Seems counter intuitive at first! We are distinctly human for what minute genetic sequences we lost in evolution!😊 Genetics is almost like a lottery you gain some, you loose some as time goes by. In the not so distant future, we will be able to take evolution into our own hands!
As I have written here before, I propose the sneezing gene to be deleted immediately. Sneezing is so annoying and occasionally contagious!
"What the human genome is lacking compared with the genomes of other primates might have been as crucial to the development of humankind as what has been added during our evolutionary history ...
In their study, the Yale team found that some genetic sequences found in the genomes of most other mammal species, from mice to whales, vanished in humans. But rather than disrupt human biology, they say, some of these deletions created new genetic encodings that eliminated elements that would normally turn genes off. ..."
In their study, the Yale team found that some genetic sequences found in the genomes of most other mammal species, from mice to whales, vanished in humans. But rather than disrupt human biology, they say, some of these deletions created new genetic encodings that eliminated elements that would normally turn genes off. ..."
From the abstract:
"INTRODUCTION
Deciphering the molecular and genetic changes that differentiate humans from our closest primate relatives is critical for understanding our origins. Although earlier studies have prioritized how newly gained genetic sequences or variations have contributed to evolutionary innovation, the role of sequence loss has been less appreciated. Alterations in evolutionary conserved regions that are enriched for biological function could be particularly more likely to have phenotypic effects. We thus sought to identify and characterize sequences that have been conserved across evolution, but are then surprisingly lost in all humans. These human-specific deletions in conserved regions (hCONDELs) may play an important role in uniquely human traits.
RATIONALE
Sequencing advancements have identified millions of genetic changes between chimpanzee and human genomes; however, the functional impacts of the ~1 to 5% difference between our species is largely unknown. hCONDELs are one class of these predominantly noncoding sequence changes. Although large hCONDELs (>1 kb) have been previously identified, the vast majority of all hCONDELs (95.7%) are small (<20 base pairs) and have not yet been functionally assessed. We adapted massively parallel reporter assays (MPRAs) to characterize the effects of thousands of these small hCONDELs and uncovered hundreds with functional effects. By understanding the effects of these hCONDELs, we can gain insight into the mechanistic patterns driving evolution in the human genome.
RESULTS
We identified 10,032 hCONDELs by examining conserved regions across diverse vertebrate genomes and overlapping with confidently annotated, human-specific fixed deletions. We found that these hCONDELs are enriched to delete conserved sequences originating from stem amniotes. Overlap with transcriptional, epigenomic, and phenotypic datasets all implicate neuronal and cognitive functional impacts. We characterized these hCONDELs using MPRA in six different human cell types, including induced pluripotent stem cell–derived neural progenitor cells. We found that 800 hCONDELs displayed species-specific regulatory effect effects. Although many hCONDELs perturb transcription factor–binding sites in active enhancers, we estimate that 30% create or improve binding sites, including activators and repressors.
Some hCONDELs exhibit molecular functions that affect core neurodevelopmental genes. One hCONDEL removes a single base in an active enhancer in the neurogenesis gene HDAC5, and another deletes six bases in an alternative promoter of PPP2CA, a gene that regulates neuronal signaling. We deeply characterized an hCONDEL in a putative regulatory element of LOXL2, a gene that controls neuronal differentiation. Using genome engineering to reintroduce the conserved chimpanzee sequence into human cells, we confirmed that the human deletion alters transcriptional output of LOXL2. Single-cell RNA sequencing of these cells uncovered a cascade of myelination and synaptic function–related transcriptional changes induced by the hCONDEL.
CONCLUSION
Our identification of hundreds of hCONDELs with functional impacts reveals new molecular changes that may have shaped our unique biological lineage. These hCONDELs display predicted functions in a variety of biological systems but are especially enriched for function in neuronal tissue. Many hCONDELs induced gains of regulatory activity, a surprising discovery given that deletions of conserved bases are commonly thought to abrogate function. Our work provides a paradigm for the characterization of nucleotide changes shaping species-specific biology across humans or other animals."
The functional and evolutionary impacts of human-specific deletions in conserved elements (no public access)
Human-specific deletions that remove nucleotides from regions highly conserved in other animals (hCONDELs).
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