Dear Readers, the Christmas and New Year issue of New Scientist is such a delight that I thought I’d share a few highlights with you over the next few days, after yesterday’s rather more pensive post. First up is the brussels sprout. Scientist Chris Pires has made it his mission to discover the ancestor of the plant, and this has led him to some very interesting places.
Brussels sprouts have the scientific name Brassica oleracea, but sadly so do fourteen other varieties of cabbage, including cauliflower, Savoy cabbage, kohl rabi and kale. So how did this diminutive little chap get his start? It was thought that the brussels sprout might have been first domesticated in the UK, but another theory pointed to the Mediterranean. After doing some genetic analysis, it turned out that the closest relative to these green Christmas ‘favourites’ (I use the word advisedly) was a weedy plant called Brassica cretica, which languishes on the sunny shores of the Aegean.
This ties up with the first recorded mention of the Brussels sprout, in Greek literature from about 2500 years ago. The botanist Theophrastus suggested using the vegetable to offset the results of too much alcohol, something which is apparently still believed in Southern Italy to this day. I have no idea if you eat the sprouts before or after the intoxicating event, but either could, I fear, lead to disaster.
To my delight, it appears that Greek legend has it that cabbages sprang up where Zeus’s sweat fell to the ground.
Still, the theory about the Aegean weedy cabbage relative remains to be proven because apparently some of the Brassica cretica that the scientists found could themselves be feral – in a dry, hostile environment I’m sure people would eat every plant that poked its head up and that wasn’t actively toxic, so I imagine there have been endless crossbreeding between the species, both natural and encouraged by people. Will we ever get to the bottom of the heredity of the Brussels sprout? Who knows. I am just holding onto the vision of Zeus raising his arms to heaven as a whole shower of round green cabbages cascades out of his armpits.
And with apologies in advance for the scatological subject of the next brief item, it appears that artificial intelligence can detect diarrhoea with up to 98% accuracy if you place an AI listening device in a toilet. It’s thought that this might be able to track outbreaks of diseases like cholera. It appears that some poor human had to listen to hundreds of recordings in order to work out if there was a problem with someone’s defecation or not, so that the AI could ‘learn’. Whenever I’m fed up at work, I’m going to remember that things could be worse.
You can read the whole article here, if you have the stomach for it.
Dear Readers, I don’t know what it is about birds, but much as I like them, they don’t always like me. As you may remember, I was chased by a goose when I visited a City Farm, and when I went for my first ever visit to South Africa, our jeep was hotly pursued by a male ostrich, which was a bit like being hunted down by a velociraptor. Gosh, those creatures can run! And they know all the short cuts! I remember our jeep bumping over potholes and careering through bushes. We’d stop, thinking we’d finally outrun Mr Ostrich, only to hear the telltale thumping of his feet as he accelerated towards us. As he was more than eight feet tall on his tippy-toes and had already given someone a nasty peck on the head, we were all semi-traumatised by the experience. For the rest of the trip, the sight of an irate hippo or a prowling lion didn’t bother us, but we’d all shriek at the sight of an ostrich. It feels a bit like the chicken’s revenge.
Anyhow, I was fascinated by this article in New Scientist this week, which is all about the neck of the ostrich. Large animals tend to have more problems with rapid temperature changes because they can’t lose heat quickly (if you all remember your surface area to volume from school biology lessons). Different creatures evolve different methods to deal with this, like the enormous flappy ears of the African elephant. For the ostrich, the key seems to be that their necks act as a radiator.
Herd of ostriches (Photo Two)
Erik Svensson, from Lund University, Sweden, spent five years taking infrared photographs of ostriches at a research farm in Klein Karoo, South Africa, and discovered that the ostrich’s neck acts as a ‘thermal window’, emitting heat when it’s too hot, and retaining it when it’s too cold, thus keeping the temperature of the head and brain stable. Our guide on our ostrich-embellished South Africa trip told us that the birds only have a brain the size of a walnut, and was very disparaging about them. However, as the ostrich had reduced a whole jeepload of English tourists to jabbering wrecks I think he might have underestimated them.
The research farm has three different subspecies of ostrich, one from Kenya, one from Zimbabwe and one from South Africa. Interestingly, the ones from Zimbabwe and South Africa, where there is more climatic variation, seem to be better at shifting the temperature of their necks. Furthermore, female ostriches who had a greater temperature difference between their necks and their heads laid more eggs in the following period than ostriches with a smaller difference, implying that the neck is a buffer for heat stress. After all, keeping our brains from frying is important for any species, hence the need for sunhats and for none of that ‘mad dogs and Englishman going out in the midday sun’ stuff.
