The rivers and lakes of Africa are filled with conversations that you cannot hear or take part in. These chats are conducted by fishes called mormyrids or elephantfishes, which can produce and sense electric fields. They use their abilities to navigate through murky waters, hunt their prey, and talk to one another. It’s clearly a successful lifestyle, for there are over 200 species of mormyrid alive today.
Bruce Carlson from Washington University in St Louis thinks that the origin of these diverse species lay in the diversity of their electric songs. Different species of mormyrid communicate with different electric signals, which work as badges of identity. When they’re ready to mate, they find partners of their own kind by listening out for their preferred electric dialect.
The evolution of these diverse signals hinged in turn on changes in the mormyrids’ brains and sense organs. These allowed them to pick up subtler differences in their electric signals and talk to each other in more varied ways. This opened up a world of communication, but it was also the mormyrid equivalent of the Tower of Babel. By gaining the ability to communicate in different dialects, the species of mormyrid grew apart.
In the mangrove swamps of Puerto Rico, four eyes are permanently fixed on the sky. These eyes are surprisingly similar to yours. They’re assembled using the same genetic building blocks, and they have lenses, retinas and corneas. But their owner couldn’t be more different – it’s a box jellyfish, and it’s looking for some shade.
The box jellyfish (Tripedalia cystophora) is far from a simple blob with tentacles. It’s an active, manoeuvrable predator, and it finds its way around with no fewer than 24 eyes. Scientists have known about these for over a century, but people are still trying to work out what they do.
The eyes are grouped into four clusters called rhopalia, each containing six eyes. Four of these are simple pits or slit that can do little more than detect the presence of light. But the other two – the “upper lens eye” and “lower lens eye” – are far more advanced. They can actually see images, with the aid of light-focusing lenses.
Now, Anders Garm from the University of Copenhagen has found that the jellyfish always keeps its upper lens eyes pointing towards the sky. Each rhopalia sits at the end of a flexible stalk. The upper lens eye sits at the top of the cluster, and there is a heavy crystal called a statolith on the bottom. The whole structure is a weighted ball, dangling from a string. As a result, it’s always vertical and the upper lens eyes are always pointing upwards, no matter how the jellyfish’s body is angled. This animal is perpetually looking straight up, even if it’s swimming upside-down.
We all know people who look like they can nod off with their eyes open. These exceptions aside, we generally think of sleep as a switch with two settings – you’re either asleep or awake. But Vladyslav Vyazovskiy from the University of Wisconsin-Madison has found that sleep is more complicated than that.
By studying the brains of sleep-deprived rats, Vyazovskiy found that individual neurons can effectively fall asleep, going “offline” while those around them carrying on firing. Even if the rats are awake, parts of their brain can be taking a nap. What we know as “sleep” is the global version of something that happens throughout the brain at a local level.
Ever since there have been IQ tests, people have debated what they actually measure. Is it “intelligence”, is it an abstract combination of mental abilities, or is it, as Edwin Boring said, “the capacity to do well in an intelligence test”? Regardless of the answer, studies have repeatedly shown that people who achieve higher scores in IQ tests are more likely to do well in school, perform well in their jobs, earn more money, avoid criminal convictions, and even live longer. Say what you like about the tests, but they have predictive power.
However, Angela Lee Duckworth from the University of Pennsylvania has found that this power is overrated. The link between our IQs and our fates becomes muddier when we consider motivation – an aspect of test-taking that is often ignored. Simply put, some people try harder in IQ tests than others. If you take this into account, the association between your IQ and your success in life becomes considerably weaker. The tests are not measuring intelligence alone, but also the desire to prove it.
Of late, space and bacteria have been in the news for all the wrong reasons. First, there was the wanton speculation about aliens that preceded the “arsenic life” controversy (NASA fanned the hype with a poorly described press conference). Then, the Journal of Cosmology made headlines with claims about fossilised bacteria in meteorites (NASA disavowed any participation).
But to me, the real story involving space, bacteria and NASA is very different, but far more important. The gist is simple: when bacteria are sent into space, they become better at causing disease. This poses a big problem for the long-term space missions planned in the future, but cracking that problem could have big benefits for public health back on the ground.
I’ve told this story in a feature for this month’s Wired UK, which has finally come online. The feature focuses on Cheryl Nickerson, an American scientist who is spearheading research in this field. I talk about Nickerson’s motivations, her latest fascinating results on how bacteria change in space, why this has already been a problem for space missions and why it’ll get worse, what it’s like to do science in space, and finally, what this means for human health back on Earth. Here’s a taster:
What happens when you dump 8,000 fire ants into a tray of water? Nathan Mlot from the Georgia Institute of Technology wanted to find out. Mlot scooped the ants into a beaker, swirled it around to roll them into a ball, and decanted them into a half-filled tray.
Over the next three minutes, the ball of ants slowly widened and flattened into a living, waterproof raft. By trapping air bubbles trapped among their interlocking bodies, the ants boosted their natural ability to repel water and kept themselves afloat. Humans build rafts by lashing together planks of wood or reeds; the fire ants do so by holding onto each other.
The experiment might seem odd, but it mirrors conditions that the fire ant (Solenopsis invicta) regularly has to cope with in its natural environment. The ant hails from the Brazilian rainforest floodplains of Argentina, where rising water regularly submerges their nests. They respond by weaving their own bodies into rafts. The ants also come together to construct bridges, ladders and walls, but the rafts are the longest-lasting of these living structures. In this form, they can float and sail for months.
Lydia Fairchild was confused. She had applied for state benefits to look after her three children, but according to DNA tests, she was not their mother. It was ridiculous – she knew full well that the children were hers, but she was being taken to court nonetheless.
This happened in 2002, but Fairchild’s case has striking parallels with one that cropped up just this year, involving a Mediterranean sponge called Scopalina lophyropoda. French scientists Andrea Blanquer and Maria-J Uriz found that around a quarter of the sponge’s larvae are genetically distinct from the parents that they come from. Somehow, they had inherited genes from a different source.
Sponges are about as far away from humans as you could imagine an animal being – their bodies are just two layers of cells, curved and folded into tubes and chambers. But even though their bodies are worlds apart, the mysteries of both Lydia Fairchild and S.lophyropoda had the same answer.