16 Jan 2018

Ants have an(other) unexpected superpower

In 2013, Gabriele Berberich’s seminar on earthquake prediction at the European Geosciences Union annual meeting, in Vienna, caused shock waves among the audience. Berberich, a geologist at University Duisburg-Essen, in Germany, presented tantalizing results from her fieldwork showing that red wood ants (Formica rufa-group) change their behaviour hours before an earthquake. Shortly after Berberich gave her presentation, headlines in the mainstream media were boldly claiming that ants sense earthquakes several hours before they strike. This was huge. Despite decades of research, geologists continue struggling to predict earthquakes more than a few minutes in advance, which is obviously not long enough to evacuate people from affected areas. Could these ants come to save the day?

Red wood ant (Formica rufa)
Schreiber discovered that red wood ants make their nests along a particular type of faults, called strike-slip faults. These are vertical cracks in the rock that can act as a chimney for liquids or gases ascending from the Earth’s crust or mantle. These faults don’t usually occur as a single, clean fracture, but are rather found in complex networks of cracks and deformations in the rock. For this reason, geologists can struggle to accurately map them. Typically laborious soil gas measurements and structural geological mappings are necessary, which are time-consuming and costly. And this is why Schreiber’s discovery was so exciting.

Tales of abnormal animal behaviours before an earthquake have been around for centuries. In 373 B.C., Diodorus, a Greek historian, reported that rats, snakes, weasels, centipedes, worms, and beetles, migrated in droves a few days before a violent earthquake hit the city of Helice, in Greece. Accounts of animals in panic seconds to hours before an earthquake are the most common, for example, dogs barking or whining, nervous cats (sometimes jumping out of windows), bees leaving their hives, cows producing less milk, to name a few.

China and Japan are by far the countries that have invested more resources into studying a connection between animal behaviour and earthquakes. In 1975, an earthquake of magnitude 7.3 was predicted months in advance in China based on accounts of weird animal behaviours, including snakes coming out of hibernation and freezing on the ground surface and rats leaving their holes en masse. The city of Haicheng, with a population of a million people, was evacuated days before the earthquake, saving thousands of lives. However, this earthquake was preceded by many smaller temblors (called foreshocks) over several months, which was probably what really convinced Chinese officials to order the evacuation. So, despite nearly four decades of research, there is still no evidence that abnormal animal behaviour can be predictive of earthquakes, well, at least not reliably.

Scientists remain skeptical because reports of this kind are typically collected after the quake, so people are biased to recall behaviours that might have always been there—they just didn’t notice them. The other reason is that while it is easy to explain why animals sense earthquakes seconds before they start (they can feel a type of weak seismic wave that reaches the Earth’s surface seconds before stronger, more noticeable waves), it’s more difficult to understand how they may do this days or weeks in advance. Some scientists have suggested these animals detect electromagnetic changes or gases released from the ground before earthquakes, but most animals definitely can’t do this. For ants though, it’s a different story.

Can ant behaviour predict earthquakes?
Red wood ants are remarkably sensitive to their environment. Besides detecting the tiniest changes in temperature, ants can respond to electromagnetic  fields and have protein receptors that sense changes in carbon dioxide (CO2) concentrations. So could these ants sense earthquakes long before they start? Berberich and Ulrich Schreiber, her then PhD supervisor at University Duisburg-Essen, thought it was worth having a look. 

During a 3-year survey, from 2009 to 2012, Berberich, Schreiber and colleagues filmed two red wood ant mounds that were on top of a seismically active tectonic fault. They used high-resolution cameras in colour and infrared to monitor the ants’ activity 24/7. After processing over 45,000 hours of video streams with an automated software that tracked the tireless ants, the team discovered that these hard-working insects have a daily routine that resembles our own: during the day they are franticly busy at work, and during the night they rest inside their nests. Initially the researchers thought this activity pattern was only perturbed when unwelcomed guests visited their nest, such as birds or badgers looking for a snack. But gradually it became clear that something else was occasionally upsetting the ants: earthquakes.

Berberich, Schreiber and colleagues found that hours before an earthquake, the ants stopped their daily routine and just hung out outside the nests until the next day. They observed these behavioural changes only before earthquake events with magnitudes between 2 and 3 (smaller temblors didn’t seem to bother the ants), but they still don’t know how the ants would react to stronger earthquakes.

“Our observations […] took place in a region with low seismic activity,” says Schreiber. “It would be better to make this research in Italy or other regions with higher seismic activity but we got no funding for this type of research.”

