Paleoanthropology
- the study of primate and human evolution in the broadest sense
-involves contributions from geology, chemistry,
- relies on insights into behavior during human evolution
by using comparative data from studies on nonhuman primates
Taphonomy
- The study of what happens to plants and animals after they die
-
can use the info taphonomy provides to infer human behavior
-Paleontological subdiscipline; concerned with the process responsible for any organism becoming a part of the fossil record and
Fossil
Any piece of evidence which bears upon the structure or way of life of organisms that lived in the past; may be bones that have turned to stone, ancient footprint, discontinuity in the soil created by plant or animal
Piltdown Man? Physical characteristics? Why was in on our family tree? What evidence did it contradict? The controversy? Method to reveal hoax?
-Piltdown man = creature that had large human cranium and ape's jaw found in Piltdown, England; teeth worn flat and looked like human teeth; showed mix between ape and human traits with a larger brain; offered proof that large brain evolved first
-many th
Relative Dating Techniques
[--- A comparative method of dating the older of two or more fossils
or sites, rather than providing a speci?c date
-estimation of date based on location, type, similarity, geology, and association; includes pollen analysis, ice core sampling, stratigraph
Absolute Dating Techniques
[-determines exact date (subject to statistical fluctuation)]
1) Radiometric (Chronometric) Dating
= relies on physical and chemical processes in
the universe that remain constant; radioactive elements discharge energy at a constant rate (deca rate); ex:
What dating techniques are used on volcano ash? Bone? Pottery?
Volcanic ash-- Uranium 238, Potassium-Argon (volcanic eruptions eliminate any initial argon gas), Argon-Argon
Bone-- Electron Spin Resonance
Pottery-- Thermoluminescence
Half-life
-rate at which radioactive substance decays
-C14 has a half-life of 5,730 years
-this means that half of the original amount of C14 in organic matter will have disintegrated 5,730 years after the organism's death
Evolutionary concept: Anagenesis
much of evolutionary change taking place within lineages
-the
transformation of an unbranched lineage
of organisms to such an extent that it is justifiably called a new species
Evolutionary concept: Cladogenesis
seeing the fossil record as evidence of frequent speciation
-type of speciation in which
branching
of new forms from an ancestral lineage occurs.
Evolutionary concept: Species
-A group of interbreeding organisms that can produce fertile and viable offspring
Evolutionary concept: Adaptive Radiation
-An increase in the population size of a species or a group of related species when they enter a new environment where there are no competitors
Evolutionary concept: Speciation
-An evolutionary concept where new species are gradually produced from previously existing ones
Geological Time: Precambrian
-Almost 90% of earth's 4.6 billion year history;earth 's history before Cambrian period of Paleozoic era
-lasted from 4,600 million to 542 Ma
-includes 3 of the 4 Eons:
1) Hadean eon
(4,600-3,850 Ma) covers the time from the origin of the earth prior to a
Geological time: Phanerozoic Eon
-4th geological eon that covers the past 542 Ma; characterized by rapid origin and continued evolution of more complex life forms
--At start of this eon, first vertebrates appeared which eventually evolved into fish, reptiles, birds, and mammals
~Paleozoi
Geological time: Cenozoic Era
~Paleocene epoch
= 65-54 Ma; Altiatlasius (60 Ma); Plesiadapis; Adaptive radiation of primate-like mammals
~Eocene epoch
= 54-34 Ma; Adapids (Notharctus) and Omomyids (Tetonius); Adaptive radiation of the ?rst true primates (primitive prosimians);
?rst an
Dental characteristics of Mammals
-Why do mammals have so many types of teeth? =
-So they can eat a wide variety of foods
-eating is more efficient than reptiles because they chew food so it aids in digestion
-The problem with mammalian teeth?=
-they wear out over time
-adult mammals may
Dental characteristics of Therapsids
-More emphasis on chewing food; mammalian like; dental adaptations made them suited to life on land and allowed them to forage and hunt
-Incisors, canine, and molars
Dental characteristics of Reptiles
-teeth are attached to the palate or to the floor of the mouth, forming additional rows inside those on the jaws proper
- teeth are generally simple and conical in shape, although there is some variation between species, most notably the venom-injecting f
The 3 models of the Origin of Primates? What is most accurate?
1) Arboreal Model = 1st and oldest;
~because these creatures lived in a three-dimensional world they evolved full stereoscopic vision to be better able to move through the environment. The orbits of these early primates under went orbital convergence to a
The 4 events? What happened, when?
