Everyone has felt pain, and many experience it daily. But for such a universal sensation, it is still a mysterious one. We are only starting to understand the molecules that produce a painful sensation. Nature, however, is well ahead of us. Many animals are armed with chemicals that hijack the nervous systems of their targets, producing feelings of intense pain. They are unknowing neuroscientists, and by studying their weapons, we can better understand how pain manifests in our bodies.
Take the Texas coral snake. This brightly coloured serpent, clad in warning hues of red, black and yellow, usually shies away from confrontation. When it’s threatened, it defends itself with venom that can cause excruciating and unremitting pain.
Update: I’ve amended this post following some harsh critical comments on the study from geneticists on Twitter, which I really should have noted while going through the paper.
Our genes can influence our behaviour in delicate ways, and these effects, while subtle, are not undetectable. Scientists can pick them up by studying large groups of people, but individuals can sometimes be sensitive to these small differences.
Consider the OXTR gene. It creates a docking station for a hormone called oxytocin, which has far-ranging effects on our social behaviour. People carry either the A or G versions of OXTR, depending on the “letter” that appears at a particular spot along its length. People with two G-copies tend to be more empathic, sociable and sensitive than those with at least one A-copy. These differences are small, but according to a new study from Aleksandr Kogan at the University of Toronto, strangers can pick up on them after watching people for just a few minutes.
There have been several stories recently about genetically modified mosquitoes, bred for the purpose of fighting diseases like malaria and dengue fever. These are exciting, sophisticated techniques, but in a new piece for Slate, I argue that they’re being let down by the fact that we still don’t know a lot about basic mosquito biology, like thier mating behaviour. Ecology may not be as sexy as tinkering with genes, but history teaches us that it’s vital if these approaches are to work.
Here’s a taster; head to Slate for more.
But all of these recent attempts to turn mosquitoes into malaria- and dengue-killing machines have something in common: The modified mosquitoes need to have lots of sex to spread their altered genes through the wild population. They must live long enough to become sexually active, and they have to compete successfully for mates with their wild peers. And that is a problem, because we still know surprisingly little about the behavior and ecology of mosquitoes, especially the males. How far do they travel? What separates the Casanovas from the sexual failures. What affects their odds of survival in the wild? How should you breed the growing mosquitoes to make them sexier? Big question marks hang over these seemingly straightforward questions.
Heather Ferguson from the University of Glasgow studies mosquito ecology. She views the knowledge gap in this field as a significant obstacle that stands in the way of the GM-mosquito initiatives. History tells us how dismally such initiatives can fare if they are not constructed on solid ecological foundations. In the 1970s and 1980s, several groups tried to control the mosquito population by releasing sterile males that would engage females in fruitless sex. The vast majority of the experiments failed.
Their poor performance is often blamed on the fact that the males were sterilized with damaging doses of radiation. But they had many other disadvantages. Lab-bred mosquitoes are frequently reared in large, dense groups, which produces smaller, less competitive individuals. The artificial lights of a lab could also entrain their body clocks to the wrong daily rhythms, driving them to search for mates at the wrong time of the day. And in several cases, the modified males ignored the wild mosquitoes and preferred to mate with their lab-reared kin instead. These problems went unnoticed in lab tests, where the modified mosquitoes were compared with unaltered ones that had been raised in the same conditions. They seemed to be perfectly competitive, but they proved to be feeble challengers to their wild peers.
Picture by James Gathany
Bumblebees begin their adult lives by eating their sisters’ faeces. After many months as helpless, hungry larvae, they spin a silken cocoon and transform their bodies. When they emerge, ready to face the world, they get mouthfuls of poo. It may not sound like an auspicious start, but it’s essential. The faeces contain special bacteria that act as part of the bee’s immune system, protecting it from an incredibly dangerous parasite.
Gut bacteria are important partners for many animals. We humans have up to 100 trillion microbes in our bowels, and this “microbiota” outnumbers our own cells by ten to one. They act like a hidden, writhing organ. They break down our food. They influence our behaviour. And they safeguard our health by crowding out other bacteria that could cause disease. It seems that gut bacteria play a similar role in bumblebees.
The bacteria that plague us during an infection are never quite the same as the ones that entered our body to begin with. With the ability to grow rapidly and swap genes, they can quickly adapt to our immune defences and the drugs we throw at them. Evolution is the greatest weapon that infectious bacteria wield, but Tami Lieberman and Jean-Baptiste Michel have found a way of turning it against them. They duo have shown that the same adaptations that make bacteria stronger can also reveal their weaknesses.
For years, Lieberman and Michel, both from Harvard Medical School, had been dreaming of following the evolution of a bacterial infection. They wanted to sequence the entire genomes of the microbes as they shifted in their host to work out which genes make them so good at causing disease, and which could be targeted by new medicines. Genetic technology had become so cheap and powerful that they knew they had the right tools. They just needed the bacteria.
Ideally, they were looking for people with infections like meningitis, which sometimes spread throughout the body. “We started a sample watch at several Harvard hospitals,” says Michel. “We said whenever you see bacterium X in a patient with disease Y, call us!” No one called. After much waiting, the duo realised that the samples they needed had been sitting in a freezer at Children’s Hospital Boston all along.
There are two ways of becoming invisible: you can either be transparent so all light passes through your body, or you can blend in by taking on the colours of your surroundings. A truly incredible animal would be able to do both, switching between the two at a whim. And that’s exactly what some squids and octopuses can do.
Sarah Zylinski and Sonke Johnsen from Duke University found that two cephalopods – the octopus Japetella heathi and the squid Onychoteuthis banksii – can switch their camouflage strategy depending on how bright their environment is. When sunlight streams from above, they choose the see-through option. When their world darkens, they go for darker colours that blend in.
Humans are remarkably fuel-efficient, or at least, our brains are. The lump of tissue inside our skulls is three times larger than that of a chimp, and it needs a lot more energy to run. But for our size, we burn about as much energy as a chimp. We’re no gas-guzzlers, so how did we compensate for the high energy demands of our brains? In 1995, Leslie Aiello and Peter Wheeler proposed an answer – we sacrificed guts for smarts.
The duo suggested that during our evolution, there was a trade-off between the sizes of two energetically expensive organs: our guts and our brain. We moved towards a more energy-rich diet of meat and tubers, and we took a lot of the digestive work away from our bowels by cooking our food before eating it. Our guts can afford to be much smaller than expected for a mammal of our size, and the energy freed up by these shrunken bowels can power our mighty brains.
This attractive and intuitive idea – the so-called “expensive tissue hypothesis” became a popular one. But Ana Navarrete from the University of Zurich thinks she has disproved it.
Some of you know Brian Switek, ace blogger who covers all things fossil. What you may not have realised is that Brian Switek hates your childhood dreams and is out to crush them by making all badass prehistoric predators seem a bit rubbish. This is the latest volley in his ongoing campaign.
Last night, I decided enough was enough and drastic action was needed to preserve the predators that stalked our young imaginations, in the face of Switek’s tawdry “facts”. After all, you could prove just about anything that’s true using facts.
Thus was born the #GRAWR hashtag on Twitter, a collection of trivia about prehistoric animals based solely on how awesome they would be, and leaving aside silly notions like evidence. I collected some of my favourites (you should see a stream of tweets below; if not, check on a different browser): Read More