Q: I am new to the Christian faith and have been wondering how after the flood animals spread across the newly created oceans. I have tried to find out online but have not had much success. Could you enlighten me, please?
A: I have addressed the question of post-Flood animal migration before, when I worked for another creationist organization called Answers in Genesis (UK). My article on the subject has been published online at their website, and also in the popular apologetics book, The New Answers Book 1.
My argument in brief is this:
We cannot be absolutely sure how animals migrated from the Ark’s landing site to all over the world. Scripture does not give us an exact answer. It is therefore open to us to speculate, so long as our speculation is not outside what scripture teaches. We should note, however, that if we make a scientific model to help explain something, we should be aware that this model may be superseded at a later date. However, scripture will always be true and never superseded.
Many creationists have suggested that the catastrophic events of the Flood would have left the oceans after the Flood slightly warmer than at present. In addition, we assume that the triggers for the Flood would have been massive volcanic activity (the ”fountains of the deep“), producing large amounts of aerial dust for the first time in Earth’s existence. Therefore, the atmosphere in the immediate post-Flood world would have been slightly cooler than at present. A warmer ocean meets a cooler atmosphere. Greater evaporation from the ocean would therefore lead to greater atmospheric precipitation, which could have been the trigger for the Ice Age.
The presence of an Ice Age for one or two hundred years after the Flood would lead to lower ocean levels than today. Therefore, there would have been land bridges, and narrower ocean passages, across which animals could migrate. For example, marsupials, having such a short gestation period, would have more speedily migrated to their current abodes in South America and Australia. The latter is more isolated today. The end of the Ice Age would have led to rising sea levels, cutting off land bridges, and widening ocean passages. In the case of Australia, the lack of placental mammals would have caused marsupial mammals to fill environmental niches normally held by placental mammals in other areas. Whereas, in South America, smaller marsupials such as opossums would have had to co-exist with other mammals. By the way, this post-Flood speciation or development of Australian marsupials is NOT evolution—the development would take place within an existing gene pool. There would be no creation of new genetic information, so this process is not evolution. It is breeding “after their kind.”