Sunday, 26 November 2017

Talk : "Who's Eating Who? Hominins and Carnivores in Human Evolution"

We have not always been the alpha predator on this planet - Dr Hannah O'Regan give this month's public lecture on "Who's Eating Who? Hominins and Carnivores in Human Evolution"

@Gav Squires was there and has kindly written this guest post summarising the event, with some linkage added by NSB.

Hannah O'Regan

To begin with, why carnivores?
Social carnivores could be a good proxy for hominins and their development. They have been in competition with hominins for resources such as food, water and shelter. They are primate predators.

7 million years ago, the first hominin, Sahelanthropus, evolved. 3.9million years ago, we had Australopithecus, the best known example of which is Lucy and 3.3million years ago, we have the earliest archaeology with evidence at the Lomekwian site of the use of stones. Evidence has been discovered from 3.4million years ago of marks on bones, implying that humans had used tools to remove flesh, which they then presumably would have eaten. 2.8million years ago the genus homo made their first appearance and 2.6million years ago was the first use of stone tools. 1.5million years ago, we have Acheulan tools, hand axes and we have bipedal hominins wandering the landscape with tools.

Artistic interpretation of Sahelanthropus tchadensis
by sculptor Élisabeth Daynès

Acheulan tools

Between 1 and 2million years ago there were a range of large carnivores in Africa including 6 types of hyena, canids including those the size of wolves and African dogs. There were also a number of felids that could take down a hominin including lions, cheetahs, leopards and sabre-tooth cats. Sabre-tooth cats were ambush predators with very powerful front-legs that they would use to wrestle prey into position so that it could use its teeth. The teeth were longer than they were wide, which made them susceptible to breaking. However, if they did break it would mean that the animal would be forced to scavenge and would not have lived for much longer afterwards. In Swartkrans in modern-day South Africa, evidence has even been found of human remains that have been predated by leopard.

As well as large carnivores, there is also predation by birds and things such as eagles will hunt primates - there is plenty of evidence in the form of primate bones beneath the nests of Crowned Eagles. The Taung child, the first ever fossil published of a hominin from Africa was discovered in 1924, was 3-4 years old when it died and the only hominin fossil ever found in Taung in South Africa. It has similar orbital damage to primates eaten by eagles and it appears that there was no population at Taung and the child was carried there by an eagle.

Evidence has also been found of crocodiles predating hominins from 1.8million years ago. Another example from down the same river has crocodile teeth marks on its foot and has also had its leg bitten off by a leopard - not a great day!

The Homotherium was one of the sabre-toothed cats that lived in Africa and Europe that seem to have died out in Europe around 28,000 years ago. In Schöningen in Germany, evidence of humans using spears 300,000 years ago has been found - the humans were mainly preying on horses at the time. There is also evidence that these humans were using the bones of Homotherium as hammers in order to make stone tools.

Artists impression of Homotherum

How can we tell the difference between predation and scavenging? It's actually very difficult as teeth will make the same marks in both cases. Looking at some Neanderthal bones, there are some fox bite marks on the hands that are clearly scavenging but there are also bite marks on the skull from a larger animal, which could be either.

While it is extinct in the UK these days, the brown bear in Europe's largest carnivore. In Ireland, a bear patella has been found showing evidence of marks from stone tools where the patella tendon has been cut. This is the first evidence of humans living in Ireland but we still don't know what they would have been using the patella for once it was removed. More recently the Romans brought bears to the country and in the 16th century there were a number of bear baiting arenas in London. By the 18th century bear shaped ceramic were being made in Nottingham, depicting bears holding dogs and even in the early 20th century, Italians were bringing over dancing bear cubs for the summer season.

 
European Brown Bear

These days we are the apex predator and this isn't necessarily a good thing for the other carnivores, for example the African lion population has dropped by 42% in the last two years. Recently a lynx that had escaped from a zoo was shot in Wales, despite the fact that there have never been any recorded attacks on humans by lynxes. There have been talks over the last few years about the possibility of rewilding species such lynx into the UK, could that still be an option?

We have interacted with and evolved alongside carnivores for millions of years and even now, without adaptations such as fire, weapons and defensive protection, we are vulnerable to predators. However, overall, carnivores are on the back foot against the spread of homo sapiens.

The Public Lecture Series returns on the 7th of December at the University of Nottingham at 6:00pm where Dr Craig Sturrock will talk on 3D X-Ray Vision: Measuring the Hidden Structure of Biomaterials Using X-Ray Computed Technology. For more information, check out the PLS website: https://www.nottingham.ac.uk/physics/outreach/science-public-lectures.aspx

Image Sources
Sahelanthropus, Cordiforme, Homotherium, Bear

Saturday, 25 November 2017

Talk - The Skyscraper - From mid-20th Century to 2030

For November's Café Sci, David Nicholson-Cole from the University of Nottingham comes to talk on "The Skyscraper - From mid-20th Century to 2030".

@Gav Squires was there and has kindly written this guest post summarising the event, with some linkage added by NSB.

