Among living primates, only humans are bipedal. It is not certain when this unique feature emerge... more Among living primates, only humans are bipedal. It is not certain when this unique feature emerged, but it must have been before the 3.6 million-year-old Laetoli footprints were made. Although the prints were not made by completely modern feet, they are unequivocally the prints of bipeds. They are the impressions of feet that lacked a distinctive human rounded ball, or swelling, at the base of the great toe, that had no well-defined arch, and that retained ever so slightly divergent great toes. Somewhat later in time, the well-known 2.9 million year old Australopithecus afarensis Lucy fossil is the earliest human ancestor to display the clear skeletal hallmarks of bipedalism. Earlier fossils are either not yet described, or lack the two most diagnostic parts, the pelvis and the distal (i.e. lower) femur. Despite the paucity of fossils near the beginning of the human lineage, most paleontologists regard bipedalism as the earliest distinctively human feature to have evolved in hominin...
We used image analysis software (ImageJ) to measure femoral shaft obliquity in 76 humans, 57 fore... more We used image analysis software (ImageJ) to measure femoral shaft obliquity in 76 humans, 57 forest chimpanzees, and four dry-habitat (Semliki) chimpanzees. We found that dry-habitat chimpanzee femora were intermediate between forest chimpanzees and humans and significantly different from each (χ2 = 6.21, p = 0.013; χ2 = 11.11, p = 0.001). We further compared human femoral obliquity with the published values of six australopiths. Mean bicondylar angles were found to be 10.9° for humans, −0.3° for forest chimpanzees, 4.2° for Semliki chimpanzees, and 12.0° for australopiths (midsex average = 11.4°). Contrary to expectation, australopith bicondylar angles were not significantly greater than those of humans (χ2 = 0.67, p = 0.41). Human females had significantly greater angles than males (Kruskal-Wallis analysis, p = 0.002). Femoral obliquity among dry-habitat chimpanzees is consistent with the hypothesis that bipedalism evolved as a dry-habitat foraging strategy.
We present 3 likely cases of testicular dysgenesis syndrome (TDS) within a community of chimpanze... more We present 3 likely cases of testicular dysgenesis syndrome (TDS) within a community of chimpanzees (Pan troglodytes schweinfurthii). We tested whether genetic drift may be the culprit, as a genetic cause has been suspected to account for TDS among other wildlife. We successfully sequenced a 367-bp segment spanning the first hypervariable region within the D-loop of the mitochondrial genome for 78 DNA samples. We found 24 polymorphic sequence sites consisting of 7 singletons and 17 parsimony informative sites. This sample contained 9 haplotypes with a diversity index of 0.78 (SD = 0.03). All tests against the null hypothesis of neutral polymorphisms were non-significant (P > .10). The mismatch distribution of pairwise differences does not fit a Poisson's curve (raggedness index = 0.166; SSD = 0.12; P = 1). Thus, we found no significant signs of genetic isolation, population expansion, or genetic bottleneck. Alternative causes of TDS and how they might pertain to this populati...
Three genera of possible human ancestors (Sahelanthropus, Orrorin, and Ardipithecus) have been da... more Three genera of possible human ancestors (Sahelanthropus, Orrorin, and Ardipithecus) have been dated to 7–4.4 mya. Where the same skeletal elements have been recovered the morphology of the three genera is similar. When compared to chimpanzees and bonobos all the three exhibit reduced incisors, smaller canines, and less sectorial lower first premolars. A single fragmentary pelvis displays a mixture of chimpanzee- and hominin-like features. Interpretation of these fossils is confounded by the many australopith-like features in Ouranopithecus, the purported common ancestor of African apes and humans. Ouranopithecus shares with Australopiths (but not these three possible hominins) a robust, prognathic face, tall zygomatics, large incisors, large cheek teeth, and thick molar enamel. Ouranopithecus shares with australopiths and the three possible hominins small canines and a shallow supratoral sulcus. The robusticity of Ouranopithecus makes it less likely that Sahelanthropus, Orrorin, and Ardipithecus are in the hominin lineage, since such a lineage would require an evolutionary progression that starts robust, becomes nonrobust, and then reacquires robusticity. Some paleontologists, however, are skeptical of the place of Ouranopithecus in the human lineage. They find compelling indirect evidence that the common ancestor of African apes and humans was quite chimpanzee-like, which would exclude robust species such as Ouranopithecus from the human lineage. If the common ancestor was chimpanzee-like, then the argument that Sahelanthropus, Orrorin, and Ardipithecus are part of the human ancestry is stronger.