Ostrich panting (Photo Three)
Ostriches also pant, and Ben Smits at Rhodes University in South Africa wonders if the hot blood from the neck is actually shunted upwards and then cooled when the animal opens its mouth, as happens with dogs (and humans).
Scientists speculate that as the climate gets warmer, the neck of the ostrich could get even longer – this appears to be a genetic adaptation, and so it can be passed on through the generations. It’s clearly beneficial for the ostrich, both in terms of survival and of reproductive success. I’m not sure exactly how I feel about an even taller ostrich than the one that we met, but maybe next time I’m planning visiting somewhere which has ostriches, I’ll take a tin hat (though that might just lead to my brain overheating).
The strawberry poison dart frog (Oophaga pumilio) (Photo One)
Dear Readers, as the frogs return to my pond I found myself curious about frogs in general, so off I went to New Scientist. First up, here is the strawberry poison dart frog. In the archipelago of Bocos del Toro, Panama, the frogs vary greatly in colour according to which island they live on, although they are all the same species. Wildlife photographer Paul Bertner headed off to the islands, accompanied by his Panamanian guide who had won one of the islands on a gameshow. It isn’t clear why the frogs on the different islands look so different – presumably the colours give them an advantage in each habitat, so my guess would be that there are slight variations in plant cover and predators. Sadly, some of the colour variants are already becoming rare, because there’s a market for them amongst exotic amphibian collectors. Leave the frogs alone, people! Amphibians and other exotic animals are extremely difficult to rear and breed in captivity, and I dread to think how many die because their conditions aren’t correct. I speak, sadly, from experience, having tried to keep reptiles and amphibians in my twenties. I soon realised that this is a very tricky area which requires specialised knowledge.
Still, here are some of the photos that Bertner captured of the wild frogs, and very pretty they are too. You would never guess from looking at them that they were the same species.
Strawberry Poison Dart Frog (Photo by Paul Bertner)
Strawberry poison dart frog (Photo by Paul Bertner)
You can see all the photos and read the article by Alice Klein here.
From rainbow frogs to fluorescent ones. Scientist Julián Faivovich has found that the polka-dot tree frog of the Amazon basin is the first one that glows in the dark. making it 30% brighter at twilight than other frogs. It’s known that many microorganisms fluoresce, and so do some fish and sea turtles – in other words, they have substances in their skin that absorb light at one wavelength, and emit it at a longer one. Faivovich believes that although this species is the first amphibian which has been proven to fluoresce, it’s unlikely to be the only one – there are 5000 species of frog, so for this to have evolved just once is very unlikely.
The fluorescence happens at a wavelength that the frog can see, and so it’s probably useful for signalling and for communication although, as with so much about frogs, it’s still a mystery.
Polka-dot tree frog (Hypsiboas punctatus) in daylight….(Photo Two)
…and when seen under ultraviolet light (Photo Three)
In other good news, a new species of frog discovered in a protected forest in India in 2019 is the only living member of a lineage that dates back millions of years. The starry dwarf frog (Astrobatrachus kurichiyana) is only two centimetres long with an orange stomach. Interestingly, the number of frog species identified in India has leapt from 200 to 400 species over the past few decades, which just goes to show what you can find when you look. You can read the whole article by Adam Vaughan here.
Starry Dwarf Frog (Photo by Seenapuram Palaniswamy Vijayakumar)
And finally, you may be aware that frog species all over the world are being decimated by chytrid disease, a fungal disease of amphibians. Frogs are widely seen as the ‘canaries in the coalmine’ by ecologists, due to their acute sensitivity to changes in their habitat. Many zoos and institutions have been in a race against time, taking whole frog populations into captivity to preserve them and breed them, with the hope that they will be able to be reintroduced into the wild when a cure for the fungal disease is found, and when their habitats are secure. So it was great to see that some populations of frogs do seem to be developing immunity to chytrid, provided that there are enough of them and their habitat is not too degraded.
