Human evolution

How old is H. habilis?

2.8-1.65 Ma

H. rudolfensis age range

2.1-1.78 Ma

H. rudolfensis features

large cranium, long and wide flat face, large teeth

H. erectus age range

2 Mya to 108 Ka

H. erectus features

successful as a species, long geological time and wide ranging.

H. naledi age range

~335-235 Ka

H. naledi features

• Mix of primitive and modern features

• possible ancestor of H. erectus

• probs went extinct w/out descendants

H. floresiensis age range

700-50 Ka

H. floresiensis features

• small, thought be an example of island dwarfism

• likely ancestor of h. erectus

• probs went extinct without descendants

h. lozonesis age range

67 Ka

H. luzonesis features

• species likely short, mosaic of ancestral and modern traits

• likely ancestor of h. erectus

• probs went extinct w/out descendants

H. longi age range

~146,000 years

H. longi features

Mix of ancient and modern traits

large, elongated cranium

heavy brow bone

h. antecessor age range

1.2 Mya-800 Ka

H. antecessor features

All skeletons those of children, not sure whether they’re a separate species

Homo heidelbergensis age range

700-200 Ka

H. heidelbergensis features

Ten tooth cavities, large brain and flat face

homo. neanderthalensis age range

400-40 Ka

Denisovans age range

~41 Ka

Denisovans features

distant from either h. neanderthalensis or h. sapiens, though evidence that it interbred with both

probs shared ancestor with neanderthals

H. sapiens age range

300 Kya-present

what are the 3 types of fossils?

1. trace fossils (coprolites, tracks, trails, nests)

2. body fossils (teeth, bones, shells)

3. sub-fossils (not quite bone, not quite fossil)

Why are some fossils more common than others?

the smaller the bone, the less likely it is to be fossilised.

why don’t we find fossils everywhere?

not every environment can produce fossils- complete skeletons are incredibly rate

fairly complete skeletons are those which you can mirror existing bones to produce a full skeleton

what can you date?

the fossil or the geological bed (rocks) around it

cannot date everything, different methods change the date, caves and rift areas are complicated (processes such as uplift make it harder)

Could different homo species interbreed?

Yes, different, related species could interbreed

often, but not always, infertile- can take 2 Ma of separation for infertile hybrids

Facts vs assumptions in fossil records

facts:

• fossil evidence (shape, size, age)

• archaeological evidence (fire, tools, shelter)

Assumptions

• relationships

• who used tools, shelters, etc

• how muscles attached to bone

splitters vs lumpers

splutters: different species unless convincing reason to unite them (variation = new species)

lumpers: same species unless convincing reason to divide them (intra-species variation is normal- age, sex, disease, genetic variation)

what is the original definition of homo genus?

Small teeth, bipedal, tool use, large brain size

What evidence has debunked the original definition of H. genus?

• Au. sediba have smaller teeth than homo sapiens

• Sahelanthropus Tchadensis are bipedal

• There is evidence of tool use ~3.3 Mya

• Paranthropus robustus have big brains

Who left African first?

Who knows?

Homo habilis were short, inefficient in walking, had small brains and were likely scavengers

Homo erectus do have fossils in Northern Africa and China, believed to leave around 1.8 Ma- had larger brains, hunters, taller, more efficient walking, better tools

What do we know the denisovans from?

finger bone and teeth

What is taphonomy?

The study of how organisms decay and become fossilized