Transcript Part 8

• Humans emerged on
one very young twig
on the vertebrate
branch.
• Humans and chimps
diverged from a
common ancestor 57 million years ago.
• Q: Are our ancestors
chimps or modern
apes?
• A: No. We represent
2 divergent branches
of the anthropoid
tree that evolved
from a common
ancestor.
• Chimps are more
like our cousins or
siblings, but not our
parent species.
•Examine the above timeline of human evolution.
• Q: Is human evolution a ladder with a series of steps leading directly from an
anthropoid ancestor to Homo sapiens?
• A: No. It is like a multibranched bush; many splinter groups have traveled
down dead ends. Several different human species coexisted. Our species is
the tip of the only twig that still lives.
• Q: Did human characteristics, such as upright posture and enlarged brain,
evolve in unison?
• A: No. Different human features evolved at different rates, with erect
posture, or bipedalism, leading the way. Ex: We had ancestors who walked
upright, but still had ape-sized brains.
• KINDS OF HOMINIDS:
• I. Australopithecus (came before Homo
genus) walked African savanna.
• A. afarensis = early species, was bipedal
• One of most complete fossil skeletons of
A. afarensis was found (see left); was
nicknamed “Lucy” by her discovers.
• (“Lucy in the Sky with Diamonds” song
was playing on radio when she was
discovered.)
• Was female, 3’ tall, softball size head,
3.2 million years old in East Africa.
• Australopithecus species extinct by 1.4
million years ago.
Lucy
• Hominid bipedal footprints
discovered in Tanzania, East Africa
in 1978.
• Are 3.7 million years old. Evidence
that bipedalism is a very old human
trait.
• A. afarensis skull, 3.9 million years
old, with a vertical backbone.
• Evidence that upright posture is at
least that old..