We would like to thank Prof. Sarmiento for his comments [1] on our paper [2]. We appreciate his support for our basic premise that (some) australopithecines may have been ancestral or more closely related to the Gorilla and Pan lineages and that possibly none were human ancestors. We agree with his view that "the need to find human ancestors has led paleoanthropologists to make baseless claims of human bipedality in australopithecines in order to justify inclusion of their finds into an exclusive human lineage", and sincerely hope that our paper will encourage others to reconsider the rarely questioned hominin status of Australopithecus and associated genera from East and South Africa.We largely agree with Sarmiento [1] when he writes: "Because it has never been shown that australopithecines are exclusive members of the human lineage or even habitual/obligate or striding bipeds they are not relevant for refuting the savanna hypothesis for human bipedal origins."We paid attention to the savanna, however, precisely because australopithecine bipedalism is generally held up as a precursor to human striding bipedalism, and the adaptation to living in open areas is often put forward as the incentive to evolve from quadrupedal locomotion or arboreal/facultative bipedalism to habitual/obligate bipedalism in our putative australopithecine ancestors.While Sarmiento [1] agrees that it is possible that none of the australopithecines are hominins, he disapproves our dismissal of the savanna hypothesis as the explanation for human striding bipedalism. We first want to point out that dismissal of the savanna hypothesis was not the primary objective of our paper. Our reason for mentioning the savanna hypothesis was to emphasize that it was never a solid hypothesis on which to base the origin of hominid bipedalism, whether it be in the form of australopithecine or human bipedalism. We offered several arguments to indicate that bipedalism or at least orthogrady is probably a primitive characteristic of all hominoids (apes), including the hylobatids.The statement by Sarmiento [1] that "Grassland savannas need not be expanding in Africa to explain the presumed australopithecine adaptations to savannas. There only needs to be the existence of savanna habitats for such adaptations to appear", denies the fact that it was forced adaptation to increasing savanna (and dwindling forest) that was the main argument of the savanna hypothesis from the beginning as an attempt to explain the odd obligate bipedalism of our genus.We fail, moreover, to understand how bipedalism can be proposed as an adaptation to open country, especially since the several primate species (such as baboons and patas monkeys) that do live in open country are among the most quadrupedal. We further find a comparison with the evolution of horses as a robust indication of an open country origin of human bipedalism, as put forward by De Vos et al. [3], not really applicable or convincing. (We were unable to check the arguments made by Osborn [4].) Our point of view was rec...
