For example we refer to infants over a year as 13 months, 16 months, 24 months, etc. Is there a reason for this convention?
In: Biology
I heard this once and it made sense to me:
Because of how fast they grow,
Refer to them in hours until they’re 2 days old
Refers to them in days until they’re 2 weeks old
Refer to them in weeks until they’re 2 months old
Refer to them in months until they’re 2 years old
An 18 month old is as different from a 12 month old as a 12 month old is from a 6 month old
They only really stop growing so fast that you have to specify month around year two.
My son just turned 2. The difference in size and ability between a 12 month old and a 23.9 month old is about 100%.
If you say “my son is 1.” They will ask you “when does he turn 2?”
Cause a 13 month old might be barely walking and only talking a little bit where as a 23 month old would be running and possibly putting together some short sentences and both are only 1 year old.
You actually start your units of measure at hours and work your way through days, weeks, and months until about 2 years. After that you’ll find people using half years (e.g., 3 and a half) until about 5-6. Then it’s just years on out from there.
Like mentioned, it’s all about speed of development and milestones so the more granule units are needed at young ages.
Even at the top end we use stuff like “late thirties” and “in the seventies” for less accurate age measurement for older people.
There’s a world of a difference in a 1 year old that is 13 months old and a 1 year old that is 20 months old.
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