Lecture 20 - Human Evolution 1 Flashcards
When was the start of the pleistocene
2.58 Myr
When was the start of the holocene
11.7 thousand years ago
Hominids
Members of the Hominidae e.g. orangutans, Gorillas, Chimpanzees, Humans
Hominins
Bipedal hominids, they occur only in the lineage that leads to modern humans
Why are human fossils rare?
Until 2 Myr ago hominins lived on the African plains, so the bodies were probably scavenged by predators and skeletons rarely survived intact
Population numbers were low and went through frequent bottlenecks
This means meant that some extinct species are defined from one or just a few fossils so difficult to know whiwhc species are on the direct route to homo sapians
How many species of hominin are alive today?
One
Homo sapians
For the last 40,000 years, before that was always at least 2 alive
What is the earliest known fossil able to walk upright?
Ardipthecus ramidus
How was Ardipthecus ramidus discovered?
Found a single intact skeleton
How tall was the Ardipthecus ramidus fossil?
1.2m
When was Ardipthecus ramidus fossil around?
4.4 million years ago
Very soon after the split between the human and chimpanzee lineages
What were the features of Ardipthecus ramidus?
Had some features more typical of chimpanzees than of modern humans, especially in dentition, but also including oposable big toes which chimpanzees use to cling on to branches
Habitat of Ardipthecus ramidus?
Thought to have spent at least some times in trees
This complicates the earlier theories that bipedalism evolved when our ancestors first moved out of the forests onto grasslands of the African savannahs
What is thought to be the direct ancestor of Homo?
Australopithecus afarensis
What fossils were found of Australopithecus afarensis?
Several fossils including an intact skeleton called lucy
When and where was Lucy the fossil found?
3.6 million years ago in Ethiopia in the Afar region
Features of Australopithecus afarensis fossils?
Around 1.2M, skull capacity of 375-550cm^3 indicating their brain was no bigger than ardipthecus ramidus
Had skeletal features much more similar to those of modern humans
In particular her pelvis bones and leg bones have modern features, suggesting that she walked much how we walk today
When did Australopithecus africanus appear in the fossil record?
3 million years ago
Characteristics of Australopithecus africanus?
Slightly taller than A.Afarensis with a bigger brain, and with teeth that are more similar to humans than are those of the earlier species
What is the debate surrounding Australopithecus africanus?
Weather it is on the direct line leading to homo or represents a side branch that became extinct
What is the difference between lumpers and splitters?
Different paleontological approaches
Lumper prefers as few hominin species as possible and so placing similar fossils in the same species
Splitters emphasizing the differences between individual fossils and so recognizing a greater proliferation of species
What was the first homo species?
Homo habilis
Where was Homo habilis found?
Olduvai Gorge, part of the African Rift Valley in northern Tanzania
What is the meaning of Homo habilis and why are they called that?
Handy man
As the first to be associated with stone tools.
These Olduwan tools were manufactured by splitting flakes from the surfaces of pebbles of flint or basalt to leave a crude chopping or scraping implement
Homo habilis skull and its significance?
Brain predicted to have an average size of 650cm3, which is 100cm3 larger than any australopithecine
Skull shape suggests that there is a feature of the brain called the bulge of Broca, which is essential for speech was more developed in Homo habilis
What did Homo habilis eat?
Not a great hunter
Used its Olduwan tools for scavenging meat from carrion, and sometimes became the prey of more successful hunters of the African plains, such as the big cats
A significant feature of Paranthropus robustus
Had a very robust jaw with large molars and flared cheek bones
Had a cranial capacity of up to 530Cm3
How long ago was the fossil of Paranthropus robustus dated?
1.5-2 million years ago
When was Paranthropus boisei dated?
1.3 to 2.3 million years ago
Key feature of Paranthropus boisei?
Even more speciaclised jaw than P. rubustus
Relatively larger molars with very thick enamel, peg-like small incisors
Sexual dimorphism in Paranthropus robustus?
Showed size variation of around 24-43Kg suggesting sexual dimorphism
Diet of Paranthropus boisei?
It is debated but likely adapted for chewing grasses or roots
What was the black skull?
A skull attributed to Paranthropus aethiopicus (alongside humans, debate on weather this is true)
Dated 2.3 to 2.6 MYA
When did Homo erectus exist?
1.9 million to 300,000 years ago
How tall were Homo erectus?
1.8m
Homo erectus brain size
1225cm3
Ecology of Homo erectus?
had advanced Acheulean tools, dominated African ecosystem
What were the first hominins to move to other parts of the old world?
Homo erectus
Fossils fond in Georgia and China from periods soon after the first appearance of species in Africa
What was the earliest hominin in Europe?
Juvenile specimen found in a cave at Atapuerca, Spain
Dated 800,000 years ago
Usually thought to be Homo antecessor but might be early Homo heidelbergensis
When was Homo heidelbergenesis first identified?
From a 500,000 year old Jaw from Heidelberg Germany
Skull of Homo heidelbergenesis?
A mixture of features seen in H. erectus and H. sapiens with a brain size intermediate between the two
What replaced Homo heidelbergenesis?
Homo neanderthalensis
Around 400,000 years ago
Physical features of Homo neanderthalensis
Average height of 1.7m and slightly larger brains than H. sapians, probably a feature of their greater robustness.
They displayed features of cold adaptation such as large sinuses for warming air entering through nostrils
When and where did Homo neanderthalensis live?
Lived throughout Europe between 400,000 to 40,000 years ago
When and where did Homo sapiens first appear?
In Omo Ehtiopia 195,000 years ago (time is debated)
Modern human features of the first Homo Sapien?
rounded skull and protruding skin
What fossils of Homo Sapiens have been found?
Ethiopia 160,000 years ago
Laetoli in Tanzania from 120,000 years ago
Border cave South Africa 110,000 years ago
Klasies River Mouth South Africa 90,000 years ago
Where were anatomically modern humans present around 100,000 years ago?
Skhul and Qafzeh in the Levant probably as a result of the African population expanding during a relatively warm period shortly after the beginning of the last glacial cycle
How was the Denisovans discovered?
From small pieces of bone and teeth found in caves in the Altai mountains, Serbia, dated to 40,000 years ago
Useful DNA sequences obtained
Initially thought to be a new species, now look to be an Asian type of Neanderthal
Where was Homo floresiensis found?
Island of Flores in Indonesia
Where was Homo luzonensis found?
Island of Luzon in the philipenes
What are the ranges of dates for Homo floresiensis fossils?
The most recent fossils being dated 60-100,000 years old
New fossils dated 700,000 years old
No DNA recovered from either
Homo floresiensis height
1-1.1 m
Homo floresiensis brain size
380 cm3
When was Homo luzonensis dated?
67,000 years ago
Homo luzonensis anatomy?
Small teeth show poor overlap with other hominins in size and shape
Foot bone shape overlaps H.erectus
No DNA discovered so hard to test
What is the arrival of modern humans associated with?
Quaternary extinction of megafauna
