"Put even more simply, humans tend to look on (and talk about) the bright side of life," researchers said.
A team of scientists at the University of Vermont (UVM) and colleagues used a massive data set of many billions of words, based on actual usage.
"We looked at ten languages and in every source we looked at, people use more positive words than negative ones," said UVM mathematician Peter Dodds who co-led the study.
Scientists gathered billions of words from around the world using 24 types of sources including books, news outlets, social media, websites, television and movie subtitles and music lyrics.
"We collected roughly 100 billion words written in tweets," said UVM mathematician Chris Danforth, who co-led the research.
From these sources, the team then identified about 10,000 of the most frequently used words in each of 10 languages including English, Spanish, French, German, Portuguese, Korean, Chinese, Russian, Indonesian and Arabic.
From these native speakers, they gathered five million individual human scores of the words. Averaging these, in English for example, "laughter" rated 8.50, "food" 7.44, "truck" 5.48, "the" 4.98, "greed" 3.06 and "terrorist" 1.30.
A Google Web crawl of Spanish-language sites had the highest average word happiness, and a search of Chinese books had the lowest, but all 24 sources of words that they analysed skewed above the neutral score of five on their one-to-nine scale - regardless of the language.
And when the team translated words between languages and then back again they found that "the estimated emotional content of words is consistent between languages.