David Nicholson-Cole

There were 4,500 years between the building of the pyramids in Egypt and Lincoln Cathedral, which was then the tallest building the world for 238 years[1311–1549, when the large central spire collapsed]. Now, the gap between the record being broken is coming down all the time and a new world's tallest building is crowned around every five years. Originally tall buildings were built to display the concepts of eternity, wealth and destiny and very little has changed.

Model of Lincoln Cathedral (the large central spire collapsed in 1549)

But what is a tall building? These days, it needs to be over 100 metres tall and must be occupied. So, the Eiffel Tower doesn't count. Usually, wide buildings aren't considered to be tall even if they are actually pretty tall, for example Queen's Medical Centre doesn't feel like a tall building but it's 10 storeys high. There really should only be one iconic tall building per city. While tall buildings should have utility, the top 300 metres of the Burj Khalifa, the tallest building in the world today, aren't used - they are just there for the look.

Burj Khalifa, 2010

In 2010, half of the world's population were living in cities and urbanisation is increasing at the rate of 200,000 people per day - a city the size of Manchester has to be built every week just to keep up. By 2030, it will be 60 of the world's population and by 2050, a massive 70% of people will live in cities. Will we keep up? If we do, it will probably be due to more tall buildings.

Skyscrapers originally started in America and apart from the occasional iconic one here and there, they never really caught on in Europe. Now, most expansion is happening in East Asia and 10 out of the 14 cities with the most tall buildings can be found in East Asia - Hong Kong alone has 2,354 buildings over 100 metres tall. Now, the average height for a super-tall building is 350 metres. Originally, tall buildings would all be used for office space as only offices could afford to build tall. They have since had to evolve into multi-use buildings as that is the only thing that makes economic sense. In the Middle East and China, they prefer building with stone rather than steel but here in the UK, steel is used for tall buildings. Cities with tall buildings and good transport links are the most energy efficient.

Tall buildings in Hong Kong

A proposal for building on the banks of the river Hudson in New York saw the land valued at $110,000 per square metre. This is why going tall becomes so popular - to make it pay you have to go tall and have to go mixed-use. The site in New York was 1,000 square metres in size so it would have cost $110,000,000 just for the land. The reason that the land is so expensive is that places like New York and London have such massive demand for housing that it pushes the prices up and means that you have to build tall.

  The two key inventions that enabled tall buildings to be constructed were the elevator (the first safety elevator was built in 1852) and the steel frame (introduced in the mid-19th century). There were other inventions during the so-called "gilded age" of America between 1869 and 1901 that were crucial to the development of tall buildings:

AC electricity
Telephone
Typewriter
Electric light
Discovery of mineral oil
Railway
Universal post
Electric tram
Elevated railway
Sprinklers

Sprinklers especially were important as before them, buildings could not be made taller than 75 feet high following the great fire of Chicago, which was actually bigger than the fire of London.

Aftermath of the Great Fire of Chicago, 1871

In 1884, the first high-rise residential building was constructed - the Dakota building in New York (the building that John Lennon was shot and killed outside) and in 1885 the 10-storey Home Insurance building opened in Chicago. These first generation tall buildings were built using steel - the Monadnock building, also in Chicago, was originally built using brick but was too heavy and started to sink into the Chicago mud. In the 1920s, the second generation of tall buildings saw form follow finance.

The Dakota Building, c.1890 - at the time,
this area of Manhattan was sparsely developed, and remote
from the core of the city's population

Home insurance Building

The Monadock Building

Between the 1950s and the 1980s, the third generation [also known as the "International Style"] saw dark glass boxes becoming popular. Post the 1970s energy crisis, generation four was still largely glass boxes but they were becoming more efficient. We are now firmly in the 5th generation where energy efficiency and sustainability are the keys to design. The Bosco Verticale, in Milan, is a green building, with facades that contain living plants and hints the way towards the next generation of tall buildings.

The Seagram Building

The Boscoe Building

In terms of maximum height, the only limiting factor is really the number of lifts - the higher that you go, the more people will be using the building and so the more lifts you need. Right now, a 1 kilometre tall building is being constructed in Jeddah in Saudi Arabia. While the future will bring new tall buildings, what will happen to the old ones as they become obsolete, which generally happens between 30 and 40 years after they are built. Only three buildings taller than 160 metres have ever been demolished, they have mainly been refurbished.

Jeddah Tower (under construction as of 2017)

Café Sci returns to the Vat & Fiddle on the 11th of December at 8:00pm where Lucy Donaldson will talk about "Bitter Now But Better Later?" For more information, visit the Café Sci MeetUp page https://www.meetup.com/nottingham-culture-cafe-sci/

Image Sources
Lincoln Cathedral, Burj Al Khalifa, Hong Kong, Chicago Fire, Dakota Bldg, Home Insurance Bldg, Monadock Bldg, Seagram Bldg, Bosco Verticale, Jeddah Tower

Related Links
Article by David Nicholson-Cole