Another problem was that during the winter the ants remained mostly inside the nests, and it’s more difficult, if not impossible, to detect their activity over the cold months. So, whether red wood ants can be used to predict earthquakes remains an open question, though at present that seems rather unlikely.

“[…] Red wood ants cannot predict earthquakes. We never stated that in our publication” said Berberich in an email to LabTimes. “Earthquake prediction would mean providing information on the exact date, time, location and magnitude. That is definitely not possible.”

Nonetheless, these tiny creatures turned out to have yet another superpower that could be incredibly useful for humans.

Nesting on active tectonic faults
Shortly before Berberich started her research on red wood ants and earthquake prediction, Schreiber had discovered that these insects have a strange preference for building their nests on top of active tectonic faults.

Faults are fractures in the rock that can extend into the Earth’s crust or mantle. Because the rocks on either side of these cracks cannot slide against each other easily, tension gradually builds up until the rocks suddenly break (and slide). The energy released propagates to the Earth’s surface in seismic waves—and this is what causes earthquakes.

Schreiber first noticed that the ant mounds lined up along tectonic faults back in 2003 during fieldwork in the Rhenish Massif, in Germany, but because this was so unusual, he spend a few more years collecting data in different sites in Germany, Austria and Southern Scandinavia. And yet, despite counting over 1000 ant mounds, “it needed a long time to convince biologists, reviewers and colleagues,” Schreiber says.

Nest of red wood ant

After these findings were finally published in 2009, Schreiber and Berberich, who in the meantime had joined his lab, continued collecting data in other sites in Germany. But even after mapping more than 3000 ant nests and consistently finding a clear statistical correlation between nest position and the active faults, the scientific community remained unconvinced.

“One of the challenges of this work has been convincing ecologists and myrmecologists [people who study ants] that there actually is a spatial relationship between ants and fault lines,” says Aaron Ellison, an ecologist from Harvard University, USA, who has collaborated with Berberich for a number of years. “The major critique is that we don’t really have a good biological mechanism for why ants should be related to faults.”

“Ants are easier to sample and identify than geological features,” Ellison says. “Ants may also be more sensitive at identifying very small or newly opened fault systems, and more quickly, than we might get with a geological survey.”

Reliable bioindicators
Red wood ants are well-known bioindicators (organisms used to monitor changes in the environment). In Australia, these ants have been used successfully to check pesticide contamination in cotton wool-producing areas, for example, and to measure the environmental impact of mining, deforestation and logging, and urbanisation.

To convince their colleagues that red wood ants can be used as reliable bioindicators for active faults, Berberich and colleagues decided to carry out a double-blind study. This idea was suggested by Ellison, who at first was one of Berberich’s strongest critics. When they met at the annual meeting of the Entomological Society of America in 2012, Ellison pointed out that not enough sampling had been done in localities where there wasn’t tectonic activity, so the sampling could have been biased.

“It’s easy to say that, there’s a fault here and there are ants here, so they’re related to one another, but to actually do a very careful and intensive spatial sampling and see if the samples are not biased is harder to do,” says Ellison.

Berberich and Ellison began their collaboration and applied for funding to do the double-blind study. They finally started the fieldwork in 2016 with a grant from the Volkswagen Foundation. Ellison recruited several students, who hadn’t previously been involved in the research, to sample ant mounds over an area of about 1400 km2 in Denmark. But there was a twist.

“[…] We didn’t tell them what they were sampling, or why they were sampling it,” says Ellison.

And not only were the students not aware of the study’s purpose, but also none of the researchers knew where the active faults were located. After mapping nearly 300 ant mounds, the team got hold of the detailed geological maps of the region. A careful statistical analysis confirmed that the ant mounds really are closer to active faults than what you would expect by chance alone, and these results were recently published in the journal PeerJ.

Double-blind experiments are designed to avoid conscious and unconscious biases in research. Although this robust method is widespread in psychology and clinical research, it is virtually absent from ecological studies. Recent alarming numbers in retractions and fraud cases resulting from the ‘publish-or-perish’ culture, however, are raising awareness for the need to improve (and test) reproducibility in science.

A recent survey in the journal Nature showed that over 70% of researchers failed to reproduce someone else’s experiments. Perhaps even more worrying, more than half of the 1576 researchers who took part in the survey said they couldn’t reproduce their own experiments. Two notorious studies tackling this problem showed that the scientific literature in psychology and cancer research is, respectively, only 40% and 10% reproducible. But despite this bleak picture, studies reproducing or failing to reproduce experiments are rare and often difficult to publish.

