Reili Argus, a professor of Estonian at the TU Institute of Estonian Language and Culture says mastering a language does not depend on how difficult or complicated a language is deemed to be. Children are able to master the most complicated grammar at an early age and with little to no effort. It turns out that the richer the grammar is, the earlier children grasp it.
We often hear that Estonian is a complicated language and it is very difficult to learn as a foreign language. We mostly get the reasoning that it is difficult due to the 14 abstract cases. For language learners the number of cases has become a scare device.
Actually, the number of cases does not determine whether a language is more or less difficult to learn. Languages have different natures and in every language there are easier and more difficult areas. So there is no reason to think that the rather blurry system and usage of English prepositions is simpler than that of Estonian abstract cases. The difference lies only in the placement of the language elements: In one situation (English) we use a separate word before the noun (e.g. to the party), while in the other (Estonian) we change the inflections (e.g. peo-le).
It has been proven that the more rich and varied grammar is (the more cases, persons and tenses used), the earlier children start to acquire the language and the sooner they master it. Dutch and Austrian researchers looked into mastering 11 languages in 2007 and got similar results: The more difficult a language’s grammar is deemed, the earlier children start to master it. Children start to learn Turkish, which has the largest number of grammatical persons, at the age of 18 months, and Finnish at a mere 14 months. Acquiring languages with simple grammar, such as Dutch, German and French, starts at a much later age.
Children in Holland, Germany and France start acquiring grammar more than 6 months after Turkish and Finnish children. The rate of learning is higher in the languages that use a lot of inflections. This is also the case in Estonian, which has fewer grammatical forms than Turkish or Finnish. Thus an Estonian child starts to acquire forms a little bit later than Turkish and Finnish children, but noticeably earlier, at about 1.5 years of age, than the average child in France and Denmark.
At the age of 12-18 months, when children start to master the language, their brain capacity is around 60 percent of an adult’s, but even at 18 months of age the Estonian child uses the genitive, partitive and illative cases along with the nominative. An Estonian child acquires the full abstract case system by the age of four.
Thus, when the Estonian abstract cases can be learned by a 1.5-year-old with a brain capacity at a mere 60 percent of an adult’s, the language should not be a problem for an adult learner.