ANT 2511 Exam 3

Bipedalism: The bipedal macaque

Israeli zoo, Safari Park Natasha, a 5 year old macaque almost died of severe stomach flu and after surgery started walking bipedally

Skeletal indicators of bipedalism: S-shaped spine

2 types of hominid spine -Great apes have a straight back -humans have an S

brains got bigger

2-2.5 mya

The Earth is about ______ years old.

4.6 billion

When did the great apes and hominids split?

7-10 mya miocene period

The first hominids appeared in Africa about _______.

7-6 MYA

"Locomotion first" vs. "brains first" theories of human evolution

-(this is the right one) Locomotion first: ape->bipedal age->intelligent bipedal age (large brain)-> human -Brains first: ape->intelligent ape->bipedal intelligent ape->human

Radiocarbon C14 dating: What kind of material does it work on?

-All living things take in carbon, including a small (but knowable) amount of carbon-14

Skeletal indicators of bipedalism: arched feet

-Big toe (hallux) enlarged and nonopposable(??) - longitudinal arch forms to better support weight

Skeletal indicators of bipedalism: basin shaped pelvis, (also know impacts on birthing with bipedal pelvis shape)

-Bipedalism creatures have short, broad, and basin or "bowel" shaped pelvis our intestines sit in - out joints are bigger, asatabula twice as apes -our joints are also more robust, heavy duty -gorillas have massive abs, keeps gut in -

Relative dating techniques: Fluorine dating and Cultural dating

-Bones that have been buried for a long time absorb more fluorine than bones that are more recently buried. - This use of fluorine concentration in bones is one of the first uses of chemical dating, and was used by Croatian paleontologist Dragutin Gorjanović-Kramberger to demonstrate that Neandertal fossils found in Krapina, Croatia, lived at the same time as the bones of extinct rhinoceros and cave bears. -Cultural: Over the 2.6 million-year-old history of material culture made by humans, certain types of tools have been invented at certain times. -By finding these tools, shown here, in particular strata, one can infer the relative age of the other fossils in the same layer of rock. For instance, discovering a fishing spear (bottom right) in a layer of strata would imply a relatively recent age, whereas Oldowan choppers (upper left) imply a much older age, perhaps as old as 2 million years. Keep in mind, though, that the presence of these cultural artifacts do not tell us the absolute age of the rock, only the relative age. But, what we are really interested in is not relative dating, but absolute dating.

Radiocarbon C14 dating

-Carbon usually has an atomic mass of 12 (six protons and six neutrons). But, occasionally, carbon has two extra neutrons and exists as carbon-14. Carbon-14 is radioactive and decays into nitrogen-14 (which has seven protons and seven neutrons). The key to using this as a dating device is that the decay of carbon-14 to nitrogen-14 happens at a constant and predictable rate.

Steno's Law of Superposition

-Danish scholar living in the 1600s named Nicolaus Steno (or Niels Stensen). -Steno studied geological formations around Italy and collected the fossils contained in these stratigraphic layers. He deduced that the higher rocks were younger than the lower rocks. This sounds quite obvious, but this logical observation by Steno is the foundation of what is called "relative dating" in which one event can be determined to be younger or older than another based on its relative position in the stratigraphic column - The chemical composition of sediments can be compared across vast areas, allowing scientists to make what are called stratigraphic correlations between rocks in different areas of the world, which must have been deposited at the same time.

What is a protohominid and how are these different?

-Earliest members of the hominid lineage-barely represented in the fossil record, ancestors of hominids -structure and behavior reconstructed hypothetically

What kinds of rock are fossils found in and why?

-Fossils generally form in sedimentary rock in which tiny bits of rock, sand, and soil are carried either by wind or water and bury the bones of dead animals

East African australopithecines: Australopithecus anamensis 4.2-3.9 mya

-Kenya and Ethiopia lake draram? -What kind of environment did it prefer? -When was the hominid alive? -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. )lake draram? -is the hominid represented by a famous specimen (e.g. Lucy) -Who discovered the hominid? Meave Leakey 1994 -Is the hominid gracile or robust? -What are some of the general features unique to the hominid? U shaped teeth row, thick molar enamel (fruit and foliage), facial prognathism, tibia displays adaptations for bipedalism -Where does the hominid fit into the scheme of human evolution? number one on chart

Skeletal indicators of bipedalism: foramen magnum position—centered (anterior) vs. toward the back (posterior)

-Positioned further forward (anteriorly) under skull in the middle (this arrangement is exclusive to us) -Apes have it in the back -latin for big hole, how spinal column connects to brain

