ANP 206 Exam 3 MSU

Paleozoic

Vertebrates appeared 500-150 mya

Mesozoic

"Age of the Dinosaurs"

-Reptiles were the dominant vertebrate

-placental mammals appeared 70mya

Cenozoic

"Age of the Mammals" (the one we're in now) 65mya

Divided into Tertiary and Quaternary periods and 7 (or 8) epochs

Palocene

First primate-like mammals

Eocene

First true primates. Later, first anthropoids.

Oligocene

adaptive radiation of anthropoids

Miocene

First hominoids. Later, first hominin

Pliocene

Radiation of hominid, later first members of genus Homo

Pleistocene

Evolution & dispersal of genus Homo, including Anatomically Modern Humans

Holocene

Beginning of agriculture through present

Hominoids

all apes and humans, both past and present

Hominin (aka, hominids)

humans and their ancestors following split with Chimpanzees

Plesiadapiforms (primate-like mammals)

-small, rodent-like mammals

-specialized for life in trees

-found throughout North America and Europe

-Very diverse, including many body sizes (though generally small), and many dental adaptations (diversity of diets)

Plesiadapiform primitive traits

-front teeth far apart from the rest (diastema)

-eyes on the side of the skull

-lack postorbital bar

-hands and feet lack grasping ability

-had claws

Requirements for life in trees

-3D spatial orientation required (depth perception)

-Vision more important than smell

-agile body

-retention of primitive form with 5 digits

-good hand-eye coordination

Why move to the trees in the first place?

Insects: arboreal traits for hunting insects along branches

Fruit: grasping hands are particularly good for eating fruit at the end of long branches

The Eocene

50-55 mya

-the beginning is marked by a tropical and subtropical climate

-plesiadapiforms are extinct in North America and Europe by the start of Eocene

-likely evolved into first true primates

Omomyids

Smaller, nocturnal fruit and insect eaters. Somewhat similar to modern Tarsiers.

Adapids

Diurnal leaf and fruit eaters, somewhat similar to modern lemurs and lorises

Old World Anthropoids

Fossils appear in deposits from the oligocene epoch (34-23 mya).

Transition associated with the cooler temperatures starting in the middle Eocene

Anthropoids distinguished from Strepsirrhinesby:

•reduction of snout and nasal area •fully enclosed eye socket

Also, were:•small and arboreal

• generalized quadrupeds(no specialized locomotion

The Oligocene

Newly-evolved Anthropoids become established and spread during the Oligocene epoch (34-23 mya)

Cooler temperatures:

-expansion of grasslands and reduction of forests

-primates in N. America become extinct

-primates in Europe move south

Evolution of New World Monkeys

Earliest fossil record of NWMs is 30 mya

-Old World & New World monkeys have common origin in early Oligocene

-continental drift already had separate Africa and South America.

How could they reach New World?

Rafting hypothesis•Storms blow clumps of vegetation into the ocean

Rats are known to do successfully make cross-Atlantic voyage this way

Divergence of Old World Monkeys and Apes

Genetic and fossil evidence suggests apes evolved between 25-30 mya

Apes begin as a specialized branch of anthropoids, follow by adaptive radiation

-recent finds in Tanzania identified distinct OWM and Hominoid fossils dating to 25 mya

Evolution of Miocene Apes

23 mya

coincides w/ a general climate shift resulting in cooler, drier conditions

more open grasslands with mixed environments (woodlands, bushland, and savannas)

(apes outnumber monkeys until 5-10mya)

Early Miocene Apes

Most cranial evidence based on dental features

-few post cranial fossils exist

Genus Preconsul (23-17 mya)

-early miocene ape

-retains primitive monkey-like body:

unspecialized quadruped that lived in trees and ate fruit

-monkey limb proportions (same length)

-arms and hands and monkey-like

Why is Preconsul considered an Ape?

