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Study: Tooth size not linked to brain size in early humans

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modern human cranium showing teeth/George Washington U

From ScienceDaily:

This research challenges the classically accepted view that reduction of tooth size in hominins is linked with having a larger brain. The reasoning is that larger brains allowed hominins to start making stone tools and that the use of these tools reduced the need to have such large chewing teeth. But recent studies by other authors found that hominins had larger brains before chewing teeth became smaller, and they made and used stone tools when brains were still quite small, which challenges this relationship.

The new study evaluates this issue by measuring and comparing the rates at which teeth and brains have evolved along the different branches of the human evolutionary tree.

“The findings of the study indicate that simple causal relationships between the evolution of brain size, tool use and tooth size are unlikely to hold true when considering the complex scenarios of hominin evolution and the extended time periods during which evolutionary change has occurred,” said Aida Gómez-Robles, lead author of the paper and a postdoctoral scientist at GW’s CASHP. Paper. (paywall) – Aida Gómez-Robles, Jeroen B. Smaers, Ralph L. Holloway, P. David Polly, and Bernard A. Wood. Brain enlargement and dental reduction were not linked in hominin evolution. PNAS, 2017 DOI: 10.1073/pnas.1608798114More.

<em>Teapot</em> Cobalt Blue Another simple explanation shot to Hull.

<em>Christmas</em> <em>Cracker</em> cookie cutter by Lindy Smith Part of the problem, as noted earlier, is that once we have a lot of information, the story begins to read like a history, not a theory. Doubtless, some big-brained people realized that they could spare their teeth by using stone tools. But that wouldn’t make their teeth smaller. Some small-toothed people might likewise survive if they realized that they could use stone tools. But the relationship between size and survival is complex…

If I were writing a Clan of the Cave Bear potboiler, I would have the question turn on whether big teeth were considered attractive or even safe… remember, we are probably already at the point where such considerations would hlp determine parenthood … 😉

See also: Study: Human brain not exceptional? Every so often something exquisitely stupid turns up, something worth celebrating…

Large human brain size easily explained? Sometimes, we devote space to a really dumb idea about how human beings came to be the way we are.

The search for our earliest ancestors: signals in the noise


Human origins: The war of trivial explanations

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One Reply to “Study: Tooth size not linked to brain size in early humans

  1. 1
    bornagain77 says:

    Fossil teeth are far more problematic for evolutionists than this study indicated:

    Human/Ape Common Ancestry: Following the Evidence – Casey Luskin – June 2011
    Excerpt: So the researchers constructed an evolutionary tree based on 129 skull and tooth measurements for living hominoids, including gorillas, chimpanzees, orangutans and humans, and did the same with 62 measurements recorded on Old World monkeys, including baboons, mangabeys and macaques. They also drew upon published molecular phylogenies. At the outset, Wood and Collard assumed the molecular evidence was correct. “There were so many different lines of genetic evidence pointing in one direction,” Collard explains. But no matter how the computer analysis was run, the molecular and morphological trees could not be made to match15 (see figure, below). Collard says this casts grave doubt on the reliability of using morphological evidence to determine the fine details of evolutionary trees for higher primates. “It is saying it is positively misleading,” he says. The abstract of the pair’s paper stated provocatively that “existing phylogenetic hypotheses about human evolution are unlikely to be reliable”.[10]

    Human Origins, and the Real Reasons for Evolutionary Skepticism – Jonathan M. – December 9, 2012
    Excerpt: “Cladistic analysis of cranial and dental evidence has been widely used to generate phylogenetic hypotheses about humans and their fossil relatives. However, the reliability of these hypotheses has never been subjected to external validation. To rectify this, we applied internal methods to equivalent evidence from two groups of extant higher primates for whom reliable molecular phylogenies are available, the hominoids and paionins. We found that the phylogenetic hypotheses based on the craniodental data were incompatible with the molecular phylogenies for the groups. Given the robustness of the molecular phylogenies, these results indicate that little confidence can be placed in phylogenies generated solely from higher primate craniodental evidence. The corollary of this is that existing phylogenetic hypotheses about human evolution are unlikely to be reliable.”

    No Known Hominin Is Common Ancestor of Neanderthals and Modern Humans, Study Suggests – Oct. 21, 2013
    Excerpt: The article, “No known hominin species matches the expected dental morphology of the last common ancestor of Neanderthals and modern humans,” relies on fossils of approximately 1,200 molars and premolars from 13 species or types of hominins — humans and human relatives and ancestors. Fossils from the well-known Atapuerca sites have a crucial role in this research, accounting for more than 15 percent of the complete studied fossil collection.,,,
    They conclude with high statistical confidence that none of the hominins usually proposed as a common ancestor, such as Homo heidelbergensis, H. erectus and H. antecessor, is a satisfactory match.
    “None of the species that have been previously suggested as the last common ancestor of Neanderthals and modern humans has a dental morphology that is fully compatible with the expected morphology of this ancestor,” Gómez-Robles said.

    supplemental notes:

    Skull “Rewrites” Story of Human Evolution — Again – Casey Luskin – October 22, 2013
    Excerpt: “There is a big gap in the fossil record,” Zollikofer told NBC News. “I would put a question mark there. Of course it would be nice to say this was the last common ancestor of Neanderthals and us, but we simply don’t know.” –

    “A number of hominid crania are known from sites in eastern and southern Africa in the 400- to 200-thousand-year range, but none of them looks like a close antecedent of the anatomically distinctive Homo sapiens…Even allowing for the poor record we have of our close extinct kin, Homo sapiens appears as distinctive and unprecedented…there is certainly no evidence to support the notion that we gradually became who we inherently are over an extended period, in either the physical or the intellectual sense.”
    Dr. Ian Tattersall: – paleoanthropologist – emeritus curator of the American Museum of Natural History – (Masters of the Planet, 2012)

    Evolution of the Genus Homo – Annual Review of Earth and Planetary Sciences – Ian Tattersall, Jeffery H. Schwartz, May 2009
    Excerpt: “Definition of the genus Homo is almost as fraught as the definition of Homo sapiens. We look at the evidence for “early Homo,” finding little morphological basis for extending our genus to any of the 2.5–1.6-myr-old fossil forms assigned to “early Homo” or Homo habilis/rudolfensis.”,,,,
    “Unusual though Homo sapiens may be morphologically, it is undoubtedly our remarkable cognitive qualities that most strikingly demarcate us from all other extant species. They are certainly what give us our strong subjective sense of being qualitatively different. And they are all ultimately traceable to our symbolic capacity. Human beings alone, it seems, mentally dissect the world into a multitude of discrete symbols, and combine and recombine those symbols in their minds to produce hypotheses of alternative possibilities. When exactly Homo sapiens acquired this unusual ability is the subject of debate.”

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