By John McWhorter, Ph.D., Columbia University
Evidential markers are signs that a language can develop far beyond communicational needs. For example, in an Amazon language called Tuyuca, some endings can show if the sentence has been heard or seen. The endings have no meaning on their own, but they show how the speaker has got the news. The perfect tense in English is another example of overdevelopment. What are evidential markers in English?

Languages are like cathedrals, in the sense that they developed unnecessary decorative things. Sculptures and decorations on the top of many Gothic cathedrals were built when people could not see them from above, as there were no planes yet. Although they used to say it is built for God, the main reason was unnecessary decoration. Languages are like that too, and evidential markers testify.
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Language Overgrowth
Grammar overgrows to contain things that are not needed in many cases. It is like a bush that simply does not stop growing. Some argue that there is a core and also periphery, which is more accurate.
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A familiar example is the present perfect tense in English. The difference between ‘I have walked to the store’, and ‘I walked to the store’ is not that significant, and they convey the same meaning in terms of the action that is done. Thus, it is an overgrown aspect which is very rare in other languages.

If a foreigner asks an English speaker to explain the difference between the past tense and the perfect, it would be difficult. Of course, the subtle difference is that in perfect, the effect of what is done in the past lingers on to the present. However, it is not an essential tense, and the full meaning would still be conveyed with the past tense.
Evidential Markers
All languages around the world go through the same unnecessary overgrowth. In English, it creates things like the perfect tense that looks very normal and common but is not. A global category of such overdevelopment is evidential markers.
One use of evidential markers in some languages is showing the source of what somebody says. For example, the main message of ‘I saw that they were tearing down the building’ is the same as ‘They are tearing down the building’. The semantic essence is the same in all languages, and whether one saw it or heard it, the building is still being torn down. However, some languages see it as an essential part and have even developed endings for it.
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Tuyuca
A good example of a language with evidential markers is Tuyuca. Tuyuca is a language in the Amazon, in which indicating the source of news is vital. Linguistic elements have been developed to show that.
For example, ‘He’s chopping trees’ in Tuyuca is kiti-gï tii. Although it is a complete sentence in English and many other languages, it is incomplete in Tuyuca as the source of the news is not specified. If the person has heard that the trees are being chopped, they should say kiti-gï tii-gí. If they saw it, it is kiti-gï tii-í. Without the ending showing the source, the sentence looks like an English sentence with no verb.
Both -gi and -i are meaningless endings, like the past tense -ed in English. The -gi ending has no meaning like hearing or listening, just like the English -ed that has no meaning like before or yesterday yet it specifies that an action has happened in the past.
Even adverbs and hearing around have different endings in Tuyuca. Apparently, he’s chopping trees is kiti-gï tii-hɔ̀i, and kiti-gï tii-yigï shows that the person has heard around that trees are being chopped.
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Translating Evidential Markers
Broadway musicals are translated into many languages but none of them has probably been translated into Tuyuca. But if they did, Annie Get Your Gun in the Amazon and they wanted to make it accessible to Tuyuca speakers, then when they got to the song They Say It’s Wonderful—in English it’s ‘They say that falling in love is wonderful, is wonderful, so they say’. In Tuyuca it would be something similar to ‘They say that falling in love is wonderful, it’s wonderful, -yigï‘. And there would be that ending. But we don’t have that in English, so it is structured differently.

Another example of such evidential markers is in Makah, a Native American language. For one to say that ‘the weather is bad’, the basic sentence is wikicaxak. However, like in Tuyuca, the sentence is incomplete. The ending –pid, which means ‘from what it looks like’, must be added to the sentence here.
Obviously, -pid is an evidential marker and not necessary for conveying the main message. However, it has become an essential part of the Makah grammar through the overgrowth. Now, like perfect tense, it is the decorative angel on top of an old cathedral, not vital, but there.
Evidential markers are only one example of language overdevelopment. There are more cases that studying a language can reveal. Yet, it is not easy to distinguish which elements are necessary and build the minimum required grammar for a complete, undecorated language.
Common Questions about Evidential Markers
A familiar example of evidential markers in English is the past tense –ed. It has no meaning on its own, but it indicates that the verb has happened in the past. Some languages have many more and in different areas. For example, in a Native American language called Makah, the sentence ‘the weather is bad’ is incomplete. The ending -pid must be added to show that ‘it looks like’.
Tuyuca is an Amazon language that has very interesting evidential markers. In Tuyuca, the speaker must specify the source of what they say as an ending, not in the form of phrases and adverbs. For example, one can show that they have heard something by adding a suffix, -gi, to the end of a sentence.
Yes. Once grammar is created in a language, it develops to make things that are not even necessary. Evidential markers, like the -gi in Tuyuca (an Amazon language), shows the speaker of a sentence has heard it. These are examples of overdevelopment.
No. the present perfect tense is a rare feature in languages and a sign of overdevelopment. Like evidential markers, some tenses are also language specific and not really necessary.