BBC Inside Science

The Hubble Constant The Hubble constant is the current expansion rate of the universe but it seems to have changed over time. Hiranya Peiris, Professor of Astrophysics from University College London and Adam Riess, Professor of Physics and Astronomy from Johns Hopkins University, are both using different methods to obtain a value for the Hubble constant. But there is a discrepancy in their values. It used to be that the error bars on the two values overlapped, and so cosmologists thought they would converge as the experiments got more precise. But instead, as the error bars have shrunk, the discrepancy is getting more serious, and something must be wrong. They chat to Adam about potential reasons for this difference in calculations and what it could mean for our cosmological model of the universe. Is new physics required to evolve the description of the age of the universe as we know it to be more accurate? A synthetic E. Coli genome Jason Chin and Colleagues at the Laboratory of Molecular Biology in Cambridge have published this week in the Journal Nature their latest work to completely synthesise a new genome of an E. coli bacteria. Not only was the genome designed and manufactured by human means, it was also recoded in a way not used by nature, involving some 18000 edits. In natural DNA, several different codes can do the same job. As Roland Pease reports, the new genome instead uses fewer of these duplicates, demonstrating all sorts of possibilities for future designs of synthetic cells. Von Humboldt Friedrich Wilhelm Heinrich Alexander von Humboldt was a celebrated Prussian geographer, naturalist and explorer. He influenced Darwin and was the first person to describe human-induced climate change, based on his observations from his travels. Yet he has slipped into relative obscurity, at least in the English-speaking world. Andrea Wulf is an acclaimed author who has previously written about Alexander von Humboldt and is now back with another book about the explorer: The Adventures of Alexander von Humboldt. It’s a graphic novel (illustrated by Lillian Melcher) that celebrates the 250th anniversary of Humboldt’s birth and depicts his adventures on his 5 year expedition through South America. Adam Rutherford chats to Andrea about her book, why she chose to make it a graphic novel and how Humboldt’s views on the environment can be interpreted today. Producer: Alex Mansfield

A damning House of Lords' report into the provision of forensic science in England and Wales makes for uncomfortable reading for some but is broadly welcomed by those in the field. Prof. Niamh Nic Daeid, one of many who gave evidence to the Science and Technology Committee, gives her reaction and suggests how a combination of unsatisfactory regulation, profit and austerity pressures in a uniquely commercialised sector, and some surprising gaps in the science knowledge base has lead to a sorry situation. Spring has sprung and it's probably not too late to get the tomato plants in, but should you water them little and often, or more but less often? Madeleine Finlay reports from Wisley, where The Royal Horticultural Society's Janet Manning has set up a new experiment this year to answer that question. Janet is the first Garden Water Scientist at the RHS, and hopes to demonstrate that giving plants less frequent, but more generous, bouts of hydration encourages deeper root growth, building in resilience for those periods when water is harder to come by whilst also allowing gardeners ultimately to use less. Do you have a fabella? Or maybe two fabellae? Michael Berthaume, "Anthroengineer" at Imperial College London tells us about a curiously under-studied bone that some people have in their knees. Present in certain primates and quadruped mammals, but thought to have disappeared from human anatomy, it seems to have made a bit of a comeback in certain populations around the world over the last century or so. Quite why, quite how, and quite what it's for, seems something of a mystery.

