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.)