Nobody knows for sure how he ended up in Africa, but according to a "lost episode" in the Dutch language, he and Maurice known each other since they were really little (they act like todders in the flashback about it, in the episode translated as "Young and Nestless", but with animal development, they might've been younger then that... most likely, only babies). During that time, Mars lived in a well put-together treehouse (Maurice shares residence) and enjoys reading a collection of comicbooks, which proves he's most likely raised by humans and learns there language. His caregivers were probably off-screen characters, as the only human shown in that episode was a burly boy (most likely grew up to be Norman the poacher) who uses games to get rid of the animals so he can raid their treehous