Derived (ape-like) traits:

-skull/brain is large relative to body size

-thin molar enamel (suggesting similar diet to modern African apes)

-molars show Y-5 pattern

-no tail

-shoulders and elbows ape-like

Sivapithecus

A genus of Miocene sivapithecids, proposed as ancestral to orangutans. (eye orbit, nose shape, incisors)

-mosaic environment of mixed grassland, woodland, and forest regions

-ate harder to chew nuts, seeds, hard fruits (thick molar enamel, large molars, and massive, shorter jaw)

Why did Apes decline after the Miocene and monkeys flourish?

Reproductive rates: if miocene apes spent a lot of time raising offspring, they might have been out-competed by the faster breeding monkeys

Environmental changes

-many fossil species have no living descendants. hard to match fossils with modern apes

Age of Humans

Anatomically modern humans (Homo sapiens sapiens) are about 200,000 years old.

All fossils in our species Homo sapiens, old and modern looking, then it is 400,000 years old.

All members of our genus Homo, then it is 2,000,000 years old.

All hominins regardless of genus, then it is at least 4,400,000 years old

Molecular Dating

Estimating the sequence and timing of the divergence of evolutionary lines by genetic analyses.

Sahelanthropus tchadensis

Location: Chad

Date: 6-7 mya

Primitive traits: small brain

Derived traits: small teeth, large brow ridges

Flat face

Possible biped: suggested by anterior location of foramen

Orrorin tugenensis

Location: Tugen Hills of Kenya

Date: 6.5-8 mya

Only one species found so far

Derived trait: bipedal legs

Primitive trait: long, ape-like arms

Unexpectedly small teeth

Other fossils (leaves and many mammals) found nearby show life in a dry, evergreen forest environment rather than savanna

Ardipitehcus ("ardi")

Primitive: relatively large canines (but more like incisors in structure), thin molar enamel, small brain, grasping big toe

Derived: bipedal (foramen magnum under skull), shape of some teeth like those of later hominids

Ard. kadabba

~5.5 mya

-large, ape-like canines

Ard. ramidus

~4.4 mya

-slightly smaller canines

Australopitehcines

-very diverse genus

-much better preservation than early hominin, more info available

Primitive traits include: small ape size brains, large faces , small bodies, long arms, big canines, apelike configurations of teeth

no big toe

Derived trains: diverse, not always human-like

Australopitecus afarensis

Location: N+E africa, including Ethiopia and Kenya

Date: 3.9-2.9mya

Prim traits: long arms and curved fingers (climb), chimp sized brain

Derived trais: reduced canines and molars, loss of abdicable big toe, features of pelvis and legs suggest full time bipedalism

AL 288-1 "Lucy"

Date: 3.2 mya

Location: Hadar, Ethiopia

40% complete skeleton

wider pelvis indicates female

3rd molar erupted (adult)

Arm and leg bone length gives stature of about 3'3" and weight of about 60 lbs.

Pelvic bones and femur indicate bipedalism

Laetoli footprints

Fossilized footprints found in Laetoli Tanzania by Louis and Mary Leakey. They proved that early hominids walked upright and in groups approximately 3.75 million years ago

A. Afarensis environments

Laetoli: grassland

Hadar: marshy lake bed

Robust Forms (genus: Paranthropus)

-highly specialized chewing mechanism

-crests on skull for chewing muscle attachments

-massive premolars and molars, small front teeth, non projecting incisors

Not large in overall body size:

-4.5 ft tall

-sexually dimorphic (100 vs. 75 lbs)

Gracile Forms (genus: Australopithecus)

-large faces (not like robust')

-slightly flared cheeks

-no sagittal crests

-450 cc brain sizes

-large incisors

Why the difference between the two australopiths?

Robust species ate courser/grittier foods such as seeds from acacia trees or roots

Gracile vs. Robust similarities

-postcrania nearly identical

-fully bipedal

-large back teeth

-brain sizes smaller and still within ape range

Paranthropus aethiopicus

2.5 mya

Loc: East Africa (Ethiopia and Kenya)

Parantrhopus boisei

Date: 2.4-1.4 mya

Loc: East Africa

-overlaps with homo; considered a dead-end side branch

Australopithecus garhi

Gracile australopithecine living prior to the homo Habilis

-likely not related to aethiopicus or Boisei either

-similar teeth, arm to leg length ratio, head size as Homo

-Oldowan stone tools found nearby

Why is A.garhi not an Australopithecine?

