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Hello and welcome to Diffusion, a science magazine run by and for Cardiff University students!

If you have not heard of Diffusion before and think you might be in-terested in getting involved, please do join us on Facebook (search for: Diffusion – student science maga-zine) or send an email to diffusionmagazine@outlook.com.

The magazine is entirely free to join and relies on article submis-sions from the student body,therefore I’d like to thank the Bioscience Society for their help getting the word out. I also can’t thank all the contributors enough, they have made all this possible – enjoy!

Cormac Kinsella

Editorial

Article editors:

Jamie MaclarenSophie HopkinsJack ParkerMiriam HowlandKatie WeetmanCormac Kinsella

Diffusion logo design:

Tom Hostick

Graphic design:

Cormac Kinsella

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4The single most important thing you will do

I wanted to make a difference.So I did.

Just 16% of pupils eligible for free school meals make it to university, compared to 96% from independent schools.*   Change their lives. Change yours.

Matt Inniss, The University of Cambridge Taught: History Now: Head of Department

*Source: Sutton Trust, 2010

teachfirst.org.ukCharity No 1098294

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It’s that time of year again where we are all starting to complain about the nights drawing in and the weather turning horribly cold, wet and windy. However, there are some animals who appreciate our relatively milder climes and migrate great distances to come here. Bewick’s swans breed on the arctic Russian Tundra and fly around 3000km to winter in Northwest Europe (Denmark, Belgium, Germany, the Netherlands, France, Britain and Ireland). The swans are more likely to fly when the weather conditions are favourable, such as easterly winds and clear skies. They feed up dur-ing the winter in order to make the return journey in February/March. Two Bewick’s swans were spotted at Welney WWT in the fens of Cambridge-shire, Norfolk, officially starting this year’s British swan season on 14th October. Shortly after this, hundreds of swans were spotted in Germany showing that they are making good progress on their migration. Thousands of birds were then seen in various regions of the Netherlands, which holds the largest proportion of Bewick’s

for the winter (up to 70%). As the condi-tions become more favourable for continu-ing the migration we will start seeing more swans grace our shores. The Wildfowl & Wetlands Trust at Slimbridge in Gloucestershire is a brilliant place to see the Bewick’s swans close up as the ‘Rushy Lake’, where they roost and are provided with supplementary grain feeds, is adjacent to a large observatory which provides incredible viewing of the birds’ behaviour and social dynamics. With 50 years of research experience, Slimbridge is one of the best places to find out more about these amazing birds. Daily commentated swan feeds between November and February are a great way of gaining insights into the birds that are on the lake. Julia Newth, Slimbridge’s resident swan expert, regularly updates her swan diary blog with interesting facts and about the swans during the winter (http://www.wwt.org.uk/wetland-centres/slimbridge/diaries/bewicks-swan-diary/category/wwt-slimbridge-diaries/wwt-slimbridge-di-aries-bewicks-swan-diary/).

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Julia, along with Slimbridge’s swan volunteer Steve Heaven, spends the winter identi-fying the Bewick’s by their unique bill patterns so that life histories for each bird can be built up. The birds tend to pair for life and it is fascinating to see pairs returning with their new families as well as seeing their previous cygnets also back at Slim-bridge. It is important to keep researching these swans as their numbers have been declining since the mid-1990’s and there are many factors thought to be contributing to this decline, including changes in climate and land-use, collisions with power lines and wind turbines, lead poisoning and illegal/ accidental shooting. Bewick’s swans are beautiful birds that take an awful lot of time and effort to come to our shores, so take some time out to visit them while they are here!

Colin Butters ©

Colin Butters ©

We tend to think of there being a big divide between cellular organisms and non-cel-lular organisms such as viruses. Cells are very obviously alive, but viruses exist in an odd hinterland between life and non-life, displaying some properties associated with living things and lacking others. Regardless of their life status, everyone agrees that viruses are definitely not as complex as eukaryotic cells. Until now that is... research published in Science from Aix-Marseille University and Grenoble Alpes University has uncovered something of an oddity. Two new species of virus have been discovered which possess large genomes (rivalling those of eukaryotes). They’re called Pandora-viruses and only 6% of their proteins are similar to those produced by other viruses or eukaryotic cells. But at the same time, they don’t have ribosomes, don’t divide and don’t produce energy. They’re pretty weird, and they’re probably not even that rare. Who said microbiology wasn’t exciting?

