Sunday 23 September 2018

Butchery marks on the bones of Elephant Birds suggest Humans reached Madagascar thousands of years earlier than previously supposed.

Madagascar previously had a diverse Vertebrate Megafuana, that included Giant Lemurs, Hippopotamus, Giant Tortoises, and Elephant Birds (Aepyornithidae), an extinct group of Palaeognath Birds that included some of the largest Birds ever to have lived. Most of this fauna disappeared between about 2400 and 500 years ago, which has widely been taken as indicative of the arrival of Humans on the island. This ties in well with the archaeological record, with evidence of Human settlement appearing in rock shelters on the west coast of Madagascar about 3000 years ago, butchery marks on Lemur bones in the southwest of the island known from 2400 years ago, the first villages appearing about 1500 years ago, and extensive coastal settlements by 900 years ago. Some recent evidence has suggested that Humans may have occupied Madagascar much earlier, including Hippopotamus bones with butchery marks dating between 4288 and 4035 years ago and tool stone assemblages from the north of the island that may be over 4000 years old, but these pieces of evidence are not universally accepted, with the dates of the stone tools manufacture being disputed and the diagnosis of the marks on the Hippo bones as being of Human origin both being questioned.

In a paper published in the journal Science Advances on 12 September 2018, James Hansford of the Institute of Zoology at the Zoological Society of London, and the National Oceanography Centre at the University of Southampton, Patricia Wright of the Department of Anthropology and the Centre ValBio at Stony Brook University, Armand Rasoamiaramanana of Mention Bassins Sédimentaires Evolution Conservation at the University of Antananarivo, Ventura Pérez and Laurie Godfrey of the Department of Anthropology at the University of Massachusetts, David Errickson and Tim Thompson of the School of Science, Engineering and Design at Teesside University, and Samuel Turvey, also of the Institute of Zoology at the Zoological Society of London, describe the results of a review of cut marks on the bones of Elephant Birds held in museum collections in Europe, United States, and Madagascar, which suggests that Humans may have arrived on the island several thousand years earlier than previously thought.

The earliest Elephant Bird bones showing signs of butchering came from the Christmas River Site near a tributary of the Ihazofotsy River and Ilakabe village in southern Madagascar. This site preserves a bone bed with numerous Vertebrate species, including Crocodiles; Tortoises; Carnivorans, Giant Lemurs, Dwarf Hippopotamus, and the Elephant Bird Aepyornis. The bones were deposited in a wetland between about 9000 and 11 000 years ago, and no previous evidence of Human activity has been found there. Hansford et al. found evidence of butchery in the form of linear grooves on the distal aspect of the lateral condyle and medial condyle of the of the central trochlea of a a single Aepyornis maximus specimen dated to between 10 721 and 10 511 years ago. The penetrating marks are intact and well defined, consistent with kerfs made by single-bladed, sharp lithic tools and multiple cutting actions intended to disarticulate the central phalanges.

Aepyornis maximus tarsometatarsus. (A) Distal aspect of Aepyornis maximus tarsometatarsus from Christmas River, showing five cut marks: three (TM-1 to TM-3) on the central trochlea (digit III), one (TM-4) on the medial trochlea (digit II), and one (TM-5) on the lateral trochlea (digit IV). (B) Cross section of TM-1 at ×30 magnification, illustrating depth using a topographic height colour scale. Ventura Pérez in Hansford et al. (2018).

These findings suggest that Humans may have reached Madagascar 6000 years earlier than even the most generous previous estimate, which provides a puzzle for palaeontologists and archaeologists studying the island, as it suggests that (assuming that the Humans who made the marks did not themselves become extinct shortly after) Humans coexisted with the Vertebrate Megafuana of Madagascar for most of the Holocene, before switching to a lifestyle that rapidly wiped out all of the islands large animals, either through overhunting or habitat destruction.

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