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

  • get first cremations

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

  • get good rock art

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

Evidence:

  • 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

  • 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)

  • 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:

  • 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?

Human Intelligence:

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

  • 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 follows a step-wise gradual trajectory:

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

Speech/Language:

  • 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:

    • 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

  • 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 from 35,000ya

    • 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

Villages, Agriculture, Animal Domestication:

  • followed herds of mammoths:

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

    • followed them into the Americas

  • After this, there was a 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)