Bipedalism evolved in a stagewise fashion. There is some evidence that prehominins were more bipe... more Bipedalism evolved in a stagewise fashion. There is some evidence that prehominins were more bipedal than living African apes, perhaps similar to orangutans or gibbons. Australopiths had cone-shaped rib cages, gorilla-like scapulae, short but chimpanzee-like fingers, and long, curved toes, all consistent with adaptation to arm-hanging. Australopiths lack chimpanzee vertical-climbing adaptations such as gripping great toes and stiff backs. Chimpanzees are bipedal when feeding from the short trees that are common in dry habitats, where the feed by reaching up from the ground and with an arm-hanging, bipedal posture in the trees. The small-diameter branches in short trees discourage sitting and encourage arm-hanging; lateral toes grip the flexible branches, the body is balanced bipedally over the gripping feet, and short fingers are adequate for the small branches. Such trees can be entered without hand-over-hand climbing and opposable toes that allow it. Two million years ago hominins evolved longer legs and narrower hips that allowed a more modern human locomotion.
Chimpanzee anatomy and body proportions are unusual among the primates, but most of their unique ... more Chimpanzee anatomy and body proportions are unusual among the primates, but most of their unique anatomical traits are related to a few general features. Chimpanzees have long arms and fingers, mobile shoulders and wrists, a shallow, wide, funnel-shaped thorax and large arm-raising muscles. Keith asserted that these features were adaptations to brachiation. Others maintain that these traits are primarily adaptations for efficient climbing, and that brachiation (sensu stricto) was unimportant in the evolution of ape anatomy. This first quantitative study of chimpanzee positional behavior attempts to resolve this issue. Without a clear understanding of chimpanzee positional behavior and its relationship to morphology the reconstruction of the early hominid lifeways is impossible. Adult wild chimpanzees were studied at the Mahale Mountains and Gombe Stream National Parks in Tanzania. Over a one year period, 784 hours of observation were logged, during which data were collected on chimp...
Among living primates, only humans are bipedal. It is not certain when this unique feature emerge... more Among living primates, only humans are bipedal. It is not certain when this unique feature emerged, but it must have been before the 3.6 million-year-old Laetoli footprints were made. Although the prints were not made by completely modern feet, they are unequivocally the prints of bipeds. They are the impressions of feet that lacked a distinctive human rounded ball, or swelling, at the base of the great toe, that had no well-defined arch, and that retained ever so slightly divergent great toes. Somewhat later in time, the well-known 2.9 million year old Australopithecus afarensis Lucy fossil is the earliest human ancestor to display the clear skeletal hallmarks of bipedalism. Earlier fossils are either not yet described, or lack the two most diagnostic parts, the pelvis and the distal (i.e. lower) femur. Despite the paucity of fossils near the beginning of the human lineage, most paleontologists regard bipedalism as the earliest distinctively human feature to have evolved in hominin...
We used image analysis software (ImageJ) to measure femoral shaft obliquity in 76 humans, 57 fore... more We used image analysis software (ImageJ) to measure femoral shaft obliquity in 76 humans, 57 forest chimpanzees, and four dry-habitat (Semliki) chimpanzees. We found that dry-habitat chimpanzee femora were intermediate between forest chimpanzees and humans and significantly different from each (χ2 = 6.21, p = 0.013; χ2 = 11.11, p = 0.001). We further compared human femoral obliquity with the published values of six australopiths. Mean bicondylar angles were found to be 10.9° for humans, −0.3° for forest chimpanzees, 4.2° for Semliki chimpanzees, and 12.0° for australopiths (midsex average = 11.4°). Contrary to expectation, australopith bicondylar angles were not significantly greater than those of humans (χ2 = 0.67, p = 0.41). Human females had significantly greater angles than males (Kruskal-Wallis analysis, p = 0.002). Femoral obliquity among dry-habitat chimpanzees is consistent with the hypothesis that bipedalism evolved as a dry-habitat foraging strategy.