-small chimp-sized brain

-very large back teeth

-prognathic (jutting) face w/large canines

-postorbital constriction

Australopithecus africanus

3.3-2.5 mya

South Africa

Gracile form of "later Australopithecine"

Derived from some earlier such as a.afarensis

Australopithecus sediba

discovered in 2008, many individuals seem to have fallen into a death trap

Prim: brain size (420cc), long upper limbs, some aspects of tooth shape

Derived features: dental anatomy, brain structor, pelvic shape, features of the hands and feet

Origins of Bipedalism

-single most critical defining factor for hominids (occurred first)

-led to considerable species diversity

-nothing proceeding bipedalism is a hominin

Tool Use Model

increasing brain size and increasing reliance on tool use led to bipedalism.

-Upright walking freed hand for carrying tools.

-Free hands to carry food/weapons.

-Weapons give ability to fend off predators, large canines were no longer necessary.

-The more tools used for defense, the more selection for bipedalism and larger brains.

Problems with Tool Use Model

-fossil records show bipedalism arose before tool use and increase in brain size

-bipedalism allows tool use, didn't evolve because of it

Predator Avoidance Model

-when hominids left the woodlands and moved to the savanna, they were in danger of predators

-two legs would allow them to stand and see

Problems with Predator Avoidance Model

-bipedalism is not needed for this temporary task

-increases chance of being spotted by predators

-tree-climbing ability would've been more of an advantage against predators

Temperature Regulation Model

-upright posture reduces the amount of sunlight that strikes the body during the hottest part of the day

-higher wind speed and lower temperature away from the ground

Problem with Heat Stress Model

-other animals in the savanna aren't bipedal; avoid midday sun or cool off in the water

Food Acquisition Model

-free hands to transport food across open woodland and savanna

-energy efficiency is increased

Problems with Food Transport Model

-primates generally feed at food source

-when chimps are bipedal they aren't eating

-bipedalism human style is less efficient than knuckle walking for apes

Bipedal Feeding Hypothesis

-first arose to increase efficiency of standing while feeding, probably in trees

-morphology of early bipeds suggests significant amount of time still in trees

ex. long arms, curved fingers, divergent big toe

Genus Homo

the genus of bipeds that appeared 2.5 million years ago characterized by increasing brain size compared to earlier bipeds. The genus is divided into various species based on features such as brain size, skull shape, and cultural capabilities

Homo Habilis "handy man"

Location: East Africa

2.33-2 mya

-first specimens found in direct association with stone tools

-postcranial skeleton looks like australopithecines; no brow ridge

Teeth: molars larger than modern humans, larger in the front

Brain: 40% larger than AUSTRAl., front lobe suggests speech and language

Oldowan tools

The oldest known tools, made by chipping stones to produce a sharper edge. Made by Homo Habilis.

-systematic breaks and fracture patterns

H. rudolfensis

there is so much variability among very early Homoskeletons that some people divide them into two species: a larger one (H. rudolfensis) and a smaller one (H. habilis)

1.9 mya East Africa

slightly larger brain than Habilis but more primitive

either or neither led to h. register

How did H. Habilis get their meat?

Scavenged and fled quickly

Teeth makes indicate H. Habilis was prey of carnivores

"scavenger-gatherers"

The Pleistocene

1.8 mya - 12kya (beginning of lower)

begins sharp cooling trend. By 900 kya, glaciers cover almost all of Europe

lots of fluctuations in temperature during this time.

Upper Pleistocene ends at about 12 kya with warming trend and disappearance of the glaciers.

Homo erectus

Upright, walking human

-N, S, E africa, SE Asia, and europe

-first member of Homo to leave Africa

-1.8 mya - 200 kya

-sometimes overlap with h. Habilis; could be due to dating error or common evolution

-rapid evolution 100-200kya

When did H. erectus leave Africa?