Argon dating: the "clock in a rock"- half life

-argon and potassium have a half-life of 1.3 billion years -Volcanic rock contains the radioactive isotope potassium-40, which decays into the stable gas, argon. When a volcano erupts, it lays down a bed of ash that contains potassium-40, but the heat of the volcanic eruption expels all of the argon. Over time, fossils are formed in strata that are sandwiched by layers of volcanic ash. This ash, which has contained radioactive potassium that slowly, but surely, decays into argon gas, can be directly dated by measuring the ratio of radioactive potassium still in the rock to the amount of argon gas trapped in the crystalline structure of the rock. This idea is known as a "clock in a rock." Fossils themselves are not dated using radiopotassium dating. Instead, the volcanic layers surrounding the fossils are dated. This technique has recently been revised to a method called argon-argon dating, though the basic idea is the same

Radiocarbon C14 dating: how far back can it date things

-carbon dating cannot be used reliably for anything older than about 50,000 years since all the carbon-14 will be gone

Radiocarbon C14 dating: What element is being used?

-carbon-14 and nitrogen-14 -Carbon usually has an atomic mass of 12 (six protons and six neutrons). But, occasionally, carbon has two extra neutrons and exists as carbon-14. Carbon-14 is radioactive and decays into nitrogen-14 (which has seven protons and seven neutrons).

Skeletal indicators of bipedalism: lower limb features: enlarged femoral head, knee angled inward, short toes

-enlarged head of femur -knee angled inward (valgus=we don't move side to side when we walk, so we don't waste calories) -short toes -long hindlimbs

What kinds of conditions give the best chance for fossilization to occur?

-happens at the molecular level, replacing the calcium and phosphorous in bones and teeth with the minerals found in the surrounding rock, like iron and silica. Importantly, this is not an all-or-nothing process and thus there are many fossils that still preserve the original chemicals of the body, allowing researchers to reconstruct ancient diets and environments. The most likely anatomies to fossilize are the harder structures in the body: bones and teeth. -forest sediments often have quite acidic soil, which is not good for bone and tooth preservation. We therefore have a fossil record that is biased against forest-dwelling animals—an unfortunate thing for us since primates tend to live in forests.

East African australopithecines: Australopithecus afarensis (Lucy, The Laetoli footprints)

-where in Africa did the hominid live? -What kind of environment did it prefer? -When was the hominid alive? -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. ) -is the hominid represented by a famous specimen (e.g. Lucy) -discovered by Donald Johansen -Is the hominid gracile or robust? -What are some of the general features unique to the hominid? 40% complete, not all bones found. all one individual mature adult, about one meter tall (3.2 feet), valgus knee, sexual dimorphism brain size 430 cc -Where does the hominid fit into the scheme of human evolution?

Earliest consensus hominid - Ardipithecus kadabba

-where in Africa did the hominid live?: Ethiopia, west side of fertile -What kind of environment did it prefer? -When was the hominid alive?: 5.8-5.5 mya -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. ) Rift Valley Ethiopia -is the hominid represented by a famous specimen (e.g. Lucy) -Who discovered the hominid?: Tom White -Is the hominid gracile or robust? -What are some of the general features unique to the hominid?: Bipedal, earliest consensus human ancestor, post cranial 1 vertebrae down -Where does the hominid fit into the scheme of human evolution?

Earliest consensus hominid - Ardipithecus ramidus

-where in Africa did the hominid live?: Middle Awash (ethiopia) -What kind of environment did it prefer? woodland -When was the hominid alive? 4.4 myo -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. ) -is the hominid represented by a famous specimen (e.g. Lucy): Ardi, announced october 2009, female, 4 ft tall, 120 pounds, long arms, short legs, flat feet, teeth suggest omnivorous diet, leg bones prove bipedal woodland seeds petrified wood BIPEDALISM DID NOT DEVELOP IN SAVANNAH AS PREVIOUSLY THOUGHT -Who discovered the hominid?: Tim White, at least 36 of them ( 145 teeth) -Is the hominid gracile or robust? -What are some of the general features unique to the hominid?: bipedal. Skull resembles Sahelanthropus, last human/ape ancestor did NOT look like any modern ape indicates much occurred between ardi(4.4mya) and Lucy (3.2 mya), arch feet, nonaposable big toe evolved 4.4-3.2 mya, forest shrinking biped becomes more refined -Where does the hominid fit into the scheme of human evolution? HE WAS NUMBER 1

Protohominids: Orrorin tuganensis

-where in Africa did the hominid live?: Tugen hills, kenya -What kind of environment did it prefer? -When was the hominid alive?: 6mya -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. ) -is the hominid represented by a famous specimen (e.g. Lucy) -Who discovered the hominid? -Is the hominid gracile or robust? -What are some of the general features unique to the hominid?: leg bones look bipedal. Human like teeth (small canines and thick enamel) grove on femural neck (leg), modern human orrain, short neck on chimp -Where does the hominid fit into the scheme of human evolution?