“We keep talking in science about how reproducibility and replication is so important, so here was an opportunity to really put that to the test,” Ellison remarks. “By doing a double-blind experiment, we were able to show that there really is a relationship here in need of an explanation and further work.”

A brilli(ant) gas sensor
The million-dollar question now is why red wood ants fancy building their nests on active strike-slip faults.

“I think that it’s a combination of different aspects: metabolism, defence against enemies due to increase the CO2 concentration in nests, CO2 content necessary for beneficial bacteria, or others,” says Schreiber. “We don’t know exactly and need more time for research.”

Red wood ant nests release large amounts of CO2 and are warmer than the surrounding ground, but it’s not known why. Berberich and Schreiber’s findings open the possibility that these ants choose to build their nests where there’s more CO2 available in the ground, like on top of strike-slip gas-permeable faults, for example. Schreiber is currently following up preliminary observations that support this hypothesis, while Ellison and Berberich, who is now working at the Technical University of Dortmund, are applying for funding to study whether red wood ants sense temperature and gases (radon, methane, helium…) released from faults.

“We really don’t know why [ants build their nests on active faults] but we’re working on promising hypotheses, and all of them will be improved by doing double-blind experiments,” Ellison concludes.

Reference: Toro​, Israel Del, et al. “Nests of red wood ants (Formica rufa-Group) are positively associated with tectonic faults: a double-Blind test.” PeerJ, PeerJ Inc., 12 Oct. 2017, peerj.com/articles/3903/.

This article was published in the printed issue of Lab Times on the 29th November 2017.

22 Sep 2017

How kangaroos avoid dehydration with their nose

Red kangaroos are the Conor McGregor of kangaroos, and it’s not because of their hair colour. They are tough, really tough. Unlike grey kangaroos, which typically seek shade in woodlands and mostly depend on human-built water holes, red kangaroos don’t shy away from living in the driest, hottest deserts.

To cool down their bodies and avoid overheating (and death), kangaroos may pant, sweat and even lick themselves. But all these strategies to lower body temperature come with a price: they use up body water. And when you’re living in a place where water is a rare commodity, licking yourself profusely might not always be the best idea… So how do red kangaroos manage to avoid overheating and save body water at the same time?

To answer this question, Dale Nelson, Gavin Prideaux, and Natalie Warburton from Flinders and Murdoch Universities decided to take a close look at the red kangaroo’s nose. Yes, the nose.

Red Kangaroo (Macropus rufus).

Mammals have complex noses with narrow, curled spongy bones that work as an air conditioning system. These so-called turbinate bones are lined with thin blood vessels that make a temperature gradient along the nasal cavity—from cooler near the exterior to warmer internally. As we inhale, the incoming air is quickly warmed as it travels down the nasal passages, and when we exhale, warm air coming from the lungs is cooled, which saves body heat. Turbinate bones have another function though, and this is where red kangaroos come back into the story.

In the late 1970s, a few research teams noticed that desert mammals have extravagantly long turbinate bones. Camels, for example, have very long, convoluted turbinate bones that swirl round and round like a corkscrew. This scrolled shape increases the nasal surface area to about 1000 cm2, which is over six times the nasal surface area of humans. But what’s the advantage of having such extreme noses in the desert?

Scientists back then suspected it must have something to do with saving body water, and they were right. It turns out that in these animals the water vapour in exhaled air condenses as it contacts the cooler nasal surface, turning into liquid water. For example, giraffes may save up to 3 liters of water a day by condensation in the nose. But as impressive as this may sound, how this water is reabsorbed into the body has remained a mystery for over three decades.

Now, Nelson, Warburton, and Prideaux add the first piece to this puzzle in a new study published in the Journal of Zoology.

During work on fossil kangaroos at Flinders University, the team started wondering how the many shapes of noses in different species of kangaroos and wallabies might be related to their environment and behaviour. They were especially intrigued by the bulging noses of red kangaroos.

“Red kangaroos are the most adapted to the very hot, arid conditions of the Australian outback”, says Warburton. “Previous studies had described some aspects of nasal morphology in kangaroos, but we still didn’t really understand how these related to the biology of the animals in the wild.”

They set off to examine the internal bones and tissues of these animals expecting to find very long, coiled turbinate bones, like in other desert mammals, but they discovered something that “has never been found before”, Warburton says.

Digital images from CT-scans, the same technology used in hospitals to image internal body structures, revealed a pocket of bone within the floor of the nasal cavity.  This small hole in the bone was unusual, so the researchers used histological techniques to look carefully at the tissues lining it. To their surprise, they found that the bone pocket was filled with lymphatic vessels.