Ubeidiya(Jordan Valley, Israel) is oldest widely-accepted site showing emigration from Africa (1 million ya)

East Asia: Fossils from Gongwangling, China are between 800,000 and 1 million years old

Java dates are still disputed

Dminisi

Location: Republic of Georgia, "Eurasia" (E. of the Black Sea)

Date: 1.75 mya•Represents earliest definite excursion out of Africa

Morphologically similar to H. ergaster

Weird mix of primitive and derived traits (which may indicate an even earlier exit from Africa)

Relatively small brain and body size•Lots of stone tools --all Oldowan

H. erectus cranial capacity

1000 cc

larger than previous hominids

H. erectus skull, jaw, and teeth

skull: lower & broader, postorbital constriction (less developed frontal and temporal lobes), face protrudes more than modern humans, large brow ridges

Jaws and teeth: still large compared to modern humans, larger front teeth, wear patterns fit w/ extensive meat eating

Nariokotome Boy

1.6 myanearly complete skeleton, KNM-WT 15000, (~12 year old boy) found in 1984 near Lake Turkana.

Called NariokotomeBoy(or the 'Strapping Youth') •Very tall for a 12 yrold boy

It is thought he would be 6'1" tall as an adult.

h. erectus

post-cranial skeleton

-Muscle attachment marks suggest robust muscularity.

-Proportions very similar to modern humans, and different from earlier hominids which had longer arms.

-Pelvis relatively narrow vs modern humans.

-Little sexual dimorphism.

Post natal growth

Narrow hips suggest that H. erectus could not have given birth to large headed babies.

Implies human pattern of postnatal bone & brain growth (more than just the doubling of chimps).

-in humans, baby is born with a brain 25% of its full size

Regional variation

H. erectus (Asia)-larger cranial capacity-short and stocky stature-rugged brow ridges-sagittal keel

H. ergaster (Africa)-smaller cranial capacity-tall stature-gracile brow ridges

-branch of erectus that remained in africa once the rest of the species went to Asia

Dmanisi (Eurasia)-smaller cranial capacity-short stature-gracile brow ridges

Cultural behavior

h.erectus/ergaster

-complicated stone tools

-skilled, cooperative hunter

-caves & temporary shelters

-fire for cooking and warmth; do not know if they could make fire

Homo and controlled use of fire

Earliest evidence dated at 1.4 -1.5 mya in Kenya

Most compelling evidence from Zhoukoudian (China) @ 400Kya in the form of burnt bones, stones, thick ash beds

Stone tool technology

-evolved with h. ergaster

-h. erectus kept oldowan tools

Achulean Tradition

1.4 mya; evolved with h. ergaster

-bifaced tools

-flatter, straighter, sharper

-require soft hammer percussion to manufacture

Hunting

H. erectus/h. ergaster were hunters of small and large game

earliest evidence: Olduavi gorge 1.5 mya

-all butchered animals @ a single site

-bones fragmented due to complete use of animal

bone evidence suggests hypervitamintosis from eating animal livers

physical adaptations to hunting

Smaller gut, despite larger brain. Suggests more reliance on energy efficient food (i.e., meat).

Modern body proportions, including structural modifications to shape of legs and torso.

Results: more efficient long distance walking and running

H. erectus (asia)

Earliest evidence in Java 1.8 -1.6 mya

Spread to Northern China by 800 kya

Persists relatively unchanged in these areas until ~30 kya

Not much change over time in brain size or body/cranial morphology

Tools remain Oldowan-like (though may have used bamboo)

H. ergaster (africa)

earliest evidence at 1.8 myain East Africa (may have overlapped for about .5 million years with H. habilisin East Africa)

by 1 mya, spreads to all areas of Africa (minus arid desert and Congo basin)

disappears by 600 kya(with transition to Archaic Homo sapiens)

perhaps adapted to drier conditions than H. erectus in Asia

Middle Pleistocene

Between 800 kya and 500 kya, transformation of H. ergasterin Africa and Europe into hominin with larger brains and more modern skulls.

Traditionally all Middle Pleistocene fossils called "Archaic Homo sapiens"

New data suggests lots of variation, most of which did not lead to us, so perhaps not quite H. sapiensyet.

H. heidelbregensis

By 400 kya, these large brained, more modern Homo populations are fairly common in Africa and Eurasia, and are known as H. heidelbergensis.

