Since ancient times there has been the common belief that the experience of a smell is impossible to put into words. The New Yorker presents an overview of more recent cross-cultural research challenging this belief: Culture, not biology, rules the relation between smell and language
And why do these two hunter-gatherer groups have so many? Interesting questions and article from The Atlantic, on the research of Asifa Majid from Radboud University in the Netherlands on the Jahai people of Malaysia and the Maniq of Thailand. But perhaps another way to look at it is via this excellent post from Dr. Avery Gilbert on The Alleged Limitations of Olfactory Language.
In addition, there is the article in the New Yorker that links the new research to other cultural and academics sources: The Uneducated Nose – The New Yorker. In addition, The Economist also discusses and summarizes the underlying research from a slightly different angle.