The Sierra Nevada yellow-legged frog (Rana sierrae) lives in the mountainous regions of California, but its population has been in decline for years. This is partly due to the stocking of the rivers where it lives with non-native trout, who eat the frog’s tadpoles, but the frog really started to decline when chytrid hit in the 1970’s. By 2000 the frog had disappeared from 93% of its habitat, and was classified as endangered. However, the good news is that the frog appears to be bouncing back, with an annual population growth of 11%. Scientist Roland Knapp puts this down partly to the Park Service’s good sense, as they stopped stocking the river with trout in 1991. However, the frogs that have survived chytrid now appear to have some resistance to the fungus, allowing the population to recover. This has also been observed in the Stony Creek frog in Australia, which also appears to have developed resistance.
However, scientists are cautious – in areas with tiny, isolated populations, or where there is already significant habitat degradation, it will be a lot harder for the frogs to survive long enough to develop resistance. It seems that those dedicated frog conservationists battling to save these animals will be busy for quite a while yet.
You can read the whole article by Brian Owens here.
Sierra Nevada Yellow-Legged frog (Photo by Joel Sartore, National Geographic Photo Ark/Getty)
Dear Readers, there are some amazing articles in New Scientist this week. First up, scientist Darko Cotoras of the California Institute of Sciences in San Francisco has found that a tiny spider found only on Cocos Island, off the coast of Central America, can make three different types of web according to the circumstances in which it finds itself.
Wendilgarda galapagagensis makes ‘aerial’ webs high above ground, attached to nearby stems and leaves. Near to the ground it makes ‘land’ webs, with long horizontal strands attached to branches, and with vertical strands anchored to the ground. Over pools it makes ‘water’ webs, like the ones in the photo, with the vertical strands attached to the water surface itself.
Cotoras wondered if this meant that the spider was actually turning into three separate species. However, when the spiders were relocated, they often started to build webs in the style that was most suited to their new home. In other words, these tiny invertebrates are not limited to just one web (which seems to be the case with many spiders) but can adapt according to circumstances. This seems to me to contradict one theory, which is that island animals adapt to occupy a very specific niche and are hence threatened if things change.
Juvenile Brown Ghost Knifefish (Apteronatus leptorhynchus) (Photo by Guy L’Hereux)
Brown Ghost Knifefish are found in the rivers of Colombia, and have a surprisingly complicated social structure. They use electric discharges to find food in the silty water, and to communicate with one another, and until 2016 little was known about them. Then scientist Till Raab and his colleagues at the University of Tübingen in Germany found a group of more than 30 fish in an area only 9 metres square. However, Raab noticed that there was little fighting between the fish, and wanted to examine what was going on.
In captivity, it was found that when a fish was denied access to a shelter by a competitor, the fish responded by targeting the other fish with electric pulses, which gradually increased in discharge before falling back to normal. The subordinate fish seemed to be deliberately provoking the fish who had control of the shelter into chasing and biting it. Although this didn’t result in a change of ownership, it did seem to improve the social standing of the subordinate fish, and over time seems to have ‘evened out’ the relationships between the fish. One fish that made repeated ‘attacks’ on the dominant fish eventually ended up with control of the shelter (one imagines a weary fish deciding that control of a piece of tubing wasn’t worth all this aggro).
Of course, the mere fact of being in captivity will have an influence on behaviour in any animal. However, what this does seem to illustrate is that fish are as capable of weighing up the delicate nuances of social relationships as any mammal.
The Chinese Continental Scientific Drilling Project (Image by Qin Wang et al)
And finally, here is something truly incredible. Scientists Hailiang Dong at the China University of Geosciences and Li Huang at the Chinese Academy of Sciences have discovered bacterial cells from a 5.1 kilometre-deep borehole in Eastern China (the Chinese Continental Scientific Drilling Project or CCSD). Previously, the deepest known microbes on land were nematodes found 3.6 kilometres deep in a South African gold mine.
At this depth, temperatures are a staggering 137 degrees Centigrade, far above the accepted threshold of 122 degrees Centigrade. Scientists now believe that temperature might not be the only factor involved – the pressure, the physical nature of the rocks and the availability of water might also play a role.
Proving that the cells are alive will be another problem – organisms living at this depth often have an extremely low rate of metabolism because of the poor availability of nutrients. However, experiments with deep sea organisms have revealed that, if fed, they often ‘wake up’ with surprising enthusiasm. It will be interesting to see what approach is taken with these new microbes.