Pandoraviruses by Ewan Selmes

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Pictured are Dr Gene Likens (left) and an aerial view of the Hubbard Brook Experimental Forest (right) showing large scale watershed manipulations of vegetation removal.

Gene Likens and the HBEF by Catherine Hunter

Dr Gene Likens is an American ecologist, who since the 1960s has been a leading pioneer in the study of acid rain. He has influenced several global policies on human emissions and has massively increased public awareness of environmental change caused by human activities. Dr Likens was the co-founder of the Hubbard Brook Ecosystem Study (HBES) in 1963. The study looked at features of the Hubbard Brook Exper-imental Forest (HBEF) which is located in the White Mountain National Forest in New Hampshire, USA. The HBEF is a 3,160 hectare reserve that is dedicated to the long term study of the forest and associated aquat-ic ecosystems. Dr Likens and his colleagues’ main method of research was known as the small watershed approach. The small watershed approach was used to study the linkages between hydrologic fluxes and nutrient cycling in response to natural and human disturbances, such as air pollution, forest cutting, land use changes, increases in insect populations and climatic factors. The HBEF can be used for long term and large scale experimentation such as the removal of large areas of vegetation and other whole system manip-ulations to study the responses of an entire ecosystem. Whole ecosystem studies like this are rare in ecology due to the resources and space needed to carry them out. Because of this, the Hubbard Brook Experimental Forest has resulted in one of the most extensive and longest continuous databases on the hydrology, biol-ogy, geology and chemistry of natural ecosystems. 1st June 2013, marked the 50th anniversary of the HBES and the research still continues as a hallmark research centre. Since working at the HBEF Dr Gene Likens has been recognised for his contributions to his field. In 2002 he was awarded the 2001 National Medal of Science for his work in ecology. He was a co-recipient of the 2003 Blue Planet prize for outstanding scientific research that helps to solve global environmental prob-lems. He has been awarded many more prizes for his work that would take far too long to write about here.In conclusion, Dr Gene Likens is one of the most important and influential ecologists of recent years, and his approach to ecosystem studies has greatly influenced the field of ecology as a whole.

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ANGRY BIRDSAVIFAUNAL ABUNDANCE AT DANAU GIRANG FIELD CENTRE

By Jamie MacLaren (former student BSc Zoology)

There are few forests in the world that are not home to birds. Birds play an inte-gral part in forest ecosystems, and have done so for many millions of years, filling the niches left behind by the dinosaurs, pterosaurs and marine reptiles over 65 million years ago. Forest bird roles range from seed dispersers to top carni-vores, pollinators to ecosystem engineers. With the growing human population on the planet, forest bird populations are falling under im-mense pressure, especially in regions of limited control on deforestation. One such region is South-East Asia, including the large islands of Borneo, Sulawesi and New Guinea. The spectacular island of Borneo houses over 420 species of bird. The island is not one nation in itself; it is territorially split between Malaysia in the north (Sabah), Brunei in the west and Indonesia in the south. Cardiff University is lucky enough to have a strong working relation-ship with a remote field centre in the Malaysian section of Borneo: the Danau Girang Field Cen-tre in Sabah. The centre is located in the middle of remote primary and secondary forest, along-side the Kinabatangan River, surrounded on several fronts by acres of oil-palm plantations. In 2010, the dipterocarp (hardwood tree family) rainforest surrounding the immediate vicinity of the centre would be the setting for the first avian abundance estimate performed at Danau Girang. Abundance estimates, in essence, enable researchers to judge how many of a given organ-ism are present in any one area, without having to count every single organism (an impossible task in a dense rainforest!). The pioneering study at Danau Girang was somewhat hampered by the limited equipment available to the