We present 3 likely cases of testicular dysgenesis syndrome (TDS) within a community of chimpanze... more We present 3 likely cases of testicular dysgenesis syndrome (TDS) within a community of chimpanzees (Pan troglodytes schweinfurthii). We tested whether genetic drift may be the culprit, as a genetic cause has been suspected to account for TDS among other wildlife. We successfully sequenced a 367-bp segment spanning the first hypervariable region within the D-loop of the mitochondrial genome for 78 DNA samples. We found 24 polymorphic sequence sites consisting of 7 singletons and 17 parsimony informative sites. This sample contained 9 haplotypes with a diversity index of 0.78 (SD = 0.03). All tests against the null hypothesis of neutral polymorphisms were non-significant (P > .10). The mismatch distribution of pairwise differences does not fit a Poisson's curve (raggedness index = 0.166; SSD = 0.12; P = 1). Thus, we found no significant signs of genetic isolation, population expansion, or genetic bottleneck. Alternative causes of TDS and how they might pertain to this populati...
Three genera of possible human ancestors (Sahelanthropus, Orrorin, and Ardipithecus) have been da... more Three genera of possible human ancestors (Sahelanthropus, Orrorin, and Ardipithecus) have been dated to 7–4.4 mya. Where the same skeletal elements have been recovered the morphology of the three genera is similar. When compared to chimpanzees and bonobos all the three exhibit reduced incisors, smaller canines, and less sectorial lower first premolars. A single fragmentary pelvis displays a mixture of chimpanzee- and hominin-like features. Interpretation of these fossils is confounded by the many australopith-like features in Ouranopithecus, the purported common ancestor of African apes and humans. Ouranopithecus shares with Australopiths (but not these three possible hominins) a robust, prognathic face, tall zygomatics, large incisors, large cheek teeth, and thick molar enamel. Ouranopithecus shares with australopiths and the three possible hominins small canines and a shallow supratoral sulcus. The robusticity of Ouranopithecus makes it less likely that Sahelanthropus, Orrorin, and Ardipithecus are in the hominin lineage, since such a lineage would require an evolutionary progression that starts robust, becomes nonrobust, and then reacquires robusticity. Some paleontologists, however, are skeptical of the place of Ouranopithecus in the human lineage. They find compelling indirect evidence that the common ancestor of African apes and humans was quite chimpanzee-like, which would exclude robust species such as Ouranopithecus from the human lineage. If the common ancestor was chimpanzee-like, then the argument that Sahelanthropus, Orrorin, and Ardipithecus are part of the human ancestry is stronger.
Bipedalism evolved in a stagewise fashion. There is some evidence that prehominins were more bipe... more Bipedalism evolved in a stagewise fashion. There is some evidence that prehominins were more bipedal than living African apes, perhaps similar to orangutans or gibbons. Australopiths had cone-shaped rib cages, gorilla-like scapulae, short but chimpanzee-like fingers, and long, curved toes, all consistent with adaptation to arm-hanging. Australopiths lack chimpanzee vertical-climbing adaptations such as gripping great toes and stiff backs. Chimpanzees are bipedal when feeding from the short trees that are common in dry habitats, where the feed by reaching up from the ground and with an arm-hanging, bipedal posture in the trees. The small-diameter branches in short trees discourage sitting and encourage arm-hanging; lateral toes grip the flexible branches, the body is balanced bipedally over the gripping feet, and short fingers are adequate for the small branches. Such trees can be entered without hand-over-hand climbing and opposable toes that allow it. Two million years ago hominins evolved longer legs and narrower hips that allowed a more modern human locomotion.
Chimpanzee anatomy and body proportions are unusual among the primates, but most of their unique ... more Chimpanzee anatomy and body proportions are unusual among the primates, but most of their unique anatomical traits are related to a few general features. Chimpanzees have long arms and fingers, mobile shoulders and wrists, a shallow, wide, funnel-shaped thorax and large arm-raising muscles. Keith asserted that these features were adaptations to brachiation. Others maintain that these traits are primarily adaptations for efficient climbing, and that brachiation (sensu stricto) was unimportant in the evolution of ape anatomy. This first quantitative study of chimpanzee positional behavior attempts to resolve this issue. Without a clear understanding of chimpanzee positional behavior and its relationship to morphology the reconstruction of the early hominid lifeways is impossible. Adult wild chimpanzees were studied at the Mahale Mountains and Gombe Stream National Parks in Tanzania. Over a one year period, 784 hours of observation were logged, during which data were collected on chimp...
Uploads
Papers by Kevin Hunt