Exciting new development, reported in Nature Communications, about the discovery of a new gene that arose very quickly, somewhere between 6 million and 1 million years ago, unique to humans. The team includes Martin Taylor from the University of Edinburgh and Philipp Khaitovitch from the Max Planck Institute in Leipzig. as this Physorg piece says: "Scientists say the gene – called miR-941 – appears to have played a crucial role in human brain development and may shed light on how we learned to use tools and language. Researchers say it is the first time that a new gene – carried only by humans and not by apes – has been shown to have a specific function within the human body."
It appears to have been assembled out of a non-coding region of the genome otherwise known as "junk DNA".
Martin Taylor is quoted saying: ""As a species, humans are wonderfully inventive – we are socially and technologically evolving all the time. But this research shows that we are innovating at a genetic level too. This new molecule sprang from nowhere at a time when our species was undergoing dramatic changes: living longer, walking upright, learning how to use tools and how to communicate. We're now hopeful that we will find more new genes that help show what makes us human."
Note that the sequence is actually a micro-RNA, that it seems very involved with cell pluripotency and the brain, and has been formed by evolution of one version of a copy number duplication in the genome. It remains to be seen precisely what effects this gene has in terms of growth in size of the brain, and neuronal organization relevant to the emergence of higher human cognition among our ancestor species several million years ago. What is exciting is that, although much evolution involves changes in the regulation of genes - how hard they work and when, rather than sequence changes in the genes themselves, there may be room in the mix for entirely de novo genes with profound and far-reaching effects. Watch this space!!
Here's the abstract for the Nature article which is open access:
microRnA-mediated gene regulation is important in many physiological processes. Here we explore the roles of a microRnA, miR-941, in human evolution. We find that miR-941 emerged de novo in the human lineage, between six and one million years ago, from an evolutionarily volatile tandem repeat sequence. Its copy-number remains polymorphic in humans and shows a trend for decreasing copy-number with migration out of Africa. Emergence of miR-941 was accompanied by accelerated loss of miR-941-binding sites, presumably to escape regulation. We further show that miR-941 is highly expressed in pluripotent cells, repressed upon differentiation and preferentially targets genes in hedgehog- and insulin-signalling pathways, thus suggesting roles in cellular differentiation. Human-specific effects of miR-941 regulation are detectable in the brain and affect genes involved in neurotransmitter signalling. Taken together, these results implicate miR-941 in human evolution, and provide an example of rapid regulatory evolution in the human linage.
And here is the url for the open access PDF: http://www.nature.com/ncomms/journal/v3/n10/pdf/ncomms2146.pdf