The logic of human destiny was inevitable 1 million years ago

Robert Wright’s best book, Nonzero: The Logic of Human Destiny, was published nearly 20 years ago. At the time I was moderately skeptical of his thesis. It was too teleological for my tastes. And, it does pander to a bias in human psychology whereby we look to find meaning in the universe.

But this is 2017, and I have somewhat different views.

In the year 2000 I broadly accepted the thesis outlined a few years later in The Dawn of Human Culture. That our species, our humanity, evolved and emerged in rapid sequence, likely due to biological changes of a radical kind, ~50,000 years ago. This is the thesis of the “great leap forward” of behavioral modernity.

Today I have come closer to models proposed by Michael Tomasello in The Cultural Origins of Human Cognition and Terrence Deacon in The Symbolic Species: The Co-evolution of Language and the Brain. Rather than a punctuated event, an instance in geological time, humanity as we understand it was a gradual process, driven by general dynamics and evolutionary feedback loops.

The conceit at the heart of Robert J. Sawyer’s often overly preachy Neanderthal Parallax series, that if our own lineage went extinct but theirs did not they would have created a technological civilization, is I think in the main correct. It may not be entirely coincidental that the hyper-drive cultural flexibility of African modern humans evolved in African modern humans first. There may have been sufficient biological differences to enable this to be likely. But I believe that if African modern humans were removed from the picture Neanderthals would have “caught up” and been positioned to begin the trajectory we find ourselves in during the current Holocene inter-glacial.

Luke Jostins’ figure showing across board encephalization

The data indicate that all human lineages were subject to increased encephalization. That process trailed off ~200,000 years ago, but it illustrates the general evolutionary pressures, ratchets, or evolutionary “logic”, that applied to all of them. Overall there were some general trends in the hominin lineage that began to characterized us about a million years ago. We pushed into new territory. Our rate of cultural change seems to gradually increased across our whole range.

One of the major holy grails I see now and then in human evolutionary genetics is to find “the gene that made us human.” The scramble is definitely on now that more and more whole genome sequences from ancient hominins are coming online. But I don’t think there will be such gene ever found. There isn’t “a gene,” but a broad set of genes which were gradually selected upon in the process of making us human.

In the lingo, it wasn’t just a hard sweep from a de novo mutation. It was as much, or even more, soft sweeps from standing variation.

4 thoughts on “The logic of human destiny was inevitable 1 million years ago

  1. Not precisely on point, but a new paper on hobbits really transforms the understanding of their evolutionary place that was not previously at the top of anyone’s list.

    Debbie Argue, Colin P. Groves, Michael S.Y. Lee, William L. Jungers. “The affinities of Homo floresiensis based on phylogenetic analyses of cranial, dental, and postcranial characters.” Journal of Human Evolution (April 2017). http://www.sciencedirect.com/science/article/pii/S0047248417300866

    It says that H. floresiensis is more basal than H. erectus, let alone H. sapiens sapiens, Neanderthals or Denisovans, or H. heidelbergensis and are closer to H. habilis. It isn’t clear is this would be from an out of Africa wave preceding H. erectus that was wiped out when H. Erectus came along everywhere else, or if they were fellow travelers with H. Erectus. (And yes, I’m sure I spelled something wrong in there).

  2. “It may not be entirely coincidental that the hyper-drive cultural flexibility of African modern humans evolved in African modern humans first. There may have been sufficient biological differences to enable this to be likely.”

    Wouldn’t the simplest explanation just be that African humans enjoyed a higher population density, which allowed their culture to advance more quickly? The denser your population, the better able you are to transmit and receive new ideas from neighbouring groups. The extant Neanderthal and Denisovan samples show very, very low effective population sizes too, and Neanderthals had only 2/3 the life expectancy of their AMH peers, did they not? Pretty hard to build up a tool set when you have 10 fewer years to teach the next generation and rarely see anyone from outside your own group.

    On H. floresiensis, I’d just highlight this paper and ask if anyone can comment on it. I find the suggestion of a “Hominin-E” that split from us 3.5 million years ago that interbred with both our ancestors and the ancestors of Neanderthals and Denisovans complements the paper on H. floresiensis well, no?

    A bit hard to read due to the language barrier though. The “Class3” segments are what I’m referring to.

    https://arxiv.org/ftp/arxiv/papers/1404/1404.7766.pdf

    1. Wouldn’t the simplest explanation just be that African humans enjoyed a higher population density, which allowed their culture to advance more quickly? The denser your population, the better able you are to transmit and receive new ideas from neighbouring groups. The extant Neanderthal and Denisovan samples show very, very low effective population sizes too, and Neanderthals had only 2/3 the life expectancy of their AMH peers, did they not? Pretty hard to build up a tool set when you have 10 fewer years to teach the next generation and rarely see anyone from outside your own group.

      john hawks said something similar 15 years ago.

      1. That’s probably where I’m regurgitating this from. I couldn’t remember where I’d seen that argument made – probably here.

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