A 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 – Animalia Phylum – Chordata Class – Mamalia Order – Primate Family – 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 size Height Diet Tool creation and use Bipedalism Signs of creativity or abstract thought Awareness of mortality

The VERY Distant Past ma – First speciation into primates (order) ma – Primates continue to split into various 15 ma – Hominidae (Family) splits off from lesser primates 13 ma – human ancestors split off from orangutan ancestors 10 ma – human ancestors split off from gorilla ancestors 7 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 – cc 3’11” tall

ma – Australopithecus Afarensis Arms adapted for trees/climbing, but well adapted for bipedalism over short distances Northeast Africa (Ethiopia, Kenya, Tanzania) Brain – cc Males – 4’11” Females – 3’5” Chimp-like social structure

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 – cc Males – 4’6” Females 3’9”

2.33 – 1.44 ma – Homo Habilis First in the Genus Homo (“human”) AKA the Tool Man Short with long arms, but bipedal Eastern Africa (Kenya, Tanzania) and Southern Africa Brain – cc Height range 3’4” – 4’5” tall Unknown 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. Ergaster AKA Working Man Generally 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 cc in earlier, 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 fire Limited vocal communications, mixed with hand gestures Reduced competition for mating May have cared for weak/ill members

1.9 ma -143 kya – H. Erectus AKA Upright Man Originated in Africa, but spread to Georgia, Sri Lanka, India, China, Java Spread out more than any previous species Slender, with long arms and legs Height range – 4’9” – 6’1” Brain 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, fruits May have hunted in co-ordinated groups Evidence they cared for the weak and ill Capable of producing sounds similar to modern speech Did not have advanced language, though there is debate about how developed their verbal communication was.

1.2 ma – 800 kya – H. Antecessor Spain Height range 5’6”- 6’0” Brain cc Possibly 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 cc

The first group to bury its dead Right handed Language was more developed than H. ergaster Sophisticated handaxes Hunted in organized groups, with stone-tipped spears Control of fire First 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 Modernity Based 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.