23 December 16:12
One study shows that domestication helped change the color of dogs' eyes, making them more friendly and youthful.
Călin Nicolescu

Science IT&C
The study, by Japanese researchers, suggests that human selective pressure favored dogs with darker eyes, which were perceived as friendlier. Dark irises are thought to be unconsciously associated with being juvenile and vulnerable, making dogs more attractive to humans.
Sources

Studiu. Câinii şi-au modificat culoarea ochilor

Studiu: Câinii și-au schimbat culoarea ochilor după ce au fost domesticiți de către om

Ce spune culoarea ochilor câinelui tău despre el

Efectul neștiut al domesticirii câinilor. Rezultatele surprinzătoare ale unui studiu