I don't think it's a coincidence at all. The closer a language and it's speakers are to English speakers the more likely those languages are to cross-pollinate, by sharing vocabulary, grammar, and culture. It makes sense that the closer someone is to you both culturally and geographically that the easier it is to speak their language, and understand their meaning.

Absent are Celtic languages, which have hardly any shared vocabulary with English, and completely different grammars (though lots of shared culture). Irish is listed as taking 1100 class hours to learn here:

    http://multilingualbooks.com/languagedifficulty.html

i.e. category 4 on the original web page.

The number of hours doesn't map directly to the FSI scale because the FSI scale is training Foreign Service Officers, who have undergone a rigorous selection process, and usually already speak multiple languages.

They are also learning full time at one of the best language schools in the world.

The average person taking average classes part time wouldn't learn nearly as quickly as they do.

the likelihood an american foreign service employee would ever need to use a celtic language is not very high. similar probably holds for basque which i hear is not the easiest to learn either.

I'm basque and I can confirm that basque is quite more complicated than english.

In fact, if you check the map, there's a gray spot on the north of Spain/South of France. That's Euskadi (Basque Country area).

The region where Basque is spoken is not gray because of its difficulty, but because there's no data [1].

[1] https://www.reddit.com/r/MapPorn/comments/7dith2/language_di...

Yes, poorly explained on my comment (not native english speaker, obviously). I just wanted to point out the region where basque is spoken. Thanks for the info.

i assume that is because the FSI does not teach Basque, though i suspect the CIA may have some basque experts for surveillance purpose.

English is a Germanic language and it originated in North West Europe. In 1066 it was invaded by people from neighbouring France, who brought with them their Italic language, resulting in lots of new vocabulary and a simplified grammar. So it's hardly surprising that Germanic languages with simple grammars, and Italic languages with similar vocabulary, are easier for English speakers to pick up than other languages.

It's not. The east-west gradient is not random. As you go east, indo-european languages grow more conservative.

And indo-european was a pretty complex language, with all the cases, declensions, plural modes, etc. The more of that is lost, the easier it is to learn.

The more conquests, trade and migration there was, the simpler the language is. That until you consider vocabulary.