Dazzling stripes are a way of deterring flies. Photo: Getty
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How the zebra got its stripes

A method for dodging predators? A means of social interaction? Or a way of getting rid of flies?

Zebras' stripes have baffled biologists since Charles Darwin. Many hypotheses have been proposed regarding their purpose but, despite hundreds of years of study, there remains disagreement.

In an attempt to end the debate, researchers have pitted various models against each other and systematically analysed data from past studies. Their results reveal the one reason zebras have stripes: to ward off flies.

A handful of ideas regarding zebras’ stripes have found some support among biologists. One proposed that the dark and light bands change how air flows around a zebra’s body and helps in heat management, which could go a long way in the hot tropical areas that zebras live in.

Another proposed the stripes were used by zebras as a way of social interaction. They may use them to identify other zebras and for bonding as a group in the wild.

A third proposal suggested zebras used the stripes as camouflage. While stripes are clearly visible in the day, there some thought that it helped at dawn, dusk, and in the night.

All these ideas were shot down when tested rigorously. Two others, however, remained intriguing.

The first was that the stripes were used to dodge predators. It is called the “motion dazzle hypothesis”, and it suggests predators are confused by zebras' stripes and cannot understand their movement. Research published in the journal Zoology in 2013 used a simulated visual system to show that zebra stripes do interfere with visual perception. But this is a difficult hypothesis to test in the field.

Martin Stevens at the University of Exeter has researched the motion dazzle hypothesis by getting human subjects to catch moving stripy objects on a computer. “It’s an artificial experimental system,” he admitted.

The second proposal was that stripes helped keep flies at bay. Zebras are especially susceptible to biting flies due to their geographic spread. These flies, which include the tsetse fly, stomoxys stable flies, and tabanid biting flies, are particularly prevalent in areas with high temperature and humidity – exactly the areas where zebras are normally found.

Bites from these flies can be nasty and, quite literally, draining. About thirty flies feeding for six hours on just one horse can draw as much as 100mL of blood. Usually the flies can number in the hundreds around one animal.

Zebras have shorter hair than other equids – the family that includes horses, donkeys and zebras – which may also increase their susceptibility to attack. Also, four diseases which are fatal to equids have been found in Africa. This could mean that investing in anti-biting defenses such as stripes is especially important for zebras compared to non-African equids.

It is possible that the dazzle effect acts on flies, rather than larger predators, and deter them from biting. “Stripes clearly have a number of functions,” Stevens said, “and these could be interacting in zebras.”

Revealing maps

In the new research, just published in Nature Communications, Tim Caro and his colleagues at the University of California in Davis, didn’t perform experiments. Instead they used ecological and observational data on zebras' geographical locations and related factors. It is the first time that a comparative approach has been applied to find the reasons for zebras' characteristic colouration. Caro thinks his findings may have nailed the answer at last.

Caro looked at seven species of equids and scored them for number and intensity of stripes. Just to be sure, they tested all five hypotheses regarding zebra stripes' use: camouflage, predator avoidance, heat management, social interaction, and warding off flies. The extent of overlap between the geographic distribution of striped equids with each of these five measures was calculated.

E. greyvi, E. burchelli and E. zebra have stripes on all their bodies. Other equids don’t. Caro, Izzo, Reiner, Walker and Stankowich

“The results were a shock to me,” said Caro. Of these five proposals, only warding off flies had statistical support. He had not expected such a clear-cut answer to the question. As the map shows, the only places where flies and equids live together are areas that are populated by striped equids.

The exact mechanism by which stripes deter flies remains unknown, but experimental studies performed by researchers at Lund University in 2012 have found support for this proposal. They created striped surfaces and stuck glue on them. Based on the number of flies on the surfaces with different thicknesses of stripes, they concluded that these flies stayed away from stripes as thin as those found on zebras.

“As is normal in science you get a solution that asks more questions,” Caro said. It is time to hand the problem over to vector biologists, who can understand the susceptibility of horses to biting flies.

In Darwin’s days, people didn’t consider animal colouration with respect to fitness advantages. “People thought that animal colouration existed simply to please humans or was caused directly by the environment,” Caro said.

Darwin “would be delighted” that researchers are now considering animal colouration as a functional trait, he said. We might not have all the answers regarding zebra stripes – but it seems we may be looking through the right lens.

The ConversationThis article was originally published on The Conversation. Read the original article.

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“There will be an absolute meltdown in 2020” : what’s holding back the introduction of electronic voting?

The government's reluctance to implement electronic voting will affect our future, and in – the case of Brexit – may have already dramatically affected our past. 

Imagine, just for a second, that the situation was reversed. Imagine if, for a hundred years, we had scanned, swiped, and tapped our votes into a secure, fool-proof electronic system and someone waddled along and said, “Alright lads, how about we try pencil and paper?”. How about we desperately try to find a spare hour to shuffle to the village hall in the rain and scratch an “X” onto a scrap of paper with a stubby bit of lead, and then let a volunteer named Deidre count it at two am? What could possibly go wrong?