1) very early Paleocene; is related to the split between primates and other mammals related to living in an arboreal environment
2) Eocene; the split between prosimians and anthropoids where prosimians forage at night and anthropoids are daytime animals
3
Therapsids
-an early group pf mammal-like reptiles, ancestors of later mammals
-appeared in Paleozoic era
-represent the beginning transitions that led to later mammals = different types of teeth, greater emphasis on chewing food
-underwent adaptive radiation in Per
Plesiadapis (plesiadapiforms)
-Paleocene epoch in Cenozoic era
--Mammal-like primate
--Has a gap between the front and back of the mouth; claws, cusps on the incisors (front teeth). It has other characteristics of primates such as the floor under the middle ear (related to balance) an
Adapids (Notharctus)
-Eocene epoch, Cenozoic era
-one of 2 families of primates @ beginning of Eocene
-lemur-like
-have characteristics of modern lemurs
Omomyids (Tetonius)
-Eocene epoch, Cenozoic era
-one of 2 families of primates @ beginning of Eocene
-tarsier-like
-have characteristics of modern primates
Amphipithecus
-Possible early anthropoid
-found in Late Eocene epoch
-had bilophondont molar (having two transverse ridges or crests)
Branisella
-Branisella Boliviana
-@ end of Oligocene
-early example of New World monkey
-the oldest fossil New World monkey discovered
-bilophodont molars
-short face based on the mandible and the small premolar
-This species had an average body mass of about 1.0 ki
Parapithecids Family
-Ancestral to New World Monkeys;
~B. apidium = one of the very earliest known monkeys, which evolved from lemur-like prosimians. They lived 36-34 million years ago
~A. parapithecus = a small Old World monkey (Oligocene)
Propliopithecids
-1st discovered in Egyptian Faiyum Depression; ape-like anthropoids dating to early Oligocene
-
OLDEST AND MOST PRIMITIVE APES
-
European
~P. aegyptopithecus =
-"Dawn Ape"
-an archaic-looking catarrhine, and is thought to be what the common ancestor of al
Proconsul (genus) (Proconsulids)
-Late Oligocene, Early Miocene hominoid (23-28 Ma); name means before chimpanzee
-
earliest family of fossil apes
; probably a common ancestor of later hominoids (apes, humans)
-lived in east African forests btwn 23-18 Ma; ate primarily fruits, adapted to
Sivapithecus (genus)
-Late Miocene after climate became cooler
-
Europe
genus of fossil ape that lived in Asia between 12.5 million and
7 million years ago, possibly
an *ancestor to modern
orangutans*
-Environment = lived in Indian and Pakistan between 12.5 and 7 million year
Dryopithecus
-
European
Miocene ape (hominoid)
-Later Miocene (10-12 Ma)
-suggested to be possible ancestors of African apes and humans, as they share a number of cranial features with living African apes and early hominins, including a long, low brain case and a lowe
Ouranopithecus
-European Miocene ape
-Later Miocene (10-12 Ma)
-suggested to be possible ancestors of African apes and humans, as they share a number of cranial features with living African apes and early hominins, including a long, low brain case and a lower face that
Oreopithecus
EUROPE MIOCENE APE
-
significant postcranial resemblance to living hominoids
-"forest ape"
-discovered in italy
-lived in swamp forests (arboreal) but may still have had some terrestrial locomotion
-Unique postcranial anatomy = suggest some terrestrial lo
Afropithecus
-Proconsulid
-very large; size of a female gorilla
Gigantopithecus
-
Europe
Miocene fossil ape
-Genus name = "Giant Ape";
largest primate that ever lived
-Asian ape; remains found in China, India, Vietnam; actually found in drugstore bc in Asia they ground the fossil teeth (dragon's teeth) and used it in potions
-remains
Hominini: Sahelanthropus tchadensis
-OLDEST SPECIES OF HOMININ; primitive hominin
-When = lived between 7 million and 6 Ma (Late miocene)
-Location = Chad in central Africa
-Fossil remains =
~ jaws, teeth, distorted cranium; back of this specimen resembles an ape, and it had a small, ape-si
Hominini: Orrorin tugenesis
-primitive hominin
-Location = Kenya in east Africa
-When = 6 Ma (Late miocene)
-Fossils = dental remains, leg and arm bone fragments
~ leg bone indicates that this species was bipedal, although the arm bone suggests that it still spent a fair amount of t
Hominini: Ardipithecus (genus)
-this genus is bipedal = bc position of foramen magnum
~A. kadabba =
-more primitive than ramidus;