One reason that finds like these are so exciting is that it greatly increases the range of habitats on other planets where life might be possible. But for me, a second reason is that it demonstrates the extraordinary versatility of life. It gives me hope that, even if we screw things up irredeemably on the surface, we might not wipe out life completely. Of course, we won’t be here to see it if things go that wrong but maybe, in millions of year time, the next inhabitants of earth won’t be quite so feckless with the planet that they inherit.
Dear Readers, following all the excitement about frogs and newts yesterday, I thought I’d dig into the archives of New Scientist and see what I could find to share with you on the subject of tadpoles. One question that I’ve always had is – why do some tadpoles mature as expected and turn into baby frogs or toads, and why do some seem to spend the winter as tadpoles? This very question was asked in New Scientist in 2018, and the answers were most interesting.
One obvious answer that occurred to me is that, as climate change makes for warmer winters, amphibians overwinter as tadpoles simply because they can: if they can get a jump (see what I did there) on the newly-hatched spring tadpoles, they will have a ready source of food (sadly many species of frogs are cannibals). However, I know from my own endeavours that frogs seem to mature according to the water temperature – when I brought some tadpoles indoors because there were problems in their pond, they grew legs several weeks before their ‘wild’ relatives. So can frogs ‘choose’ when to metamorphose?
It also seems to me that in a population of tadpoles, if some mature quickly and some slowly they are covering all eventualities – whatever the winter weather, some will survive. That’s how evolution works, after all.
Another suggestion was that the rate of maturation can be delayed by imperfect conditions in the pond – overcrowding, and hence lack of food, or low water temperature will all slow things down.
But finally one lady, who is definitely a soulmate, used to observe the development of the tadpoles in her garden over seventy years ago. She returned home after the school holidays to find that the tadpoles all had four legs but still had a tail, and that it was long past time when they should be fully-developed. She had a nature book by Enid Blyton (better known for Noddy), and found that tadpoles needed iodine to mature, presumably because of its influence on thyroid hormones. Medicine cabinets used to hold iodine for cuts and grazes in those days, so she put a few drops into the pond.
‘Days later, the garden was teeming with froglets’.
Fascinating stuff. I remember treating a goldfish who had a fungal disease with a few drops of iodine, and it cleared that up too.
Now, here’s something amazing.
Newly-hatched tadpoles need to breathe air, but are too weak to puncture the surface tension of the water. So, instead they suck at the surface of the water from below so that they break off a bubble which contains fresh air from the outside world. They breathe this in to their lungs and then exhale it out. And furthermore, you can watch it in the article below.
Common vampire bat (Desmodus rotundus) (Photo One)
Dear Readers, there are more species of bats on Earth than any other mammal group except for rodents, and yet we know very little about them. So for today’s update from New Scientist, I wanted to pick up on a few stories that shed light on their complex lives.
Vampire bats are not everyone’s choice as favourite small furry animal, but this article shows how little we know about their social structures. Imran Razik of Ohio State University was studying a colony of vampire bats which comprised 23 adult females and their young. Although vampire bats roost together, they normally raise their young individually, although bats form close ‘friendships’ with one another. The researchers noticed the burgeoning relationship between Lilith, a nursing female, and BD, a single bat with no offspring of her own.
When vampire bats form a friendship, they spend a lot of time grooming one another, and sharing food. It was noticed that BD spent a lot of time feeding Lilith, and that this increased as Lilith became ill, even though she was not sharing food reciprocally with BD. As Lilith became sicker, BD also spent more time looking after the baby, grooming it, carrying it and even feeding it.
When Lilith eventually died, BD adopted the baby fully. It is extremely rare for this to happen even amongst mammals that are more closely related to us, such as chimpanzees, so this is a very exciting observation. Why, though, do bats choose one individual over another to be their friend? As it’s hard enough to work this out even in humans, I think this could be a fascinating study.
European free-tailed bat (Tadarida teniotis) (Photo Two)
Now, let’s have a look at the European free-tailed bat, a rather melancholy-looking creature if the photo is anything to go by. It’s long been known that birds can often reach extreme heights by finding thermals and riding them, but these are much less common at night. However, by attaching light-weight GPS monitors to lactating female bats, it was found that they could reach heights of up to 1600 metres. How do they do it? It appears that, although they fly in almost total darkness, they have an excellent knowledge of the landscape of their territory, and use the uplift from where south or west-facing slopes meet the prevailing winds of north-west Portugal, where the colony is located. They soar upwards, gently sail down and then find another slope of similar topography so that they can repeat the process. The team who studied the bats, led by Teague O’Mara from Southeastern Louisiana University, note that this gives a flight-plan that looks rather like a rollercoaster ride. One question would be ‘why go so high’? I would speculate that the bats’ insect prey may also fly high, probably to avoid predators, but this style of flight would be energetically very efficient for the bats. You can read the whole article here.
