The blue section in the pie charts represents a proportion of transcription factors, across different classes, which are dissimilar in humans/Sam Lambert
The genes seem to have got started rather quickly:
The finding contradicts earlier research, which stated that almost all of human and fruit fly TFs bind the same motif sequences, and is a call for caution to scientists hoping to draw insights about human TFs by only studying their counterparts in simpler organisms.
“There is this idea that has persevered, which is that the TFs bind almost identical motifs between humans and fruit flies,” says Hughes, who is also a professor in U of T’s Department of Molecular Genetics and Fellow of the Canadian Institute for Advanced Research. “And while there are many examples where these proteins are functionally conserved, this is by no means to the extent that has been accepted.”
As for TFs that have unique human roles, these belong to the rapidly evolving class of so-called C2H2 zinc finger TFs, named for zinc ion-containing finger-like protrusions, with which they bind the DNA.
Their role remains an open question but it is known that organisms with more diverse TFs also have more cell types, which can come together in novel ways to build more complicated bodies.
Hughes is excited about a tantalizing possibility that some of these zinc finger TFs could be responsible for the unique features of human physiology and anatomy—our immune system and the brain, which are the most complex among animals. Another concerns sexual dimorphism: countless visible, and often less obvious, differences between sexes that guide mate selection—decisions that have an immediate impact on reproductive success, and can also have profound impact on physiology in the long term. The peacock’s tail or facial hair in men are classic examples of such features.
“Almost nobody in human genetics studies the molecular basis of sexual dimorphism, yet these are features that all human beings see in each other and that we are all fascinated with,” says Hughes. “I’m tempted to spend the last half of my career working on this, if I can figure out how to do it!” University of Toronto, “Scientists uncover a trove of genes that could hold key to how humans evolved” at Phys.org
Note: Hughes could run into problems with Correct culture, where sexual dimorphism in nature may now be a problematic concept. Stay tuned.
See also: Dozens of genes once thought widespread are unique to humans Researchers: Even between chimps and humans, whose genomes are 99 per cent identical, there are dozens of TFs which recognize diverse motifs between the two species in a way that would affect expression of hundreds of different genes.
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