Lymph vessels are responsible for returning fluid from tissues into the circulating blood, so this pocket could be used to reabsorb the water condensed in the nose into the body.

“The condensation of water vapour from air as animals breathe out is known to […] conserve water in arid environments, but this is the first time that a possible mechanism for the reabsorption of that condensed water has been found in the nose of any mammal”, says Warburton.

Kidneys are the main site of water reabsorption in the body, and this is why in hot days we need to visit the WC less often. Desert mammals including kangaroos have special kidneys that produce very concentrated urine, which helps to save body water.

Nelson and colleagues may have discovered a new mechanism of water reabsorption in the nose that helps explain how desert mammals cope with the harsh conditions of their environment, but “further physiological testing is necessary to see if this is what is really going on”, Warburton claims.

In the future the team also plans to look at fossils of kangaroos to try and understand how extinct species adapted to changes in their environment.

“Through understanding how animals interacted with the environment in the past, we are able to better predict how they might adapt to environmental changes in the future”, Warburton concludes.

Nelson, D. P., N. M. Warburton, and G. J. Prideaux. "The anterior nasal region in the Red Kangaroo (Macropus rufus) suggests adaptation for thermoregulation and water conservation." Journal of Zoology (2017).

18 Jul 2017

Why life got so big

About 570 million years ago, large, frond-like creatures suddenly invaded the ocean floors. For over a billion years, the Earth’s oceans were filled with bacteria and microscopic algae, but during the Ediacaran period, from 635 to 541 million years ago, larger multicellular organisms began crowding the seas.

Fossil imprints from the Ediacaran derive from soft-bodied organisms resembling modern-day sea anemones (Cyclomedusa), annelid worms (Dickinsonia) and sea pens (rangeomorphs such as Charnia). Among these bizarre creatures, the rangeomorphs are the most abundant in the fossil record—and also some of the largest.

Artist impression of rengeomorphs (credit: Jennifer Hoyal Cuthill)

Rangeomorphs were unlike any creature on Earth today. Some were as small as a coin, while others could grow up to 2 meters high. They looked like ferns, with branches spreading out from a central stem, but they likely fed by filtering nutrients from the water, similar to corals. Because rangeomorphs were so different from any known life form, paleontologists still don’t agree whether they were primitive animals related to soft corals, some sort of weird fungus or even a new (now extinct) kingdom of life, the Vendobiota.

These ocean dwellers eventually disappeared after the Cambrian explosion, some 541 million years ago, when fast-moving predators emerged (and probably ate them).

Changes in ocean chemistry
Based on the chemical signature of ancient seawater left on rocks, geochemists think there was a sharp rise in ocean oxygen levels soon after the end of the Gaskiers glaciation, about 580 million years ago. These changes in the ocean chemistry could explain the appearance of larger and more complex marine organisms—more food, bigger bodies. However, even though this may seem quite obvious, it’s actually quite difficult to demonstrate.

Jennifer Hoyal Cuthill and Simon Conway Morris, from the University of Cambridge (UK) and Tokyo Institute of Technology (Japan), used an original approach to tackle this problem.

“We wanted to see whether the increase in body size could point to a rise in oxygen, since the type of growth can tells us whether the animals have nutrients available or not”, says Hoyal Cuthill.

They suspected that Ediacaran organisms were large because they had a ‘nutrient-dependent’ type of growth, rather than an evolutionarily new genetic makeup.

‘Seeing’ extinct creatures grow
Many organisms can’t grow beyond a certain size, regardless of how much they eat. Humans for example, will (unfortunately) just get fatter, not taller, because they are genetically programmed to reach a specific maximum height. But for some organisms nutrient availability can affect body size. This type of nutrient-dependent growth is quite common in invertebrates and plants. Some plants will grow almost indefinitely, as long as there are nutrients (and light) available in the environment.

But how do you measure growth in organisms that lived nearly 600 million years ago?

This is where rangeomorph fossils come in handy.

Hoyal Cuthill and Conway Morris had previously worked with several rangeomorph specimens to study the unusual body plan of these animals. During this research it dawned on them that the rangeomorphs’ complex fractal branching shape, with larger older branches at the bottom and smaller younger branches on top, was the key for testing the nutrient-dependent growth hypothesis.

“It’s like looking back at your childhood photographs and comparing your height through your old photos up to the present day”, says Hoyal Cuthill. “We were inferring the history of growth of a rangeomorph by looking at parts of the structure of different ages”.

