Ch.5 Flashcards
Compare and contrast microevolution and macroevolution.
Macroevolution: a subfield of evolutionary studies that focusses on long-term evolutionary changes, especially the origins of new species and there diversification across space and over millions of years of geological time.
Microevolution: subfield of evolutionary studies that devotes attention to short term evolutionary changes that occur within a given species over relatively few generations of ecological time.

What are the two lines of evidence used in macroevolutionary studies?
Phyletic gradualism: A theory arguing that one species gradually transforms it self into a new species overtime, yet the actual boundary between species can never be detected but only drawn arbitrarily. For Darwin this process is called anagenesis: The slow, gradual transformation of a single species overtime.
Punctuated equilibrium: A theory claiming that most of evolutionarily history has been characterized by relatively stable species coexisting in an equilibrium that is occasionally punctured by sudden burst of speciation, where extinctions are widespread and many new species appear. Such that drastic changes in the natural environment trigger extinction and speciation by destroying habitats and breaking reproductive communities apart.
What is a hominin? 
Outline the four major trends in hominin evolution.
The African great apes and humans together as hominoids; and within the hominoid category, they separate out humans and other bipedal species, who are classified together as hominins.
Briefly sum up the four different sorts of selective pressure that may have favoured bipedal locomotion in hominoids.
•Moving easily on the ground might have improved hominoids’ ability to exploit food resources outside the protective cover of the shrinking Miocene forests. 
•Upright posture would have made it easier for them to spot potential predators in open country.
•Skilful bipedal locomotion would have made it easier for them to escape.
•Walking up right simultaneously reduces the amount of skin surface exposed to the sun, allows greater distances to be covered.
•Walking would have enabled the first hominins to cover long distances between widely scattered sources of plant food or water. 
What is the earliest evidence of bipedalism?
The earliest evidence of Hominin bipedalism comes from the 3.6 million a year old fossil foot prints preserved in hardened volcanic ash at Laetoli, Tanzania. Before 3.6 mya.
Who are the oldest known hominins? Where are they found?
The oldest known Hominins are the australopiths and their fossils come from Africa. Some dating back into the Miocene.
Consisting of Ardipithecus, Australopithecus, and Paranthropus. 
Briefly describe how some features of the skeleton Au. (Australopithecus) afarensis reveal it’s adaptation to bipedalism (I.e., Three key differences between apes and humans.) 
• The spinal column of an ape joins its head at the base of the skull, as is normally the case in quadrupedal animals. This is revealed by the position of a large hole, the foreman magnum, through which the spinal cord passes on its way to the brain.
•The ape pelvis is long and broad, and the knee is almost directly in line with the femur (or thighbone) and therefore ill-adapt to support the apes centre of gravity when it tries to move on it’s hind legs. As a result, when apes walk bipedally, they appear to waddle in an awkward attempt to stay upright.
•The great toe of the ape foot diverges like a thumb from the rest of the digits, a feature that allows apes to use their feet for grasping but inhibits their ability to use their feet for the push off so important for effective bipedalism.
• By contrast, the modern human head balances on top of the spinal column. The foreman magnum in humans is located directly beneath the skull rather than its back.
•The basin-shaped human pelvis is the body’s centre of gravity, supporting and balancing the torso above it.
•The bones of human legs have a knock-kneed appearance, with the femur pointing inward toward the knee joint at the valgus angle. As a result, humans can easily transferred their centre of gravity directly over the stepping foot during bipedal walking.
The skeleton of Au. closely resembles that of modern human beings than that of apes.
•Great toes were generally in line with each other toes.
•It’s femur bent inward toward the new joint at the Valgus angle.
•It’s pelvis was short and basin like.
•The skull balanced on top of the spinal column.
-Nevertheless, elements of the postcranial skeleton still identified it’s recent ape ancestry. 
•Longer arms in proportion to its legs than any other hominin.
•The bones of it’s fingers and toes are slightly curled, and the toes are much longer, resembling the finger and toe bones of apes. 
