First up is Lindsey, talking about the plague – To Flea or Not to Flea?
The first outbreak of the bubonic plague was in 541CE – the plague of Justinian, which affected the Roman Empire. Between 25 and 40 million people died. The second instance was the Black Death, which spread through Europe between 1346 and 1353, killing 65-200million people – somewhere between 30 and 60% of Europe's population at the time. There was a third pandemic in 1855 in Asia that led to 15 million deaths.
The first symptoms of the plague are bubonic, and include the swelling of the lymph nodes. At this stage, there is a 40-60% chance of survival. Then comes the pneumonic stage, which sees the sufferer cough up blood, with a 20% chance of survival. Finally, septicaemia, when the plague is in the blood. Once the infection is septicemic, there is only a 1% chance of survival. It only takes ten bacteria to cause plague in an individual.
Why is the plague so good at spreading? It comes down to fleas. They bite infected hosts such as rats or mice, and then spread the disease between hosts. The Black Death started in China and then sped along trade routes. At the time, cities were densely populated and full of rats. As the rats died of the infection, the fleas moved onto biting people, spreading the disease to us.
1720 saw the last major outbreak in Europe, and the last documented case in England was recorded in 1918. The last recorded case in Africa was in Madagascar was in 2017. The most recent cases in Asia and the Americas are considered to be ‘current’, while in North America, they have cases almost every year. The last worldwide death was on January 9 2017, when a man caught the disease from his dog. Interestingly, dogs are actually resistant to the plague but cats are not. Five people died of plague in the US in 2015 and the World Health Organisation classify it as a re-emerging pathogen.
After a flea bites a host, the blood meal is taken into its gut. The bacteria in the blood form a biofilm, which protects them from outside stresses. This film is formed on the valve in the flea's throat and prevents it from feeding. The flea stars biting more and more hosts, trying to get food, which spreads the disease, and the flea starves to death.
The question is, how do we stop this life cycle? Can we stop the biofilm forming on the valve in the flea? Lindsey is looking at bacterial DNA, trying to remove the genes that enable biofilm creation. She is also looking at human lice, which lived in clothes in medieval times, trying to understand whether these can spread plague too.
Next, we have Oscar, asking -- What Does the Brain Need to Hear?
In a quiet room with a clear speaker, it’s easy to hear speech. But what about in a noisy environment with disrupted speech, competing talkers and bubbling background noise? You lose information and your brain tries to fill in the gaps. The brain is quite good at this but it can struggle sometimes. If you have a group of three men and one woman, it is easier to pick out the voice of the woman due to the difference in pitch. This also works the other way round. Bilinguals struggle more if they are trying to hear in their second language when compared with native speakers.
Oscar is also exploring ‘zebra speech’. This is temporally interrupted speech, where chunks of speech are removed. By either leaving the gaps silent or filling with white noise, it's possible to determine the best thing to do with cochlear implants. Since they can't pick up everything, should they fill the gaps with silence or noise bursts?
Sound comes in through the ear canal and vibrates the ear drum. From there, an electrical impulse is sent into the cortex. The temporal lobe looks after hearing, speech and language and there is also a link with the frontal lobe, which deals with perception. We can see this using brain imaging. fMRI – functional magnetic resonance imaging – show where the most oxygen is being used in the brain. Unfortunately, it’s not great for seeing when this activity took place. EEG – an electroencephalogram – is the opposite in that it's great at telling when things happen, but the signals are mushed together so it's not so good at telling where they happened.
However, there may be a solution. Epilepsy sufferers have electrodes implanted in their heads for a week for treatment. It may be possible to use these patients to get more accurate EEG readings, helping us understand more about how the brain processes sound.
Then it's Lizzie, taking about Supernormal Supersexy…
We all know about Darwin's model of survival of the fittest, but is it actually the other meaning of the word ‘fit’? Is it really survival of the most attractive?
