work I mean plural (several studies). So how should I treat the verb that comes after it?
Similar to previous work that identifies
Similar to previous work that identify
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In this case, you're using work as an uncountable noun (mass noun). Uncountable nouns are always treated as grammatically singular:
Similar to previous work that identifies...
If you use a countable noun in the plural, then the verb changes:
Similar to previous studies that identify...
It is possible to use work as a countable noun, in the sense of "works of art," for example, in which case you can pluralize both the noun and the verb:
Similar to previous works that identify...
This is somewhat unusual and would only be used if you were using the countable work[s] in the surrounding text. In general, when referring to preceding studies or research, the uncountable work is used.
Semantically, OP's "work" may involve several studies, but it's still a singular noun.
My favourite work by Bach is his Toccata & Fugue in D Minor (a single piece of music)
My favourite works by Beethoven are his symphonies (multiple pieces).
Hence the choices for OP are...
[My analysis is] similar to previous work that identifies [Africa as the cradle of humanity]
[My analysis is] similar to previous works that identify [Africa as the cradle of humanity]
Unlike other English grammar, the rule for singular-plural verb-subject agreement is pretty straightforward:
Unless the subject is clearly plural, use the singular conjugation.
While some words, like "work", have both abstract and concrete meanings, the abstract is considered singular. Even a general "body of work", which can include many articles, is still singular when considered as a group.
His work, written over the course of a long and distinguished career, is considered required reading for students of the field.
If you want to refer to multiple articles, considered individually, use the plural:
His works, written over the course of a long and distinguished career, are considered required reading for students of the field.
This is the same for the very many similar nouns which have both an abstract/ figurative/ uncountable meaning, and a concrete/ literal/ countable meaning: philosophy, memory, paper, hair, space, experience, light, and many, many more.