The fourth article in the series, pictured left, explained how primitive beings evolved into modern-day mankind. "Man was not created suddenly out of nothing either in Eden or elsewhere nor on any definite date," Free wrote, so where did he originate? While examining our ancestry, where do we draw the line between animal and human? Free explained that 70 to 80 million years ago, catlike creatures skipped about in the North Pole before migrating down to North America, and then to Central America, where they evolved into lemurs. Eventually, the lemur-monkeys moved down to Asia, where they grew stronger, moved from the trees to the ground, and became ape-like half-walkers, which in turn evolved to an a "man-ape" called Pithecanthropus erectus (homo erectus erectus), also known as Java Man. Need proof? Examine your own body and note the similarity of its structure to the make of a primate's, Free said. While he went on to name Pithecanthropus as the possible missing link between modern humans and the common ancestor we share with apes, anthropologists today believe that humans descended from homo erectus rather than Java Man.