-Because these features are related to the typical tree climbing adaptation of most hominoids, some paleoanthropologists have concluded that Au., must have had significant tree climbing ability along with bipedalism. 
Compare and contrast ape dentition to human dentition.
What is the shape of the dental arch for each?
What is a diastema?
Do both groups have diastema?
What are the largest teeth for each group?
Apes dentition- Is a U-shaped dental arch that is longer front to back then it is side to side.
Human dentition- The human dental arch is parabolic, or gently round it in shape and narrower in front than in back.
Diastema (plural: diastemata) A space in the tooth row for each canine of the opposite jaw to fit into when the jaws are closed.
Apes have large, sexually dimorphic canine teeth that project be on the tooth row, and they possess diastemata.
Human canine teeth do not project beyond the tooth row and show little sexual dimorphism, and have no diastemata.
The canines are the largest of the teeth for apes.
The molars are the largest teeth for humans. 
What are the two main grouping of Australopithecus? 
Gracile and robust australopiths
Gracile:
• Smaller, more lightly built faces
•Small front teeth and large cheek teeth
• Bipedalism
• Foramen magnum is found directly underneath the skull
•Highly dexterous hands despite having slightly longer and rounded fingers. 
robust:
•More rugged jars, flatter faces, enormous molars, Sagittal crests.
• Bipedalism
• Foramen magnum is found directly underneath the skull
•Highly dexterous hands despite having slightly longer and rounded fingers.
What is the key criterion they use to place a gracile fossil within the genus Homo?
Cranial capacity.
The cranial capacities of these early hominin prices range from 510 to 750 cm³.
Larger brains resided in larger, differently shaped skulls. Compared to more elongated australopiths cranium, the cranium of early homo has thinner bone and is more rounded; face is flatter and smaller in relation to the size of the cranium; and the teeth and jaws are less rugged, with a more parabolic arch. 
Is the increase in the brain size (I.e, cranial capacity) accompanied by a marked increase in body size? What does this mean?
Early homo’s expansion in the brain size was not accompanied by a marked increase in body size, meaning that the enlarged brain was a product of natural selection.
The most significant changes occurred in our lateral cerebellum (located below the larger cerebral cortex), which allowed us to improve our memory and learning abilities.
What is the earliest evidence of culture?
The oldest undisputed stone tools or at least 3.3 million years old, found at Lomekwi in Kenya. 
Briefly describe the oldowan tradition.
A stone to traditional named after the Olduvai Gorge (in Tanzania).
Consisted of cores (Tennis ball sized rocks with a few flakes knocked off to produce cutting edges) and flakes (Chipped off pieces of rock that may or may not have been used a small cutting tools). 
The tools are extremely simple.
What do palaeoanthropologist who specialize in stone tool analysis often use to examine stones and bones for evidence of human activity?
Taphonomy- The study of various processes that objects undergo in the course of becoming part of the fossil an archeological records.
For example stones used as tools, have characteristic manufacturing scars and wear patterns along their flaked edges. Flaked rocks that lack these identifiers are not usually considered to be tools unless they’re unmistakenly associated with other evidence of human activity. 
Briefly describe the main points of shipman and colleagues’ examination of carnivore tooth marks and stone cut marks and subsequent argument that the Olduvai hominins were scavengers rather than hunters.
Shipman learned how modern hunters butcher animals and discovered that carnivore tooth marks and stone cut marks on fresh bone looked very different under the scanning electron microscope. 
(1) Fewer than half the cut marks seemed to be associated with meat remove all. 
(2) The stone to cut marks and carnivore tooth marks showed basically the same pattern of distribution.
(3) Nearly 3/4 of the cut marks occurred on bones with a little meat, suggesting they resulted from skinning.
(4) In eight out of 11 cases where cut marks and tooth marks overlapped, the cut marks were on top of the tooth marks.
Taken together, these patterns suggested that, rather than hunting for meat, Olduvai hominins regularly scavenged carcasses killed by carnivores, taking what they could get.
