First, the observation may be unreliable in that two or more observers may not agree that the particular response occurred, or to what degree it occurred.
First, at least some of the observed differences between the enzymes of the Atlantic and Pacific fish populations were not random, but were the result of evolutionary adaptation.
First, Venice's intermediary functions in the Adriatic Sea, where it had dominated the business of shipping for other parties, were lost to direct trading.
First through a low velocity core, and then through a high velocity shell, where their speed is increased before they are transmitted into the surrounding seawater.
In any field of endeavor, it is impossible to make a significant contribution without first being strongly influenced by past achievements within that field.
Other innovations of the late fourth millennium include the wheel, probably developed first as a more efficient way of making pottery and then transferred to transport.