Homo naledi is a recently discovered species of fossil hominin from South Africa.
A considerable amount is already known aboutÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â but some important questions remain unanswered. Here a team of scientists report a study that addressed two of them: "Where doesÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â fit in the hominin evolutionary tree?" and "How old is it?" They used a large supermatrix of craniodental characters for both early and late hominin species and Bayesian phylogenetic techniques to carry out three analyses. First, they performed a dated Bayesian analysis to generate estimates of the evolutionary relationships of fossil hominins includingÂ
±á.Ìý²Ô²¹±ô±ð»å¾±. Then they employed Bayes factor tests to compare the strength of support for hypotheses about the relationships ofÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â suggested by the best-estimate trees. Lastly, they carried out a resampling analysis to assess the accuracy of the age estimate forÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â yielded by the dated Bayesian analysis. The analyses strongly supported the hypothesis thatÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â forms a clade with the otherÂ
±á´Ç³¾´ÇÌýspecies andÂ
Australopithecus sediba. The analyses were more ambiguous regarding the position ofÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â within the (
Homo,Ìý
Au. sediba) clade. A number of hypotheses were rejected, but several others were not. Based on the available craniodental data,Ìý
Homo antecessor, AsianÂ
Homo erectus,Ìý
Homo habilis,Ìý
Homo floresiensis,Ìý
Homo sapiens, and
Au. sediba could all be the sister taxon ofÂ
±á.Ìý²Ô²¹±ô±ð»å¾±. According to the dated Bayesian analysis, the most likely age forÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â is 912 ka. This age estimate was supported by the resampling analysis. The team's findings have a number of implications. Most notably, they support the assignment of the new specimens toÂ
Homo, cast doubt on the claim thatÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â is simply a variant ofÂ
±á.Ìý±ð°ù±ð³¦³Ù³Ü²õ, and suggestÂ
±á.Ìý²Ô²¹±ô±ð»å¾±Â is younger than has been previously proposed.
The evolutionary relationships and age of Homo naledi: An
assessment using dated Bayesian phylogenetic methods
Mana Dembo, Davorka Radovcic, Heather M. Garvin, Myra F.
Laird, Lauren Schroeder, Jill E. Scott, Juliet Brophy, Rebecca R. Ackermann,
Chares M. Musiba, Darryl J. de Ruiter, Arne Mooers, Mark Collard
DOI:
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