human evolution; developing the big brain (Introduction)

by David Turell @, Friday, March 06, 2015, 14:27 (1085 days ago) @ David Turell

Using many modification 'switches' in DNA. Note it required 'thousands' of new (think mutations) modifiers in a relatively short 4-6 million-year period to do this. Not by chance!:

"Thousands of genetic "dimmer" switches, regions of DNA known as regulatory elements, were turned up high during human evolution in the developing cerebral cortex, according to new research from the Yale School of Medicine.
(my bold)
"Unlike in rhesus monkeys and mice, these switches show increased activity in humans, where they may drive the expression of genes in the cerebral cortex, the region of the brain that is involved in conscious thought and language. This difference may explain why the structure and function of that part of the brain is so unique in humans compared to other mammals.

"First, Noonan and his colleagues mapped active regulatory elements in the human genome during the first 12 weeks of cortical development by searching for specific biochemical, or "epigenetic" modifications. They did the same in the developing brains of rhesus monkeys and mice, then compared the three maps to identify those elements that showed greater activity in the developing human brain. They found several thousand regulatory elements that showed increased activity in human.

"Next, they wanted to know the biological impact of those regulatory changes. The team turned to BrainSpan, a freely available digital atlas of gene expression in the brain throughout the human lifespan. (BrainSpan was led by Kavli Institute member Nenad Sestan at Yale, with contributions from Noonan and Pasko Rakic, a co-author on this study.) They used those data to identify groups of genes that showed coordinated expression in the cerebral cortex. They then overlaid the regulatory changes they had found with these groups of genes and identified several biological processes associated with a surprisingly high number of regulatory changes in humans."

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