L15- Evolution of Modern Humans

Into Australia:

• the ice caps were much larger, Russia was joined to Alaska

• but Australia was still isolated, at low sea levels it is attached to New Guinea

• can only get to New Guinea by island hopping and had to travel 30 miles (beyond what the eye can see over the horizon)

  • either voyagers were going from island to island for fishing and were blown off course or could see smoke from wildfires

  • had to get there by boat

• arrived to Australia 60-50,000 years ago

There are 2 theories of the invasion into Australia:

1. 2 invasions→

   • gracile sapiens came from China by New Guinea and went right

   • robust sapiens came from Africa by Java and went left

2. 1 invasion→ sapiens came from Africa by Java and hopped onto Australia, one population went one way, the other went the other way

   → evidence suggests there was only 1 invasion

Australian homos:

• get first cremations

• ‘Mungo Man’ fossil→ Homo sapien, 50ya

• get good rock art

• changed the landscape dramatically and burnt a lot of the vegetation

Evidence for into Australia:

• Archaeology

• Anatomy→ suggests 2 invasions but is disputed now

• Molecular Studies→ suggests a single origin for all Australians (1 invasion)

• Megafauna→ all megafauna were wiped out at the same time as the migration through Australia

  → changed the environment by overhunting, burning, getting rid of other Homos

Into the Americas:

• tracked mammoths across the Mammoth Step→ tundra grassland from Eurasia across to North America

  → the society hunted and used the mammoths

Ice sheets:

• there were 3 ice sheets at the time

  • either sailed down the coast or came across from Beringia and walked down between the mountains and the ice sheets (more likely)

America→ South America:

• spread to South America very quickly ~30,000ya

  • either one group came in from the Americas and another sailed across the Pacific Ocean

  • evidence suggests that all Americans remains’ closest relatives are Siberian→ there was only one group came in and spread out

Clovis→

• sites with very distinctive flint tools that are found all over South America

  • humans went into the Americas, went across and there was a population explosion with clovis culture developing across the Americas

  • Monte Verde (famous site) is an outlier

  → the Americas were colonised earlier and then there was an internal population explosion

Evidence for into the Americas:

• Archaeology

• Anatomy

• Molecular Biology

• Language→ hundreds of languages came from 3 languages

• Megafauna→ wiped out these as humans expanded during the clovis time, e.g.:

  • the shasta ground sloth disappeared around the clovis time

    → human arrival and overhunting are the main cause of extinction

  • only get megafauna in Africa today→ humans grew up with them

Why was Homo so different?

1. human intelligence (brain expansion)

2. speech/language

3. technology/tools

4. art

Brain size in hominin evolution:

• there is a continuous brain size increase in hominin evolution (used for socialising more now than hunting, similar to monkeys)

• Have a huge expanded brain size that doesn’t fit our body size

Brain expansion is able if…

we increase mother’s metabolic rate and have a longer gestation time leading to smaller litters

Problems with such a large brain:

• requires a stable, high energy food source

• birth problems→ skull collapses in during birth and develops more after birth, needing an extended childhood

Homo brain size:

Homo brain size follows a step-wise gradual trajectory:

Australopithecines brain size vs Homo vs apes:

Australopithecines brain size x body weight is similar to apes but Homos are completely different:

Speech/Language evolved in…

The ability to speak evolved in Homo heidelbergensis who passed it on to Homo neanderthals and Homo sapiens

Evidence for speech:

• Hyoid bone→ bone that holds the tongue, is very different in Homo erectus but is similar to Homo heidelbergensis and its descendants

• Endocasts of skull→ know areas of the brain involved in speech

• Larynx/Pharynx structure→ Adam’s apple is low to allows breathing and speaking but also allows more choking

• Tongue nerve hole→ big

• Spinal canal→ wider nerves, more traffic

• Tools/Art→ comparing grades of art with intelligence

• FOXP2 gene→ controls speech (if mutated in mice, they cannot squeak)

can use different technologies to look at intelligence/speech:

• get an archaeological signal of complexity using tools

• put in neurobiological measures to work out how the person would have reacted and the brain areas involved

• can look at skull features to understand intelligence and speech

Technology→ Tools:

• Archeulean tools coinciding with Homo habilis, ergaster, erectus and then there are step-wise changes in tools:

• Africa, Asia and Europe are out of step with tools and are not connected:→ detail increases with newer tools

• Classified different technologies and tried to date them→ is hard due to interconnectivity e.g. one population dropping tool and other population taking it and it spreading then

Art:

• From Homo neanderthals and Homo sapiens

1. Ochre

2. Paintings in caves

3. Figurines

4. Sungir

Ochre-

• 100,000ya in South Africa, burning of metal oxides, made bright colours, put on faces and walls

Paintings in caves-

• 35-10,000ya throughout Europe, Africa and China

• coincides with the last glacial maxima→ was very cold and so went into caves

• the paintings are usually just single animals and hands

• humans are rarely depicted but are more in newer paintings

Figurines-

• 35,000 years ago

• can interpret them e.g. fertility symbols

• had the time to make these→ shows conciousness

Sungir-

• Upper Palaeolithic, 28-30,000ya

• was a man buried in 2936 ivory beads from mammoth tusks

• lived in hunter-gatherer groups and had time to spare

There have been rapid progressions:

• 100,000ya→ Jewellery beads from North Africa

• 40,000ya→ Flutes discovered in Europe (hollowed out bones)

• 30,000ya→ Wild flax (vegetation) used to manufacture clothes

• 30,000ya→ Dogs were domesticated from wolves among hunter-gatherer populations

• 20,000ya→ Pottery used to carry water around

Followed herds of…

• mammoths:

  • made huts out of bones, painted and (3D) carved them:

  • followed them into the Americas

After hunter-gatherers into the Americas, there was a…

supernova

Supernova→

• lived independently by growing crops and animals

• happens independently 3 times around the world:

  → allows a more stable food source, can settle down and don’t have to follow meat (mammoths)

Agricultural Neolithic Supernova→

• population explodes at this time (10million→ 100million) and keeps rising from this point

  • Can see transition from hunter-gatherers to farmers (living there temporarily to living there permanently) from 13-9,500ya in Syria

  • Can see the earliest walled city (trading post) 10,000ya in Jericho

  • The Bronze Age begins 5,300ya (Homer)