[Paper] The affinities of Homo floresiensis based on phylogenetic analyses of cranial, dental, and postcranial characters

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This newly published paper by ANUs Debbie Argue has been making the news recently. A new analysis of the bones puts Homo floresiensis closer in time to Homo habilis than it does Homo erectus or Homo Sapiens, which suggests the the Hobbit’s lineage was more ancient than recent.

Although the diminutive Homo floresiensis has been known for a decade, its phylogenetic status remains highly contentious. A broad range of potential explanations for the evolution of this species has been explored. One view is that H. floresiensis is derived from Asian Homo erectus that arrived on Flores and subsequently evolved a smaller body size, perhaps to survive the constrained resources they faced in a new island environment. Fossil remains of H. erectus, well known from Java, have not yet been discovered on Flores. The second hypothesis is that H. floresiensis is directly descended from an early Homo lineage with roots in Africa, such as Homo habilis; the third is that it is Homo sapiens with pathology. We use parsimony and Bayesian phylogenetic methods to test these hypotheses. Our phylogenetic data build upon those characters previously presented in support of these hypotheses by broadening the range of traits to include the crania, mandibles, dentition, and postcrania of Homo and Australopithecus. The new data and analyses support the hypothesis that H. floresiensis is an early Homo lineage: H. floresiensis is sister either to H. habilis alone or to a clade consisting of at least H. habilis, H. erectus, Homo ergaster, and H. sapiens. A close phylogenetic relationship between H. floresiensis and H. erectus or H. sapiens can be rejected; furthermore, most of the traits separating H. floresiensis from H. sapiens are not readily attributable to pathology (e.g., Down syndrome). The results suggest H. floresiensis is a long-surviving relict of an early (>1.75 Ma) hominin lineage and a hitherto unknown migration out of Africa, and not a recent derivative of either H. erectus or H. sapiens.

Source: The affinities of Homo floresiensis based on phylogenetic analyses of cranial, dental, and postcranial characters

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Hobbits from a seperate branch?

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Yet another paper lends support to the idea that the Flores Hobbit is a seperate species and not a deformed human. This time, a study uses cladistics, or the comparison of physical characteristics to determine ancestry, and determined through computer modelling that homo floresiensis split off from homo sapiens nearly two million years ago. Pretty exciting stuff because of the unexpectedly early date, which, if proven true from later finds, will force a rewrite of how we understand how early man came about and populated the earth. However, as with all the hobbit studies previously published, we’ve still been looking at only one set of bones. I think what we really need now is some independent confirmation in the form of another hobbit find.

Flores
photo credit: Ryan Somma

Hobbit early off the family tree: New research
ANU Media Release, 31 July 2009

Humans, Flores ‘hobbits’ existed together: study
ABC News, 2 August 2009
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