Explain how we classified humans before evolution.
“homo” - defined by Carl Linnaeus.
- people and apes in the same order.
- based on morphological characteristics.
- still thought species to be made by god and ‘unmutable’.
Explain Lamarck’s beliefs.
Lamarck thought that acquired characteristics can be inherited (e.g. giraffe necks).
First to suggest that humans and ape had a shared evolutionary history.
Thought that through acquired characteristics and over many generations humans became bipedal and lost the ability to climb trees.
Why was there such a debate about human evolution?
We had only found a fraction of the fossil record which we have discovered today.
Until the 1800s, no fossils found of ancient human species, only a few stone tools.
What was the first piece of human fossil record found? What were people’s reactions?
Homo Neanderthalis - first human species identified besides our own.
People were not pleased, controversial.
Describe Australopithecus.
Base of the human tree.
- bi-pedal, ape-like.
- small brains, but some made tools.
- change in diet.
- greater sexual dimorphism.
Habitat: Africa.
Describe homo habilis.
The first Homo.
- brain is getting bigger, teeth smaller.
- definitely made stone tools (“the handyman”).
Habitat: Africa.
Describe Homo erectus.
Most successful human species identified to date.
- believed to be the first to leave Africa.
- big brains, tools, hunters.
- possibly fire, art, speech.
Habitat: Africa.
Describe Homo antecessor.
Two lineages from homo erectus that became us and other species.
- sister species to H. Sapiens.
- suggests an entire other lineage of human evolution.
Habitat: Western and Southern Europe.
Describe homo heidelbergensis.
Overlapped with (evolved from) h. Erectus.
Habitat: Asia, Europe, Northern Africa.
Describe homo neanderthalensis.
- sister species to us.
- survived many ice ages.
- had many technologies we recognize.
habitat: Europe, Central Asia.
Describe Homo Florensis.
Nicknamed the hobbit.
- species which lived alongside our own.
- may have experienced insular dwarfism.
- many primitive features: possibly directly evolved from H. Erectus, or H. Habilis.
Habitat: Flores, Indonesia.
Describe Denisovans.
A sister species to us - believed to have descended from the same common ancestor.
The only human species identified solely by DNA, no skull identified to date,
Habitat: Western and Central Asia.
Describe Homo sapiens.
Only extant species in the Homo genus.
- skull morphology has changed distinctly over time.
- evolved in Africa and left, current global distribution.
- interacted with other Homo species.
Describe the progression of evolution.
It was once believed that there was a straight line of evolution - home species did not go extinct, instead they became the next species in the homo genus.
Evolution is associated with physical and technological changes that opened up new niches.
Explain why there are debates about focusing solely on morphological traits.
- Fossil record is very fragmented, there may be intermediates missing.
- Difficult to distinguish chrono species.
- Difficult to tell apart natural variation within species from differences separating species.
What is the issue with using DNA to characterize evolution?
Widely believed that we would never be able to analyze DNA past its half-life.
Half-life = 521 years.
What is ancient aDNA?
DNA that gives the ability to sequence DNA beyond its hard-life.
Current theoretical upper limit for analysis: 1.5 million years.
How does aDNA work?
PCR lets us amplify tiny samples, so it is not an issue that DNA breaks down significantly over time - we can analyze it past its half-life.
We can build ancient genomes from fragments y comparing them to modern ancestors.
How do we expect degree of genetic diversity to differ between populations in different continents?
Africa: high diversity.
- greater portion of rare alleles.
- rare alleles are likely to be found in founder populations.
Europe: lower diversity.
- greater proportion of deleterious mutations.
- expected in recent founder population.
Asia: lowest diversity.
