anthro 105 uw-madison exam 4

Two to four million years ago, hominins diversified into many different species, but what characteristics did most of these species have in common?

Small brains, skilled upright walking, retain tree-climbing ability, chimpanzee-sized with pronounced body size dimorphism, reduced canine dimorphism, and large molars.

What do we know about the cranial and postcranial features of Australopithecus anamensis?

Bipedal evidence; tibia, long arms and curved finger, canines smaller than modern apes

What do we know about the cranial and postcranial features of Australopithecus afarensis?

Smaller canines, larger molars than Au. anamensis, slightly larger brains than a chimpanzee, bipedal adaptations in spine, hip, knee, ankle, and foot, body size dimorphism, more u-shaped dental arcade than humans, a smaller diastema compared to chimpanzees, some dimorphism in canines, and molars similar to chimpanzees.

What do we know about the cranial and postcranial features of Australopithecus africanus?

Foramen magnum = bipedal, small canines, challenged large brain first idea, cranially like Au. afarensis - bigger molars, smaller canines, bipedal, large size dimorphism, and rapid tooth development.

What do we know about the cranial and postcranial features of the Paranthropus genus? List Paranthropus species, but know common features throughout the genus.

Paranthropus aethiopicus, Paranthropus boisei, and Paranthropus robustus are the species. Cranial adaptations are: enormous back teeth, sagittal crests, large temporalis muscles, and huge cheekbones (zygomatic arches). Postcranial features are bipedal, sagittal crest (for Paranthropus aethiopicus), hyper-robust (for Paranthropus boisei), and cranial/dental adaptations for heavy chewing (for Paranthropus robustus). Additional evidence for extended growth in males, leads to older males being significantly larger than younger males and females.

What can we learn from the Laetoli footprints and Australopithecus afarensis foot morphology and bipedalism?

The big toes of Au. afarensis are more like humans than chimpanzees, provides some of the oldest evidence known for upright bipedal walking, some tree climbing is seen based on fingers and scapula.

Describe the evidence for Paranthropus bone tool use? How do we know that these tools were likely used to dig for termites?

Modified bones at Swartkrans Cave in South Africa used by Paranthropus robustus, most likely to forage or dig for termites. Microtopography of use-wear on the tips of experimental bone tools used to dig in termite mounds; through repeated use, the ends of these tools became rounded and polished.

Define Australopithecus anamensis.

Primate found 4.2 to 3.9 mya in Ethiopia/Kenya; showed evidence of bipedalism (tibia and parallel ankle joint act as evidence) and had small canines.

Define Australopithecus afarensis.

Early Australopithecine from East Africa that had a brain size equivalent to a modern chimpanzee's and is thought to be a direct human ancestor.

Define sexual dimorphism (including canine dimorphism and body size dimorphism).

Body size dimorphism is the difference in size within a species between male and females. Canine dimorphism is the difference in size of canine teeth between males and females.

Define diastema.

Gap between teeth to make room for large canines, outside where canines and premolars erupt.

Who is "Lucy"? Why is she important?

A 40% complete Australopithecus afarensis fossil. She was important because she is the first fossil to show human-like bipedalism (non-divergent hallux).

Who was the "Dikika Child"?

The 3.3 mya juvenile fossil of a three-year-old Australopithecus afarensis female, suggested more climbing by juveniles and rapid maturation. Bipedalism suggested tree climbing, thyroid bone is chimpanzee-like, and brain suggests slower maturation.

Define hydroid bone.

The u-shaped bone at the base of the tongue that supports the tongue and its muscles; critical for language.

What were the Laetoli footprints?

Found 3.7 mya, evidence that Lucy and other specimens had a walking foot and a big toe in line with other toes.

Define Australopithecus africanus.

Primate - existed 2.2-3.0 mya in woody grasslands. Cranially similar to Au. afarensis (bigger molars, smaller canines). Bipedal with large body size dimorphism and rapid tooth development.

Who was the "Taung child"?

The first Australopithecine found, discovered in 1924 in South Africa and identified as Australopithecus africanus. Had a small brain case, high levels of prognathism, small canines, a foramen magnum (signifying bipedalism) and large teeth, but proportions similar to modern humans. Challenged the idea that large brains developed first.

Define saggital crest.

A bony projection on top of the cranium, meant for the attachment of chewing muscles.

Define Paranthropus genus.

Existed approximately 2-1 mya in Eastern Africa, signifies the beginning of brain size increasing. No evidence of tool use.

Define zygomatic arch.

The bridge of bone (cheekbone) extending from the temporal bone at the side of the head around to the maxilla (upper jawbone) which allowed for the attachment of neck muscles.

Define temporalis muscle.

The muscle on the side of the head that moves the mandible upward and backward.

As we have seen during other major events in primate evolution, climate change plays a very important role. Starting around 1.8 million years ago, during a period known as the Pleistocene what was global climate like?

