Garth wants to know, given the skin can block water from passing through it, how do certain skin creams allege to permeate into our body? James Tytko took on the question with help from Richard Guy, Professor of Pharmaceutical Sciences at the University of Bath... Like this podcast? Please help us by supporting the Naked Scientists

Garth writes in wanting to know why the prevalence of lactose intolerance is nearly 100% in countries like South Korea, but down in the low single digits in countries like the UK. James Tytko asked Mark Thomas, Professor of Evolutionary Genetics at UCL, for the answer... Like this podcast? Please help us by supporting the Naked Scientists

Dan wants to know what the likelihood is of him being here if neither him, his parents, nor his grandparents had had any vaccinations. James Tytko sought to provide an answer, with the help of Helen Bedford, Professor of Children's Health at UCL... Like this podcast? Please help us by supporting the Naked Scientists

Thanks to Philippa Browning for the answer! Like this podcast? Please help us by supporting the Naked Scientists

Bill sends his question in all the way from Australia. A regular listener, he enjoys our programme through bone conduction headphones. But what are these devices, and does listening to loud sounds through them predispose a person to damaging their hearing in the same way as traditional headphones? James Tytko seeks the answers, with help from audiologist Roger Lewin... Like this podcast? Please help us by supporting the Naked Scientists

Kevin wants to know, assuming many of us will be driving electric cars in the future, what will happen to the vast quantities of petrol currently refined from crude oil? Will we scale back production? Or can industry adapt? To help James Tytko with the answer, we hear from Professor Nilay Shah, Director of the Centre for Process Systems Engineering at Imperial College London... Like this podcast? Please help us by supporting the Naked Scientists

George writes in to ask whether his gum-chewing habits are related to his tinnitus, or whether it's just a coincidence that it comes back when he gets back into the habit. James Tytko investigates, with help from ear, nose and throat doctor Malcolm Hilton... Like this podcast? Please help us by supporting the Naked Scientists

In our Question of the Week, Andrew wants to know why many people may experience dreams differently when holidaying in the mountains. To find out what might be behind the 'high-definition' dreams associated with high places, James Tytko sought the help of Andrew Murray, Professor of Metabolic Physiology at the University of Cambridge... Like this podcast? Please help us by supporting the Naked Scientists

Damian wants to know, if at one stage all of the continents were joined together, what was on the other side? Was it all just water? James Tytko investigated whether this was the case, and what the consequences would be for conditions on Earth of one giant global ocean... Like this podcast? Please help us by supporting the Naked Scientists

Dave writes in wanting to know whether there is any way to get nuclear energy onto the grid without heating up water to turn a steam turbine. A great question that sees James Tytko dip his toe into the uranium heated waters of nuclear engineering... Like this podcast? Please help us by supporting the Naked Scientists

David wants to know, after looking at distant galaxies in the night sky, how long it took to create them. James Tytko took on the question with the help of the University of Cambridge's Public Astronomer, Matt Bothwell... Like this podcast? Please help us by supporting the Naked Scientists

Parasites have to come up with all sorts of tricks to evade the immune system of their hosts. But Kate wants to know, how do they know they've found the right place? James Tytko took her question on with help from Catherine Merrick, professor of parisitology at the University of Cambridge... Like this podcast? Please help us by supporting the Naked Scientists

Thanks to Cambridge University's Andy Wheeler for the answer! Like this podcast? Please help us by supporting the Naked Scientists

Rick wants to know why the Canada geese he's been observing, who are preparing to migrate for the winter, are honking so incessantly while flying in formation. Viola Ross-Smith from the British Trust for Ornithology was on hand to help James Tytko with the answer... Like this podcast? Please help us by supporting the Naked Scientists

Van writes in with, 'A friend is encouraging me to take a cancer screening test that screens for many different cancers. A review of one test says: "While overall it picks up 90% of stage 4 cancers, it only detects an average of 17% of stage 1 cancers. Yet it is being touted as a test that can detect cancer early." Are these tests worthwhile?' James Tytko took on the question with the help of Professor Rebecca Fitzgerald, Founding Director of the Early Detection Institute at the University of Cambridge... Like this podcast? Please help us by supporting the Naked Scientists

If dinosaurs hadn't been wiped out by a mass extinction event, would there have been room for humans to grow into the successful species we are today? That's what Colin wants to know, and James Tytko has promised to find the answer. He spoke with Dr Charlotte Kenchington from the University of Cambridge's Department of Earth Sciences... Like this podcast? Please help us by supporting the Naked Scientists

Pamela wants to know whether the distribution of chemical isotopes is the same on other planets as it is on Earth. Take carbon, for example, 99% of which is carbon-12 on Earth while 1% is carbon-13? To find the answer, James Tytko asked Xander Byrne from the University of Cambridge's Institute of Astronomy... Like this podcast? Please help us by supporting the Naked Scientists

David wants to know whether the intricate and varied spiders' webs seen in nature are a product of arachnid instinct, or something that is cultivated across their life. To get to the truth, James Tytko sought out spider expert Professor Sara Goodacre from the University of Nottingham... Like this podcast? Please help us by supporting the Naked Scientists

Jim writes in to say, 'Sometimes when I pinch near my knee, I will feel a tingling or tickling sensation behind one of my shoulder blades. What's up with that?' James Tytko found him an answer, with help from neuroscientist Dr Mark Hoon from the NIH... Like this podcast? Please help us by supporting the Naked Scientists

Oscar asks whether the snail stuck on the inside of his car wheel while he went for a drive would have felt the effects afterwards. Jon Ablett from the Natural History Museum helped James Tytko with the answer... Like this podcast? Please help us by supporting the Naked Scientists