The researchers could basically “see” in a single fossil specimen how the animals were growing during their lifetime, by comparing the relative size and shape of younger and older branches.

A unique rangeomorph fossil
Fossil of Charnia (Jennifer Hoyal Cuthill)
The new study focuses on an exquisitely preserved specimen of Avalofractus abaculus, one of the last fossils removed from the Trepassey Formation, in Newfoundland (Canada), before strict restrictions were imposed to protect the site (currently called Mistaken Point Ecological Reserve). Hoyal Cuthill obtained a high-resolution cast from the Royal Ontario Museum and scanned it by CT- microtomography, a technique which uses x-rays to make detailed digital 3D reconstructions.

Two other specimens (Charnia masoni and an undescribed specimen from the South Australian Museum) were also analysed based on digital photographs.

Mathematical and computer models comparing the surface area and the volume of younger and older branches showed that growth gradually slowed down as rangeomorphs got bigger, which is exactly what happens in modern organisms with nutrient-dependent growth.

 “… You’re getting less nutrients as you get larger, so you cannot sustain the same rate of growth, and it slows down”, Hoyal Cuthill explains.

But there was more. Nutrient availability can also affect body shape, which is technically called ecophenotypic plasticity. Hoyal Cuthill and Conway Morris also found that rangeomorphs could rapidly change shape to access higher levels of oxygen in the seawater above them, by growing into a long, tapered shape.

Nutrient-dependent growth provides a mechanism to explain why changes in ocean chemistry caused the appearance of these large organisms in the Ediacaran, some 30 million years before the Cambrian explosion.

Hoyal Cuthill next wants to investigate whether rangeomorphs really are animals, and to which modern groups are they related to.

“Rangeomorphs are quite mysterious and were only relatively recently discovered and identified as Precambrian organisms”, she says. “This is an exciting time and many researchers are looking at the biota of the Ediacaran and finding new fascinating things”.

Reference: Hoyal Cuthill, Jennifer F., and Simon Conway Morris. "Nutrient-dependent growth underpinned the Ediacaran transition to large body size." Nature Ecology and Evolution (2017). DOI: 10.1038/s41559-017-0222-7

This article was published originally as a guest post in the PLOS Paleo Community blog with the title "Why Precambrian life got so big" on the 18-07-2017. You can read it here. 

20 Apr 2015

Miracle fat-burning hormone doesn't exist after all

Scientists are humans, and as such, they can sometimes get carried away when they make a breakthrough discovery. Because of this premature excitement, they may lose attention to detail, over-interpret results, or cut corners to speed up that much-desired Nature publication. The discovery of irisin, or ‘exercise hormone’, is one such example. Once thought to be a promising exercise-free solution for obesity and diabetes, irisin has now been shown to be no more than a random blood protein detected by flawed reagents.

Irisin was first discovered in 2012 by Bruce Spiegelman and colleagues at Harvard Medical School (US). In a Nature article, the researchers reported that after exercise muscle cells release a fragment of a pre-hormone-like protein called FNDC5 into the bloodstream, where it travels to adipose cells to trigger the conversion of white fat into calorie-burning brown fat. They concluded that this small molecule is a “newly identified hormone”, which they named irisin, after the Greek messenger goddess Iris.

Whereas white fat stores energy, brown fat is converted to heat—that’s how hibernating animals and newborn babies stay warm. So, unless you starve or exercise a lot, your white fat will remain stubbornly lodged on your hips, while brown fat burns calories. Unfortunately for most of us though, only about 10% of our adipose tissue consists of brown fat-producing cells. And this is why the discovery of irisin was so exciting. What if we could take an irisin pill to turn our white fat into brown fat? Could we burn calories while lying comfortably on the couch eating ice cream? 

It is no surprise then that in just three years over 170 studies were published on irisin. It didn’t take that long though for someone to question the Spiegelman study. Harold Erickson from Duke University (US) first voiced his concerns about irisin in 2013, and recently he showed that the commercial antibodies most widely used to detect irisin are unspecific—instead of irisin, they detect cross-reaction blood proteins, basically unknown random proteins.

Antibodies are proteins produced by immune cells that stick to specific bits of other proteins, and they’re used by scientists to detect their proteins of interest. In the original irisin paper, Spiegelman’s team identified irisin with a polyclonal antibody produced by Abcam that should in theory attach to the tail of FNDC5. But irisin is a fragment of FNDC5 that is chopped from the other end of the protein, so this antibody couldn’t possibly detect it, Erickson argued back in 2013. Spiegelman replied to this by saying that Abcam had not correctly annotated the antibody in their catalogue.

