How can homo erectus and homo sapiens, at their times, migrate from africa to all over the world, including australia and americans? i mean, they can't swim hundreds of kilometers in the ocean, but they arrived anyway.

answer:

homo sapiens evolved from their early hominid predecessors between they all shared the trait of bipedalism, or the ability to walk upright on two legs. we can't be sure of the exact reasons humans first migrated off of the african ..

the american rail road was the most influential and useful transportation system developed in the 1800's with steam locomotives and in the very late 1800's and early 1900's diesel electric locomotives being used to transport goods and people around the newly expanded united states!