155 newly identified genes reveal humans are continuously evolving
Are humans still evolving? This question is a mystery for many, as about seven million years have passed since humans left the chimpanzee lineage. The factors that forced us to adapt, evolve, and survive harsh environments in the past are no longer relevant.
Today, humans have much longer lifespans and advanced healthcare facilities at their disposal. We live in a comfortable and protected environment almost all the time. The external factors (also known as selection pressures) that previously kept us in continuous survival mode don't affect us anymore.
So does that mean we have stopped evolving?
A team of researchers from Trinity College Dublin (TCD) and Alexander Fleming Biomedical Sciences Research Center (BSRC Fleming) in Greece explored this question in detail. Interestingly, they came across 155 new genes in the human lineage during their study. These newly discovered genes strongly suggest that humans are still continuously evolving.
Secrets linked to the new genes
The researchers argue that new genes in the human genome can also form as a result of DNA duplication. However, this is not the case with the newly identified 155 genes. They examined the genes with regard to their connections with existing genetic material and found that the genes are completely novel.
They emerged from segments of unique DNA. The significance of these new genes can be understood from the fact that 44 out of the 155 genes were found to be linked to growth anomalies in cell cultures.
So they could help us spot growth defects and ensure the optimum health of living systems. The patterns in the unique DNA also suggested that the new genes could also be associated with various human-specific diseases.
For instance, the researchers noticed three genes with DNA markers related to disorders such as rod-cone dystrophy(an eye disorder that causes the retina to break over time, eventually making a person blind), Alazami syndrome (leads to impaired physical and intellectual development), and muscular dystrophy.
The authors suggested that one particular gene of this new collection originated in humans as soon as our ancestors broke out from the gorilla lineage. This gene is now linked to human heart tissue development.
While highlighting the importance of the newly identified genes, senior author and geneticist at TCD, Aoife McLysaght, said, "These genes are convenient to ignore because they're so difficult to study, but I think it'll be increasingly recognized that they need to be looked at and considered. If we're right in what we think we have here, there's a lot more functionally relevant stuff hidden in the human genome."
New genes and adaptations are signs of evolution
Evolution is basically the change in our behavior, physiology, and genetic makeup from previous generations. Interestingly, the current study is not the only research work that proves that humans are continuously evolving. There have been various studies in the past that shed light on the ongoing evolutionary changes.
For instance, in 2016, a group of scientists at Cornell University discovered that many people in Pune, India, who (and their previous generations) have been eating only vegetarian diets, have undergone a mutation of the FADS2 (Fatty Acid Desaturase 2) gene.
This particular mutation allows their body to turn omega fatty acids into brain-nourishing nutrients. Such mutations were not observed in meat-eaters or people who consume an omnivorous diet.
A 2020 study from Stanford University reveals that in the last 150 years, the average human body temperature has changed from 37°C (98.6°F) to 36°C (97.9°F). According to NASA, Earth's mean temperature has raised by 1.1° C (1.9° F) during the same years.
There are many other research works that indicate various other new developments in the human body and genome. All these new adaptations, new changes, and new genes are strong evidence suggesting that human evolution is still going on.
The newly discovered 155 genes also have ample amounts of unexplored information about human genetics. Therefore, the current study is a big step towards identifying and studying the changes we are likely to go through in the future.
Lead author and Junior investigator at BSRC Fleming, Nikolaos Vakirlis, said, "It will be very interesting in future studies to understand what these micro-genes might do and whether they might be directly involved in any kind of disease."
The study is published in the journal Cell Reports.
Small open reading frames (sORFs) can encode functional "microproteins" that perform crucial biological tasks. However, their size makes them less amenable to genomic analysis, and their origins and conservation are poorly understood. Given their short length, it is plausible that some of these functional microproteins have recently originated entirely de novo from noncoding sequences. Here we sought to identify such cases in the human lineage by reconstructing the evolutionary origins of human microproteins previously found to have measurable, statistically significant fitness effects. By tracing the formation of each ORF and its transcriptional activation, we show that novel microproteins with significant phenotypic effects have emerged de novo throughout animal evolution, including two after the human-chimpanzee split. Notably, traditional methods for assessing coding potential would miss most of these cases. This evidence demonstrates that the functional potential intrinsic to sORFs can be relatively rapidly and frequently realized through de novo gene emergence.
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