-When = 5.8-5.2 Ma (Late Miocene)
-Where = Africa
-kadabba = basal family ancestor
-Fossil characteristics =
very apelike teeth
; teeth and only a couple ot
Hominini: Australopithecus (genus)
-Primitive hominins that lived in Africa (in Pliocene and Pleistocene 4.2-1.8 Ma)
-retained ape-like features in teeth and ape-like small brains; bipedal but probably climbed trees and walked on ground; ate primarily fruit in woodlands and savanna
-ancest
Hominini: Paranthropus
Africa 2.5-1.4 Ma (Pleistocene)
-A. afarensis was probably an ancestor of this genus
-NOT OUR DIRECT ANCESTOR, BUT SHOW BREADTH OF EARLY HOMININ DIVERSITY
-paranthropus = beside humans
-By 3 Ma (end of Pliocene) rapid diversification led to this genus
-ak
Hominini: Homo
-Genus Homo evolved from a species of Australopithecus btwn 2.5-2 Ma (beginning of Pleistocene)
~H. habilis = on other slide
~H. rudolfensis =
- A species of early Homo from Africa that lived 1.9 million years
ago, with a brain size somewhat larger than H
Differences between Anthropoids (Haplorhini) and Prosimians (Strepsirhini)?
~Size
~Intelligence
~Eye sight
~Tooth patterns
~Locomotion
How to classify fossils into Linnean classification scheme?
...
Characteristics of Hominini vs. Apes
~Dentition = long narrow incisors (while apes are short and squat), no diastema, no projecting canines, jaw is parabola shape
~Locomotion = bipedal (foramen magnum right under skull while its more posterior on apes); apes are quadrapeds and associated wit
Bipedalism?
; -first arose 6-7 Ma around the time of the divergence of hominins and African apes as estimated from genetic data
-this is the first unique human trait that evolved (NOT BRAIN SIZE); evolved millions of years before the beginning of signi?cant brain exp
Fossil evidence: Quadruped
form of movement in which all four limbs are of equal size and make contact with the ground and spine if parallel to the ground
-walk on all fours
-new and old world monkeys and apes
Fossil evidence: Brachiator
A method of movement that uses the arms to swing from branch to branch
-associated with apes
Fossil evidence: Bilophodont
molar having two transverse ridges or crests
-Amphipithecus, Branisella, Oligopithecids
Fossil evidence: Prognathism
- Prognathism is an extension or bulging out (protrusion) of the lower jaw (mandible) that occurs when the shape of the face bones cause the teeth to be improperly lined up (misaligned)
-humans have orthognathic faces (faces that lie almost entirely benea
Fossil evidence: Larnex
-The larynx in pongids and early hominins is too short and high in the throat to produce the sounds used in human speech. The necessary length was acquired by 60,000 years ago, a time when other changes were occurring in cultural evolution.
-Ape larnex is
Fossil evidence: Nuchal crest
- nuchal crest is attached to muscles that hold the head upright
- the ridge at the back of the skull, just above the neck
-The nuchal crest is larger in apes than it is in humans because apes are mostly quadrupeds and have to keep their head from droopin
3 basic ideas of where we come from and the origin of life?
1) Creation: we were willed into existence by supernatural being; unacceptable in science bc it deals with supernatural and science only concerns natural phenomena
2) Biogenesis: idea that life arose from preexisting life; doesn't explain origin of life;
How does science view the origin of life today?
As an event that emerged at least once out of conditions that existed billions of years ago that were favorable to the buildup of organic molecules out of simpler protobiological compounds. The earth could have joined amino acids together to form protein
Why are early human fossil sites not common?
1) Humans existed in small numbers, reproduced slowly, and lived longer; there's a lot of marine fossil which reflects their abundance
2) Hominids have only been around about 6 million years; marine animals have been around for hundreds of millions of yea
Fossil sites where we might find human remains?
-Cave where corpse can be covered with dust, soil or mud and preserved
-Cave with fissure in back used as garbage dump where bodies were places
-Cave that is occupied a long time and the dirt and debris build up
-Some of the earlier sites are in the open
How and why are dating techniques used?
-Both relative and absolute techniques must be used
-used to date a site, artifact, or fossil
What fossil groups can be found in which sedimentary environments?