researchers; instead, simple but effective math-ematical solutions were employed, and an index derived, enabling the researchers to ascertain with a good degree of accuracy the composi-tion of the avifauna in the forests surrounding Danau Girang. Abundance estimates were based on positive sightings and audible identifications along transects through the forest. By splitting the forest into two broad categories, riparian and semi-inundated (floodplain), comparisons of both methodology success and constituent avi-fauna in two habitats could be drawn. Riparian forest comprises, in short, the trees and shrubs along the river-bank; semi-inundated forest lies further from the river, and can be categorised as a ‘floodplain forest’. Due to the dense foliage of the riparian zone, we predicted that birds would be more difficult to spot in this habitat than in the floodplain forest. In addition, our preliminary observations led us to suggest that the largest birds would inhabit the upper storey of the forest, with a higher number of small (<15 cm) birds inhabiting the shrub layer. When the data were fully analysed, and anomalous/skewed data removed with Occam’s broom, two clear patterns began to emerge. Firstly, the composition of birds in each storey of the forest appears to be in keeping with original observations; large birds such as hornbills and eagles were positively identified more often higher in the canopy, with a tremendous abun-dance of small birds such as babblers and sun-birds inhabiting the understory and shrub layers (see Figure 1). Two groups of birds (swifts and egrets) were removed entirely from the study, as their inclusion skewed the data somewhat – these are not forest birds (rather they inhabit the water’s edge) and as such could be

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justifiably eliminated from the study. The pat-tern retrieved does not come as a great surprise; however, it is a useful base from which to launch further investigations into actual community composition within the rainforest at Danau Girang. An effective detection distance of < 30m came as little surprise; the probability of accurately detecting birds at greater than 30 m in dense undergrowth is low. This can be seen in the results for riparian forest detections (see Figure 2).

Interestingly, the detection of birds in the floodplain forest did not show such a marked decrease at 30 m. Such results would benefit greatly from further investigation. Overall avian abundance within 10 ha of forest surrounding Danau Girang was calculated at 207 birds. When compared to a similar sized section of forest in New Guinea, the results are far higher in New Guinea (690/10 ha). Such a small abundance estimate for Danau Girang could be due to many factors, not least the limited time and equip-ment during the 2010 study. It is imperative that more such studies are carried out at Danau Girang, in an effort to expand our knowledge of the avifaunal composition of this idyllic and quite wonderful part of the world. Terima kasih Danau Girang!

Figure 1 (Left). Observations of birds of differ-ing size category within riparian and floodplain forests. red (birds <15cm long); blue (birds be-tween 15 and 30cm); yellow (large birds >30cm). Trend lines for histograms represent predicted pattern with greater sample size.

Figure 2 (Above). Observations of birds com-paring riparian and floodplain forest. Logo-rithmic trendline (blue) highlights drop-off in observations within riparian forest beyond 30m observation distance. Includes diagrammatic representation of riparian and floodplain forest habitats.

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Are GM crops better for the environment?

By Catherine Hunter Genetically modified crops and the use of pesticides have long been controversial topics and there are many activists and campaigns against both of them due to their possible negative impact on the environment. However, a recent study in the U.S has found that the use of a certain genetically modified corn reduces the need for insecticides thus lessening the possible chemical damage to the environment from the potentially harmful chemicals. Genetically modified sweet corn expressing a gene that allows the plant to produce a protein that is toxic to certain insects but safe for human consumption has been grown in the USA since 1996. The ‘Bt corn’ contains Cry genes from Ba-cillus thuringiensis (Bt) which encode for proteins that act as insecticides towards specific insects. The primary action of these proteins is to lyse the midgut epithelial cells of the insect by inserting into the target membrane and forming pores. Cry toxins interact with specific receptors on the host cell surface and are activated by host proteases. The toxins have an effect on Lepidoptera. The study had a particular focus on the corn ear-worm (pictured) which is a major pest across Northern USA. The corn earworm is the larva of the moth Helicoverpa zea, the second most im-portant economically costly pest species in North America and causing damage of over $100 million a year. The moth’s high fecundity, being able to lay between 500 to 3000 eggs and its larval feeding habits have led to the success of the pest.

