Here’s the Herodotus reference to Persian birthdays:
Of all the days in the year, the one which they celebrate most is their birthday. It is customary to have the board furnished on that day with an ampler supply than common. The richer Persians cause an ox, a horse, a camel, and an ass to be baked whole and so served up to them: the poorer classes use instead the smaller kinds of cattle. They eat little solid food but abundance of dessert, which is set on table a few dishes at a time; this it is which makes them say that “the Greeks, when they eat, leave off hungry, having nothing worth mention served up to them after the meats; whereas, if they had more put before them, they would not stop eating.” They are very fond of wine, and drink it in large quantities. To vomit or obey natural calls in the presence of another is forbidden among them. Such are their customs in these matters.
Wikipedia explicitly mentions the word “originate”:
It is thought the large-scale celebration of birthdays in Europe began with the non-Christian cult of Mithras, which originated in Persia, and was spread by soldiers throughout the Roman Empire. Such celebrations were uncommon previously so practices from other contexts such as the Saturnalia were adapted for birthdays. Because many Roman soldiers took to Mithraism, it was distributed widely and its influence was spread throughout the empire until it was supplanted by Christianity.
Thanks to Ari Siletz: arisiletz.com