Terrestrial= spores, pollen; can find vertebrates or larger fossils only if sediment samples are large (this limits their use to outcrop samples); but using spore or pollen samples is limited bc the older they are, the more oxidation they have experienced
Where can we derive clues about past human evolution?
-fossil record
-archaeological record = evidence of past behaviors
-studies of genetic of living humans an nonhumans to create family trees
B.P. and B.C.; ka and Ma
-B.P. = Before Present; present is set as the year 1950; 800,000 years B.P. would be 800,000 yrs before 1950; internationally accepted
-B.C.= Before Christ;
("years ago" can also be used)
-ka = thousands of years ago
-Ma = millions of years ago
Brunhes-Matuyama Reversal
-780,000 yrs ago
-separated the current period of normal polarity (Bruhnes) from the previous time of reversed polarity (Matuyama)
How do you make species assignments with fossils when you don't have evidence of interbreeding?
must look at morphology of fossils and compare them with other fossils and living organisms
-if fossils are too different, they could be assigned to different species
Paleospecies
Species identi?ed from fossil remains based on their physical
similarities and differences relative to other species
-paleospecies relationship to biological species is subjective bcthe question of interbreeding is complex and not easily resolved from fos
Lumpers
Scientists who think the range of variation within species is often rather large and suggest that it therefore makes more sense to assign fossils to species already known than to create new categories
-usually believe in anagenesis
Splitters
scientists who believe in cladogenesis
anticipate numerous species at any point in time and tend to call any new fossil that is somewhat different a new species
Sources of variation WITHIN a species using fossils? Why do these variations pose problem?
-if you find fossils that differ in overall size/shape, you must consider sexual dimorphism instead of supposing they are different species
1) Difference between males and females = sexual dimorphism (ex: male gorillas have different sized skulls than fem
Difference between males and females in fossils
-Skull size
-overall size and shape of features on skull (males usually larger)
-Pelvis (BEST way to determine sex) bc women are capable of childbearing
Paleoecology and different methods associated with it
-the study of ancient environments
-can answer what early organisms ate, if they were predators or prey, what vegetation and water was available; the study of environments helps us infer behavior of past organisms
1) Palynology = study of fossil pollen; b
Tools and toolmaking. What fossils of tools can we find?
-many primates like chimps can make and use tools, not just humans
-the last common ancestor of humans and african apes, therefore, would also have this ability
- these skills were present throughout hominin evolution
---we can only find stone tools bc th
Experimental Archaeology
-?eld of archaeology that
involves the study of the
manufacture and use of
tools in order to learn how
they were made and used by
people in the past;
-helps infer behavior of past organisms
-can test efficiency of blades in different tasks, test what mate
Debate about which primate species should be used to provide insights into early hominin evolution
-Early studies focused on baboons: multi male/multi female society, male dominance, and, specifically, a similar savanna environment that was believed to be inhabited by first hominins (which isn't true); baboon behavior is actually very variable so they
Eons, era, period, epoch
-History of earth is divided into 4
Eons
which is a major subdivision of geologic time
-Eons are divided into
Eras
-Eras divided into
Periods
-Periods divided into
Epoch
Tetrapods
Vertebrates with limbs
Monotremes
egg-laying mammals that evolved during Triassic period of Mesozoic era
-ex: Platypus which still survives today
What caused mass extinction in Cretaceous period of Mesozoic era?
-most accepted hypothesis = asteroid or comet hit earth which kicked up vast clouds of dust blocking the sun; temperatures then dropped, plant forms became extinct; then plant eaters became extinct then carnivores
What events separated Precambrian from the Paleozoic era?