At the beginning of the Pleistocene, 1.8 million years ago, the Earth entered an even cooler phase, with jerky temperature variations causing a series of ice ages.

What's a key feature that researchers see in early Homo fossils that distinguishes them from the Australopithecus species?

Deep-rooted species diversity, reduction in tooth/jaw size.

A nearly complete skeleton of a Homo erectus boy provides an excellent picture of their postcranial skeleton. What features of Homo erectus are clear from this individual?

Long legs, narrow hips, narrow shoulders, barrel-shaped chest, and less dimorphism.

Which hominin species was the first to migrate out of Africa? Where outside of Africa do we first have evidence of hominins?

Homo erectus, and Dmansis, Georgia.

What kind of tool use do researchers observe in wild nonhuman primates?

Sticks to extract insects, cracking nuts with stones, testing water depth with a stick, etc.

Who were the first hominin tool makers? What kinds of evidence is there in the fossil record that helps researchers study the origins of tool use?

Au. afarensis site, cut marks on animal bones in Dikkia, Ethiopia.

Define Homo erectus.

Known as the "Upright man," these hominoids became skillful hunters and invented more sophisticated tools for digging, scraping, and cutting. They also became the first hominids to migrate from Africa and the first to use fire.

Define Homo ergaster (some researchers categorize African Homo erectus fossils as a different species, Homo ergaster)

Primate species very similar to Homo erectus, arose in Africa 2 mya and was bigger than Homo habilis. Also had a bigger brain and downward facing nostrils.

Define Oldowan tools.

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

Define Acheulean tools.

Hand axe tools, sharper and more specific for hunting

What kind of evidence do researchers find at fossil hominin sites for meat eating?

Concentrations of butchered bones and tools and bovid concentrations outnumber all other.

How does the phylogeny of a type of tapeworm help researcher examine meat eating in hominins?

Human-specific tapeworm evolved around 0.8-1.7 million years ago, it infects the hominin after consuming the meat.

Were hominins likely hunting, scavenging, or both for meat?

Both.

How humans differ from other primates in how they acquire their food?

Chimpanzees collect more and don't extract/hunt as much. Humans hunt more, extract an average amount, and don't collect as much.

Hunter-gatherer populations of humans today and in recent history can give us insight into evolution of human diet and behavior but they are NOT living fossils, they are contemporary modern populations just like you and me. What do we know about the features of the hunter-gatherer lifestyle from these human populations?

Hunting, tuber extraction, hard to acquire food, and requires hard to learn skills.

Ever since the 1960s, anthropologists have emphasized the idea that men are hunters and women are gatherers during human history; more recent evidence suggests that women likely played a larger role in hunting during human history. What is physiological evidence for "woman the hunter" and what is archeological evidence for "woman the hunter"?

Physiological: Wide pelvis, increased amount of Type I muscle fibers for endurance, estrogen for improvement of performance in physical settings.
Archeological: 9,000 mya burial of a woman with a tool kit, some Neandertals have at least one healed bone which indicates there were no differences between sexes (like hunting).

There was a lot of climate fluctuation/change during the middle Pleistocene. What are the implications of that for hominin evolution?

Repeated changes only in population density and variable conditions of natural selection.

What are some characteristics of Homo heidelbergensis?

Large brained, larger brow ridge, no chin, and higher levels of prognathism.

Define taphonomy.

The study of what happens to something/an organism/bone after it dies.

Define hunting versus/and scavenging.

Killing prey as a predator or searching for food by any means necessary.

Define Pleistocene climate fluctuations.

It was colder in the Pleistocene, climate fluctuating from warm to cold and then continued to get warmer.

Define Homo heidelbergensis.

Middle Pleistocene hominins from Africa and Western Eurasia. These hominins had large brains and very robust skulls/postcrania.

Define Levallois tools.

Tools formed by a distinctive method of stone knapping involving the striking of flakes from a prepared core. This technique was much more sophisticated than earlier toolmaking styles, and flakes could be shaped into sharp scrapers, knives, and projectile points (associated with Homo heidelbergensis).

When and where was the first Neanderthal fossil found? Why are they called Neanderthals (or Neandertals)?

They were found in 1865 in a cave in the Neander Valley in Germany, called Neandertals due to the location of discovery.

What was the geographic range of Neanderthals based on fossil evidence and genetic analyses?

Large parts of Eurasia from the Atlas Mountains in the east of Spain + Great Britain in the west.

What are two theories about the origin of tool cut marks made on Neanderthal bones?

Butchering/scavenging, or cannibalism/ritualistic postmortem processes.

At a Neanderthal site in Iraq, what is unusual about one humerus of an individual named Shanidar 1? What other cranial and postcranial features does this individual have that may indicate injury or need to be cared for by others?

The right humerus indicates paralysis, evidence shows crushing blow to the head, leading to damage of the left eye, a withered left arm, and possible paralysis of the left leg. The left foot shows osteoarthritic changes and tooth wear shows incisors were used tools.