Corn earworm, larva of the Helicoverpa zea moth.

Most Bt corn grown in North America is used for animal feeds or is processed into corn meal, starch and other products. Pressure from activist groups against GM crops has led to some supermar-kets refusing to stock Bt corn. The study, “Multi-State Trials of Bt Sweet Corn Varieties for Control of the Corn Earworm (Lepidop-tera: Noctuidae),” in the journal Entomological Socie-ty of America, analysed the performance of Bt sweet corn, comparing its rate of infestation and marketa-bility to genetically identical varieties that lacked Bt proteins. In 2010 and 2011, sweet corn trials were conducted in New York, Minnesota, Maryland, Ohio, and Georgia, locations that vary in climate, manage-ment practices and pest pressure. The researchers found that for control of the corn earworm, Bt sweet corn performed consistently better than its non-Bt counterparts, even those that were sprayed with conventional insecticides. In New York in 2010, one of the plots showed the most impressive results with 99 to 100% market-able ears of corn of the Bt variety without any

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Are GM crops better for the environment?

By Catherine Hunter

pesticide sprays, compared to the non-Bt corn which, despite having 8 sprays of conventional pesti-cide, only had 18% marketable ears. The authors of the study predict that growers could realise increased profits with Bt sweet corn because of lower inputs and higher marketability, while simultaneously conserving populations of beneficial insects that keep damaging pests at bay. Although the Bt corn seems to be good for the environment, other studies from the USA have found evidence of the insecticidal proteins in neighbouring waterways. The authors found detectable Cry protein levels in streams within 500 metres of a corn field. This result suggests that corn by-prod-ucts can persist in the surrounding landscape and enter waterways. This linkage between corn fields and streams has warranted further research into the potential effects of insecticidal proteins from corn crops on non-target ecosystems such as streams and wetlands, as many other commercial pesti-cides can have negative influences. In conclusion, Bt corn has the potential to improve the farming of sweet corn and due to the specific nature of the toxins, protect the crop from prolific pests without killing other non-target in-sects.

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The clock on the wall reads five min-utes to ten. You glance furtively at the other candidates, all sitting silently and avoiding eye contact with each other. One nervously plays with her hair, another blankly stares at the floor and the man next to you hunches over his CV as if cramming for an exam. You quickly run through the instructions your mother gave you: keep your back straight, smile broadly and don’t fidget. Is there anything else you can do with these final five minutes before your interview? Decisively, you stand up and walk away from the others, looking for an empty room. In truth, the advice your mother gave you was spot on. Your posture, expressions and movements all make up your body language. This in turn contributes to your non-verbal communication: statements which leave an im-pression on someone else without you having to speak to them. An expansive category, this also includes your appearance, speech pattern and tone in addition to use of personal space and body contact. An ironed shirt, clear voice and firm handshake would be useful additions in an interview context: smartness suggests you are organised, which probably means punctual too. Your neutral tone of voice hints you are calm in

stressful situations. A good handshake implies you aren’t shy and will get your opinion across. If a picture is worth a thousand words, the same is true of your non-verbals. The skill of non-verbal communication is rarely taught, yet its importance cannot be over-stated; it is crucial to human interaction, making up a majority of our communication (study esti-mates vary from 60-90%). Most of us have a nat-ural ability to detect it that matures with age or training. Such training is useful for interrogators, who can pick up when someone is being less than honest from a range of non-verbal cues, such as feet pointing towards an exit, freezing of the up-per body, formal speech patterns or even holding a gaze for too long (compensation for the fact that the liar feels awkward holding eye contact). The immediate implication is that the counter is also true: you can train to ‘lie’ with your non-ver-bals - a fact not lost on politicians, many of whom receive body language coaching in order to come across as friendly and trustworthy. It is usually easy to tell someone’s mood or emotions from their non-verbals. Contempt or anger, adoration or joy, we are hard-wired to know. Some clues we process consciously, others such as scent we usually decipher on autopilot. Our perception differs from that of other species, each of which is armed with a different sensory repertoire, often vastly more specialised than our own. For example scent marking becomes pos-sible with a high power nose, unlocking another communication avenue. However, despite the differences, many of the principles of non-verbal