Compared to H. ergaster, H. heidelbergensisis more modern, having:

-substantially larger brains (1200 -1300 ccs)

-more vertical and higher foreheads

-more rounded back of skull

H. heidelbergensis culture

achulean and core tools

Definitive evidence of hunting (in the form of large game kill sites) and more diverse diets (including fish and vegetables)

Site in Schoningen, Germany dated to 400 kya

-wooden javelins

-bones of hundreds of horses, some with processing marks

300kya- new tool kit using Levallois technique to make spears (prepared flakes)

H. heidelbergensis in Asia

dated specimens by ~200 kya

either migrated from Eurasia/Africa, or represents convergent evolution of H. erectusin Asia

likely coexisted with H. erectus

Denisova cave

DNA relationships suggest that these individuals represent a separate early migration out of Africa

LCA of Neanderthal and "Denisovians" = 640 kya

LCA of Neanderthal and modern humans = 500 kya

(specimen found was 41 Kyo)

H. naledi

Found in South Africa in 2013•335 kya-236 kya

Has a bunch of weirdly primitive traits, so probably not a direct ancestor.

Intentional burial of dead in a cave?

H. floresiensis "hobbit"

Flores, Indonesia 100-60kya

size: ~3 feet tall•very, very small brain (385 -417 ccs)

--perhaps less encephalizedthat H. erectus

body shows many primitive features, including very long arms and unarchedfeet.

found with stone tools (surprising given its tiny brain)

Small size likely due to "evolutionary dwarfism" which occurs on islands with limited resources

**floresiensis and denisovians show great variation in homo groups

Neanderthals

Atapuerca, Spain has many sites of different ages

Simade los Huesos("Pit of Bones")•600-530 kya•~2000 bones from 24 different individuals

mosiacof primitive (H. ergaster) and derived (Neanderthal) features.

Transition to "Neanderthal in Europe"

By 130 kya, H. heidelbergensisin Europe has developed a set of distinctive features.

Likely lived in very small populations in harsh ice age environment (so subject to both selection and genetic drift)

These features disappear entirely by 30 kya, after which there appears to be only Anatomically Modern Homo Sapiens (except for the Hobbits)

Neanderthal's distinctive features

Large brains-average brain size is 1520 ccs, which is larger than both H. heidelbergensis(1200 ccs) and modern humans (1400 ccs)!

More rounded crania--long and low (like H. heidelbergensis), but with an "occipital bun".

Big faces-brow ridges and noses are massive, though no chin•

Small back teeth, large front teeth. Molars have fused roots "taurodont"

Heavily muscled, with thick bones

Slightly shorter and stockier than we are

Evidence from Neanderthal child from Devil's Tower, Gibraltar suggests that Neanderthals develop faster than contemporary humans

Growth rings of teeth = 3•cranial anatomy = 4 -5

Ice Age Adaptations

-crural index consistent with cold-adapted modern populations

-large mid face and noses

-large brains predicted by Bergman's rule

Neanderthal culture

Little evidence for shelters or organized camps(rockshelters)

Probably buried their dead. Dead carefully arranged in graves, sometimes in association with tools, food, and flowers.

Heavily worn front teeth suggests the processed animal hides

Very few old people, suggesting short, brutal lives

Skilled and organized hunters: sites littered with stone tools, and bones of small animals like red deer (elk), bison, aurochs, wild sheep, and some large game (rhinoceroses and elephants).

Neanderthals and Rodeo Riders

Berger and Trinkhaus(1995) showed that high incidences of head and neck trauma was similar to modern rodeo riders: "suggests frequent close encounters with large ungulates unkindly disposed to the humans involved

Neanderthal symbolic behavior

-very little art, no cave art

-personal adornments: shells

-bear femur flute

-elders had wounds: people were cared for; injuries but had not lost teeth or had arthritis

Could Neanderthals speak?

Share human speech gene FOXP2

brains large and complex, needed to communicate to hunt

bones and larynx similar in structure to amh

Mousterian tools

Black-core tools used by Neanderthals.

disappeared with extinction

300-30kya

(also made by heidelbergensis)