BIOL SCI 150 Study Guide - Midterm Guide: Homo Heidelbergensis, Homo Erectus, Homo Sapiens

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Is human evolution linear?
No. Scientists used to think that human evolution was linear, with one organism
morphing into another over time. The current hypothesis, instead, is that human evolution is
thought more of a bush with lots of side branches and dead ends, where different similar species
evolved from a common ancestor if you trace back their lineage far enough.
What did the Lucy fossil tell us?
Lucy is a fossil from australopithecus, that is estimated to be dated from about 3.2 million
years ago. Her pelvis and femur fossil show that she was bipedal. Before australopithecus,
hominids walked on 4 legs. She also had a much smaller brain than modern humans.
What is unhelpful about fossils?
There aren’t that many fossils, and by far the most prevalent fossil is teeth, which doesn’t
give that much information. Certain climates preserve fossils better than other, so we have a
imbalance of information about species and organisms based on where fossils were found, rather
than where species actually lived.
Name 4 character trait evolution in hominids.
1. Brain grew - probably because of a change in diet - stronger food sources provided more
energy to sustain a larger brain.
2. Quadrupedal (4 legs) - bipedal (2 legs)
3. Canine teeth disappeared (no longer needed to cut food w/ addition of tools)
4. Increasingly rare to be arboreal
What were the hominid migrations out of Africa?
1. Homo erectus moves out of Africa into Europe/Asia about 1.8 million years ago.
2. Homo heidelbergensis migrates out of Africa about 600,000 years ago
3. Homo sapiens leave Africa about 100,000 years ago into the Middle East. Make it to
Europe by about 40,000 years ago.
How can comparing DNA tell you about evolution?
You compare the DNA of related species, to see how much it varies and estimate how
long ago the species diverged.
Why is mtDNA preferred to nuclear DNA?
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