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Tooth wear patterns suggest Paranthropus early hominins had softer diets than expected


Analysis of wear patterns on fossil teeth from East African hominins suggests the diets of Paranthropus aethiopicus and Paranthropus boisei were softer than had been thought, according to a study published in the open-access journal PLOS ONE by Laura Monica Martinez from Universitat de Barcelona, Spain, and colleagues.

Tooth wear patterns suggest Paranthropus early hominins had softer diets than expected
Wear patterns on the fossil teeth from East African hominims, including the Paranthropus boisei (pictured), 
suggest that they may have eaten softer food than previously thought [Credit: WikiCommons]
Two species in the Paranthropus genus of early hominins, P. aethiopicus and P. boisei, co-existed for some time with early Homo species including H. ergaster, but seem to have had different diets.

Previous isotopic analysis has supported the theory that while H. ergaster, which had relatively small jaws and teeth, consumed a lot of meat, Paranthropus species, which had massive lower jaws and molars with large chewing surfaces, may have specialized to eat a high proportion of fibrous, abrasive C4 plants.

Tooth wear patterns suggest Paranthropus early hominins had softer diets than expected
Paranthropus boisei was a long-lived species of archaic hominin that first evolved in East Africa 
about 2.3 million years ago [Credit: Reuters]
However, examination of wear patterns on the grinding surfaces of hominin teeth has not supported this theory. The authors of the present study aimed to resolve this discrepancy by gathering additional tooth wear data. They examined microscopic scratches on the cheek surfaces of teeth from 167 fossil specimens of Paranthropus and early Homo species from sites in Ethiopia, Kenya and Tanzania.

The researchers found that, contrary to the previous isotopic evidence, the scratch patterns on cheek surfaces of P. aethiopicus and P. boisei teeth suggested that their dietary habits 'did not involve chewing significant amounts of abrasive foods'.

Tooth wear patterns suggest Paranthropus early hominins had softer diets than expected
Well-preserved buccal microwear surfaces in which buccal striations could be measured: (a) LP4 OH-69 Homo habilis. 
(b) RM1 KNM-WT-15000 Homo ergaster. (c) LM1 Peninj Paranthropus boisei. Scale line is 200 μm 
[Credit: Laura Mónica Martínez et al, PLOS]
However, they note that these species might have eaten less abrasive, brittle C4 plants; which would be consistent with both the isotopic and the dental evidence. Meanwhile, the scratch patterns found on H. ergaster teeth suggest that they ate more abrasive foods that had been expected, which could indicate that early Homo species also underwent a dietary shift to C4 plants as they evolved.

This study provides valuable additional evidence concerning the evolution and composition of the diets of Paranthropus and Homo species over time.

Source: PLOS [November 16, 2016]
TANN

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2 comments :

  1. Good thing the P. boisei pictured was vegan. A mug like his ruled out any possibility of inter-genus dating because no self-respecting H. ergaster female would have gone out with him for a steak dinner anyway.

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  2. Very interesting article, but it requires a few comments.
    - Paranthropus is no valid taxon, but is paraphyletic: different studies (e.g. Verhaegen 1994 Hum.Evol.9:121-139) suggest that gracile Pliocene East-African australopiths (afarensis) evolved into robust Pleistocene East-African australopiths (boisei) in parallel & at about the same time as gracile South-African australopiths (africanus) evolved into robust South-African australopiths (robustus). This is a typical example of synchronous allopatric parallel evolution.
    - Microwear studies suggest that generally East-African australopiths probably had softer foods in their diet than the South-African australopiths (e.g. Verhaegen & Puech 2000 Hum.Evol.15:175-186), but Martìnez cs only studied the East-African data, which explains the softer diet in "Paranthropus".
    - Comparative, morphological & paleo-environmental data show that australopiths dwelt in swamp forests & wetlands, wading bipedally & climbing vertically, more frequently than extant bonobos & lowland gorillas who often feed on shallow aquatic plants (aquatic herbaceous vegetation AHV), e.g. papyrus, sedges, frogbit, waterlilies etc. (google e.g. bonobo wading). Prof.Puech suggested that some of the microwear in australopithecines might be due to hard-shelled invertebrates (e.g. small snails) living on AHV (cf. refs of A.Shabel in the paper of Martìnez cs).
    - Turkana Boy (ergaster) is not found in dry savanna, but amid catfish, turtles, hippo footprints & reeds. H.erectus-ergaster did not live in arid savanna: this is physiologically & otherwise impossible, e.g. water & salt (= sweat) is scarce in savannas. Pleistocene Homo dispersed intercontinentally (+ islands) along African & Eurasian coasts & rivers, where they collected littoral, shallow-aquatic & waterside foods, which are extremely rich in brain-specific nutrients: DHA, iodine, taurine etc. They were no hunters, although they of course butchered waterside carcasses of ungulates & stranded whales (Dungo V): frequent shellfish consumption best explains their brain enalrgement & stone tool use (google e.g. econiche Homo).

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