Brazilian free-tailed bat (Tadarida brasiliensis) (Photo Three)
And now for another free-tailed bat. The Brazilian free-tailed bat was cited as the fastest vertebrate in the world at level flight during tests on the population from the Frio cave in south-western Texas. The bats clocked speeds of 100km an hour, with one bat having a maximum speed of 160km, faster than the spine-tailed swift at 112 km per hour. However, then the controversy started, over the way that the bats were measured, uncertainties about the wind speed, and whether the ‘level’ flight was actually level. Nonetheless, there is no doubt that these are extremely speedy bats – they travel more than 50km to their feeding grounds every night, and fly at heights of more than a kilometre. Perhaps they’re in an arms race with speedy prey?
Now you might think that with all these speedy, high-flying bats around, moths would stand no chance. In fact, some moths are able to hear the echolocation clicks given by bats and literally fold their wings and drop out of the air to avoid capture. What happens, though, if you have no ears?
Chinese Tussar Moth (Antheraea pernyi) (Photo Four)
Marc Holderied was studying earless moths, such as the Chinese Tussar Moth, at Bristol University. He found that when sound waves were projected at the wings of the moth, they bounced back much more quietly. Structures on the wings absorbed the sound at the specific frequencies that are emitted by the bats, in effect acting as a ‘stealth coating’. Holderied also studied another species of earless moth, Drury’s Owl Moth (Dactyloceros lucina) and found that it had the same structures on the wings. Moths who could hear didn’t have them.
Drury’s Owl Moth (Photo Five)
Scientists are speculating whether similar structures could be designed to help with things like sound-proofing and noise-cancelling headphones. In our increasingly noisy world, that could surely be good thing.
Dear Readers, long-term followers will know that I am fascinated by animal ‘personality’ – scientists have found that even creatures that barely have a brain (in our terms) can still be consistently shy, or aggressive, or friendly, or curious. So a recent study in which Zoltan Barta at the University of Debrecen in Hungary, investigated not only the personality of individual birds but how they did in groups was always going to be interesting.
Individual sparrows were first assessed for ‘personality type’ by leaving them alone in a cage for ten minutes. Some tried to get out, some sat quite happily and others hopped around looking for something to eat. At the end, the sparrows were put into groups either with birds of their own personality type, or in a diverse group, and left to get on with it for nine days. What interests me is that the birds in the diverse group were much happier and healthier on all measures, from weight to appetite to stress levels, than the birds that were just with cage mates of their own character. I do hope that they were released in the end, to form groups of their own choosing.
Observers of sparrows in the wild have long noted that one sparrow is always the first to explore a new food source, or to threaten a predator. It seems to me that having a variety of personalities within a species or community is useful in an evolutionary sense – after all, if all the sparrows were bold there’s a good chance that they’d be wiped out by a particularly clever predator, but if some were a bit more cautious they would be more likely to survive. But more than that, it shows that animals are not just automata, but are different from one another. As anyone who has ever been a farmer or owned a pet can tell you.
Olympic Swimmer Michael Phelps in a ‘sharkskin’ suit (Photo One)
Now, lest you wonder what a semi-naked man is doing on Bugwoman I would like to point out that this chap is wearing a ‘sharkskin’ swimming suit. Biomimicry – the use of design features from plants and animals – has been popular forever, ever since someone looked at the bud of a burdock and thought ‘velcro’, but it seems that we don’t always do it right. Do you remember the controversy about these sharkskin suits at the Olympics? They seemed to help the swimmers go faster, and I seem to recall that they were banned, at least for a while. However, it seems that we might not have got it right anyway, because according to Josephine Galipon at Keio University Institute for Advanced Biosciences in Japan and her colleagues, when sharkskin is on a shark, it helps most when the fish is accelerating and turning rather than when it’s cruising along. So was the effect of the suits psychological, I wonder? Or was there something about them being full-body suits that reduced drag? The jury is out.
