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.