Now here's genetic research made for great headlines! A new research paper is being distilled into news articles along the lines of "scientists now believe the definitive difference between humans and other primates comes down to a single gene." Do they? Does it? If it does, what might that mean, if anything, for faith in Jesus Christ as redeemer of humanity?
He has set eternity in the hearts of men; yet they cannot fathom what God has done from the beginning to the end (Eccl. 3:11). This verse came to mind as I worked my way through the original research article, which is first rate work. Genetics has come so far, so fast. Most of the key discoveries that led to this work were themselves unforeseen until recently. How much more don't we know?
Biological life on Earth manages its daily affairs and reproduces using the molecules DNA and RNA. These are the information hardware and software of life, commonly called genes. Generally, the permanent versions of genes are written in DNA; temporary RNA copies are made for use as instructions to make the gene's product. You hopefully remember this foundation from somewhere. Each discovery since has added complexities. One is that genes often have their RNA cut and edited before the product is made. The cut out RNA pieces are called introns. Introns turn out to be not just throwaways, but sometimes essential genetic machinery.
Hai Yang Hu and his associates are studying microRNA (miRNA). These are very tiny strands of RNA that function as regulatory gene products, mostly to turn other genes off. Their existence as an essential part of genetics was only understood in the last 10 years. Thousands of miRNA have now been found. Some seem universal, and these are remarkably uniform among diverse forms of life.
Some miRNA, however, are unique to a single species: miR-941, which Hu et al. studied, seems to exist only in humans, and was present in each of 29 ethnically diverse human populations from every continent. No primates similar to humans—chimpanzees, gorillas, orangutans, or macaques (rhesus monkeys)—showed evidence of miR-941, nor did representative non-primate animals. In case you missed this, for some time scientists have been retrieving and sequencing DNA from the bones of extinct species or subspecies of humans, such as Neanderthals and Denisovans. Hu and his associates found that DNA sequences of Denisovans also possessed miR-941. (They did not examine Neanderthals.)
What might miR-941 do? It comes from an intron, in this case RNA cut out from a gene for a nerve cell protein. That protein has many functions in the brain, such as release of neurotransmitters allowing communication among nerve cells. Thus, miR-941 is a regulatory product of the very gene its RNA was cut from, and has diverse effects on brain functions. Hu et al. found expression of miR-941 in the prefrontal cortex and the cerebellum of human brains, but not chimpanzee or macaque brains. Since miR-941 is only in humans, it's reasonable to hypothesize it contributes directly to our unique brain and mental development. Some results indicated miR-941 could influence prenatal development. More speculatively, they suggest it might influence genes that aid humans to live longer than other primates.
What might these results mean? This is remarkable work, apparently uncovering an important genetic element unique to human life that wasn't even glimpsed a few years ago. It also isn't a "traditional" gene, producing one to a few protein products, but a tiny RNA that is part of a very complex program involving hundreds of other, different, tiny RNAs and proteins.