Erickson also noticed that none of the commercially available irisin antibodies had been properly tested by the companies that made them. But despite this worrying observation, several research groups continued to use them, and what’s worse, without attempting to verify their specificity for irisin. And there was more.

A few months after Erickson published these findings, Juergen Eckel and colleagues at the German Diabetes Centre (Dusseldorf, German) found that the human FNDC5 gene has an unusual START codon (the bit of DNA that is translated into the first ‘letter’ of a protein). This weird (and rare) codon is associated with very inefficient protein production. In the case of FNDC5, only about 1% of normal FNDC5 protein levels are produced by human cells, Eckel showed. At such low amounts, it would be highly unlikely that irisin had a physiological role in humans.

Over the years contradictory data from dozens of studies that relied on dodgy reagents cast doubts on whether irisin really exists or is a miracle fat-burning hormone, but that wasn’t enough to dissuade most researchers from working on it. Could this be about to change?

In their new study, Erickson's team and colleagues from three other research groups tested four commercial irisin antibodies used in over 80 studies. They employed a technique called ‘western blotting’, which separates proteins by size. To be sure they were looking at the right thing, the researchers synthesised irisin molecules and then compared them side-by-side with the proteins detected by the commercial antibodies. They tested several tissue samples from humans and other animals, including blood serum from horses after strenuous exercise. None of the antibodies detected a protein with the predicted size for irisin, and even more worrying, they didn’t detect synthesised irisin. However, the antibodies reacted with many other proteins of the wrong size. This shows that all previously published studies based on assays using these antibodies “were reporting unknown cross-reacting proteins”, the authors claim in the study.

The question now was… does irisin exist at all?  

To answer this question, the team looked for irisin in human blood serum using a sensitive technique that detects tiny amounts of molecules without the use of antibodies, called mass spectrometry. They were able to identify a molecule corresponding to FNDC5 or irisin, which is the “first mass spectrometry identification of an irisin peptide at the correct size, and might be considered as supporting the existence of irisin in human serum”, the authors say in the study. However, the very low amounts of irisin detected “makes a physiological role for irisin very unlikely”, they add. According to Erickson and colleagues, the exercise hormone is a myth.

These new findings are bad news for irisin researchers and food lovers, but they’re very good news for science. They show than even though human nature might at times corrupt scientific discoveries (voluntarily or involuntarily), science infallibly corrects itself, and we can therefore trust the scientific process.

Albrecht E., Bernd Thiede, Torgeir Holen, Tomoo Ohashi, Lisa Schering, Sindre Lee, Julia Brenmoehl, Selina Thomas, Christian A. Drevon & Harold P. Erickson & (2015). Irisin – a myth rather than an exercise-inducible myokine, Scientific Reports, 5 8889. DOI: http://dx.doi.org/10.1038/srep08889

An edited version of this article was published in Lab Times on the 17-04-2015. You can read it here

27 Mar 2015

The genetics of musical talent: an interview with Irma Järvelä

Would Mozart have become a great composer had his family not encouraged his musical career? Irma Järvelä is a clinical geneticist at the University of Helsinki, Finland, who investigates the molecular genetics of musical traits. After devoting 25 years of her career to the identification of genes and mutations involved in human diseases, she now works in close collaboration with bioinformaticians and music educators to study the influence of genes and the cultural environment in music perception and production. 

What got you interested in studying the genetics of musical talent?
Järvelä: We were studying a lot of things that affect human diseases and I found that it’s also important to understand how the human normal brain functions. This could be helpful to understand the diseases in more detail. In genetics we have genes and then we have environmental effects. […] Our genes do not always tolerate our environment—when you think of carcinogenics, for example—and this kind of crosstalk between genes and the environment is also present in music. […] I was interested in this interaction between the environment and studying music, or listening to music.

Your research shows that several genes involved in inner-ear development and auditory neurocognitive processes are linked to musical aptitude. Does this mean musical talent is innate?
Järvelä: Yes, our recent study points to the genes that are associated strongly with an innate, or inborn, musical aptitude. It was already known before that newborns are interested in very complex musical patterns already at the age of a couple of days, and from research studying human brain function in musicians and non musicians, there is evidence that music is a biological trait. In our study we identify the regions in the human genome that are strongly associated with the ability to perceive and listen to sounds and structures in music.