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The answer was, conclusively, yes. Those in high power positions showed significantly raised testos-terone, lowered cortisol and reported a raised level of confidence. When presented with an opportu-nity to gamble for a prize, they were more likely to do so. The complete opposite was true of subjects in low power positions. A blind evaluation of the volunteers led assessors to agree: those who had been in high power positions were more ‘impres-sive’ individuals. With that in mind, let us finally return to your interview. Glancing down at your watch, you realise it’s time. Breaking out of your Usain Bolt pose, you head back along the corridor to the wait-ing room. You’ve barely sat down when the door opens and your name is called. With a smile, you start forward to the office, ready for anything. I’d wish you luck, but I don’t think you’ll need it.

communication are universal. An archetype of this is dominance or threat displays, the rule be-ing: ‘make yourself bigger and open up to look more powerful’. From puff adders to peacocks, and of course humans facing off to each other, power displays convey a high status, virility and threat level. An ‘alpha’ individual like a president or CEO will stride but never shuffle, he or she will gesticulate to emphasise and never talk with their hands in their pockets. This interesting psychology led Dr Amy Cuddy and other researchers from Harvard University to ask a simple question. If your body language, in particular the perceived ‘power’ of your stance, influences how others perceive you, could it also influence how you perceive your-self? Might the way you hold yourself propagate associated emotions? This was tested by putting volunteers into either high or low power poses for just two minutes, then studying the effects upon two key hormones (cortisol, a stress hor-mone, and testosterone, the hormone linked broadly to dominance and aggression).

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The human animal, with no impressive roar, sharp teeth, or claws to boast of, makes up for his lack of violent traits with tools. A tool has a premeditated purpose, a premeditated design. If a tool failed to achieve the end for which it was purposed, we might say it was poorly designed. What is it that I am writing about? Something that is all too human. It is because of the sort of ani-mal that we are, that we are accustomed to think about design in a certain way; technology, innova-tion, and the intentional designing of such is acute-ly related to the human story of survival. Yet, as many scientists (and other philosophical naturalists for that matter) will rightly tell you, recognizing function and purpose in nature does not necessari-ly infer a designer. Implicit in William Paley’s famous argument is the mistaken view that there is only one way to think about design: creation. Natural things differ from the artificial things that the human animal can create and this is because of the process that caused them to be. We recognize that a hammer is supposed to hit nails into things; that is the tool’s purpose. The purpose of something tells us what that something is supposed to be doing. But what can be said of that tool when it functions usefully out of that context? Perhaps it could function as a paperweight and not a flat heavy surface to hit nails into wood? We can grant that the hammer is functioning usefully, but not in the way it was designed to function. What this requires, in the case of human artifices, is the idea of a conscious purpose or premeditated design.

This manner of think-ing is teleological. When

thinking in a teleological man-ner, we ask: “what is the ham-

mer’s purpose?” given what end it is meant to accomplish.

Furthermore, this farsight-edness in one’s thought

infers conscious design. As pattern-seeking animals that have survived predominantly

by our instrumental use of designed technology, it would

make sense that our default way of thinking is teleological.

Nonetheless, our pattern seeking has looked beyond the instrumental thinking for

survival and towards a more comprehensive un-derstanding of nature. We have discovered that

physical and biological mechanisms, without any premeditated design, can cause an animal such

as us to be. Indeed our capability to think in a tel-eological manner emerged, at least in some part,

from these natural unconscious mechanisms. However, when teleological thinking is

married with the unconscious process of evolu-tion, a problem is created for us naturalists. For instance, the proper function of a seed (crudely

speaking) is to nourish the plant in order for it to grow into its adult form, but this may not hap-

pen. Lacking a premeditated design, how can we say it was meant to grow into this later form in

the case of it not happening? Likewise, although the proper function of the heart is to pump oxy-genated blood around the circulatory system, it

also makes a rhythmic sound. How, then, can we say that pumping blood around the circulatory

system is what the heart is meant to do, without referencing a designer?

