How far back does the word "baby" as a term of endearment for a significant other date to?

UK songwriters use Americanisms more frequently than the general population. They listen to a lot of NA music and they want to sell there too.

Arabic “habibi” means darling and sounds like English “baby,” but I have no idea whether they have a common derivation.
habibi Meaning & Origin | Slang by Dictionary.com.

There’s nothing about “Baby” or “Babe” that prevents their objects being male.

And empiry also shows that the use of “baby” by a female as a name of endearment for a male is not uncommon at all.

I hear that a lot - a female calling her SO, Babe.

“Ooh, baby, that feels good!” is gender-indeterminate.

I was in New Orleans with a group of friends years ago. We went into a store looking for bandaids after one woman drunkenly tripped and did a faceplant on the sidewalk. The store owner heard us talking about the situation. He was an older black gentleman and looking at our wounded companion, he said, “Awww, baby, did you talk a bite outa Bourbon Street?”

I suspect the use of the word “baby” as a term of endearment was infantilizing during a time when it was the norm for men to treat their wives almost as if they were children (given allowances, spankings, etc). But concurrent with the dawn of women’s liberation in the Sixties, the counterculture (soon to be mainstream culture) adopted “baby” as a broader, more general term of address. For a few years, heterosexual men could address each other as “baby”. That was pulled back a bit when the hippy counterculture was appropriated by the mainstream in the Seventies, but “baby” still emerged as a non gender-specific term with no infantile implications when used to address any number of acquaintances or even strangers.

I have my doubts about that theory. The use of “baby” as a name of endearment is very similar to the use of diminutives as names of endearment, and that usage has a long history that goes back millennia, in many different languages, and for both male-to-female and vice versa. Human beings have a natural predisposition towards finding little children cute; so it’s not far-fetched to use such terms also for grown-ups they are fond of. It’s quite an overtheorisation, in my view, to view and explain everything in terms of gender imbalances.

I study the history of popular culture and I can think of nothing that would support this. Babe and baby have been simple endearments for a hundred years, used by both sexes.

I’ll concede that point since I have no inclination to delve into song titles and love letters of a hundred years ago, but I still stand by my contention that its use in the Sixties made it an even more general term of endearment than it was before then. It was a more intimate term before that.

And I stand by the all the hours of reading and listening that I’ve actually done. It was a general term of endearment, no different from dear or honey or the rest.

I too, have an extensive knowledge of mid-Century pop culture, especially the Fifties and Sixties. I’m sorry our conclusions don’t jibe. I’ll admit, I haven’t made a focused investigation on the specific use of the word “baby”. Have you? What are some examples, say, pre-WWII?

Snip from OED. Baby itself recorded in 1400 Piers Plowman

use #6 colloquial

a. A lover; (also) a spouse. As a term of endearment: darling, sweetheart. Cf. babe n. 4b.In early use only applied to women. After the isolated example in quot. [1684], the modern use of this sense originates in the United States.

1684 A. Behn Love-lett. between Noble-man & Sister 328 Philander, who is not able to support the thought that any thing should afflict his lovely Baby, takes care from hour to hour to satisfie her tender doubting heart.

1862 H. M. Naglee Let. 8 Jan. in Love Life Brig. Gen. H. M. Naglee (1867) 119 Dear, dear, dear Baby, how often, how incessantly I think of you.

1869 H. B. Stowe Oldtown Folks xiv. 147 Yes, Tina, I am glad,…but, baby, we can’t stop to say so much, because we must walk fast and get way…off before daylight.

1889 B. Harte Heritage of Dedlow Marsh 9 ‘Lean on me, baby,’ he returned, passing his arm around her waist.

That’s probably enough for now but there are many many more.

It’s already been established that it has been a term of endearment for well over a hundred years. My contention was that it’s use evolved during the Sixties. It’s use is no longer confined to a love interest.