I'm just curious about which languages Esperanto is closest to, in order to know for whom it would be easiest to learn this language! For example, could a Spanish speaker learn it more quickly than a French speaker?
Let me break your question into several parts and answer them one by one.
How much would a person not knowing Esperanto understand from a newspaper article in Esperanto?
If you are asking solely about vocabulary, then from my experiences of teaching Esperanto worldwide, German speakers can recognize the origin of about 70% words and can directly understand about 40%. My French students at first understand about 30% of the vocabulary, but go up to 70% too once they learn some basic principles of the vocabulary building. Russian students can understand about 20-25% of usual Esperanto texts (unlike the common belief of 40%!), and again go up to the same level when becoming more advanced.
As pointed out in a comment, the reason for that might lie also in population bias, for:
- For most of the Russian students Esperanto is the first foreign language where they reach the level of fluent speech (usual schools teach languages only up to level A2 that does not include fluent conversation), and they primarily study Esperanto to participate in the social activities of Esperanto-movement, not due to linguistic reasons.
- European students are usually fluent at least in one (English), but many also in several foreign languages and social aspect of learning is much less pronounced here.
Would native speakers of certain language learn Esperanto much faster than the others?
Since Esperanto has an a-priori grammar (see below for explanations!), learning the language itself it similar for everybody irrespective of their mother's tongue.
The grammar of Esperanto is well balanced, so that if Russian native speakers might have less problems to understand the system of active and passive participles (naturally existing in Russian), the speakers of Romane languages have much less problems with a definite article la that does not exist in Slavic languages.
Speaking about vocabulary, one need to admit that speakers of Romane and Slavic languages have some advantages in memorizing Esperanto words, as they often resemble words that exist in their languages (international lexis, see below). However, since "internationalism" is just one of several principles of Esperanto vocabulary (see below), learning the correct spelling of the word is required for everyone.
To be honest, native speakers of Asian languages, especially those employing a different writing system (Chinese, Korean) might require more time to learn Esperanto, because they need to get used to the new alphabet. But from my experience, all Asian students already knew at least one European language and were past this step.
If we compare, however, learning Esperanto as a second language vs. English as Second Language (ESL), the former requires about one eights (1/8) of the learning time to reach the comparable level (meaning that the level that one reaches in English in 2 years can be reached in Esperanto after 2/8 = 1/4 years).
How is Esperanto similar to natural languages?
But talking about similarities between constructed and natural languages, one should understand two basic principles of language design:
- a priori languages are created "from scratch", without any reference to existing (natural, creole or other constructed languages) languages, rather they try to introduce other principles (schematicity, regularity, predicate logic, laws of musical harmony etc.) to language construction.
- a posteriori languages borrow principles from already existing languages, trying to mimic the latter ones while eliminating their disadvantages (like irregularity, difficult to pronounce sounds, irregular stress etc.).
Speaking about similarity between languages, we can talk separately about similarity of grammar and similarity of vocabulary.
Esperanto is a constructed language with a-priori grammar (not similar in any way to any existing language, i.e. created completely from scratch), and a-posteriori vocabulary (every Esperanto word, except those derived directly from grammar constructions (like ina, ree, arigi etc.), has an origin in an existing language).
Similarities in grammar
Despite being an a-priori language from a grammatical viewpoint, the only pure a-priori part here is the so-called correlatives (tiam, kiam, iam ...), the other affixes are usually selected so that the resulting word sounds similar to a word or affixes existing in natural languages (like -ar- for grouping, similar to English arity (unary, binary, ternary) etc.), hence even memorizing these affixes is usually very natural for speakers of any major Romance language).
Principles of Esperanto vocabulary and similarities
The vocabulary of Esperanto is, in its turn, based on so-called international lexis, i.e. the words used in most of the languages (both as inherent and borrowed). This is somewhat similar to the concept of "common denominator" in mathematics, for these words are known to representatives of many nations, either directly (with the same meaning) or indirectly (as foreign words or parts of borrowed words).
Let me give you some examples now.
Nation is nacio in Esperanto, and many words derived from its root (naci-), like inter-nacia, naci-isto, naci-ismo are understandable for me as a native Russian speaker (and definitely to English, French, German, Spanish and Italian speakers too).
Looking at the first word, inter-nacia, you can see that in Esperanto you can use this pattern to derive further words, like inter-urba (something going from one city to another, a "long distance" [train, call, taxi]), and again I know the root urb- (=city) from other borrowed words in Russian, like urbanization (this is an example of that "international lexis"), even though the word "city" is completely different in Russian (gorod).
"Internationalism" is not the only principle of Esperanto vocabulary.
Another principle is simple pronunciation, that makes some words get "crippled" to fit into Esperanto vocabulary: bread => pano (most likely from Italian "pane", but also French "du pain"), sausage => kolbaso (from Russian "kolbasa" etc.). If several international words exist, the one with the simpler pronunciation for most of the nations is selected (compare pano vs.
bredo). Sometimes it leads to Esperantization of quite unexpected words, like bulko (=bread roll or loaf).
One more principle is avoidance of homonyms. Hence "planet" is in Esperanto planedo, not
planeto, that could also be understood as plan-eto (=small plan).
The latter principles make Esperanto sound or write less similarly to natural languages, but they contribute to its other features, like easiness to learn and pronounce, comprehension (both written and speaking) etc.
I found a quick breakdown in the Esperanto.net FAQ:
About 75 % of Esperanto's vocabulary comes from Latin and Romance languages (especially French), about 20 % comes from Germanic languages (German and English), and the rest comes mainly from Slavic languages (Russian and Polish) and Greek (mostly scientific terms).
And I got to learn something about the common ground with Russian!
The words derived from Romance languages were chosen to be as recognizable as possible throughout the world. For example, the word "radio", although technically Romance, is now used internationally. Someone knowing only Russian and looking at a text in Esperanto would immediately recognize perhaps 40 % of the words, without even having studied the language.
The majority of Esperanto's original vocabulary came from French, German and English, so if you already speak any of these languages it would certainly give you a head start. According to La deveno de Esperanto by Geraldo Mattos, by 1987 an estimated 84% of Esperanto's basic vocabulary was Latinate, 14% Germanic, and 2% Slavic and Greek. The French language, specifically, has had a strong influence on Esperanto; however, Esperanto pronunciation is entirely phonetic, unlike French, and this could hinder reading comprehension for French speakers.
According to the proportion of common lexemes, French, English and Italian are the most similar to Esperanto.
The proportion of lexemes that are common to Esperanto and other languages: 91.64 percent French; 89.50 percent English; 89.12 percent Italian; 87.79 percent Portuguese; 87.12 percent Spanish; 81.70 percent German; 64.78 percent Latin; 53.26 percent Russian.
Source: Language Learning Research