How did man migrate around the world following Noah's Flood?
We have to take a look at a few things which give us some very important clues. First, right after expulsion from the Garden of Eden by God, God stated that He brought death into the world because of Adam and Eve sinning. This clearly means all animal life had been immortal until this happened and then everything became mortal. God also said that He created thorns and thistles to punish man. Both of these would have required God to make some significant genetic changes in all life forms, especially man and animals to remove our immortality.
Second, following the flood and man's fall at the Tower of Babel, the scriptures tell us that God did a number of things. First, God decreased the life expectancy of man to a maximum of 120 years in order to decrease the mischief we could cause, which would have required more genetic changes to man. Second, God turned man and a number of animals into carnivores or meat eaters which would have also required genetic changes to man and all carnivores along with reprogramming their brains at the molecular level for the knowledge required for successful hunting, which would later be taught to their off spring. Third, God changed the languages of all people so they could no longer communicate with more than just a few people, probably their immediate families or clans. This would have required reprogramming human minds in small groups at the molecular level so they would no longer remember how to speak the original language and could be fluent in their new languages.
But I believe something else was done by God at this time and I have sufficient proof for it. Creationist believe that they must explain how Adam and Eve had the genetic traits for all races and physical features to answer evolutionists attacks about how we got all of these races from just two people. But, if you keep in mind that God made significant genetic changes in humans twice after the creation, then you realize that God didn't have to program Adam and Eve to carry the genetics for every race, even though God could have. Since God was already making significant genetic and other molecular changes to EVERYONE following the flood and Tower of Babel incidents, why would He not have also included changing different groups of people to different races?
If everyone suddenly couldn't speak the same languages, it would have freaked them out and some would have started migrating away from the rest but you know that some would have tried to learn the languages of others and stayed around, contrary to what God wanted.
But, if God would have changed their languages and their races, that would have freaked everyone out so bad that they would have all fled to other areas.
The proof for this?
Look at the way we were arranged around the world in pure racial groups about 500 years ago and less than 4,000 years after the Tower of Babel. In Africa, parts of Brazil, and Australia, we had nothing but black tribes of people, in the Americas, we had a variety of Indian tribes, in Asia, we had the Asian peoples, and in Europe, we had the white people. If all of those people had migrated based on language alone and they all had all of the different racial traits, there would have been black, red, brown, yellow, and white tribes scattered throughout Africa, the Americas, Europe, Asia, and the Pacific, which did not exist.
Therefore, it is only logical and probable that, when God made molecular changes to our brains to cause us to speak different languages, He would have also made genetic changes to include the different races in the different groups based on a combination of race and language so people would tend to migrate in racial groups with common languages. Therefore, we should be able to track man's migration around the world from the Tower of Babel based on a combination of race and language, which is very easy to do.
BTW, concerning genetics and God's Law, we know that people married immediate family members such men marrying their mothers, sisters, and daughters for thousands of years prior to God dictating the scriptures to Moses. We not only see this recorded in the Bible but in other history such as Egyptian history. We know of a number of leaders, such as Pharaohs, who married their own mothers, sisters, and daughters. Abraham of the Bible married his half sister.
How did they get away with this for thousands of years without having really severe birth defects like we would have today?
If a brother and sister were to marry today, they would have an average probability of at least 50% of each child having very serious birth defects, especially mental retardation. We see significant numbers of birth defects in groups such as Muslims who tend to always marry within their family clans, such as first cousins. This is caused by siblings having the same mutations in their genes caused by thousands of years of reproduction, disease, use of drugs, and other things which would cause genetic damage. If two people with the same gene mutations have children, it is much more likely that those matched mutations will cause birth defects in the children.
But God gave Adam and Eve perfect genes with no mutations so they and their off spring could bare children with each other without birth defects. By the time of Moses, God knew the gene pool had become so corrupted that it became necessary to stop immediate family members from reproducing so God included that in the Law He gave to Moses.
The very fact that so many people had children with siblings for so many thousands of years without serious birth defects is proof we are devolving to a lower genetic level and not evolving to a higher genetic level disproving evolution and proving the Bible and creation. Our genetic pool has gotten so bad today that increasing numbers of people are becoming infertile and can't have children, which is one of the side effects of inbreeding, drugs, and diseases.