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What this problem requires is for us to think about design differently. An aetiological manner of thinking refers to antecedent causes rather than future (consequent) end states. The normative force of ‘purpose’ is hence licensed differently than it would be from teleo-logical thinking. ‘Purpose’ is not established at what may happen in the future, but by many intstances of successful replication of something that occurred in the past. The functioning of a heart behaves in much the same way as its ancestor’s heart behaved, and it is because it functioned in this way that the organism was able to survive and reproduce. Therefore, and thinking in this way, we can say that the proper purpose of the heart is to pump blood around the circulatory system.

One can establish a vague teleological notion of purpose in biological phenomena, but only in a vestigial sense intrinsic to life: the purpose to perpetuate itself. No farsighted-ness is presupposed in the designs of nature. Indeed many extant hearts are prone to failure and malfunction, but so long as they work sufficiently to allow an organism to reproduce, it can be said to have reached its relaxed design criteria. Allowing for slight mutations over the ages it could be said that the design improved: allowing the more athletic organism to avoid predation and to breed. Yet, no premeditated thought is required; no acts of creation are presupposed in this process. Whereas teleological thinking looks to the future, aetiological thinking looks to the specific past effects of ancestral-X making a difference for X to be replicated in the present. It is this succession of replicates in history that allows us to assert what X’s normal, or prop-er function is, and so its purpose. By one manner of thinking it can be said that a hammer has a designer, whilst by another correctly recognizing that the heart was designed without one.

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People have wanted to live longer than we naturally do since, well, probably since we first worked out what death was. Death is scary and from looking at the huge variety of reli-gions and spiritual beliefs that exist, it’s a univer-sal fear—or concern, at least. We’ve developed religions which profess to offer eternal life – after you die, usually, whether it’s by transcending the physical universe to enter an afterlife, or through some form of reincarnation – and pretty much the whole of modern medicine seeks to enhance our lifespans through science and research. On the whole, I think we’ve done pretty well out of it. We’re staying healthy for longer, and we come up with new ways of fighting dis-ease and senescence all the time. But all the stuff we’ve developed so far has been plucked from the ‘low hanging fruit’ of the life extension tree. Some people are content with this – those lucky few of us who happen to live in the developed world typically live to about 70 - 80 years of age, with some people going beyond that. But there are some people who aren’t happy with this, who think that maybe it’d be nice to live for a bit longer, and be healthier too. One of those people is Ray Kurzweil, the Director of Engineering for Google and a renowned futur-ologist and businessman. He wants radical life extension. If you want to hit a hundred, he wants to hit a thousand. He’s also the author of a num-ber of books on the subject, but perhaps his most well-known publication is The Singularity is Near (2005), in which he discusses many things includ-ing radical life extension.

Radical life extension is essentially the idea that we can continue to improve and en-hance our biology and physiology through scien-tific and technological means. The end-goal is to live longer, yes, but also to remain fit and healthy for longer, too. We’ve already sort of been doing this with medicine, but as a civilisation we’re reaching a point where we’re beginning to think, “Why can’t we go further?” Proponents of this particular goal are looking to increase the healthy lifespan of hu-mans through a variety of methods, including through biotechnology and robotics. Google has recently announced the creation of a life-exten-sion company called Calico, headed by former Genentech executive and scientist Art Levinson. Calico is just one company among quite a few, although other anti-ageing companies such as Elixir Pharmaceuticals have failed and shut down. Despite that, it seems like it’s probably time to question what we want out of modern medicine and medical science. Is radical life extension something we even want? Speaking personally, I’d quite like to live a lot longer than I’m currently predicted to, so long as I can remain fit and healthy for longer too. But this kind of technology will always come with problems – what do we do about overpop-ulation? Would radical life extension entail by necessity one child policies such as those imple-mented in China, or would people compensate for the increased lifespan by having fewer chil-dren, later in life – as we’ve seen happen in the West already?