-Period of intense volcanic activity along edges of continental masses
-period of extreme mountain building and extreme fluctuations in temperature
-long process of erosion weathering down of uplifted surfaces and the consequent effects on sea levels on c
Continents during Paleozoic era
-Constantly shifting position, contour, and distribution of water on surface
-At times, North America was completely underwater and below equator
-South America, Africa, and Australia joined near south pole
-arrangement of continents during Paleozoic era
PALEOZOIC ERA
545-245 Ma; rapid diversi?cation and evolution of many complex multicelled organisms (Cambrian Explosion);
--*chordates, vertebrates, & mammal-lie reptilians appeared; there are fossil remains from this era representing all plant and animal phyla; no phyl
How amphibians evolved
-evolved as a lineage of fish attempting to retain an aquatic adaptation while the pools they lived in were slowly drying up
-Paleozoic era
CENOZOIC ERA
-After the mass extinction of dinosaurs 65 Ma; first bipeds appeared 6 million years ago and modern humans appeared 200,000 years ago
-BEGINNING = no humans or true primates;
Overview of Early Primate Evolution (All in Cenozoic era)
1) Adaptive radiation of primate-like mammals led to origin of true primates (Eocene epoch) that showed initial adaptation to life in trees; many of these species died out, but some evolved into primitive primates that were fully adapted to living in tree
Colugos
Group of mammals that living primates are closely related to
-gliding mammal; called "flying lemur"
-genetically very similar to primates (insect eating Tree Shrews are similar and are also closely related to primates)
Fossil evidence of early primate evolution
Evidence of primate ORIGINS come from deposits over 55 Ma in North America and Europe of a
group of insectivores known as primate-like mammals
-during early Cenozoic era, continents were in different position due to continental drift and that's why these
Continental Drift and how it effected primate evolution
The movement of continental
land masses on top of a
partially molten layer of the
earth's mantle that has al-
tered the relative location of
the continents over time
-continues today, North America is slowly drifting toward Asia
-First= Pangea (230 Ma); S
PRIMATE-LIKE MAMMALS (plesiadapiforms)
-First evidence of them seen in Paleocene epoch
-no larger than cats, quadrupedal (4 footed) mammal, arms/legs adapted for climbing
-lots of diversity in this group due to adaptive radiation (more than 120 species) especially in body size and dental speci
Carpolestes simpsoni
-Primate-like mammal; lived in Wyoming btwn 56-55 Ma
-small, arboreal, fruit eater, NO stereoscopic vision
-SIMILARITY TO PRIMATES = foot adapted for grasping and opposable big toe, nail not claw on big toe
-serves as model for primate origins and an inte
EOCENE EPOCH
-Climate= warm, humid, tropical, subtropical
-Continents = europe and north america still joined
-Mammals = many orders of modern day mammals appeared (whales porpoises, dolphins, rodents); general increase in diversity of mammals bc climate
- Fossil prim
Anthropoid origin
-Living anthropoids are more similar to tarsiers than to lemurs and lorises
-Identification of the first anthropoids and their relationship to fossil primates is not clear
-
We don't know
whether they first evolved in Asia or Africa
-However, there is evi
OLIGOCENE EPOCH
-Anthropoids went through adaptive radiation
-Major changes during this period = 1) appearance of first elephants with trunks; early horses; appearance of many grasses; mammals such as horses, deer, camel, elephants, cats, dogs, and primates began to domi
Most important characteristic of Oligocene primates
-The small eye orbits bc it shows they were
diurnal
- transition from a nocturnal lifestyle to a diurnal lifestyle was extremely important in the later evolution of the anthropoids
-Daylight living offers increased opportunities for social interactions be
Evolution of NEW WORLD MONKEYS
-Fossils = earliest fossils of New World monkeys date back to 25 Ma; mostly fragmentary dental remains; many resemble living New World monkeys, but some unusual ones don't have living counterparts
-Origin = there was single origin of anthropoids in the Ol
Anthropoid (Simiiformes)
-characterized by a relatively flat face, dry nose, small immobile ears, and forward-facing eyes, comprising humans, apes, Old World monkeys, and New World monkeys
-larger, more intelligent, better vision, social groups; diurnal
-Humans belong to this gro
Premolars in different primates?
-Eocene Prosimians = 4 premolars
-Modern Prosimians = 3
-New World Monkeys = 3
-Old World Monkeys, Apes, Humans = 2
Prosimians
type of primate that includes all living and extinct strepsirrhines (lemurs, bush babies, lorisoids, and adapiforms),[5] as well as the haplorhine tarsiers and their extinct relatives, the omomyiforms. They are considered to have characteristics that are
Simians
New World Monkeys, Old World Monkeys, Apes, Humans
When must a characteristic that's distinctive of a group have appeared?
characteristics that are distinctive of a group must have appeared
at or near the origin of that group
for all of them to have the trait
Characteristics of New World Monkeys
-Where they're found = from South Mexico to central South America except in high mountains
- Classified into 2 groups =
1) Callatrichids = very small; marmosets, tamarins, small mokeys with claws
2) Cebids = similar in size to Old World Monkeys; all the r
Oligopithecids
- catarrhines that make their first definitive appearance in the fossil record in the latest Eocene of Egypt
~P. Oligopithecus = bilophodont molar cusp pattern
MIOCENE EPOCH
-between 23.0 million
and 5.3 million years ago.
