chimera

A chimera (pronounced ky-MEER-uh or kih-MEER-uh, depending on who you ask) is something made up of different parts. The original Chimera (with a big C) was a fire-breathing creature n Greek mythology with the head of a lion, the head of a goat on its back and a serpent for a tail. The name comes from ‘khimaira’ (Χίμαιρα) which means ‘she-goat’.

There’s also a mountain in southern Turkey named after the chimera. Mount Chimaera (or Yanartaş) is a rocky hillside where natural gas seeps from cracks in the earth, creating flickering fires that burn night and day. With lions, goats and snakes roaming the surrounding hills, it’s easy to see how it came to be named after a hybrid beast that spat flames.

Chimeras aren’t just mythological. Don’t worry though, you’re not going to run into a fire-breathing goat mix on your next package holiday. We’re talking science here – specifically, genetics. A chimera is an organism made up of cells from two different sources, something that can happen naturally or in a lab. Humans and animals can be chimeras when two fertilised eggs fuse into a single embryo, which means they end up with two sets of DNA. This can go completely unnoticed or reveal itself in surprising ways, like different coloured eyes or patches of skin with different pigmentation.

One famous example of a human chimera is an American woman called Karen Keegan. In 2002, she needed a kidney transplant and used genetic testing to find a donor in her family. But the tests showed that genetically she couldn’t be the mother of her sons. The mystery was solved when doctors discovered that Keegan was a chimera – the DNA in her blood cells was different to that in the other tissues in her body. That’s because when her mother was pregnant with her, two separate eggs had been fertilised, creating two separate balls of cells each with its own DNA. At some point, these two groups of cells fused into one, and Karen was born with cells from both balls randomly distributed throughout her body. I’m pleased they figured that out – it could have led to some super awkward questions otherwise.

Chimeras are also a godsend for crime writers – I’ve definitely seen them used in more than one drama when DNA evidence at a crime scene was discredited because the suspected perp was actually a chimera.

This is Venus the Two-Faced Cat, an American tortoiseshell cat whose face is half black and half red tabby. Opinions differ as to whether she’s a true chimera or her markings are simply a matter of luck and heterochromia (two different coloured eyes). Whatever the real answer, she looks awesome. (And you can of course follow her on Instagram.)

diadromous

‘Diadromous’ is a scientific word used to describe fish that migrate between fresh and salt water at different stages of their life. Diadromous fish are divided into two categories – those that move from the sea to rivers to spawn (like salmon) are called anadromous, while those that go in the opposite direction (like eels) are called catadromous. Ooh, that’s actual proper science.

‘Diadromous’ comes from a Greek word, diadromos, meaning ‘running through’ or ‘passing through’. It first appeared in English in the early 20th century.

Even this picture gives me the willies

If you know me personally, you might know that I have a bit of a phobia of fish in general (called ichthyophobia, fact fans), and particularly of sharks (I didn’t see Jaws until I was well into my twenties for precisely that reason). But it’s okay, because sharks only live in the sea, which I don’t go near very often. OR DO THEY? Let me introduce you to the bull shark which, unlike most sharks, can thrive (THRIVE) in both salt and fresh water, and regularly moves between the two. Oh, and bull sharks are also one of the most dangerous sharks in the world – they’re aggressive, have a powerful bite and often hunt in shallow, murky waters. Along with great white sharks and tiger sharks, they’re responsible for the highest number of recorded shark attacks on humans.

Bull sharks’ salt/fresh water adaptability has lead to them being found far inland in rivers and lakes including, famously, at the Carbrook Golf Club in Queensland, Australia. A flood in the 1990s swept six bull sharks into the golf course’s water hazard. When the water receded, they were stuck there, which made for an interesting game of golf, I’m sure.

The bull sharks’ invasion of the golf course has actually been good for both the club, and for science. The club made the most of the publicity by adding a shark to their logo, renaming their youth programme the ‘Junior Shark Academy’, and holding feedings at tournaments and corporate events – including one wedding in 2009 where all six sharks appeared at once (is that a good or a bad omen, I wonder?). Science-wise, previously no one had studied how long bull sharks could survive in low-salinity water – they had only been recorded twice before surviving for years in isolated bodies of water. One group made it at least four years in a freshwater lake in Panama in the 1980s, while another survived a decade in high salinity in South Africa’s Lake St Lucia after becoming trapped in 2002. Our golfing sharks stayed in the water hazard for at least 17 years – more than half a bull shark’s lifespan – which was unprecedented. It showed scientists that there’s presumably no limit to how long these sharks can live in freshwater environments like lakes and rivers, and that they could theoretically spend their entire lifetime in these habitats. Great.

No sharks have been seen at Carbrook since 2015 (although a comment on the YouTube video below begs to differ). But I’m sure people still think twice about retrieving any balls that find their way into that water hazard.

scavenger

A scavenger is a creature that survives by picking through leftovers, scraps, rubbish and dead things. Think vultures circling roadkill, foxes raiding bins or that friend who says they’re on a diet then eats all your chips.

You wouldn’t want to mess with that, would you?

‘Scavenger’ didn’t always conjure up images of vultures and bin-diggers though. In fact, its origins are less animal-ly and more administrative. It comes from ‘scavager’, which is from an Anglo-French word, ‘scawageour’, which means ‘collector of scavage’. WTF is scavage, I hear you say. Well, in ye olde medieval times, ‘scavage’ was a tax (grrr) levied by towns and cities on goods sold by non-residents. This was actually a fairly well-intentioned tax, as it was supposed to give resident merchants a competitive advantage.

