The human genome.
Here's the old model. The genome - our DNA - is vitally important because the genes code for the proteins that are essential for life.
Well yes, that's true. And if you like your ice cream only in vanilla, this may be a good enough description.
But allow your taste buds to wander and some fascinating new flavours may seduce you.
There are lots of situations where two things are genetically identical, but which aren't the same. This is the field of epigenetics, and it tells us that there must be more to us than just our DNA code. The science is weird, heretical and fascinating.
If the genes that code for proteins are so important, why do they comprise only 2% of the human genome? For years, the rest was dismissed as unimportant "junk DNA". But now we know that these neglected regions have a huge range of important functions.
Both epigenetics and junk DNA affect huge amounts of life on earth and have a big impact on human health.
I'm the author of The Epigenetics Revolution and Junk DNA: A Journey Through The Dark Matter Of The Genome, books aimed at a non-specialist readership, which discuss the amazing biology behind so much of life around us.
Go on, dive in. You won't regret it. And you won't think about the world in the same way ever again.