Several adaptive radiations
of hominoids occurred dur-
ing the Miocene, and the
oldest known possible* hom-
inins appeared during the
Late Miocene*
-Old World anthropoids continued to evolve into 2 branches
When did hominins appear? What was the time span of Hominins?
Late Miocene
-End of the Miocene epoch, the Pliocene epoch, and Pleistocene epoch
The oldest evidence for fossil hominoids
based on dental remains from old world sites in the Miocene Epoch
Eurasia
The combined
land masses of Europe and
Asia.
-during Miocene epoch
Monkeys vs. Apes
-Monkeys = bilophondont; quadruped; more genera and species; more diverse EXCEPT DURING MIOCENE
-Apes = 5-Y (lower molars have 5 cusps; brachiator; APES WERE VERY DIVERSE IN MIOCENE (diverse until the past 5-10 Ma, now the number of species has been decli
DIVERSITY OF MIOCENE HOMINOIDS
-Huge diversity in fossils of Miocene hominoids: dozens of species from Africa, Europe, and Asia (now there are way less); its probably even more diverse than we know
-Bc there were more species of Miocene hominoids in the past than alive today, many foss
Why have the number of apes declined and the number of monkeys ?ourished since the Miocene?
-the slow reproduction rate of modern apes and species dies out
Postcranial
Referring to
that part of the skeleton
below the skull.
Postcranial structure of Miocene Hominoids
-Not much evidence exists of miocene hominoid postcranial skeleton; most of it is dental and cranial features
-What there is of postcranial evidence, it shows characteristics different from those of modern apes.
-Overall, it appears that the postcranial s
General hominoid characteristics
-Superfamily of anthropoids consisting of apes and humans
-no tails
-larger than monkeys
-larger and more complex brains than monkeys
-provide more parental care
-share same 2-1-2-3 dental formula with Old World Monkeys
-lower molars of hominoids have 5 c
Diastema
A gap next to the
canine tooth that allows
space for the canine on the
opposing jaw
-ape jaws have this
-allows jaws to close
LATER MIOCENE HOMINOIDS
-Btwn 17-14 Ma, climate became drier and seasons more pronounced
-Fossil Record = provides evidence ( Figure 9.8 ) of a number of new ape species arising when climate changed in later miocene
-Continental Drift Effect = After the time that Africa and Eura
Orangutan ancestors
-Sivapithecus
-Gigantopithecus
Pierolapithecus
-Another possible common ancestor is fossil ape Pierolapithecus which could actually be Dryopithecus;
-pierolapithecus lived in spain 13 Ma
-specimen consists of both a cranium and a partial skeleton
-The post-cranial anatomy shows a mixture of monkey and
Ape and Human common ancestors
-Dryopithecus
-Ouranopithecus
-Pierolapithecus
---these suggested common ancestors of African apes
and humans are all European fossil apes;
~~ most likely explanation is that as the climate changed and Eurasian apes became extinct, some dispersed back int
MIGRATION OF MIOCENE HOMINIDS
we can then see the evolutionary history of many Miocene apes as an initial dispersion from Africa into Eurasia, a subsequent extinction of most Eurasian forms other than those ancestral to modern Asian apes and those that dispersed back into Africa befor
Molecular dating
The application of methods of
genetic analysis to estimate
the sequence and timing of
divergent evolutionary lines
-compare genetics of living organisms from different species using this technique can show the evolutionary relationship among them and prov
What happens when 2 species separate from a common ancestor?
When two species separate,
mutations occur, and neutral mutations accumulate in each line independently. If the rate of accumulation is constant in both lines, then a comparison
of molecular differences in living forms will provide us with a relative idea
How old are human beings?
--Humans who are anatomically same as modern humans = 200,000 yrs
-- all large-brained
humans, even those with a somewhat different skull shape = several hundred thousand years
--all members of the genus
Homo, with some significant cranial expansion and a
First major increase and brain size and first use of stone tool technology?
2.5-2 Ma (Pliocene and Pleistocene)
First appearance of brain size roughly equivalent to human beings?
the past few hundred thousand years
First appearance of modern cranial shape of human beings?
past 200,000 yrs
When humans began to rely on agriculture?