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What about creating more and greater divides between the rich and poor? That’s surely a problem. How do we make it so that this kind of life-changing technology is available to every-one, not just those who can afford it? Should we even be doing that? On the other hand, if peo-ple remain fit and healthy for longer, they can contribute to the economy for a much longer period of time. At a time when we’re suffering from the associated costs of housing and caring for our elderly, radical life extension seems like something we’d want to have. Inevitably technological and scientific advances bring with them controversies. Radi-cal life extension could change so much about our society, and probably in ways we can’t even begin to conceive. At the moment it seems like something out of a sci-fi novel or film, but the

current scientific landscape at least suggeststhat we should start talking about it seriously. After all, there’s funding to allocate, researchers to train and a public to convince, if this is a road we’re going to travel. It looks like we’re heading there anyway even without a concerted effort – in many ways, this sort of technology is just an extension of regular medical research. At what point does it become unethical, or ethical, or something to avoid? I’m in favour of radical life extension. But I’m also aware of the many issues that we’re going to have to confront before we can begin implementing it; otherwise we’re going to find ourselves in a bit of a mess. But what do you think? I’d love to receive readers’ comments and thoughts on this particular issue.

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Sci-fi and fantasy films have invisibility cloaks throughout, from Harry Potter’s cloak to Klin-gon cloaking devices. The reality is that the science to make things invisible exists in the present day, al-though when I try to explain this to people they think I am pulling their leg. So, to convince them of this feat, I point out that it uses the negative refractive index and cloaking properties of photonic metamate-rials, and then I receive some rather strange looks. The field of complex photonic media (which encompasses photonic metamaterials) is a new area of physics, engineering, material science, and nanotechnology. So new that it is still very much experimental with some interesting results in a lab, but with no real life applications in use at the present moment. Unfortunately, due to technological limita-tions, items can only be cloaked against certain types of electromagnetic radiation (light), and these types of light are not within the visible spectrum. This means that your invisibility cloak will not turn you invisible to the human eye, yet. The closest scientists have been able to get to visible light is with micro-waves. So, if someone could see in microwaves, your cloak would work and you would be invisible. The ap-plications for this area are extremely varied; they can be used to provide solutions for telecoms, imaging, power, data-storage, computing, security and nation-al defence. You have probably read this and thought it all sounds good, but perhaps you are still wondering: ‘What on earth are photonic metamaterials?’ So I shall explain. A metamaterial is a synthetic com-pound that exhibits properties that are not seen in nature. Specifically, photonic metamaterials react with light in such a way that they can be used to ma-nipulate light to achieve extraordinary results. Met-amaterials, unlike materials found in nature which receive their properties from their chemical composi-tions, exhibit these bizarre properties because of the way their constituent parts are arranged.

Moving onto the invisibility part in detail, how does it work? It works because these metama-terials have a negative refractive index. This means that as the light passes through the material, it ‘bends’ in the opposite direction to light passing through a normal transparent medium, like a glass block. Using rings made of the material you can build up several layers surrounding the object you intend to render invisible. Once you have suffi-cient layers arranged in the correct manner, the object should become invisible to the appropriate wavelengths. Unfortunately, a few problems have arisen when it comes to meeting the expectations on how well an invisibility cloak should work. These problems are that, firstly, the object is not perfectly invisible to the wavelength because there are im-perfections in the layers; and, secondly, the cloak is restricted to only one wavelength (and visible light has a broader range). The main challenge faced with making met-amaterials is that the structures that give the ma-terial its exciting properties need to be minuscule; they must be smaller than the wavelength of the electromagnetic radiation they wish to manipulate. Making such small structures requires advanced technology, and this restricts the wavelengths that we can cloak materials from, as I mentioned ear-lier. Microwaves are centimetres in length, which means that the structures need to be of the milli-metre size. By the standards of technology today, structures of this size can be manufactured. With visible light, however, the waves are a few hundred nanometres in size; this makes them hundreds of thousands of times smaller than microwaves, and as such their structures need to be in the nano-metre range. To create anything that is several nanometres in size is a technological achievement in itself.

