We have an extraordinary relationship with dogs - closer than with any other animal on the planet. But what makes the bond between us so special? Research into dogs is gaining momentum, and scientists are investigating them like never before. From the latest fossil evidence, to the sequencing of the canine genome, to cognitive experiments, dogs are fast turning into the new chimps as a window into understanding ourselves. Where does this relationship come from? In Siberia, a unique breeding experiment reveals the astonishing secret of how dogs evolved from wolves. Swedish scientists demonstrate how the human/dog bond is controlled by a powerful hormone also responsible for bonding mothers to their babies. Why are dogs so good at reading our emotions? Horizon meets Betsy, the world's most intelligent dog, and compares her incredible abilities to those of children. Man's best friend has recently gone one step further - helping us identify genes responsible for causing human dise

Just months ago, the world stood in fear of an emerging new disease that threatened to kill millions. A new flu variant H1N1 had arrived. In the UK alone, 65,000 deaths were predicted. Yet to date, these dire warnings have not materialised. If this latest pandemic has taught anything, it is just how little is understood about the invisible world of viruses. But that has not stopped scientists trying. Horizon follows the leading researchers from across the world, who are attempting to unravel the many secrets of viruses to understand when and why they kill.

Over a person's lifetime they are likely to be prescribed more than 14,000 pills. Antibiotics, cholesterol lowering tablets, anti-depressants, painkillers, even tablets to extend youth and improve performance in bed. These drugs perform minor miracles day after day, but how much is really known about them? Drug discovery often owes as much to serendipity as to science, and that means much is learnt about how medicines work, or even what they do, when they're taken. By investigating some of the most popular pills people pop, Horizon asks, how much can they be trusted to do what they are supposed to?

For centuries scientists have been attempting to come up with an elixir of youth. Now remarkable discoveries are suggesting that ageing is something flexible that can ultimately be manipulated. Horizon meets the scientists who are attempting to piece together why we age and more vitally for all of us, what we can do to prevent it. But which theory will prevail? Does the 95-year-old woman who smokes two packets of cigarettes a day hold the clue? Do blueberries really delay signs of ageing or is it more a question of attitude? Does the real key to controlling how we age lie with a five-year-old boy with an extraordinary ageing disease or with a self-experimenting Harvard professor? Could one of these breakthroughs really see our lives extend past 120 years?

By our third year, most of us will have learned to count. Once we know how, it seems as if there would be nothing to stop us counting forever. But, while infinity might seem like an perfectly innocent idea, keep counting and you enter a paradoxical world where nothing is as it seems. Mathematicians have discovered there are infinitely many infinities, each one infinitely bigger than the last. And if the universe goes on forever, the consequences are even more bizarre. In an infinite universe, there are infinitely many copies of the Earth and infinitely many copies of you. Older than time, bigger than the universe and stranger than fiction. This is the story of infinity.

Could you have come up with Einstein's theory of relativity? If not - why not? This is what Marcus du Sautoy, professor of mathematics, wants to explore. Marcus readily admits that he is no genius, but wants to know if geniuses are just an extreme version of himself - or whether their brains are fundamentally different. Marcus meets some remarkable individuals - Tommy, an obsessive artist who uses his whole house as his canvas; Derek: blind, autistic, and a pianist with apparently prodigious gifts; Claire who is also blind, but whose brain has learnt to see using sound. Marcus is shown how babies have remarkable abilities which most of us lose as teenagers. He meets a neuroscientist who claims he has evidence of innate ability, a scientist who's identified a gene for learning, and Dr. Paulus, who has discovered how to sharpen the brain... by electrically turbo-charging it.

Horizon examines the evidence that our ancestors' changing diet and mastery of fire prompted anatomical and neurological changes that took us out of the trees and into the kitchen.

There's something very odd going on in space - something that shouldn't be possible. It is as though vast swathes of the universe are being hoovered up by a vast and unseen celestial vacuum cleaner. Sasha Kaslinsky, the scientist who discovered the phenomenon, is understandably nervous: 'It left us quite unsettled and jittery' he says, 'because this is not something we planned to find'. The accidental discovery of what is ominously being called 'dark flow' not only has implications for the destinies of large numbers of galaxies - it also means that large numbers of scientists might have to find a new way of understanding the universe. Dark flow is the latest in a long line of phenomena that have threatened to rewrite the textbooks. Does it herald a new era of understanding, or does it simply mean that everything we know about the universe is wrong?

Dr Kevin Fong investigates a technique that is used to bring people back from the dead.

Sir David Attenborough reveals the findings of one of the most ambitious scientific studies of our time - an investigation into what is happening to our oceans. He looks at whether it is too late to save their remarkable biodiversity. Horizon travels from the cold waters of the North Atlantic to the tropical waters of the Great Barrier Reef to meet the scientists who are transforming our understanding of this unique habitat. Attenborough explores some of the ways in which we are affecting marine life - from over-fishing to the acidification of sea water. The film also uncovers the disturbing story of how shipping noise is deafening whales and dolphins, affecting their survival in the future.

They are the biggest questions that science can possibly ask: where did everything in our universe come from? How did it all begin? For nearly a hundred years, we thought we had the answer: a big bang some 14 billion years ago. But now some scientists believe that was not really the beginning. Our universe may have had a life before this violent moment of creation. Horizon takes the ultimate trip into the unknown, to explore a dizzying world of cosmic bounces, rips and multiple universes, and finds out what happened before the big bang.

Horizon explores the strange and wonderful world of illusions - and reveals the tricks they play on our senses and why they fool us. We show how easy it is to trick your sense of taste by changing the colours of food and drink, explain how what you see can change what you hear, and see just how unreliable our sense of colour can be. But all this trickery has a serious purpose. It's helping scientists to create a new understanding of how our senses work - not as individual senses, but connected together.

A decade ago, scientists announced that they had produced the first draft of the human genome, the 3.6 billion letters of our genetic code. It was seen as one of the greatest scientific achievements of our age, a breakthrough that would usher in a new age of medicine. A decade later, Horizon finds out how close we are to developing the life-changing treatments that were hoped for.

Famed for their ability to inflict Armageddon from outer space, asteroids are now revealing the secrets of how they are responsible for both life and death on our planet.

Horizon reveals the untold story of the 87-day battle to kill the Deepwater Horizon oil blowout a mile beneath the waves - a crisis that became America's worst environmental disaster. Engineers and oil men at the heart of the operation talk for the first time about the colossal engineering challenges they faced and how they had to improvise under extreme pressure. They tell of how they used household junk, discarded steel boxes and giant underwater cutting shears to stop the oil. It's an operation that one insider likens to the rescue of Apollo 13.