[taion]

The premise of the argument seems wrong. Even in just Europe, there’s evidence for an increase in animal size during the Roman period, a decrease during the early middle ages, and then an increase into the high middle ages, e.g. https://link.springer.com/article/10.1007/s12520-021-01426-w

These correspond to economic changes which made different sizes of animal more appropriate. Size and productivity aren’t the only criteria anyway – disease resistance, hardiness, or ease of feeding seem like they’d be just as important to subsistence farmers.

Earlier techniques may have been less good than modern ones, but they quite evidently worked to some extent. Specialized horse breeds had gotten to the point where they needed to be specially fed way before the start of the period in the book reviewed here!

Instead of positing a lack of understanding, the observed phenomenon is likely more a factor of limitations in documentary evidence (how many people engaged in stockbreeding were actually writing books anyway?) and in the actual goals of the people involved around optimizing for robustness and practicality over pure productiveness.

[Robotbeat]

Artificial selection can and does happen without being intentional.

[gumby]

Yeah, fishing limits on the size of fish caught (and legal for sale) in the Atlantic has led to smaller mature fish.

[anonymouskimmer]

> (how many people engaged in stockbreeding were actually writing books anyway?)

Yeah, I was thinking that a lot of this knowledge would have been kept secret as proprietary trade information.

[taion]

Or less kept secret than not written down, especially before the early modern period, especially outside of things like war horses, just based on who was engaged in that activity.

In fact a quick glance at the Wikipedia page for medieval horse breeding shows documentation for quite deliberate, centralized, and successful operations quite far back! https://en.m.wikipedia.org/wiki/Horses_in_the_Middle_Ages

[pixodaros]

Yes, I think Gwern might want to look into practical animals such as sheep not luxury animals such as racehorses. Just getting those big, strong, docile racehorses required selective breeding!

Edit: And amusingly he does talk briefly about sheep but is not interested in where the types of sheep in 18th century England came from because the people who bred them did not leave records and get praised in a book on early modern history :)

[aidenn0]

This is the second post on HN to Gwern's site recently with fairly dubious assertions about the late development of something.

If he reads the comments here, that's good, but I'm going to have to take everything he writes now as "X doesn't exist" to "I don't know about X, but people generally familiar with the field might"

[pixodaros]

To be fair, he does notice that Roman historians are saying things about antiquity which are different than what this specialist in 18th/19th century said in 1986 (footnote 11). There is a famous passage by one of the ancient Greek poets that cobbler competes with cobbler and singer with singer and this leads to excellence.

Many medivalists suspect that monasteries and abbeys drove scientific agriculture in medieval Europe because they had capital, literacy, and education. Some berries seem to have been first domesticated in monastery gardens with nets to keep the birds out. Medieval people may not have had good theories of how to breed animals for traits but they could make it work with enough time and effort.

[pixodaros]

Turning to a Hacker News friendly theme, Mr. Watt and Herr Doktor Haber und Bosch have a lot to do with why livestock today are so big and produce so much milk and wool or so many eggs. Internal combustion engines and artificial nitrates let you feed animals more energy-rich food which let them grow bigger and produce more milk and wool and eggs. Animals also grow bigger if they are vaccinated against diseases, medicated against parasites, protected from pests by cheap steel, and watered with filtered water. Animal breeding was just one of the aspects of British agriculture that started to rapidly improve around the 18th century.