HW reading: Wood and Collard, Leaky Tobias Napier, Gary Bogan, Pickering and Bun – Part 1
HW writing: What in your opinion are the most important differences between chimps as a proxy
for the last common ancestor and humans?
What happened to that group, what was it doing that
What were they doing that moved them out? Top 3 ranked.
-“Discoveries” don’t really change how we see human evolution, haven’t in the past 25 years.
They have reinforced what we already know.
Basic outline of human evolution seems to be set,
no real disturbances.
We agree on time and place of most events.
What do we know?
-evolution is not a straight line
-for a long time, we thought there was a LCA (last common ancestor), and evolution progressed
in a line with one species evolving into another
-there have been lots of experiments happening, branches, “bushiness”, and this means that at
any particular time there could be more than one species of humans living
-it is unusual that we are the only human species living
-evolution starts and stops: punctuated equilibrium, long periods of stasis may occur and then
lots of new species will appear, blossoming evolution.
Then selection takes care of those who
are not well suited.
-Almost certain that the genus Homo is East African in origin around 2 million years ago,
humans moved out again and again in pulses
-Ancestral groups never went anywhere, but Homo’s appearance involved northern movement
-Homo was dispersing, not just expanding their range.
They were developing new adaptations
and new ways to deal, such as new dietary patterns
-The ability to make these adaptations means that the basic morphology of Homo was in place;
larger body size (better competitor, expands range), obligate bipedality (different than the one
starting 7 million years ago that allowed arboreals to go to the ground)
-Certain social patterns in place: strong cooperative bonds, strong male and female groups,
cohesive social groups, altruism
-Neanderthals are separate species, separate lineage
Surprises? What are we unsure about?
-First immigration out of Africa: we always assumed that the people who first did this used a
sophisticated tool technology and had fire.
They actually had a tiny brain and they had primitive
tools (Oldowan, mode 1) that were not standardized
-Now there were questions between relationship between cultural and biological evolution.
bigger brain = better made tools…now we know this isn’t true.
There is a disjunction between
cultural and biological evolution.
-Dwarf human discovery in Indonesia, smaller brains than chimps, yet they had sophisticated
tools and fire