiny, tiny morsel from Norman Geras:
…The lessons have evidently still not been learned of earlier, sometimes calamitous, misjudgements – which produced the Third Period of the Comintern, when social democracy, not Nazism, was said to be the main enemy; and which landed the world communist movement, along with much fellow-travelling liberal opinion, in denial and excuse towards the criminality of Stalinism despite a flood of evidence about this; and which have led, time and again, to a complaisant attitude towards terror and murder for alleged purposes of liberation, so putting in question the claim of those with that attitude to represent a movement for democratic, egalitarian and humane objectives. There is no reason intrinsic to the central values and principles of socialism for these misjudgements or their continuation. But there are clearly, as always and everywhere, simplifying tendencies of thought – in the present case, seeing in imperialism, not merely a crucial feature of the world, but the answer to every question. A thing held too close to the eye obstructs the vision.
To read the Essay in its entirety, go here:http://mail.bris.ac.uk/~plcdib/imprints/normangerasinterview.html
Geras is not easy for me to read, I’m old and never got to college, but I have tried all my life to learn and have created my own philosophy. However, those of us who care so much, need to do our homework so that we do not waste our time with such a MikeB. The Socialist of old would turn over in their graves if they heard what the American, nay the world Left is spewing forth!