Argon dating: the "clock in a rock"-What is the time period to which it can date?

...The time period is 50,000+ years. I assume the limitations are it can only date hominids which are surrounded by the volcanic layers contain argon gas.

About when did the Australopithecine lineage go extinct?

1 mya

Where have fossil remains of genus Australopithecus been found?

Africa only

The Piltdown hoax—what effect did it have on the development of paleoanthropology? - Bipedalism

Charles Dawnson pretended to find remains of creature with ape like jaw and teeth but with a big brain, later found to be fake and from different animals. -set paleoanthropology back 40+ years bc no one wanted to believe scientists

What was Darwin's theory about the split between hominid and ape?

Darwin speculated that upright walking freed the hands to make and use tools, which led to increased cleverness. His ideas were impressive in light of the fact that they came without the rich fossil record that is known today, or the knowledge of the gene.

Charles Lyell is considered the father of vertebrate paleontology.

False

Radiocarbon dating relies oin an element that has a half-life of 5,730 years. Therefore, it is a useful technique to date materials that are millions of years old.

False

Evidence that genus Orrorin was bipedal comes mainly from which part of the skeleton?

Femur

What is a fossil?

Fossils are physical evidence for life that no longer exists. They, therefore, are very strong evidence for evolution, which hypothesizes that there must have been organisms, similar to, but different from, the inhabitants of Earth today.

Bipedalism: How is bipedalism in hominids distinct from that of birds and kangaroos?

Hominids use one foot at a time, while birds and kangaroos hop on both feet for each step they take

Dendrochronology

In the 1920s, an astronomer by the name of A. E. Douglass discovered that the seasons caused trees to suspend their growth in the winter and resume it in the spring. This resulted in an annual formation of a discernible tree-ring and a pattern of tree-rings in a cross-section of a fallen tree. Because each ring corresponds to a year, and the pattern corresponds to the local environment, the tree ring patterns can be overlapped with one another, as is shown here, and used to literally count, year-by-year, back in time.

What makes a hominid?

Members of the family Hominidae that occurred after the split from African great apes

The ________ tradition includes the oldest recognizable cultural artifacts--simple stone tools dating to about 2.6 million years ago.

Oldowan

Argon dating: the "clock in a rock"- why is it useful for dating hominids?

Potassium Argon dating is effective for sites over 100,000 years in age and has been widely used in dating Pliocene and Pliestocene events. It is widely used in paleolithic archaeology and paleoanthropology and has been most widely used for dating early hominin sites where hominin activity can be found stratagraphicly between two lava flows. It has been used particularly in East Africa. The most famous of these site are most probably Bed I of Olduvai Gorge which represents one of the earliest applications of the methods, and also at Hadar in Ethiopia, famous for the discovery of Lucy the Australopithecus afarensis.

Relative versus absolute dating techniques—how they differ

Relative is a guesstimate absolute is specific - what we are really interested in is not relative dating, but absolute dating. Scientists do not just say that dinosaurs lived before humans did, they say that dinosaurs lived up to 65 million years ago, and the first human ancestors are not found until about 6 million years ago.

At which site would you be most likely to recover fossil remains of Australopithecus africanus?

Sterkfontein, South Africa

Radiocarbon C14 dating: Half-life

The key to using this as a dating device is that the decay of carbon-14 to nitrogen-14 happens at a constant and predictable rate. In fact, half of the radioactive carbon in a substance will decay into nitrogen in 5,730 years. All living things take in carbon, including a small (but knowable) amount of carbon-14. While the organism is alive, the ratio of carbon-12 to carbon-14 is the same. But, once the organism dies, the carbon-14 begins to decay into nitrogen-14. The longer it has been dead, the less carbon-14 it will contain. If the bone contains half carbon-14 and half nitrogen-14, then it is 5,730 years old (the half-life). If it contains 25% carbon-14, then it is 11,460 years old. Notice that it will not take too long before the carbon-14 has completely decayed and is gone. In fact, carbon dating cannot be used reliably for anything older than about 50,000 years.

