Before the state and federal governments provided assistance, who was providing relief to americans

Local Charities provided relief to Americans during the great depression assisting poor people in getting a well-balanced meal.

Later on, Harry Hopkins, an American social worker, spent plenty of time as a “friendly visitor” improving the condition of the poor, he later became part of the Roosevelt family heading the "Temporary Emergency Relief Administration" (TERA) to provide direct relief for the unemployed in New York.

Around 1930’s due to the Great Depression many people were unemployed, so the federal government stepped into the matter and Roosevelt Administration established the Federal Emergency Relief Administration (FERA) that aided many people. Later in 1935 came up the Social Security Act which offered grants for poor, elderly people, blind and other vulnerable groups. Before it the relief was mainly provided by religious charities and other private groups. A minimal assistance was provided by state and local governments as well.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.