12,000 yrs ago
When 1st civilization and complex state-level societies appeared?
6,000 yrs ago
Homo sapiens (anatomically modern humans )
-reached Australia by 60,000 years ago and the New World 15,000-20,000 years ago. Starting 12,000 years ago, human populations in several different places developed agriculture, and the human species began to increase rapidly in number. Cit-
ies and state
Different models of origins of bipedalism
-Bipedalism probably originated bc all of these things played a role
1) Tool use model
= Darwin; as tool use increased and became more important, natural selection led to larger brains and enhanced
learning abilities. As larger brains evolved along with l
Early hominins
Location= only Africa; support Darwin's idea of African being birthplace of humans; mostly south and east africa (Chad, Ethiopia, Kenya, Tanzania, South Africa)
Environment = woodlands and tropical grasslands for the most part. Not until later in hominin
Foramen Magnum
The
large opening at the base of
the skull where the spinal
cord enters. This opening
is located more toward
the center of the skull in
hominins, who are bipeds,
so that the skull sits atop
the spine
What does A. ramidus tell us about how bipedalism evolved?
-the common ancestor of African apes and humans is probably a climber, but a different kind of climber
-also tells us that both african apes and humans have diverged considerably from a common ancestor
GENERAL CHARACTERISTICS OF AUSTRALOPITHECUS
-we count them as hominin bc they're
biped
-less primitive than Ardipithecus and overall is more similar to Homo
-small apelike brain but larger than Ardipithecus, large face (apelike)
-smaller canines, large molars w/ thick enamel (human like)
-@ least 5
Dental characteristics: Apes vs. Humans; Intermediate dental condition of A. afarensis??
Apes = canines of apes are
generally large and protrude past the surface of the other teeth; jaw has diastema; lower premolar is pointed and has one cusp so it will sharpen upper canine
Humans = small, non-projecting, rather puny canines; no diastema; pre
Dental characteristics of later Australopithecus
-teeth were barely apelike; still larger than modern humans though
Did Australopithecus use tools?
-Butchered animal bones found near Australopithecus garhi show distinct stone tool cut marks and suggests that species used stone tools 2.5 Ma
Zygomatic arch
- The cheekbone, formed by the connection of the zygomatic and
temporal bones on the side
of the skull
-the cheekbone and skeleton anchor masseter muscle
-In hominins with large jaws and large masseter muscles (Paranthropus) , the face and zygomatic arch
Sagittal crest
A ridge of bone running down the
center of the top of the skull
that serves to anchor chewing muscles (temporalis muscle)
-found in Paranthropus
- ridge at the top of the skull. It goes from the top of the forehead to the back of the head along the top
Paranthropus : isotope analysis of their teeth
- reveals that they had a more diverse diet
- In addition, microscopic analysis of wear on their teeth shows
that they did not regularly eat hard objects but often had a softer diet typical of other hominins
- These results suggest that the powerful chewi
Why did Paranthropus become extinct?
-competition from genus Homo
GENERAL CHARACTERISTICS OF GENUS HOMO
-Evolution of this genus occurred in Pleistocene abt 2 Ma;
-a little less than 2 Ma, Homo habilis and Homo erectus existed
- A genus of hominins
characterized by large
brain size and dependence
on culture as a means of
adaptation and use of stone tools
-r
HOMO HABILIS
~H. habilis = -characterized by increase in brain size relative to earlier hominins and widespread manufacture and use of stone tools;
-earliest species of Homo; Africa 1.9-1.44 Ma (pleistocene) (may have existed earlier)
-MORE SIMILAR TO HUMANS THAN RUDO
Oldwan tradition
-the oldest known stone tool cuture
-relatively simple chopping tools
made by striking several ?akes off a rounded stone to give it a rough cutting edge. These tools were normally made from materials such as ?int, obsidian, or quartz. The stone core was h
Endocast
A cast of the
interior of the brain case
used in analyzing brain size
and structure
Evolutionary Relationships of H. habilis and H. rudolfensis
H. habilis
~REPRESENTS TRANSITION FROM AUSTRALOPITHECUS TO LATER LARGER BRAINED SPECIES IN GENUS HOMO;
~ This transition consisted
of a slight increase in brain size and a slight reduction in dental and facial size. Based on the postcranial skeleton, H. h
Why and when did thicker enamel evolve?
-Bc adaptation for biting and crushing hard foods
-appeared for the first time in hominoids during middle Miocene