Humans are animals – we are programmed to procreate. But how do we choose our mate? Where the peacock has its tail, what ornaments do humans have? How has culture and society affected this? Why do we keep coming back to the same physical features that we find attractive? Are we hardwired?
We have responses to certain stimuli, but now, our society has created similar super stimuli. For example, if we see big teeth, we feel fear, and this is played on in film with monsters. Food drives hunger, fast food especially so. Similarly, movement makes us pay attention. Now, we have movement on TV or phones that demands our attention. As animals, we also have supernormal stimuli. We respond to these even though we know they are fake and sometimes we respond even more than to regular stimuli. Through the evolution of culture, we have created these supernormal stimuli as ornaments.
Your waist to hip ratio is calculated by dividing the size of your waist by the size of your hips. In women, we find a ratio of 70% attractive, while in men we find 90% attractive. This is oestrogen vs testosterone and is a normal stimulus. Oestrogen is an indicator of fat distribution, fertility, existing pregnancy and general health. The supernormal version of this comes from things like corsets, push-up bras, photoshop and shoulder pads. In men, testosterone is an indicator of strength, fertility and bone density. Supernormal for men comes from suits, military ornaments, photoshop and ‘gym rats’.
With eyes, we prefer bigger, whiter and brighter. So, we use eyeliner, mascara, false eyelashes and in ancient Egypt, they lined their eyes with poison. Teeth are non-replaceable so they can be a good indicator of overall health. We use teeth whitening, fake tan and even stubble to make our teeth look whiter and our jaws look stronger – the jawbone is commonly given as the strongest bone in the human body.
Lips are an indicator of oestrogen levels, circulation and immune health. So, we enhance them with lipstick and fillers. Finally, there is walking style. The female gait has a reduced knee bend, shorter stride length and greater hip rotation than men. Supernormal is high heels and it's been shown that men find women in high heels 12% more attractive. So, next time you are out ask yourself whether you're falling for something supersexy or supernormal.
Finally, we have Adam, who is Making Stuff…
The survival of our nation hinges on our ability to make stuff. Adam Smith is on the back of a £20 note for revolutionising the manufacture of pins. Before the industrial revolution, everything was a cottage industry with things made to order. Suddenly, things could be made in a more efficient way.
3,800 years ago, Tutankhamun's death mask was created. It's a marvel of engineering and took between 150 and 200 people to make. History is populated with similar artefacts. In the fifteenth century, suits of armour were becoming increasingly popular. These required incredible metal working skills. People with similar skills would come together to create these things and to share their ways of working metals. The eighteenth century was the time of Watt, Stevenson and Brunel. There was a huge revolution in society, and people were relocating to find work.
We are now in the age of powered flight – in 2016 there were 3.5billion air passengers. Flights are getting cheaper and there is massive growth in places like China. This is great news if you work in the aerospace sector. Rolls Royce, who make jet engines in Derby, sell a single engine for £20-40million. These contain huge amounts of technology that has been developed over decades. The turbine blades alone are the epitome of British manufacturing – creating them is extremely difficult but if one breaks it's a disaster. Failure cannot be tolerated.
None of the materials that are required to create jet engines, or mobile phones for that matter, is found in Western Europe. The places that do have these materials are among the fastest growing economies in the world. We want to buy these materials and add value to them. Recently, Airbus signed a $4billion deal with Russia for titanium. That didn't include any actual titanium, it was just for the infrastructure to supply it.
As people live longer we have to change the way that we make stuff. For example, we will probably need more hip replacements. In fact, there is an industry springing up looking into how to recycle and recondition hip implants after they are no longer required. 3D printing will also change how we manufacture things. Now, using a metal powder, melted by a laser you can quickly and easily build something instead of carving out of a block of metal. This is just the start, there are always new materials and new processes in development.
If this has whet your appetite for this year’s Pint of Science Festival, get your tickets online now.
Pint of Science website