In 2018, the International Association of Athletics Federations (IAAF) introduced new eligibility regulations for female athletes with differences in sex development (DSDs). These regulations are based on the contention that women with high levels of endogenous testosterone and androgen sensitivity have a performance advantage over their peers. South African middle distance runner, Mokgadi Caster Semenya, who won two Olympic gold medals in 2012 and 2016, and Athletics South Africa, are contesting the legality of these new regulations. The basis of their objection, at the Court of Arbitration for Sport, is that there is a lack of scientific evidence showing that endogenous testosterone concentrations substantially enhance sports performance. Caster, who is DSD herself, has lost her case and Adam turns to expert in sport, exercise and genomics at Manchester Metropolitan University, Dr. Alun Williams to explain the implications. Less than a decade ago, an entirely new branch of the ancient human tree was discovered. These new hominins were named the Denisovans, after the Denisova cave in the Altai Mountains in Siberia where fragments of finger bone and teeth were discovered, and genetic sequencing of a finger bone revealed that they were a new hominin group, an extinct sister group to Neanderthals. This exciting find contained a tantalising puzzle. Traces of Denisovan DNA are found in modern-day population groups like Sherpas, Tibetans and some other neighbouring populations and this includes genetic variants which help them to survive at high altitudes where the oxygen levels are low. The original Denisovan cave is only around 700 metres, so why would such an adaptation be necessary at these altitudes? This week a new paper in Nature slots a big piece into the puzzle. Teams from the Institute of Tibetan Plateau Research and the Max Planck Institute for Evolutionary Biology have found another Denisovan fossil – this time a mandible, a lower jawbone, still containing teeth – from the vast Tibetan plateau in China. At 2.3 Km above sea level, it’s very high and the air is thin, and 160,000 years ago, which is when the fossil has been dated to, it would have been a very challenging place to live indeed. In fact this jawbone is the earliest known hominin fossil found on this enormous plateau. Adam calls in Professor Fred Spoor, from the Centre for Human Evolution Research at the Natural History Museum in London, to examine the facts and to see if we can work out how far and wide these hominins travelled. Producer: Fiona Roberts

Patients who suffer neurological impairments preventing them from speaking potentially face a severely limited existence. Being able to express yourself in real time is a large part of our identity. In the journal Nature this week, scientists from the University of California, San Francisco, report a new technique for synthesising speech based on measurements of neural signals taken from the brain. Author Dr Gopala Anumanchipalli tells Adam about how this proof of principle could one day form the basis for a speech prosthesis for patients who have lost the ability to converse. Around the world this weekend (April 26th-29th 2019) people are being encouraged to participate in the City Nature Challenge, a global effort to catalogue urban wildlife using a free mobile app. Reporter Geoff Marsh travelled to the California Academy of Sciences, home of the initiative, to meet those behind it and how we might all take part. The third act in our drama is a chat with journalist and writer Will Storr about his new book - the Science of Storytelling - which explores the structure of stories with relation to our evolution and brain structure. Primeval instincts of expectation, subversion and causation intertwine with camp-fire sagas from the beginning of conversation. What can this science of storytelling contribute to the art of telling stories about science? A ripping yarn indeed. Producer: Alex Mansfield

The horror of the blazing Notre-Dame cathedral in Paris has been slightly quenched by the fact that so much of the French landmark has been saved. But what was it about the structure of the roof, with some the beams dating from the 13th century, that meant it burned like a well-stacked bonfire? Guillermo Rein is Professor of Fire Science at Imperial College London , and he explains to Adam Rutherford how wood burns and how it was the intricate mixture of large and small beams, and very poor fire protection measures that made the iconic roof, so vulnerable. An experiment to see whether isolated dead pig brains could be preserved at the cellular level in order to study post mortem brains, had a surprising outcome. The BrainEx technology of perfusing the brains with chemicals that should have just halted the rapid degradation of cellular structure in the brain, that occurs soon after death, actually caused them to start firing neurons, reacting to drugs and generally behaving as if they were alive. Although, it has to be stressed, there was no whole-brain connectivity or consciousness achieved, it does raise ethical questions about death, if this method was to be developed for use in humans. Bioethicist at Kings College London, Silvia Camporesi explores the facts that reveal that death is a process rather than a single event and what this might mean for patients that are diagnosed as brain dead. Where is the Martian methane? This is the question Mannish Patel at the Open University has been left pondering after the ExoMars Trace Gas Orbiter came up empty handed in detecting the gas on Mars. Methane could be a signature of past of present life on the Red Planet, it's been measured by NASA's Curiosity rover and by telescopes on Earth, but the far more sensitive and specialised TGO has so far failed to detect the gas. It could be because methane levels in the thin Martian atmosphere is a seasonal event, we'll just have to ait for an entire Martian year of surveys to be able to solve this mystery. Our faces are incredibly important in our lives, we feed through them, they are the conduit for our sensory interaction with the universe, via smell, hearing and vision; we speak, and we convey the subtlest emotions with a raised eyebrow, a wry smile, a clenched jaw or eyes wide open. It is the central importance of these features that has meant we’ve been intensively studying the evolution of the face for decades, to work out why we look the way we do, and how much of our looks reflects adaptations that enhanced our survival, and how much is just down to quirks of evolution. Anatomist, Paul O’Higgins from York University is interested in how all that has influenced our faces. Producer: Fiona Roberts