Evolutionary changes in the human brain may have led to bipolar disorder and schizophrenia | ScienceDaily.When you get past the superficial resemblance of design in living organisms it become impossible to regard any putative designer as anything other than spectacularly inept or gratuitously malevolent.
In this paper published in the American Journal of Human Genetics a few days ago we are given evidence of bad design similar to the bad designs associated with bipedal locomotion, upright posture and smaller jaws that have given us bad backs, problem knees and impacted wisdom teeth.
This time the problems are associated with our large brains, specifically, bipolar disorder and schizophrenia.
The research team led by David Kingsley, professor of developmental biology at Stanford University, found evidence that:
... that the prevalence of neurological diseases in modern humans may stem from recent evolutionary changes in genes controlling brain size, connectivity, and function.
Changes in the structure and sequence of these nucleotide arrays likely contributed to changes in CACNA1C function during human evolution and may modulate neuropsychiatric disease risk in modern human populations.
Bipolar disorder and schizophrenia affect 3% of the human population, worldwide. The team identified a human-specific tandem repeat in this region that is often repeated hundreds of times. This large tandem repeat is unstable which may have resulted in its incorrect size in the human reference genome.David Kingsley, Senior author.
Professor of developmental biology at Stanford University.
Professor of developmental biology at Stanford University.
The CACNA1C gene, which controls activity in a key calcium channel, has previously been associated with psychiatric diseases. Different versions of these highly repeated sequences showed different abilities to activate the gene and so regulate these calcium channels. These variations are tightly linked to genetic markers of bipolar disease and schizophrenia disease susceptibility in humans.
These large variations in the DNA sequences associated with the CACNA1C gene are unique to humans so the likelihood is that they are the result of other changes connected with neurological development which were evolutionarily advantageous. Like our bad backs, problem knees and impacted wisdom teeth, the advantages of the changes that cause them outweighed the disadvantages associated with those changes.
In the intelligent (sic) design model, all of this was the intended outcome of an omnipotent, omniscient designer. The reality is that any designer of this system would have to have been either astonishingly inept and oblivious of the consequences, or it was malevolent and intentionally created a system which causes 3% of humans to suffer from serious psychiatric diseases, just as it intended us to have bad back, etc.
Reference:
Song, J., Lowe, C. B., & Kingsley, D. M. (2018).
Characterization of a human-specific tandem repeat associated with bipolar disorder and schizophrenia.
BioRxiv, 311795. https://doi.org/10.1101/311795.
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