Falcon shades

Like American football players, many birds of prey have dark black markings just below their eyes. Most of these birds are falcons and all of them hunt flying animals. Given this, ornithologists have argued for years that these markings, known as malar stripes, help prevent light from bouncing off of feathers just below the predator's eyes and blinding them on sunny days. It is a nice idea and makes a lot of sense. The problem is that there hasn't been any proof that this is how the birds actually use these markings... until now.

Got my sunnies on!

Image courtesy of US Fish and Wildlife.

The team behind the new work reasoned that if malar stripes really evolved to reduce solar glare, then they should be bigger and darker in regions with particularly high annual solar radiance than they are in areas with less radiance. To test this out, they turned to the most widespread falcon on the planet: The peregrine.

The peregrine falcon is present almost everywhere globally*. As such, the researchers set up an international effort to source photos of peregrine populations that have long been established in locations with radically different levels of annual solar radiation. They found that the size and prominence of the malar stripe was greater in areas with lots of annual solar radiation and lesser in areas with little annual brightness.

So we now know that, aside from being able to fly at speeds of 390 kilometres per hour, these birds are also effectively wearing sunglasses. You can almost here the Top Gun theme playing as they bolt through the sky…

The academic paper published online in Biology Letters in June.

*Which is really saying something given that we almost drove the bird into extinction with DDT poisoning during the 1960’s.

Cultural magic resistance

The Ebbinghaus illusion.

A two centimetre circle surrounded by six four centimetre circles looks larger than a two centimetre circle surrounded by eight one centimetre circles. Known as the Ebbinghaus illusion, this bit of visual trickery is difficult for people to see through. Indeed, most struggle to see that the two central circles are actually the same size. An exception to this are the Himba. Found in the Kunene Region of Namibia, the Himba people are semi-nomadic pastoralists and, when presented with visual illusions by a team of psychologists in 2012, they proved remarkably resistant to this illusion. At the time, the team suggested that there was something about their intimate relationship with nature that was leading them to respond to illusions so differently from people living in the developed world*. Now new work is revealing that the relationship with nature that the Himba have is irrelevant here. Instead, their cultural resistance to this illusion appears to stem from having slower reaction times and being much less easily distracted.

The new work presented participants with a range of illusions and asked them what they saw at different points in time. For some illusions, like the Ebbinghaus, the power of the illusion weakened over time and with increased concentration by the participants. For others, like the double-decrement contrast illusion grey-scale contrast illusion, the power of the illusion strengthened the longer participants were presented with it and the more they concentrated. These findings alone are interesting in that they reveal some illusions as strengthening the longer they are studied and some weakening. Yet, where this work gets really interesting is when it is applied to the findings with the Himba.

The double-decrement contrast illusion.

The researchers in 2012 bribed the Himba people to participate with bags of sugar and flour. While a bag of sugar or flour might not seem all that exciting to you or me, these commodities were valuable to the Himba and the experience of being presented with visual illusions was an exciting novelty. This made more engaged in the task and led them to spend much more time studying the illusions than the British students in the control group. This, they argue, is why the Himba so consistently saw through the Ebbinghaus illusion while the British students could not. Lending support to this theory is Himba performance on a grey-scale contrast illusion that the new research shows gets stronger with time and attention. Unlike the British, who easily saw through this illusion, the Himba were almost always deceived by it.

All told, the findings reveal that the power of illusions varies with cultures and that a key force behind this variance is the novelty of the illusion itself and whether it is one that strengthens or weakens with increased attention.

This just published online in Psychological Science.

*They used a bunch of British students as a control group.

Melons in ancient Egypt

Watermelon is off the menu for me. Just a couple of bites and I am in the emergency room with anaphylactic shock. That being said, I hear wonderful things about the fruit. As a science journalist I also hear lots of bad news about the future of watermelons. The crux of the problem is that melons are facing a host of new diseases and pests as the climate warms and may soon go extinct. Fortunately, a team of researchers have just identified help for the watermelon by studying ancient Egyptian art.

Already a sweet success.

Image courtesy of Dr Lise Manniche.

The researchers behind this work started by engaged in an extensive genetic analysis of domesticated watermelons from around the world and compared what they found to the genetics that they obtained from six other melon species. They also had historians on their team who examined ancient artistic depictions of melons (we're talking about stuff like Egyptian art) to try and understand when the fruit's flesh became red, when it gained its iconic green stripes and when it developed a sweet flavour.

All of this work revealed that the Sudanese Kordofan melon, which has whitish pulp and does not taste terrible*, is the closest relative of the modern watermelon and is likely the precursor of all domesticated watermelons. The researchers think that early farmers likely cultivated variants of this melon and that it obtained its sweet flavour and reddish colour over time. As for when the watermelon actually became sweet, the team identified illustrations from two Egyptian tomb paintings dating to around 4,450 years ago portraying oblong fruit with dark green stripes on trays and tables with other sweet foods like grapes, suggesting that watermelon as we know it, had come to be by that time.

