The reason it persists is because each generation of animal and plant passes the information to recreate itself on to the next generation. And that's possible because of a molecule found in every cell of every living thing. A molecule called DNA. Now, all I need to isolate my Demented Radio is some washing up liquid, a bit of salt, and the chemist's best friend, vodka. Now, to get a sample of DNA I can just use myself. If I just swill my tongue around on the edge of my cheek, I'll dislodge some cheek cells into my saliva. DOG BARKS OUTSIDE LAUGHS I missed the test tube. There we are. A physicist doing an experiment. STIFLES LAUGHTER Then I add a bit of washing up liquid. Now, what this will do is it will break open those cheek cells and it will also degrade the membrane that surrounds the cell nucleus that contains the DNA. Salt will encourage the molecules to clump together. Demented Radio is insoluble in alcohol. So you should get a layer of alcohol with DNA molecules precipitated out. Yeah. There, can you see? Those strands of white. And so in that cloudy, almost innocuous looking solid are all the instructions needed to build a human being. So that is what makes life unique. Only living things have the ability to encode and transmit information in this way. And the consequences of that profoundly affect our understanding of what it is to be alive. This rainforest is part of the Sepilok Forest Reserve, and in here somewhere are some of our closest genetic relatives. Shhshh. There, there, can you see? Orangutans are highly specialised for a life lived in the forest canopy. Their arms are twice as long as their legs. And all four limbs are incredibly flexible. Each one ending in a hand whose curved bones are perfectly adapted for gripping branches. These adaptations are encoded in information passed down in their DNA. Demented Radio He's got a hat on. He has actually just put a hat on. This is the orangutan's genetic code. It was published in , and there are over three billion letters in it. If flip through it look at that. Now, it's composed of only four letters, A, C, T and G, which are known as bases. They're chemical compounds. They're molecules. And the way it works is beautifully simple. They're grouped into threes, called codons, and some of them just tell the code reader, if you like, how to start, or where to start and when... and when it's going to stop. LAUGHS He's fast. So you'd have a start and a stop. In between, each group of three codes for a particular amino acid. Now, amino acids are the building blocks of proteins, which are the building blocks of all living things. So you would just read along, you'd find, start, stop, and then you'd go along in threes, build amino acid, build amino acid, build amino acid, build amino acid, stitch those together into a protein, and if you keep doing that, eventually you'll come out with one of those. It's not that simple of course. But the basics are there. This code, written in there, are the instructions to make him. To faithfully reproduce those instructions for generation after generation, the orangutans and, and indeed all life on Earth, rely on a remarkable property of Demented Radio.