7 March 2018
Dark DNA: The missing matter at the heart of nature
The discovery that some animals thrive despite hugely mutated DNA hidden in their genome is forcing us to rethink some basics of evolution
THE fat sand rat is a strange creature. It lives in burrows, eats around 80 per cent of its body mass in leaves each day and doesn’t drink water. But the really odd thing about this gerbil is that some of its DNA appears to be missing.
No doubt you have heard of dark matter, which is thought to make up over a quarter of the universe. We know it’s there; we just haven’t been able to detect it. Well, something similar is afoot in the genome. My colleagues and I have dubbed this elusive genetic matter “dark DNA”. And our investigations into the sand rat are starting to reveal its nature.
The discovery of dark DNA is so recent that we are still trying to work out how widespread it is and whether it benefits those species that possess it. However, its very existence raises some fundamental questions about genetics and evolution. We may need to look again at how adaptation occurs at the molecular level. Controversially, dark DNA might even be a driving force of evolution.
The sand rat (Psammomys obesus) is a desert species native to North Africa and the Middle East, but put it in a lab and something strange happens. When fed a “normal” diet – the standard fare for laboratory rodents – sand rats tend to become obese and develop type 2 diabetes. This was discovered in the 1960s, and has made sand rats the focus of study for biologists interested in understanding nutrition-induced diabetes in humans. Yet, in all that time, the mystery of why these gerbils are …