It used to be thought that below 1000 metres the oceanic abyss was pretty much a desert. More recently, it was found that lots of scavengers can be found around whale carcasses and such, but this group of Pacific eels, found on an underwater mountain 3100 metres below the surface, was the biggest collection of fish ever seen at such a depth, with over 100 individuals. The scientist who found them, Astrid Leitner from the Monterey Bay Aquarium Research Institute in California. explained that baited cameras were dropped into the deep ocean.
‘When they retrieved the lander, the first images they saw were initially disappointing as they seemed to show a black screen. But a closer look revealed the frame was so full of eels that it just appeared black.
“We basically landed on top of eels, then they just swarmed at us,” says Leitner.’
Eels in the abyss (Photo Two)
The sad part of this tale is that the area where the fish live is coming under increasing pressure from those who want to mine there (yes, even at 3000 metres deep). The fish seem to like the seamounts rather than the plains where the mining would take place, but so little is known about these areas that untold damage could be caused before we even know what’s there.
Dear Readers, domesticated dogs split genetically from wolves at some point between 27,000 and 40,000 years ago, but we don’t know where it happened, or why. Some scientists believe that the wolves helped humans to hunt, and the relationship developed from there. Others think that wolves scavenged around waste dumps, and so became used to humans.
However, Maria Lahtinen of the Finnish Food Authority has another explanation. She and her colleagues estimated how much food was available during the Arctic winters, and has calculated that humans probably ended up with more meat than they could eat – humans have a limited capacity to process protein, which would have led to food being available to feed to orphaned wolf cubs. To my mind, this is part of an explanation rather than the whole thing: after all, lots of animals eat meat, but only wolves ended up becoming domesticated. Maybe the cubs were recognised as being useful in the hunt, and so were treated as working animals rather than pets? It’s an interesting theory, however, and helps to fill in the mosaic of reasons for why dogs rather than wolverines or badgers or otters ended up becoming ‘man’s best friend’.
Argentinosaurus with human for size comparison (Photo Two)
Stop press! Scientists in Argentina are excavating a fossil that they *think* might belong to the largest land animal that ever lived. Known as Argentinosaurs or titanosaurs, these huge animals lived about 98 million years ago. They are sauropods, more familiar to old ‘uns like me via animals like the brontasaurus and brachiosaurus – all of them have small heads, a long, long neck and tail, and four pillar-like legs. When I was growing up, it was assumed that they had to be at least semi-aquatic to bear the weight of their bodies, but these days scientists think that, while they probably lived in wet and coastal areas, they had plenty of physical adaptations to ensure that they could wander across the landscape like so many gigantic reptilian giraffes.
So, how big were they? The scientists, led by researchers from Argentina’s National Scientific and Technical Research Council, are saying that, from the remains that they’ve discovered, they think that their sauropod is ‘bigger than Patagotitan’, a creature that measured 37 metres (121 feet) long, and weighed 85 tonnes. However, everyone is a little nervous about definitively stating that this is ‘the big one’, as researchers have been found to have overestimated the size of ‘their’ critter before.
One very interesting thing is that there were sauropods of various sizes walking around 98 million years ago – some were a mere 6 metres long (which is still bigger than a car of course). It’s likely that each species had a particular ecological niche, preferring specific plants or types of habitat. Oh for a time machine, to go back and see these amazing creatures in action! Though I’ve watched enough science fiction films to know what happens if I accidentally drop a hair pin or a pair of nail scissors, so it’s probably not a great idea.
The original article by Joshua Rapp Learn is here.
Cave paintings showing three pigs (one complete, two vestigial) plus two handprints (Photos by A. A. Octaviana)
And finally, cave paintings found in Indonesia show the oldest known image of an animal in the world – they are at least 45,000 years old, and could be older. The paintings, in Sulawesi, show a complete life size Sulawesi warty pig (Sus celebensis), an animal that was extremely important to the early hunter-gatherers of the region. The painting has been partly covered by a mineral deposit, and it’s this that gives the approximate date although, as the deposit overlaps the image of the pigs, the image itself could be much older.
The hand prints in the top left-hand corner are usually made by someone taking a mouthful of paint and blowing it over the hand, so the researchers hope that they can extract some residual saliva for DNA analysis.
The date of the paintings, which makes them as old as those found in Europe, raises interesting questions about the routes taken by humans when they left Africa – it used to be thought that eastern Asia was inhabited rather later. There is a scarcity of human remains in the area, so there are some thoughts that the paintings could actually have been made by Neanderthals, rather than humans. It will be very interesting to see how this story develops, but what it does point up, to me, is the extremely close observation of animals by early societies, and the significance that such creatures had in the lives of humans.