Which US President reported the discovery of a fossilized ground sloth in Virginia to the American Philosophical Society?

Thomas Jefferson

In terms of geologic time, when did humans appear on Earth?

Very recently

The English surveyor who developed the technique of stratigraphic correlation between regions was

William Smith

What is taphonomy?

an entire science that devotes itself to the study of what happens to an organisms' remains after death -ex. A hominid who has died on a lakeshore begins to decay as bacteria and fungi consume the soft tissues and organs of the individual. If the circumstances are right, the lakeshore sediments may bury the bones, though often these bones are moved around by the water, or parts of the skeleton are dragged away by scavengers. The sediments at the bottom of the lake replace the minerals in the bones and teeth, slowly turning bone to stone, as more and more sediment is deposited over time, creating layers, or strata. But, the building sediment can also prove problematic, as the pressure of building sediment can crush, twist, and distort fossils. A change in the environment, or geological activity that causes this ancient lakebed to elevate and erode, exposes these old layers of rock, and bring old bones back to the surface for discovery. The circumstances just described are rare and have to be just right for a fossil to not only form, but be found.

Radiocarbon C14 dating: limits of radiocarbon dating

cannot be used on things that have never lived, or more than 50,000 years old. assumes same amount of carbon 14 present today same amount present in the past

Among the living apes, which is humanity's closest relative?

chimpanzees

East African australopithecines: Australopithecus (Kenyanthropus) platyops

flat face man of kenya, where in Africa did the hominid live? -wodland habitat -3.5 mya -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. ) Lake turkana -is the hominid represented by a famous specimen (e.g. Lucy) -discovered by Meave Leakey -Is the hominid gracile or robust? -What are some of the general features unique to the hominid? flat face with some primitive characteristics -Where does the hominid fit into the scheme of human evolution? no one knows what to do with it

Why is the fossil record biased against forest dwelling animals?

forest sediments often have quite acidic soil, which is not good for bone and tooth preservation. We therefore have a fossil record that is biased against forest-dwelling animals—an unfortunate thing for us since primates tend to live in forest

East African australopithecines: Australopithecus garhi- what does garhi mean? What was found alongside this specific hominid?

garhi means surprise -where in Africa did the hominid live? -What kind of environment did it prefer? -When was the hominid alive? -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. ) -is the hominid represented by a famous specimen (e.g. Lucy) -Who discovered the hominid? -Is the hominid gracile or robust? -What are some of the general features unique to the hominid? -Where does the hominid fit into the scheme of human evolution?

Bipedalism: "habitual"/obligate bipedalism

hominids do this. we constantly are walking on two legs

In addressing the origin of bipedalism, Charles Darwin focused on the impact of ________.

hunting

Skeletal indicators of bipedalism: Valgus angle

knee angled inward (valgus=we don't move side to side when we walk, so we don't waste calories)

Protohominids: Sahelanthropus tchadensis

oldest possible hominid species -hominid live?: Chad, central/northern Africa -What kind of environment did it prefer?: -When was the hominid alive?: 7-6 mya -Which, if any, famous site is associated with the fossil finds? (i.e. Lactoli, Bouri, etc. ) -is the hominid represented by a famous specimen (e.g. Lucy) -Who discovered the hominid?: Michael Brunet -Is the hominid gracile or robust? : -What are some of the general features unique to the hominid?: small brain 350 cc. Hominid like teeth. little prognathism (degree to which lower face goes forward, snout bc size of teeth). less prognathic is derived (Primitive traits are those inherited from distant ancestors. Derived traits are those that just appeared (by mutation) in the most recent ancestor -- the one that gave rise to a newly formed branch.) not known whether it was bipedal. S. tchadensis has many primitive apelike features, such as the small brainsize, along with others, such as the brow ridges and small canine teeth, which are characteristic of later hominids -Where does the hominid fit into the scheme of human evolution?:

Hypotheses of the origin of bipedalism: freeing hands, running after game, looking over tall grass, keeping cool, ability to make tools, and sexual display. Know which one's Prof. agrees with.

prof agrees with freeing hands

In what kind of rock are fossils usually found?

sedimentary

which of the following is NOT an absolute dating method?

stratigraphy

Which of the following body parts has the best chance of fossilizing?

teeth

Dendrochronology relies on a record of tree rings.

true

Sahelanthropus is the oldest known potential hominid genus.

true

Using direct radiometric dating of ____ provides very accurate dating for many East African Rift Valley hominid sites.

volcanic rocks