You might think that scavenger came to mean one who roots through crap as a way to insult the taxman (or woman). But it actually happened because the officers in charge of collecting this tax were later made responsible for keeping streets clean (I’m not entirely sure how these two skills became interchangeable, but I suspect it was to do with budget cuts).

Over time, ‘scavenger’ stopped referring to people altogether (apart from the chip guy I mentioned above) and settled on animals that lived off refuse, carrion and other unappetising delights.

Fun scavenger facts:

• vultures have stomach acid that’s so strong it can digest anthrax, botulism and cholera. I don’t want to know how they found this out. They also have a diet that’s 90% bone. Yum

• hyenas are often mistaken for scavengers, but they actually hunt most of their food – spotted hyenas (the most well-known type) catch up to 80% of their food themselves and have a hunting success rate that rivals lions. They are, however, very opportunistic and won’t turn down an easy meal if they happen to find one on the floor. Same as me, to be fair

• my parents once saw a seagull steal a piece of cake with a whole fork in it – a metal one too.

It’s worth saying that scavengers play a vital role in our ecosystem by getting rid of all the dead crap on the ground. So without them, the world would be a much messier place.

psychrophilic

You’ve probably noticed that stuff is really expensive these days. And one of the most expensive things is staying warm (as I type this I’m wearing two jumpers, a scarf and gloves, and I have an extra-long hot water bottle wrapped round me – still cold though). Thanks to soaring energy prices, we’ve all had to become psychrophilic.

As you’ve probably guessed, psychrophilic is a scientific term for organisms that love living in cold environments – think glaciers, deep-sea trenches and the like. They’re usually bacteria, fungi, microbes and other tiny little critters like that.

‘Psychrophilic’ first turned up as a scientific term in the early 20th century. It’s a combination of two Greek words – ‘psychros’ meaning ‘cold’ and ‘philos’ meaning ‘loving’. Sometimes etymology really isn’t rocket science.

The opposite of psychrophilic is, of course, thermophilic. These heat-loving organisms thrive in temperatures above 45°C. Psychrophilic and thermophilic organisms are often also extremophiles, another former word of the week.

Psychrophilic organisms are super helpful to science. Here are a couple of examples:

Antarctic krill in action – actual size, around 6cm

• colwellia psychrerythraea: a bacterium found in the deep sea, particularly in the Arctic and Antarctic. It produces proteins that stay active at really low temperatures, which is handy for things like food preservation

• pseudoalteromonas haloplanktis: this is another type of bacterium which also thrives in the Antarctic. It’s studied for its enzymes, which we use to clean clothes in cold water

• Antarctic krill: this tiny shrimp-like crustacean also lives in the freezing waters around Antarctica. It’s what’s known as a keystone species, which means it plays a critical role in maintaining the structure and balance of its ecosystem. Without this unassuming little creature, the Southern Ocean ecosystem would be completely devastated, as would the wider environment. The best things really do come in small packages. (Oh, and just to end on a positive note, you’ll be pleased to hear that Antarctic krill is one of the few species in the world that isn’t endangered. So the Southern Ocean ecosystem should be okay for now. Apart from all the climate change. Sorry.)

recalcitrant

Despite sounding like a medical complaint, recalcitrant is an adjective (AKA a describing word) for someone or something that stubbornly refuses to follow rules or instructions, while also being a dick about it. Think stroppy teenagers, Donald Trump or my dog*.

Recalcitrant’s angry roots are Latin, from ‘recalcitrare’, which is a combo of ‘re-’ (meaning ‘back’ or ‘again’, as in ‘return’, ‘recall’ and ‘recover’) and ‘calcitrare’, which means ‘to kick’. Why kicking? Well, in its original sense, ‘recalcitrare’ was used to describe the behaviour of a stubborn or unruly horse that literally kicked back at someone trying to control or train it. Over time, we’ve extended the term’s meaning to describe people who resist authority, are uncooperative, or are unwilling to be controlled or directed.

I asked my friend ChatGPT if he (it’s definitely a he) had any stories about stroppy horses. And he told me about Clever Hans. Now Clever Hans wasn’t actually stroppy (so I don’t think ChatGPT is going to be taking over the world just yet, seeing as he can’t even get that right), but it is quite an interesting story, so I thought I’d include it here anyway.

Clever Hans was a horse born in 1895ish who became famous for doing sums and other clever things. He would answer questions by tapping his hoof, and became a sensation in Germany in shows run by his owner, Willhelm von Osten. Hans could add, subtract, multiply, divide, work with fractions, tell time, keep track of the calendar, differentiate between musical tones, and read, spell, and understand German, which makes him much cleverer than yours truly.

Sadly, it turns out although Hans was a very clever horse, he was perhaps not quite as clever as everyone thought. A psychologist called Oskar Pfungst carried out a series of experiments to understand how Hans was answering questions correctly. And he discovered that the horse was actually responding to subtle (and unconscious) cues from his trainer and human audience. For example, when he was asked a question, he would start tapping his hoof. When he reached the right number of taps, the audience would involuntarily exhibit subtle body language changes like tensing up or relaxing. Hans would stop tapping when he detected these cues, giving the appearance of getting the question right.

One of the ways Pfungst realised he was doing this was that he only got the answer right when the person asking the question knew the answer themselves. This is now called the ‘Clever Hans effect’, and has changed the way scientists all over the world investigate animal intelligence.

Even after he was debunked, von Osten, who refused to believe Pfungst's findings, continued to show Hans around Germany, where he still attracted large and enthusiastic crowds. It’s worth pointing out that Willhelm never charged for any of these shows, either before or after Clever Hans was outed. Nice, right?

Also, I still think Hans was pretty clever.

*I love you really, Gus.

Clever Hans with Willhelm