If you picture this scenario – posited by my colleague Anna – then it quickly becomes clear how ridiculous it is that the UK has not yet implemented electronic voting in any lasting way, shape, or form. Not only are we not on board with popping online to vote, we’re also reluctant to use technology when it comes to marking our ballots, authenticating voters’ identities, and counting votes. Despite the success of electronic voting in countries such as Brazil, Estonia, and India, the UK continues to reject reform. Why?

 “I think the problem is political at the moment,” says Mike Summers, the program manager at Smartmatic, an electronic voting company who have run three national elections in the Philippines, have a 15 year contract with Belgium, and have counted around 3.7 billion electronic votes in 12 years. “I think there is a fear that if you enfranchise groups of younger people, then you don’t necessarily know how they’re going to vote.”

We can, however, make a pretty good guess. Smartmatic’s own research shows that 57 per cent of 18-24 year olds would be more likely to vote if they could do so online and 55 per cent said they would have used online voting at the last general election. As Labour's vote share could have been boosted at the last election if only more young people had turned out to vote, this might make electronic voting an uninviting prospect for Theresa May.

“Prior to the last parliamentary election the Labour party were vehemently in favour of electronic voting,” says Summers. “Things are moving very slowly compared to other developing and developed nations so our reading of the situation is that it’s a largely political one.”

The consequences of this inaction are severe. Holding off on a voting system that provides greater accessibility to all compromises the very notion of democracy, but it also has potentially more immediate repercussions. “In 2020 everything is going to hit the proverbial fan we’re going to be a laughing stock,” says Summers.

The reason for this is because of the wide array of elections sheduled for 2020. Not only will there be a general election, there are also police and crime commissioner elections, the London Assembly and the London mayoral elections, and also local elections. “There is real concern that because of the complexity of this event there is going to be an absolute meltdown.”

Electronic voting would help prevent such a meltdown by ensuring, among other things, that voters couldn’t accidentally mark a first past the post ballot with a preferential voting system (or vice versa), that votes could be counted faster, and that overseas votes would not be lost in the post. The last is of particular importance as the government are now planning to scrap the 15-year rule that bans long-term expatriates from voting in UK elections.

“That’s a potential five million additional expats who will be eligible to vote,” says Summers, “How are you going to service them?” The answer to that is via the postal vote, and the limitations of this traditional method make the case for electronic voting even stronger.

“Postal voters authenticate themselves with a signature – mine is easily forgeable – and their date of birth,” says Summers. “The traditional methods are not secure. With online voting we can use facial biometrics to compare a person’s digital facial portrait – a selfie, if you like – with their ID, and we can verify there is a match.

“The next problem is security, and putting your ballot in an envelope is not secure. We have very, very strong application level cryptography. The moment a voter casts their ballot we encrypt it on the voting side and digitally sign it as a method of proving the integrity. Additionally, when postal voters put their vote in the post box they have no way of checking it was received or counted, so you have no verifiability. We have a number of tools that voters can use to verify their vote was received and was included in the final tally.”

Nowhere is the importance of the postal vote clearer than in the case of Brexit. “You could argue that the outcome would have been different,” says Summers. “Lots of expats voted by post and a lot of the votes didn’t come back before the close of the election count. We have an office in Amsterdam and one of the guys plays in a local rugby club in The Hague. There are ten Brits on that team and six of them received their postal vote after the close of the election. If you’re an expat living overseas then are you going to vote for or against Brexit? If those voters had voted then the outcome could have been completely different.”

Yet the benefits of accuracy, transparency, verifiability, and accessibility are easily side-lined by one bloodcurdling word. Hackers. If Hillary Clinton’s emails can become your bedtime reading, isn’t it possible – nay, probable – that elections will be hacked, falsified, and corrupted?

“The easiest election to hack is a paper election,” says Summers. “It is important to educate people on the difference between election information systems, which the DMC use, and voting systems. The protections of voting systems are above and beyond anything you will use in any other online application, including online banking and ecommerce solutions.”

As a representative of Smartmatic, Summers would say this, but they and other companies have created a wide variety of solutions which – even if imperfect – are vulnerable to fewer mistakes than Deidre in the village hall. Even if there are flaws, it seems important to iron these out now – before 2020 – to ensure the success of electronic voting in the future.

Although the House of Commons’ Commission on Digital Democracy recommended that the UK should adopt electronic voting by 2020, there is little evidence that steps are being taken towards this goal. “I’d love to turn around and say I think steps are being taken but there is a lack of willingness to acknowledge the shortcomings that we have in terms of UK elections,” says Summers. For now, then, the debate rages on. Should we stick to the tried-and-tested, or should we transform the electoral process forever? I know – let's vote on it. 

Amelia Tait is a technology and digital culture writer at the New Statesman.