So do ‘musical geniuses’ really exist? Would Mozart have become a great composer if his family hadn’t encouraged his musical training?
Järvelä: Mozart is a typical example of a talented composer whose family was musical. There are a lot of families in our days that have several professional musicians, so part of the musical talent is explained by the genes but of course also to exposure to music. It’s like an allergy; the risk for an allergy is only expressed when the pollen is coming, so you need this environmental trigger. And music is an excellent environmental trigger. Children who have an ability for music have to be exposed to music, otherwise we don’t know whether they can become musicians. So a rich musical environment is of course needed.

Is it possible to compensate for the lack of genetic musical ability with musical training?
Järvelä: I think it can be compensated to some extended but never fully. […] Some researchers have claimed (and I agree) that children first of all inherit the ability to perceive music and hear music. And if the parents are also very musical and good teachers, that is the ideal setting for the transmission of both the genes and the perfect environment.

Are there also examples of musically talented people that don’t come from a family of musicians?
Järvelä: We have a couple of cases in our family collection, which consists of 800 people in Finland, where the parents are not very interested in music but the child is very talented. Also vice versa, we also have cases where the parents are professional musicians, but the children are not at all interested, or their musical scores are moderate or low.

How do you explain these exceptions?
Järvelä: I think it’s possible that these cases are explained by a novel mutation, because the human genome is supposed to have de novo mutations quite frequently. But we cannot say anything concerning just a couple of cases, this kind of studies are not reliable. We would need more cases.

In a recent study you show that listening to classical music affects gene expression in musically experienced, but not inexperienced, individuals. How do you explain this?
Järvelä: Yes, this is true. We had a group of participants who were professional musicians or experienced listeners [of classical music], and in the other group the participants told us they were not so interested in music. The participants were not informed which music they came to listen […]. Some people would come out and say “yeah, I know this music, this was nice”, and of course those who had no musical experience didn’t know what was played. […] If you think about it people always choose what they like. We saw an effect in people who knew the music, or who were used to listening to classical music.

Do you see this effect on gene expression with any type of music?
Järvelä: I don’t know because this is the first study and you have to start somewhere. This was with classical music but I agree that we should study other genres like jazz or hip hop, or whatever other type of music. I would suggest that jazz would be the next one because imagination, improvisation and creativity in jazz are more prominent and we might get some different effect. I think there might be shared effects and non-shared effects.

Have you thought of studying other ethnicities, maybe semi-isolated tribes, which have a completely different type of music and culture?
Järvelä: It would be nice but it’s easier said than done. I suspect they would have different genetic profiles because of the long distance in genetics, and also the cultural effects are different. It would be extremely interesting to compare these different natural surroundings and it might be that that is the most true effect of music. I think the basic similarities are there, because the human inner ear is very well conserved in evolution. 

What other questions would you like to address in the future?
Järvelä: We are currently studying the genes for creativity in music, and this will hopefully be published this year. This week we have just published a paper on the genetic profiles of professional musicians, just before and after they played a fabulous symphonette at a concert. […] Then we want to look at the different musical genres, and gene regulation and evolution of music.

Oikkonen J., P Onkamo, L Ukkola-Vuoti, P Raijas, K Karma, V J Vieland & I Järvelä (2014). A genome-wide linkage and association study of musical aptitude identifies loci containing genes related to inner ear development and neurocognitive functions, Molecular Psychiatry, 20 (2) 275-282. DOI: http://dx.doi.org/10.1038/mp.2014.8

Kanduri C., Minna Ahvenainen, Anju K. Philips, Liisa Ukkola-Vuoti, Harri Lähdesmäki & Irma Järvelä (2015). The effect of listening to music on human transcriptome, PeerJ, 3 e830. DOI: http://dx.doi.org/10.7717/peerj.830 

Kanduri C., Minna Ahvenainen, Anju K. Philips, Harri Lähdesmäki & Irma Järvelä (2015). The effect of music performance on the transcriptome of professional musicians, Scientific Reports, 5 9506. DOI: http://dx.doi.org/10.1038/srep09506

An edited version of this interview was published in Lab Times on the 27-03-2015. You can read it here.

17 Mar 2015

Hippos are (almost) definitely whales, not pigs

Hippos are strange mammals. They lack hairs and sweat glands, and have an unusually thick skin. The only other mammals that share these features with hippos are whales, but they look nothing alike, except they’re also huge and live in water. Coincidence?

