Hubisz and Pollard recently reviewed the [recent] history and current state of research on Human Accelerated Regions (HARs). Since 2006 a series of studies have emerged regarding the discovery and exploration of HARs, regions of the human genome that have undergone rapid changes since our divergence from chimpanzees that are widely conserved in non-human organisms.
This methodological approach is distinct from positive selection studies which test for phylogenetic changes in the ratio of synonymous to non-synonymous mutations (dN/dS). In fact, as 96.6% of HARs are non-coding (ncHARs) and tend to cluster near genes, their function appears to be almost entirely regulatory. Many of these nearby genes are developmental transcription factors, and/or expressed in the central nervous system. These findings supports previous assertions that most of the morphological and cognitive differences between humans and non-human apes are regulatory in nature. By applying these same methods to the study of ancient DNA, it was also found that "7.1% of human–chimp differences in ncHARs occurred after divergence from archaic hominins [Neanderthals and Denisovans]."
That said, many ncHARs have not yet been annotated or lack experimentally established functions. Future exploration of these regions using transgenic animals models therefore hold promise in the search for what makes humans the way they are.
This methodological approach is distinct from positive selection studies which test for phylogenetic changes in the ratio of synonymous to non-synonymous mutations (dN/dS). In fact, as 96.6% of HARs are non-coding (ncHARs) and tend to cluster near genes, their function appears to be almost entirely regulatory. Many of these nearby genes are developmental transcription factors, and/or expressed in the central nervous system. These findings supports previous assertions that most of the morphological and cognitive differences between humans and non-human apes are regulatory in nature. By applying these same methods to the study of ancient DNA, it was also found that "7.1% of human–chimp differences in ncHARs occurred after divergence from archaic hominins [Neanderthals and Denisovans]."
That said, many ncHARs have not yet been annotated or lack experimentally established functions. Future exploration of these regions using transgenic animals models therefore hold promise in the search for what makes humans the way they are.
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