Cladistics (from Greek , "klados", i.e., "branch") is an approach to biological classification in which organisms are categorized based on shared derived characteristics that can be traced to a group's most recent common ancestor and are not present in more distant ancestors. Therefore, members of a group are assumed to share a common history and are considered to be closely related. 

The techniques and nomenclature of cladistics have been applied to other disciplines. (See phylogenetic nomenclature.) 

The original methods used in cladistic analysis and the school of taxonomy derived from the work of the German entomologist Willi Hennig, who referred to it as phylogenetic systematics (also the title of his 1966 book); the terms "cladistics" and "clade" were popularized by other researchers. Cladistics in the original sense refers to a particular set of methods used in phylogenetic analysis, although it is now sometimes used to refer to the whole field. 

What is now called the cladistic method appeared as early as 1901 with a work by Peter Chalmers Mitchell for birds and subsequently by Robert John Tillyard (for insects) in 1921, and W. Zimmermann (for plants) in 1943. The term "clade" was introduced in 1958 by Julian Huxley after having been coined by Lucien Cuénot in 1940, "cladogenesis" in 1958, "cladistic" by Cain and Harrison in 1960, "cladist" (for an adherent of Hennig's school) by Mayr in 1965, and "cladistics" in 1966. Hennig referred to his own approach as "phylogenetic systematics". From the time of his original formulation until the end of the 1970s, cladistics competed as an analytical and philosophical approach to phylogenetic inference with phenetics and so-called evolutionary taxonomy. Phenetics was championed at this time by the numerical taxonomists Peter Sneath and Robert Sokal and the evolutionary taxonomist Ernst Mayr.

Answer this series of questions:

1. What is the main topic?
2. What's the word's country of origin?
3. What is it?
4. How long ago did it appear?
5. By who?
6. How?
7. Did anyone else write about it?
8. Who was next?
9. How many years later?
10. What was his focus?
11. Who was next?
12. What was his focus?
13. When?
14. How are organisms classified under this approach?
15. Who coined "clade"?

Numbered answers:
1. Cladistics
2. from Greek , "klados"
3. an approach to biological classification in which organisms are categorized based on shared derived characteristics that can be traced to a group's most recent common ancestor and are not present in more distant ancestors
4. as early as 1901
5. by Peter Chalmers Mitchell
6. with a work about birds
7. yes
8. Robert John Tillyard
9. 20
10. insects
11. W. Zimmermann
12. plants
13. 1943
14. organisms are categorized based on shared derived characteristics that can be traced to a group's most recent common ancestor and are not present in more distant ancestors
15. Julian Huxley