Post on 02-Jan-2016
description
Human EvolutionA brief history of the past 4 million years
The March of Progress?Human Evolution is often misunderstood to
be a clear development; people often mischaracterize it as “humans descended from monkeys”.
Human evolution is NOT a clean continuum – we do not have a full picture of every species and how they all interact.
Current understanding is how different genera and species are generally connected, and the relative timelines, but this understanding changes as more discoveries are made, and with advances in dating techniques and DNA testing.
Human Evolution as a Tree
King Philip Came Over For Ginger Snaps (or Good Soup or Good Spaghetti, or…)Kingdom, Phylum, Class, Order, Family,
Genus, Species
For our purposes, we will generally be focusing on genus and species. So, assume…Kingdom – AnimaliaPhylum – ChordataClass – MamaliaOrder – PrimateFamily – Hominidae
Signs of “Progress”Traditionally, when discussing human evolution and the
concept of progress, certain features have been emphasized.
These features are the ones that made these groups look more like AMH, or any movement towards behavioral modernity (BMH).Brain sizeHeightDietTool creation and useBipedalismSigns of creativity or abstract thoughtAwareness of mortality
The VERY Distant Past85-65 ma – First speciation into primates (order)63-25 ma – Primates continue to split into various15 ma – Hominidae (Family) splits off from lesser
primates13 ma – human ancestors split off from orangutan
ancestors10 ma – human ancestors split off from gorilla
ancestors7 ma – human ancestors split off from
chimpanzee ancestors
4.4 ma – Ardipithecus (genus)Facultative biped –
bipedal on ground, quadripedal in trees
Could not run/walk long distances, but much better adapted than ancestors/other primates
Northeast Africa (Ethiopia)
Brain – 300-350 cc3’11” tall
3.9-2.9 ma – Australopithecus AfarensisArms adapted for
trees/climbing, but well adapted for bipedalism over short distances
Northeast Africa (Ethiopia, Kenya, Tanzania)
Brain – 380-430 ccMales – 4’11”Females – 3’5”Chimp-like social
structure
3.3-2.1 ma – A. Africanus
Much doubt if this is a human ancestor. Many believed they evolved into a different, now extinct, genus.
Anatomically similar to A. afarensis, with slightly more developed bipedalism
Southern Africa (South Africa)
Brain – 400-500 ccMales – 4’6”Females 3’9”
2.33 – 1.44 ma – Homo HabilisFirst in the Genus Homo
(“human”)AKA the Tool ManShort with long arms, but
bipedalEastern Africa (Kenya,
Tanzania) and Southern AfricaBrain – 550-687 ccHeight range 3’4” – 4’5” tallUnknown if a human ancestor
– experts disagree. Possibly an ancestor of H. Ergaster
Made stone tools by shaping rocks
Used for cutting scavenged meat, but not defense or hunting
More sophisticated social organization than previous species.
Believed to have intelligence about equivalent to a 12 year old today
1.8 – 1.3 ma – H. ErgasterAKA Working ManGenerally considered to be
a direct ancestor of later hominids, including H. sapiens, but some consider them to be only the African H. erectus
Eastern and southern Africa
Brain 700-900 cc in earlier, 900-1100 in later individuals
Males - 6’3”
More diverse and sophisticated stone tools
First use of bifacial hand axes 1.6 ma
May be the first to use fireLimited vocal
communications, mixed with hand gestures
Reduced competition for mating
May have cared for weak/ill members
1.9 ma -143 kya – H. ErectusAKA Upright ManOriginated in Africa,
but spread to Georgia, Sri Lanka, India, China, JavaSpread out more
than any previous species
Slender, with long arms and legs
Height range – 4’9” – 6’1”
Brain 850-1100 cc
Due to darker skin pigmentation, so were not prone to overheating; could run/ walk/ forage for long periods of time
Stone tools less advanced than those of H. ergaster
Used rafts to travel across oceans
Used fire, but no evidence of using it for cooking
Ate mostly meat, but also nuts, berries, fruitsMay have hunted in co-ordinated groupsEvidence they cared for the weak and illCapable of producing sounds similar to
modern speechDid not have advanced language, though there
is debate about how developed their verbal communication was.
1.2 ma – 800 kya – H. AntecessorSpainHeight range 5’6”- 6’0”Brain 1000-1150 ccPossibly cannibalistic –
flensed bones found in Spain
Much debated; there is very little evidence for this species
Some consider the fossils to be members of H. heidelbergensis
1.3 ma (?), 600 – 200 kya – H. Heidelbergensis
Eastern and southern Africa, Europe, western Asia
Probably descended from H. ergaster
Possible common ancestor of Neanderthal and H. sapiens
Males – 5’9”Females – 5’2”*One small group in Africa
had males routinely 7 feet tall)
Brain 1100-1400 cc
The first group to bury its dead
Right handedLanguage was more
developed than H. ergaster
Sophisticated handaxesHunted in organized
groups, with stone-tipped spears
Control of fireFirst to build shelters
Conclusions?For millennia, progress was measured by
small changes, such as increased brain size, advances in stone tools, use of fire, and other signs of intelligence.
This will be followed by a period of rapid change over a comparatively short period of time with the development of behavioral modernity.
Paragraph – Towards ModernityBased on your understanding of the concept
of behavioral modernity, how behavioral modernity and “progress” are measured, and on the evolution of the genus Homo, make an argument for what we should consider to be the most important indicator(s) of evolutionary improvement and intelligence. Explain your answer.