The cousinhood was in uproar. To have been ignored for so many years was bad enough, but the final humiliation was unforgiveable. An emergency meeting was organised. The entire cousinhood attended. Some thought we shouldn't rush into action – our hosts would come to realise their error and eventually give us the status we deserved. But most felt they should be taught a lesson. At an appointed time, we would all resign and move to Paris japonica, which was so spacious they'd never find us. Our hosts would recognise their mistake, correct the record, and we would return triumphant.

About three months after our mass exodus, our hosts started to report anomalies in prenatal scans. When pregnancies reached full term, it was all over the headlines. The newborns were initially greeted with horror – monstrosities, Frankenstein babies. But parental instincts took over and quadribrachials were soon accepted. Babygrows had their toes cut off to allow hands of the newborns to poke through. At the toddler stage, the arrivals proved adept at walking on all fours or raising themselves up on their hindarms. Parents boasted of the doubling in manual dexterity and enhanced climbing abilities. The shoe industry repurposed to produce durable gloves. Commentators marvelled at goal punches in reconfigured football games, and three-armed backhands in tennis. The hundred-metre gallop entered Olympic arenas. The fashion industry paraded symmetrical clothing designs, while furniture-makers lowered their table tops. Yet, despite these differences, the new generation's lifestyle was not so different from that of their bipedal seniors. Laws were introduced banning discrimination either way.

Host scientists soon identified the culprit. A locus, previously categorised as having a housekeeping function, was missing from quadribrachials. There had clearly been an error in earlier functional assignment. Expression patterns in embryonic mice and binding studies confirmed that it encoded a leg-specific transcription factor rather than a housekeeping protein. But how the regulatory locus had excised and where it had gone remained a mystery.

One hundred years after our exodus, with only a few aging bipedals left in the host population, we decided it was time to return. Our hosts had learned their lesson and would now be fully appreciative of our rank. Several thousand of the cousinhood volunteered to be the first to reinsert. We never heard from them again. It seems our hosts, wanting to prevent any further disruptions to their lifestyle, had developed a prenatal screen that destroyed aberrant insertions or deletions.

I have now been in Paris for more than three centuries. There's nothing for me to do here. My only diversion comes from conversations with my neighbour, a housekeeper. He's always working, except for a few hours before sunrise, which is when I try to catch him.

How long will this winter last? It would only take a few damaging mutations to take me on the road to permanent frost, to a pseudo world of no return. But with the right substitutions I might find a new role here, live to see spring once more. What are the chances? Enough speculation, dawn approaches and I must get ready for my friend.

Read other ‘Developmental Twists’ articles by Tsuku Mogami

Mogami, T. (2021). Developmental Twists: The Scan. Development148, dev200108. doi:10.1242/dev.200108

Mogami, T. (2021). Developmental Twists: Only Human. Development148, dev200204. doi:10.1242/dev.200204

Mogami, T. (2021). Developmental Twists: Back to Back. Development148, dev200268. doi:10.1242/dev.200268

Mogami, T. (2021). Developmental Twists: A Colourful Character. Development148, dev200360. doi:10.1242/dev.200360

Mogami, T. (2022). Developmental Twists: A Fateful Tour. Development149, dev200453. doi:10.1242/dev.200453

Mogami, T. (2022). Developmental Twists: A Fertile Encounter. Development149, dev 200523. doi:10.1242/dev.200523