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Sixty-five million years ago, the last of the non-avian dinosaurs hunted for food in vain, in a cold land under a black sky. All around the scarred planet, forests, plains and valleys fell silent; whilst in the emptying seas life was just as badly affected. Globally around three quar-ters of all species died out. Life was brought low by the K-T mass extinction, yet if it (and many others like it) had not occurred, we would not be here. This monumental death event took away with one hand, and with the other gave our own species life. The end of the Mesozoic period (a period including the Triassic, Jurassic and Cretaceous and commonly referred to as ‘the age of dino-saurs’) was precipitated by a chance event – a giant meteorite striking the Earth in what is now Northern Mexico (the Yucatán Peninsula). Tsunamis raged around the world and rock and dust were ejected into the atmosphere (enough rocks were ejected all the way into space that there is a significant chance they reached Mars, Titan and Europa). This caused an almost total blackout and brought on an impact winter for upwards of a decade, whilst vaporised sulphur returned to the Earth as strong acid rain. Com-plete trophic collapse was the immediate con-sequence, with much of the plant life unable to cope with the acid, cold and dark. The creatures that normally fed on plants followed, and the carnivores in turn. However, scurrying below the wilting undergrowth many animals did survive; our ancestors included. Their small size, high reproductive rates and invertebrate loaded

diets (insects generally cope especially well during mass extinctions – only being affected majorly by the end-Permian) helped ease them through the worst of the conditions. When the Sun finally dawned on mammals again, they found themselves on a planet with the slate wiped clean. Free of large competitors, they were able to evolve into any and all niches avail-able to them. They took to the air as bats, to the sea as cetaceans (whales and dolphins) and numerous groups emerged on land, including eventually primates and ourselves. The prominent evolutionary biologist Richard Dawkins has speculated rather fancifully that the survival of mammals may have been (at one point in time) contingent on whether or not a single dinosaur sneezed. Had the dinosaur not sneezed it may have caught our ancestor as a meal, potentially diverting the evolution of our group radically. This kind of example is for illustrative purposes only, as we can never know consequences in alternative situations (until we achieve time travel of course); however there is no denying that tiny influences at one time can create major snowballing effects later. This is the butterfly effect, so named after the example of a butterfly flapping or not flapping its wings, with the consequence of a hurricane on the other side of the world forming or not forming several weeks hence. A demonstrable example is tiny differences in gradient and surface at the peak of a hill surrounded by valleys. Each time you place a ball on the peak, it could roll into a different valley, with only small differences insti-gating far-reaching results.

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The mathematics involved in the proba-bility of your existence are preposterously large. Had any one of billions of reproductive events, fortuitous circumstances or chance happen-ings not occurred, the result would undeniably have been different. Applying this truth to giant events like mass extinctions is counterintuitive-ly far easier, as we can see the low resolution effects on life by studying what appears before and after, and what may have been the compet-itive edges survivors had over their peers. What we see is that these events are big players in the game of life, changing the course of evolution time and time again. Although the dinosaur destroying event is the most famous of mass extinctions, it is by no means the only one, nor the largest. Events range in size, and many of the smaller ones remain to be discovered by future palaeontolo-gists. The Ordovician extinction 450 million years ago cut swathes through families of marine life, and the Devonian event 80 million years later

massacred half of all genera. The true titan of the mass extinctions, the end-Permian 250 million years ago, killed up to 95% of life on Earth, lead-ing to its description as ‘When Life Nearly Died’ by Professor Michael Benton in his book of that name. Each of these events shook up the bag of life, bringing new groups to the surface while others descended never to be seen again. Lob-sters owe their relative success to the end-Per-mian extinction, whilst Trilobites ended their 300 million year career there. Rather ironically, the emergence of dinosaurs may also be the result of an opportunistic replacement of vacated nich-es following an extinction event, just as would later happen to them. I think this should serve as a warning to us: good times don’t last. We are currently destroying the planet and its life at an accelerating rate, and possibly entering a new mass extinction. Unless we act soon, the lessons of the past won’t have taught us anything, and we will be presiding over our own deaths, which in turn, will give life to others.