While this might all sound rather academic, it is not. The watermelon of today has been extensively bred to be sweet and easy to grow. All of the genes that the plant once had for fighting off diseases and insects of days long ago have been lost. It is for this reason that identifying the Kordofan melon as the wild relative of the watermelons is such a big win for botanists looking for disease and pest resistant genes that can be brought into this crop to keep it healthy as the planet goes to hell. You can read more in The Economist article that I wrote on this here.

*Yeah, I know that isn’t selling much but most wild melons need to be boiled with sugar to be edible. The Kordofan can at least be eaten raw.

Heat tolerant coffee

Coffee is a multibillion dollar global industry that supports the economy of several tropical countries all on its own. Roughly 100 million farmers depend upon this crop for their survival. Unfortunately for them and for the countless millions who savour coffee every morning, the plant is under significant threat from climate change. Now a team is reporting some welcome news by revealing that they have found a wild coffee species that can both put up with higher temperatures and produce beans that taste good.

But can they take the heat?

Image courtesy of JM Hullot

The two coffee species that dominate the world market are Arabica and Robusta. Arabica is, to put it bluntly, screwed. It grows poorly in high temperatures and the only way it can continue being farmed is through a mix of farm engineering with shading and cooling measures being taken to keep crops alive as temperatures soar. Arabica can also be kept on life support by moving farms up mountains but this is expensive and socially challenging since it will require transplanting low elevation communities to places where it will be harder to survive. Robusta, as its name suggests, is a tougher variety of coffee and can put up with warmer temperatures than Arabica. The catch is that is requires a lot of rainfall and is not as tasty.

Given the problems, the search has been on for another coffee variety. There are 120 other known coffee species. Many grow in warmer and drier environments relative to Robusta and Arabica but all were thought to taste terrible. The new work reveals a species that is climate change tolerant, farmable and (most importantly) delicious.

The species, known as C. stenophylla, grows wild in Guinea, Sierra Leone and Ivory Coast. It was tasted by late Victorian explorers and they noted that coffee made from the beans was good but those reports have been ignored for years (we had Arabica so who cared?). Indeed, there has been no published taste description of this coffee since the 1920's due to its rarity in the wild and absence on farms. Worse it is threatened with extinction in the wild as Robusta coffee that has escaped from farms is currently out-competing it.

The researchers argue that, properly managed, this wild coffee can be grown on farms and used to continue generating a coffee supply for the world as temperatures rise. You can read more in The Economist article that I wrote on this here or listen to my podcast with The Intelligence on this topic here.

Inception... only real

Dreams take people to a different reality, a hallucinatory world that feels as real as any waking experience. These often-bizarre episodes are emblematic of human sleep and yet, the research community knows more about the moon than it does about dreaming. A key problem here is that, unlike an astronaut returning from the lunar surface who can recall what they saw with reasonable accuracy, the dreams that people have quickly get distorted and forgotten when they wake up. Given these challenges, there has been an intense interest in working out how to ask dreamers questions while they are dreaming and have them answer without waking them up. Now a team led by Ken Paller at Northwestern University is revealing that they have figured out how to do this and, yes, the results are straight out of the film Inception.

The researchers took aim at lucid dreams as these are dreams where people are vaguely aware that what they are experiencing is not quite real and have some level of consciousness. This led the researchers to suspect that, if done right, they might be able to get questions heard by dreamers and possibly answered too. To manage this, they worked with 35 people. Some had a long history of frequent lucid dreaming and some were given exercises that helped them to lucid dream more often. All participants were trained to make eye movements or contract facial muscles to answer questions when they encountered them.

The questions were all basic counting or mathematics queries. They were delivered via light flashes, touch (taps on the arm) or audio. In total, the team attempted two-way communication during sleep in 57 sessions. In 26% of these sessions, participants successfully signalled that they received the message. In 47% of these signal-verified lucid-dreaming episodes, the team obtained at least one correct response to an experimental query.

After they had woken up, all participants correctly reported when they had received experimenters’ questions, however, the events of communication were often recalled in a distorted manner. Many participants reported that signals sent by the researchers were transmitted through components of the dream. For example, one participant reported that an audio question was heard as if played through a radio during a party while another reported that four flashes of light sent by the researchers manifested as a light in the dream flickering on four times. Intriguingly, details of communications that were recalled in dream reports taken afterwards often diverged from the recordings made during the dream. For example, participants frequently reported a mathematics problem that differed from the one that had been presented to them (i.e. they would say they saw five or six flashes when only four were given) even though they actually gave a correct response of four with their eye movements whilst dreaming.

These findings refute the common belief that it is pointless to try to communicate with people who are asleep to gain knowledge about their dreams. On the contrary, the collection of results described by Dr Paller constitutes proof-of-concept of two-way communication during sleep. he argues that this opens the door to a new approach for scientific exploration of the dream state.

You can read more in The Economist article that I wrote on this here or listen to my podcast with The Intelligence on this topic here.