You can read the original story, by Ibrahim Sawal, here, and there is also a short film which gives an idea of the scale of the painting.
Phyllanthus rufuschaneyi oozing nickel-rich sap (Photo One by Anthony van der Ent)
This post is based on this article from New Scientist by Michael Allen.
Dear Readers, for many years it’s been known that plants are useful for bioremediation: some species of brassica guzzle up metals such as nickel from the soil, cleaning it in the process, and lichens are also known to help clean up pollutants. It’s thought that plants do this because the metals are toxic, and might therefore help to protect them against insect predators. Such plants are known as hyperaccumulators because they store so much of the element.
However, when Anthony van der Ent, a plant-hunter based at the University of Queensland in Australia, found a shrub called Phyllanthus rufuschaneyi at a park ranger’s station in Malaysian Borneo, he noticed that it oozed a bright blue-green sap. Upon analysis, it turned out that the sap contained 25% nickel by weight.
Nickel is an essential ingredient in products such as computers and smart phones, but will become even more important with the advent of the rechargeable batteries in electric cars. The metal is also needed for wind turbines. It’s estimated that for electric cars alone, the amount of nickel needed will double, to 256,000 tonnes, by 2025. But the normal method of getting the metal is by strip-mining, one of the most environmentally devastating extraction methods: it creates defoliation, soil erosion and pollutant run-off which contaminates sea water and rivers. One of the leading world nickel producers is the tiny island of New Caledonia.
Open cast nickel mine in New Caledonia (Photo Two)
So, would it be possible to grow hyperaccumulating plants so that the nickel could be extracted from them, rather than despoiling the environment? One problem is that the plants don’t grow just anywhere: the metals in the soil are found in areas which had a lot of tectonic activity which meant that instead of just sinking, the elements were raised to the surface. Such soil is known as ‘ultramafic’.
Having found his plant, Anthony van der Ent set about creating the world’s ‘first tropical metal farm’ in Sabah in Borneo. He and his colleagues are growing Phyllanthus ruruschaneyi: every year the shrub is coppiced, the stems and leaves are pulped, and the nickel is extracted. In 2019 they reported a yield of 250 kilograms per hectare, currently worth almost $4000.
A long-time collaborator of van der Ent’s, Guillaume Echevarria of the University of Lorraine in France, also wanted to see what was possible, but using a tropical plant didn’t seem the right way to go. Instead, he used a different hyperaccumulator (not specified in the article but probably an Alyssum species). He has chosen some plots on ultramafic soil in Albania, and the plant is sowed and harvested by local farmers. The plant is then transported to France and burned to produce nickel-rich ash, from which the metal is extracted. The energy yielded by the burning is used as a heat source for nearby buildings, so Echevarria considers that the whole project comes in as carbon-neutral.
Although the results are not as promising as in Borneo, the plant still yields about 200 kilograms per hectare which, at around $3000 at today’s prices still makes this a viable business. For comparison, a hectare’s worth of wheat in the UK can be sold for about $2100.
While Van der Ent thinks that the whole project could be scaled up in areas where there are ultramafic soils, such as Indonesia, Echevarria is more cautious, and I have to say that I would be worried about large scale ‘phytomining’ too. Many areas of the world which are otherwise suitable for growing hyperaccumulators are also biodiversity hotspots and protected areas, and having seen the palm oil plantations in Sabah, the last thing the world needs is more hectares of monocultures. However, there are some areas, particularly in Greece, Albania and Bulgaria, where farms are being abandoned because the soil is so poor for other agricultural applications, and at least growing plants could help to stabilise and revegetate such areas, whilst providing the farmers with some extra income. Echevarria thinks that phytomining could provide a few percent of the global nickel requirements, which is not to be sniffed at.
It’s not just nickel either. Plants that hyperaccumulate arsenic, cobalt, manganese, zinc and rare earths have been discovered. Marie-Odile Simonnot, also at the University of Lorraine, has been assessing Dicranopteris dichotoma, a fern that grows naturally on spoil heaps near rare earth mines in China’s Jiangxi province.
