Bio 115 Ecology and Evolution Human Evolution Haploid

Bio 115 Ecology and Evolution Human Evolution

Haploid chromosome number. Humans have not lost a chromosome; rather, two smaller chromosomes fused to make a single chromosome.

Darwinius masillae Middle eocene (47 Mya) Germany Root species of primates.

Percent divergence in DNA Species pair % Divergence of DNA Human - Chimpanzee 1. 7 Human – Gorilla 1. 8 Human - orangutan 3. 3 Human - Gibbon 4. 3 Human – rhesus money (OW) 7. 0 Human – spider monkey (NW) 10. 8 Human - Tarsier 24. 6

Ardipithecus ramidis (4. 4 Mya) Science October 2, 2009

Ardipithecus ramidus Unexpected anatomy. Ardi has an opposable toe (left) and flexible hand (right); her canines (top center) are sized between those of a human (top left) and chimp (top right); and the blades of her pelvis (lower left) are broad like Lucy's (yellow).

Ardipithecus ramidus Filling a gap. Ardipithecus provides a link between earlier and later hominins, as seen in this timeline showing important hominin fossils and taxa.

Science 29 January 2010 (327) p 532.

Dr. Tim White

Evolution of hominids and African apes since the gorilla/chimp+human (GLCA) and chimp/human (CLCA) last common ancestors. Pedestals on the left show separate lineages leading to the extant apes (gorilla, and chimp and bonobo); text indicates key differences among adaptive plateaus occupied by the three hominid genera.

Map showing the Middle Awash area (star) and rift locations (red lines). Photo shows the 4. 4 -Ma volcanic marker horizon (yellow bed) atop the locality where the skeleton and holotype teeth of Ar. ramidus were discovered. Also shown are some of the fossil seeds.

Abundance of birds (left) associated with Ar. ramidus. These distributions are consistent with a mostly woodland habitat. (above) An example of the many small mammal and bird bones.

(Right) Oblique and side views of a female chimpanzee (right) and the Ar. ramidus female reconstruction (left; the oblique view includes a separate mandible). (Left) Comparison of brain and tooth sizes (arrows) of chimps (Pan, blue), Ar. ramidus (red), and Australopithecus (green). Means are plotted except for individual Ar. ramidus and Au. afarensis cranial capacities. Canine unworn heights (bottom) are based on small samples, Ar. ramidus (females, n = 1; males, n = 3), Au. afarensis (n = 2), Pan (females, n = 19; males n = 11).

Dentitions from human (left), Ar. ramidus (middle), and chimpanzee (right), all males. Below are corresponding samples of the maxillary first molar in each. Red, thicker enamel (~2 mm); blue, thinner enamel (~0. 5 mm). Contour lines map the topography of the crown and chewing surfaces.

The Ar. ramidus pelvis has a mosaic of characters for both bipedality and climbing. Left to right: Human, Au. afarensis (“Lucy”), Ar. ramidus, Pan (chimpanzee). The ischial surface is angled near its midpoint to face upward in Lucy and the human (blue double arrows), showing that their hamstrings have undergone transformation for advanced bipedality, whereas they are primitive in the chimpanzee and Ar. ramidus (blue arrows). All three hominid ilia are vertically short and horizontally broad, forming a greater sciatic notch (white arrows) that is absent in Pan. A novel growth site [the anterior inferior iliac spine (yellow arrows)] is also lacking in Pan.

COVER The right forearm and hand (hand skeleton ∼ 12. 3 centimeters long) of (Australopithecus sediba), specimen Malapa Hominin 2. Papers in this issue present a detailed look at the hands, feet, pelvis, brain endocast, and age of this hominid, which lived 2 million years ago, near the emergence of our genus, Homo.

Deathtrap. Lee Berger (left), his son Matthew, and dog Tau visit the pit at Malapa.

Head first. This virtual reconstruction of Au. sediba's skull shows the endocast of its brain surface (green) with an enlarged frontal gyrus (blue) (Areas reconstructed from a mirror image shown in yellow).

Fig. 3 Comparisons of virtual endocasts in (A) superior, (B) inferior, (C) anterior, and (D) left lateral views. Homo Sapiens Australopithecus sediba Australopithecus africanus Australopithecus sediba Pan troglodytis K J Carlson et al. Science 2011; 333: 1402 -1407 Published by AAAS

Fig. 2 Comparison of the MH 1 (left), Sts 14 (center), and MH 2 (right, mirror-imaged) pelves in anteroinferior (top row) and anterosuperior (bottom row) views. J M Kibii et al. Science 2011; 333: 1407 -1411 Published by AAAS