The new 2017/18 season is fast approaching, but before we reveal the new Programme we are taking a look back on the past year's events to see what gave us food for thought in 2016 and 2017.
2016/17 Science & Technology Lectures
The lecture series started early (8th September) to take advantage of the agronomist Jonathan Gressel’s presence in the UK for an editorial board meeting. Professor Gressel, of the Weizmann Institute in Israel, spoke to Hammering Two New Nails in Malthus’ Coffin with Genetic Engineering. He explained how modern crops were the result of millennia of selective breeding, and now lacked the genes that could be manipulated for desirable qualities: consequently, major strain improvement could come only from the transfer of genes from other organisms (“horizontal transfer”). He gave a number of examples where strains were improved for nutrition and pest resistance. He pointed out that the molecular changes involved in conventional plant breeding (e.g. with irradiation of seeds) were bigger than the targeted changes to produce transgenics, and that horizontal transfer took place in Nature anyway.
Professor Stephen Scott (18th October), the discoverer (as a PhD student) of periodic reactions in the gas phase comparable to the Belousov-Zhabotinsky reaction in solution, spoke about 35 Years of Chaos – Have we learned anything important? He concentrated on his own gas-phase work and reminded us how powerful paper-and-pencil methods had become just before high-powered desktop computing became generally available.
Professor Joanna Haigh, CBE FRS (Imperial College), talked on Climate Change on 1st December. She gave a masterly treatment of the basic physics involved in the greenhouse effect of carbon dioxide and other gases, and an objective account of anthropogenic changes. There was a clear comparison of the measured emission spectrum of the earth with the theoretical curve for a black body at 21oC. The measured spectrum had a large “bite” around 670 cm-1 corresponding to the bending vibration of CO2, and smaller bites corresponding to methane. Emission did not fall to zero at 670 cm-1, refuting climate sceptic arguments that the earth’s atmosphere is already black at this wavelength, and will not respond to additional CO2. Despite the intrinsic difficulty of the subject, Professor Haigh held her audience until the end of her lecture, after which there was a protracted, interested and cordial question session.
Dr. Eamonn Kerins (Jodrell Bank) displayed some of the most beautiful slides of the year. In his talk on 13th February about An Astrophysicists Guide to Curtain Twitching – the hunt for exoplanets and our interstellar neighbours he described the four methods used, all of which depended on very precise measurements of a star’s luminosity. The most powerful method (gravitational lensing, involving the simultaneous observation of 108 pairs of stars, required major advances in IT before it became practical. The work could only be carried out at the Southern Observatory in the Andes, where there was no light pollution and the air was very dry. It turns out that many exoplanets can be detected, some orbiting two stars rather than one: there are even planets not attached to a particular star. The idea that the Earth is a uniquely fitted for the evolution of Life is wrong. Enrico Fermi’s question about extra-terrestrial conscious life – “Where are they?” now requires an answer, since Fermi estimated that it would take only a few million years for an advanced civilisation to traverse the Milky Way. After the talk, Dr Kerins had to be rescued from a crowd of enthusiastic members and guests who seemed able to ask unlimited numbers of friendly questions.
Mr. Robert Harris, the acoustic designer of Manchester’s Bridgewater Hall, talked on 30th March on The Art and Science of Concert Hall and Opera House Design. Surprisingly, the dominant phenomenon in the experience of sound in a concert setting is reflection, rather than diffraction (middle C has a wavelength of ~1.3 m). Consequently it is possible to build a model of a concert hall with reflective surfaces and use light to see how sound gets to the listener; the listener’s orientation is also, of course, important. It is also now possible for the dimensions and surface reflectivity of a hall to be fed into modelling program: sound modified by this program, when played back in an acoustically-dead, cork-lined room reproduced the sound heard in the modelled hall. The acoustics of the Leipzig Gewandthaus, destroyed in WWII, were confirmed to be nearly perfect for orchestral music in this way. The various uses to which a hall was put imposed conflicting requirements: to get clarity and intelligibility of speech you needed a dead acoustic, but to get the “immersion in sound” effect from an orchestra reverberance is needed. These conflicting requirements were summarised in the aphorism “an art is a science with more than seven variables”, and removable acoustic panels were one solution to complex demands. The speaker then went on to describe how the “shoebox” shape was best for opera, the “vineyard” shape for orchestral music, but the vogue for seating audiences behind the orchestra gave them a poor acoustic experience.
Professor Harry Brumer (University of British Columbia) was the speaker on 27th April, with a profusely illustrated talk on Getting by with a Little Help from my Friends: the key role of symbiotic human gut microbes in health. The human genome contains relatively few genes encoding carbohydrate-degrading enzymes: those that we do possess are largely concerned with degrading starch. Many of the complex structural polysaccharides in fruits and vegetables do in fact contribute to nutrition, thanks to symbiotic microbes in the lower gut. These microbes are anaerobes, and are consequently difficult to culture, which is why they have only recently been recognised. The general importance of a healthy microbial ecosystem in the gut has long been recognised, but exaggerated claims, even for increased serotonin (hence the title), have not until now been supported by mechanisms. The chemical structures of plant polysaccharides can be very diverse and complex, and it is thought that gut bacteria are very highly specialised. The speaker described his work, as part of a consortium, on a single locus in Bacteroides ovatus. The locus, XyGUL, was essential for hydrolysing a particular xyloglucan found in Solanaceae (tomatoes, peppers, etc), and coded for eight glycohydrolases, including a membrane-bound enzyme facing extracellularly, which made the initial cut in the macromolecule, and a couple of transport/binding proteins. The individual sugars are disproportionated to short-chain fatty acids by the microbes, and then absorbed by the host. Xyloglucan can contribute 10% of calories.
DNA and the Settlement of Europe was the title of the talk given by Professor Martin Richards (University of Huddersfield) on May 16. Archaeogenetics is the application of molecular genetics to the study of the human past, and has had three phases. The first used classical markers such as blood groups, and gave the first indications of a poor correlation between language and genetic origin, when the Icelanders were shown to have blood group frequencies typical of the NW British Isles, rather than Norway. The second used modern DNA techniques with non-recombining markers in living populations, the Y chromosome in the male line and mitochondrial DNA in the female. The mitochondria are the energy powerhouses of the cell, and whereas an egg will contain hundreds, a spermatozoon contains only a handful: any that do get incorporated into the fertilised egg are recognised and destroyed. For the last decade the automation of DNA sequencing, which had made it possible to re sequence human genomes in a few days, and the development of techniques for extracting ancient DNA, have made it possible to sequence archaeological specimens. mtDNA sequences had shown that all non-African humans derived from a single African lineage L3, 70,000 years ago (the “mitochondrial Eve” from who all humans derived was 200,000 years ago). L3 first moved out of Africa to the Gulf coast and Mesopotamia, where it remained for 15,000 years before sending descendants into South Asia, Near East and Europe, and back into Egypt. The L3 line interbred with Neanderthals before the split between South/East and West Eurasians. Genome-wide analysis suggests there were indigenous Europeans before the Neolithic migrations, and that the Saami (Lapps) and Basques are significantly derived from them. When Y chromosomes are examined, a group appears north of the Black Sea which migrates north and west, and then south and east, and has been correlated with male-dominated Indo-Europeans.