Last Ape Standing

What I expected was a lot more detail on the approximate twenty-seven “human” species that the author, Chip Walter, mentions, perhaps with drawings of what the species looked like, maps of ranges, and other various concrete details. What I got was some “gosh-wow!” big science speculation/insight. I like “gosh-wow” science, but I wanted to see more of the details, although, frankly, the details I want are probably beyond the information we have available.

The material is organized into broad thematic/chronological units chapter by chapter. Thus, the first chapter is a reflection on the deep time of the “Human Evolution Calendar” and the gradual development of brain size, walking ability and other details of the human anatomy. Walter does provide a nice chart showing his view of what species evolved into what species in this chapter, although I wondered about his loose definition of “human.” How three feet tall creatures with the 1/3 our brain capacities are human is not clear. Walter includes the robustus group in his definition of human. There may be a good reason for doing this, but I wasn't clear what the ground was, albeit for purposes of the book and stretching our imagination, it does make a point.

Succeeding chapters discuss the importance of neoteny and childhood. Neoteny involves the preservation of childish features in older individuals. In the human species, the movement to bipedalism and the increase in brain size meant that human species had to have more development of children outside the womb. According to Walter, the extended period of childhood made human species more individual, more flexible, and more able to learn. Walter also ascribes much of the homo sapien form to radical neoteny as compared to other species. Further, Walter makes the interesting argument that the reason for sapiens success over that of the neanderthals was simply that sapiens had longer childhoods, which made for more flexibility and creativity.

Flexibility and individuality meant that even greater brain power was needed to deal with social interactions. Social interactions for developing humans might have been more important than speed or strength, and that set up a feedback loop for brain development. Walter also theorizes that brain power in the form of imagination is a kind of display behavior that shows reproductive fitness, like the Impala's “stotting” behavior.

Walter has some fascinating insights as to interspecies interaction. It seems clear based on lice that humans have that our species met another human species intimately enough to share lice. Likewise, it is clear that we share some genes with Neanderthals and the mysterious Denisovan species. This is all fascinating, and provisional as imaginable since all we have as hard evidence is a couple of molars and a finger tip. That we can do this much analysis with so little is mind-bending.

Two more fascinating insights. First, Walter has a description of the genetic bottleneck seventy thousand years ago in Africa when sapiens were reduced to less than ten thousand individuals. Walter speculates that this was due to the Toba eruption. Other species of humans were not affected because the ash might have blown west from Indonesia, blanketing Africa, but leaving Europe and Asia relatively unaffected. Walter explains:

“Given these apparently enthusiastic migrations, you might think that as a species we were finally off and running, but there was that wintry climate that was setting in. By seventy thousand years ago it was in full, frigid swing and had begun to systematically rub out life everywhere on the planet. (We are living right now in what scientists call a slim “interglacial” period of this ice epoch, a bit of information that is itself chilling.) Genetic studies confirm that during this time Homo sapiens underwent what scientists call a “bottleneck event.” That is to say, we had been worn down to something like ten thousand total adult members, a troop or tribe here or there, scraping out a living, probably along ocean shorelines and receding lake beds. Ice ages rarely result in cold weather in Africa. Instead they parch the land, turn rivers into dry wadis, evaporate lakes, and wipe out the sustenance each provides. During some of these periods, the Nile itself was reduced to swamp and muck. Even today the continent is filled with ancient lake beds scarred by desiccated mud cracks that testify to exactly how arid the landscape had become. Whichever humans survived the first waves of these droughts, they had tools, but little else, and when water disappeared, so did the other animals, nuts, tubers, and fruit that supported them. Being at the top of the food chain did them little good once the chain itself was demolished.”

Another interesting bit of speculation is Walter's speculation that human self-identity emerged only within the last 50,000 years:

“To understand why we have come to operate this way, think of social interaction as a kind of rapidly changing ecosystem made up of a mix of personalities that requires constant adaptation to the shifting agendas, relationships, alliances, and power struggles within the group. In the highly social and very bright species that preceded us, part of the battle for individuals would have been to keep motives and relationships straight in their own minds. Those among our ancestors who could successfully track and recall the behaviors of their friends and enemies would have excelled, survived, and passed their genes along.

To manage this, they must have learned to symbolize different personalities. Maybe Goog tended to be aggressive; Targ, helpful and friendly; Moop, well organized and smart. This would have helped them “slot” others into organizational categories so they could deal with them in ways they saw fit, depending on their own personalities. Since these relationships only matter in so far as they are connected to you, along the way it would have been impossible not to eventually apply the same index to you. We became to ourselves another person in our social ecology.

As evolution continually favored smarter and increasingly self–aware creatures from Homo erectus to ergaster to heidelbergensis, Neanderthals, Denisovans, and Homo sapiens eventually emerged. Both we and Neanderthals developed large brains and complex prefrontal cortices, but we developed in different parts of the world, under entirely different circumstances, split from a common ancestor.g We both may have developed spoken language, but very different kinds. We were both self–aware and capable of symbolizing, but to what extent remains unclear. Neanderthals may never have developed a highly complex and fully symbolic inner world, and Homo sapiens may not have pulled off this level of cerebral legerdemain themselves until fifty thousand years ago, maybe later.”

Walter offers some speculation as to what the world might have looked to these individuals:

“Mithen imagines Neanderthals took a different path and evolved a complex combination of iconic gestures (think of the “crazy” gesture we use, an index finger twirling beside our head), songlike sounds to express emotions (more complex versions of the cooing and keening sounds we make), outright song and highly expressive dance movements (à la ballet and Broadway), all in concert to communicate on levels so intricate that they are beyond what we can even imagine.

These weren't muddled, caveman efforts to ape our Homo sapiens language, according to Mithen. He believes and makes a compelling argument that Neanderthals were musical and gestural virtuosos compared with us and the other human species that came before them. While we specialized in using our brains and vocal gifts as ways to deliver packets of symbols made of sound, Neanderthals evolved hyperrefined senses of sound, movement, and emotion.”

Walter ends with some speculation about future human evolution. He speculates that such evolution might involve further augmentation of intelligence and memory via cybernetics. At this point, the book becomes a useful guideline for science fiction writers.

Walter is an excellent writer. He makes his arguments in a lucid and coherent fashion.