Transcript Slide 1

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.
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.
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
africanus
Australopithecus
sediba
Pan troglodytis
K J Carlson et al. Science 2011;333:1402-1407
Published by AAAS
Fig. 2 Comparison of the MH1 (left), Sts 14 (center), and MH2 (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
Arm vs. hand. Au. sediba's hand
has some humanlike traits (large
tumb and shorter fingers), but
its arm is long and primitive.
Fig. 1 Au. sediba MH2 right hand.
T L Kivell et al. Science 2011;333:1411-1417
Published by AAAS
Fig. 6 Relative length of the thumb in the Au. sediba MH2 hand.
T L Kivell et al. Science 2011;333:1411-1417
Published by AAAS
Homo floresiensis
Flores, Indonesia
Homo floresiensis
Homo sapiens
Homo sapiens
microcephalic
Homo floresiensis
Homo erectus
Chimpanzee
Science 29 January 2010 (327) p532.