The first humans adapted and modified their environment, by manipulating soils and rich silt form the irrigation of the river valley. This allowed for greater use of agriculture which helped the population sizes increase and eventually evolved into a surplus. The humans began to domesticate animals and use them for work. All these adaptation and modifications let civilization eventually grow to the society it is today.
This sentence is correctly punctuated because it separates the initial adverbial clause with a comma, and then puts another comma before the conjuncting adverb "while," which is correctly used joining two sentences.