Traditionally hippos were included in the Suidae (pigs) branch of the mammalian evolutionary tree, but molecular data unambiguously shows that they're closely related to cetaceans (whales, dolphins and porpoises). This not only sounds unlikely (hippos look much more like pigs than whales), but it's also quite difficult to testthere is simply not enough fossil evidenceSo the origin of hippos has remained something of a mystery. Now, a new fossil discovery by a team of French and Kenyan palaeontologists may have tipped the balance of the hippo evolutionary history.

Common hippo showing off its mandibles.
Fossils of hippo are rare. Every now and then a tooth pops up, but bones are nearly impossible to find. “To make a comparison between whales and hippos we need to find their ancestors. We had the whale ancestor but until now the hippo ancestor was unknown,” says Fabrice Lihoreau, a palaeontologist at the University of Montpellier, in France.

In 2005, Lihoreau and colleagues discovered a mandible with teeth of unusual morphology in the paleontological collection of the National Museum of Kenya, in Nairobi. Lihoreau is an expert on anthracotheres, a diverse group of semi-aquatic herbivorous mammals that lived in Africa from around two to 40 million years ago. For some time palaeontologists had suspected that anthracotheres could be the ancestor of hippos. “We published many studies suggesting hippo is related to anthracotheres, and not to pigs. This new discovery not only supports that, but it tells us precisely to which lineage of anthracotheres hippos originated from,” Lihoreau explains.

The newly found teeth have morphological features of both anthracotheres and hippos. They belonged to a large herbivorous mammal that thrived in Lokona, Kenya, around 28 million years ago. The discovery of this new hippo-like anthracothere, named Epirigenys lokonensis for ‘hippo’ (Epiri) and ‘origin’ (genys), shows that hippos are definitely not pigs—they originated from an old lineage of antrachotheres, the bothriodontines. And not only that, Lihoreau says, “we added a bit more to the history of mammals in saying that hippos are African, they were born in Africa.”

Evolutionary transition of the upper molar from an anthracothere (left),
Epirigenys (middle) and a primitive hippo (right). 
Many African mammals (rhinos, elephants, giraffes…) originated in Eurasia and then migrated to Africa in two large waves of migration, around 35 and 20 million years ago. Because the oldest fossils of a ‘true’ hippo are about 16 millions years old, palaeontologists have assumed they crossed into Africa on a land bridge during the second wave of migration. But Epirigenys lived 28 million years ago, so hippos must have originated from their anthracotheres ancestor in Africa. This also explains why fossils of hippo ancestors hadn’t been found before: palaeontologists were looking in the wrong place.

But are hippos whales? The discovery of Epirigenys doesn’t prove that hippos and whales came from the same ancestor, but it makes any different scenario rather unlikely. “This study is very important because now we have a hippo ancestor. And we know that the ancestors of hippos are from South-East Asia, and the ancestors of whales are also from South-East Asia, from the same period”, Lihoreau says.

Phylogenetic relationships between hippos, anthracotheres and cetaceans.
Lihoreau and colleagues are now going to focus on searching for the ancestor of anthracotheres in South-East Asia, to then compare it with the ancestor of whales, which is well known. If the team gets lucky, they might find their  holy grailthe common ancestor of hippos and whales.

Jonathan Geisler, a palaeontologist at the New York Institute of Technology who studies the evolution of dolphins and whales says “About 15 years ago there was a big gap between the age of the earliest hippos and the oldest whales. These authors, and their collaborators, have been steadily filling in this gap through the discovery of new fossils, as well as detailed studies that have moved known fossil species into this gap.”

Many questions remain unresolved. Lihoreau suspects that hippo ancestors hopped into Africa around 30 million years ago alone and… swimming. “This is somewhat speculative but certainly seems possible,” says Geisler. “There is evidence to suggest some anthracotheres were semi-aquatic, and were able to make this crossing.” This hypothesis implies that the hippo-whale ancestor already lacked hairs and sweat glands, which would have “constrained the evolution of the hippo group to get into water”, Lihoreau says. His team is going to collaborate with geologists and geochemists to try and figure out in what sort of environment hippo ancestors were living. This should help us understand what shaped the evolution of hippos towards their semi-aquatic lifestyle, which is very rarely seen for herbivorous mammals (capivaras and beavers are the only other exceptions).

Lihoreau F., Fredrick Kyalo Manthi & Stéphane Ducrocq (2015). Hippos stem from the longest sequence of terrestrial cetartiodactyl evolution in Africa, Nature Communications, 6 6264. DOI: http://dx.doi.org/10.1038/ncomms7264

An edited version of this article was published in Lab Times on the 17-03-2015. You can read it here.