Maybe I missed something, but he seems to be using the same math as the guy who projected his baby would gain a weight of a trillion pounds if the rate of increase remains constant.
Not only that, it kinda implies that everyone wants to be a Sato, otherwise they could chose the other surname upon marriage. Which people would most likely do if it is too common. Given this assumption, the option to keep your maiden name wouldn't help (but should still be there).
Assuming the choice is never exercised, couples produce the same amount of children with the same gender distribution regardless of surname and these children are all just as likely to find a partner, in theory, the distribution of surnames should be in equilibrium. Of course ignoring name changes, migration and other things playing into the availability of surnames.
Following this logic, these 5% of couples using the maiden name of the bride are the ones actually leading to any kind of long term change. Which to me implies Sato can only be the surname of a majority if the majority wants it to happen.
Maybe I missed something, but he seems to be using the same math as the guy who projected his baby would gain a weight of a trillion pounds if the rate of increase remains constant.
Yeah it is weird that he didn't account for the fact that non-Satos would decrease as Satos increase. But then again I don't think this is a serious research work.
Currently, couples can choose which surname to take. And a lot of pressure has been building for the right to have different surnames on the same family register.
(And thanks to gaijin like me, new surnames are being introduced into Japanese lineage all the time.)
Riddle me this, Professor: With the native birthrate at an all-time low, and the influx of foreign residents at an all-time high, how long until 50% of Japanese surnames are written in katakana?
I already think it's weird that people taking their partner's surname is an option at all, since that's not how we roll over here. And the conservative objection listed here is more absurd than the warning. By a lot.
That said, wouldn't the biggest impact be on the way children are named instead? On a cycle of multiple generations whether your partner takes your name or not is irrelevant, the only relevant issue is what surname the kids have.