Evolution Quote

Comments (11)

1. “But evolution doesn’t really care.”

   Or perhaps “But evolution really doesn’t care.”

2. I think “evolution as progress” is the much bigger obstacle to proper understanding of biology than “Vishnu/Thor/Yaweh/Buddha did it”.

3. Niven has put up a strawman here. I don’t think many of the anti-floresiensis people would disagree that brains could have evolved to be smaller in a hominid. After all, our brains really have evolved to be smaller in the last 10,000 years.

   Some of them have argued that a brain a third the size of ours must have come with trade-offs, so that we can’t attribute “advanced” archaeological artifacts with such hominids.

   But most of the resistance to H. floresiensis is framed in terms of the specimen actually looking abnormal in ways additional to its small brain. That is disputed by H. floresiensis supporters, of course. The debate continues because of disagreements about how to diagnose pathology, not because of misconceptions about orthogenesis.

   1. I think Henneberg’s argument, not to say Teuku Jacob’s, was based exactly on orthogenetic assumptions, and I think Niven is quite right here. As to the brain size being incompatible with technology, again I think this relies on some unstated assumptions about evolution. It’s one of the few things you say that I disagree with. [However, this is not my speciality, so I stay shtum, some of the time.]

      Brain size does not correlate directly with ability to manipulate or learn (as chimps and other primates show us). The issue is, I think, a matter of innovation, and if the technology either predated the dwarfism but was passed on (with environmental feedback) or was taken over from other hominids, then I see no deep problem (although the details are highly contentious, I admit).

4. Thanks, John!

   I think Henneberg’s argument, not to say Teuku Jacob’s, was based exactly on orthogenetic assumptions, and I think Niven is quite right here.

   But Maciej has published extensively on the reduction of brain size in the last 10,000 years. He has also written much about the global increase in brain size across the Pleistocene, his view being that it was mostly less important than we think. If you ask him, his argument is all about pathology and standards of evidence. Bob Eckhardt certainly doesn’t think a shrinking brain is impossible.

   I think most of the anti-floresiensis group is united by the standards of evidence issue, and irritated that many in the pro-floresiensis group seem *want* the brain to have shrunk, in order to *prove* something about evolution.

   Now, to me the thing that sounds like orthogenesis is the idea that *technology* can’t be lost, no matter what happens to the brain.

   1. Did I say “can’t be lost”? I merely said that it can be retained. There’s a difference. Since I think one of the things big brains do is increase the rates of novelty in cultural evolution, if hobbitdom showed evidence of rapidly evolving technology (more Acheulean than Oldowan) then I’d say that they were unlikely to have had that technology themselves. However, that still leaves diffusion across species boundaries (just as chimps, with similar sized brains, can learn some tools from humans).

      Anyway, I suspect the main driver of cultural novelty is population size, not brain size, although clearly the cognitive resources available have to be a variable. Hobbits may have had less novel ideas or learned fewer techniques than other hominids, but that doesn’t mean they couldn’t transmit them when they had them.

      And I do not think that orthogenetic ideas have anything to do with directions of trends, but instead to do with the necessity of trends one way or the other. [Unless you meant that Henneberg has been publishing for 10,000 years, in which case I am impressed.] Why can’t reduction of brain size coexist with a steady state technology? The presumption to the contrary seems odd to me. At least it is question begging.

      I am not expert in any of these fields, so you are getting the views of an innocent bystander, but I am influenced a lot by Colin Groves, who is my goto guy for this stuff. Even if he does have a false species concept…

5. No worries, I appreciate your thinking. I’ll try to explain in brief but I don’t want to turn a comment into a dissertation!

   Why can’t reduction of brain size coexist with a steady state technology? The presumption to the contrary seems odd to me. At least it is question begging.

   For the last 10,000 years, rapid reduction of brain size has been accompanied by a rapid increase in technological complexity. So empirically we know that this is possible.

   I would hypothesize that it has happened because of larger population sizes, enabling rare changes to optimize the tradeoff of size versus function. But there’s an obvious alternative hypothesis: Our new environment removed some selection for the functional properties of large brains. Two stories, both suppose strong selection for smaller brains, but they differ as to the strength of countervailing selection for functional properties.

   The first hypothesis would be surprising if the population had never grown, if were always very small. Those are the demographic conditions on Flores — a population that must have been much smaller than the continental human populations, that must have been limited in variation. If that population could reduce its brains by half or more, and yet keep the same functional abilities, that seems very surprising.

6. Speaking of straw men, someone hasn’t read the more detailed archeological papers published on the stone tools of Homo floresiensis. The core-and-flake artifacts are not technologically “advanced” by any standard.

   And depending on who their ancestors were, relatively little brain size reduction may have occurred. “Island dwarfing” is not the only idea out there…

   Virtually everything that Eckhardt and Henneberg have written on the subject of “pathology” in H. floresisneis (which is precious little), has been thoroughly debunked in peer-reviewed journals. Eckhardt’s presentations at professional meetings are loony tunes fits of arm-waving. How anyone can take him seriously is beyond me.

   1. Groves thinks, I recall, that its ancestral species was habilis based on certain synapomorphies. Moreover, it doesn’t follow that the only island dwarf population was on Flores, so there may have been a lot of trade in tools across the archipelago. See here.

7. The core-and-flake artifacts are not technologically “advanced” by any standard.

   Hence the quotation marks. The “advanced” tools were completely a fairy tale, and yet one that remains widely believed.

   There is the question of reduction sequence, which Moore and Brumm say is basically the same before and after the putative disappearance of H. floresiensis (and others argue goes back to the Mata Menge assemblages).

   How anyone can take him seriously is beyond me.

   I wouldn’t think that very many of these things should be taken seriously.

8. “widely believed” by whom?

   Yes, the first Nature report was misleading in this respect, no argument there, but that “fairy tale” has been duly corrected by follow-up analyses of the lithics.

   The first (2004) Nature paper of H. floresiensis also argued for the island dwarfing scenario based on the fossils and info in hand at that time. However, the followup Nature paper in 2005 backed way off this theory and suggested the possibility of an ancestor more primitive than Homo erectus. These 2 competing explanations continue to be debated and explored in peer-reviewed journals.

   New data and new analyses change things. Normal science.

   Scientific reporting, however, is a very preculiar and all too often asymmetrical enterprise. The latest pathology du jour gets hyped in the press (ooooh, more controversy), but when it’s thoroughly debunked, nary a word by the same journalists. The rebuttal of the Laron Syndrome hypothesis is a good example of this. Journalists seem to have a very short attention span…

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