I'm not suggesting they actually do depict Africans, but there really is something odd about them. They are said to be non idealized portraits of Olmec rulers, but they look nothing like Native Americans, at least not to me. Perhaps they looked very realistic to the Olmecs but to modern viewers who have seen Africans and Native Americans they look more like the former? Anyway, what if any credible scholarship has been written about what I am describing?
Something to keep in mind is that you are comparing contemporary population phenotypes to those in the past. A lot of the diversity you would have seen in the past no longer exists for a multitude of reasons we can only guess at. Just think of the amount of time between when they were carved and now. That's ~3000ish years. That's a lot of time for things such as phenotype to change.
There's also artistic liberty and license for these carvings and other pieces of Olmec art. The wear-jaguar figures don't accurately depict half-human half-jaguar people, but rather a religious or spiritual transformation. The flaming eyebrows and jaguar mouth, both of which are quite common, are simply artistic elements. Perhaps to the Olmec having a wider nose and fuller lips was more attractive and thus those features were accented. Much later in time the Maya chose to emphasize crossed-eyes, large sloping noses, and elongated heads. Shaft tomb figures from West Mexico also emphasize large noses and elongated heads.
I read the same book you did.
The flat, wide nosed, large lipped South American face was apparently pretty common. But pretty much it's less easy to find now.
http://ancientaliensdebunked.com/wp-content/uploads/2014/01/Native-Olmec-compare-1.jpg