Dicranopteris dichotoma (Photo Three)
It seems to be possible to harvest about 300 kilograms of mixed rare earth metals per hectare, including lanthanum, cerium, prasedoymium and neodymium from this plant, and Simonnot is working with Chinese scientists to run trials at old mining sites. This seems like a win-win to me, as the plant seems to grow in landscapes that are already environmentally devastated, and which could only be improved by a bit of native plant cover.
Nowadays, though, Van der Ent is no longer trudging through the jungles of Borneo. Instead, he is hunting through the herbariums of the world’s museums with a handheld X-Ray flourescence spectroscope. This gives an instant read-out of the elements that a specimen contains, and hundreds of new hyperaccumulators have been found in this way. Who knows what other secrets the plant kingdom contains? Let’s hope that this time we are able to work with nature to make the most of them, rather than against her.
Dear Readers, before we finally say goodbye to 2020, here are a few final stories from New Scientist that caught my eye.
The first is pandemic-related, as nearly everything seems to be at the moment. White-crowned sparrows (Zonotrichia leucphrys) were found to be singing differently during the Covid lockdown in San Francisco, and scientist Elizabeth Derryberry, from the University of Tennessee, wondered how, and why.
The birds were found to be singing more quietly and at a deeper pitch – it’s known that birds react to the low-frequency background drone of traffic and air conditioners by singing not only louder, but at a higher frequency so that they can be heard over the racket. The noise level in San Francisco had dropped by a full 7 decibels, and so the birds seem to have reverted to their older, sexier songs – birds actually seem to prefer deeper sounds (think Barry White as opposed to Tiny Tim). If you go to the full article here, you can hear both birdsongs. The scientist says that ‘they sing like they used to thirty years ago’. I suppose this is both sad, but also hopeful – birds and other urban animals seem to be so much more adaptable than we thought.
Skeleton of cave bear showing enormous sinuses! (Photo Two)
But not all animals are able to adapt. The prehistoric cave bears (Ursus spelaeus) that used to weigh over 1000 kilograms, and existed alongside our present-day brown bears (Ursus arctos), probably became extinct because they had over-large sinuses. Who knew? These huge animals, who disappeared about 24,000 years ago, lived on a largely plant-based diet. When the ice-ages made vegetation difficult to come by, the cave bears couldn’t switch to a meat-based diet, because their sinuses meant that they could only chew food with their back teeth, while carnivores typically cut up their food with their incisors and canines at the front. The brown bears had smaller sinuses, and hence could switch from a herbivorous to a carnivorous diet.
But why have such big sinuses in the first place? They are thought to play an important role in gas-exchange during hibernation, allowing the bears to hibernate for longer. However, as the poor cave bears wouldn’t have been able to fatten up due to the lack of plant food, they probably starved while they were sleeping. It was one of those evolutionary trade-offs that failed.
Hagfish are extraordinary animals. Early ancestors of the eel, they have four times as much blood compared to their volume as any other fish, four hearts and only half a jaw. When trapped by a predator or accidentally stuck in a tight spot, they throw complex knots and shapes in an attempt to escape. Because this is a very slippery fast-moving process, it’s taken modern technology and a slow-motion camera to decipher what’s going on. Now, scientist Theodore Uyeno has discovered that the animals prefer more complex knots – the hypothesis is that the simpler ones may be more uncomfortable because the loops are so tight.
So, 45 percent of the time the hagfish do a trefoil knot:
Trefoil knot (Photo Four)
33% of the time they do a figure-of-eight knot…
Figure-of-eight knot (Photo Five)
and 4% of the time they manage a three-twist knot, the only animal able to do so (Moray eels can knock up a knot, but nothing this complicated). Kompologists rejoice!
Three-twist knot (Photo Six)
And finally, how about this little creature with its ‘hats’?
Uraba lugens caterpillar – the moth is also known as the ‘gumleaf skeletoniser’ (Photo Seven)
Each ‘hat’ is the moulted skin of the caterpillar’s head – they moult up to thirteen times before they metamorphose into moths, and from the fourth moult on, each ‘hat’ stays stuck. You can see how the size of the head gets bigger from the top down, as the larva munches on eucalyptus leaves: an alternative name is the ‘gumleaf skeletoniser’ because the foliage is eaten right back to the veins.
The ‘hats’ seem to fulfil a useful purpose: biologists have watched the caterpillar using them to swat away predators, and they may also serve to distract a curious bird who will hopefully peck at the wrong ‘head’. You can read the whole article here.
And so, dear readers, onwards and into 2021. Who knows what those scientists will discover next?