What is a common feature of Neanderthal incisors? What does this feature indicate? (hint: related to using a body part as a tool)

Chipped incisors, indicating they frequently used their teeth as tools.

How are Neanderthals very similar to modern humans? Consider cranial morphology, postcranial morphology, and artifacts like tools.

Similar brain size, body size, and way of life/tool use.

Calcified dental plaque (called calculus) on Neanderthal teeth was analyzed to examine regional variation in Neanderthal diet. What did researchers find?

Neandertals in Spy Cave, Belgium had a heavily meat based diet, while Neandertals in El Sidron Cave, Spain had no meat in their diet, which included pine nuts, mushrooms, and moss.

How is it possible to get DNA from ancient bones?

Bones are mineralized organic matrix, supported by collagen. After cell death, DNA begins to degrade; the process of DNA diagenesis includes breaking up into fragments and chemical modifications of some subunits.

What variables make DNA more or less likely to be preserved over time?

DNA survives better in colder and dryer environments, DNA can bind with minerals in the soil or environment, and sediment samples have yielded usable ancient hominin DNA. Additionally, DNA is more abundant in certain parts of the skeleton, like hard bone at the base of the skill and dentin under enamel.

Do you wear personal protective equipment (PPE) in ancient DNA labs? Why?

Yes, to reduce contamination.

What can we learn from Neanderthal DNA?

We can identify Neanderthal vs non-Neanderthal remains, learn about the population history of Neanderthal groups and regional populations, and determine the functional genetics of Neanderthal genes in Neanderthals AND humans.

What areas of the world include people who have the most Neanderthal ancestry? The least?

They are primarily found in Eurasia, as opposed to Africa.

Define Homo neanderthalensis.

The species immediately prior to Homo sapiens; lived from 30,000 to 300,000 years ago; they were stronger and had bigger brains.

Define nasal aperture.

The nasal gap/opening.

Define retromolar gap.

The space between the third molar and the rear portion of the mandible.

What are some characteristics of Homo floresiensis that surprised researchers?

They were roughly three feet tall, small-brained, and used sophisticated stone tools.

What are three hypotheses about the origins of/who was Homo floresiensis?

The ancestral lineage of early Homo, island dwarfism of Homo erectus, and diseased Homo sapiens.

What do researchers know about Homo luzonensis?

Existed possibly as early as 900,000 years ago, share more similarities with afarensis than with modern humans.

Where in the world have Homo floresiensis and Homo luzonensis fossils been found?

Luzon, Philippians.

Where in the world have Homo naledi fossils have been found?

Chamber of the Rising Star Cave System, South Africa.

What cranial and postcranial characteristics did Homo naledi have?

Cranial: much of the morphology of the cranium, mandible, and dentition is consistent with the genus Homo, brain size is within the range of Australopithecus.

Postcranial: lower limbs, foot, and ankle morphology similar to humans.

What evidence do some researchers provide for burials and art by Homo naledi? Why do some researchers disagree about burials and art by this species?

There is no scientific evidence this happened.

What do we know about Neanderthals from DNA evidence?

Neanderthals were not alone; other populations lived including several groups called Denisovans. The common ancestor of Neanderthals and modern humans lived around 700,000 years ago and genetic evidence shows evidence of population mixing (Neanderthals, Denisovans, and modern humans).

Why is Denisova Cave a great environment for presentation of ancient DNA?

It is cold and dry in Siberia.

How were the hominin group called the Denisovans discovered?

They were found in the Denisova Cave, Siberia.

What areas of the world include people who have the most Denisovan ancestry? The least?

The Philippines and Papua, New Guinea have people with Denisovan ancestry.

Was there intermixing of these hominin populations that we discussed in this lecture? How do we know that there were instances of Neanderthals and Denisovans having children together?

Yes, there was intermixing; we can tell by genome sequencing.

All the diversity you see among people of the world today is very slight in terms of genetics. The genetic similarity of modern humans points to a recent common shared heritage. Review the two figures on slides 33 and 34 in Lecture 22. Note in the graph showing populations outside of Africa, you see a dip in effective population size at 50-70,000 years ago that indicates a genetic bottleneck that affected all groups outside of Africa. How are African populations (slide 34) different in this genetic history?

Populations were more steady.

Define Homo floresiensis.

Primates that lived 125,000-65,000 years ago in Flores, Indonesia; extremely small (nicknamed hobbits!)

Define Homo luzonensis.

Primates that lived 65,000 years ago (but possibly as early as 900,000 in Luzon, Philippines. Callao sample had seven teeth, three foot bones, two finger bones, and a fragment of a femur, but attempts to extract ancient DNA from the Callao sample were unsuccessful.

Define Homo naledi.

Primates that existed 335,000 years ago, found in Chamber of the Rising Star Cave, South Africa.

Define Denisova cave and the Denisovans.

A cave in Siberia, related to half Neanderthal and half Denisovan genomes. The Denisovans were a newly discovered group of archaic Homo sapiens from southern Siberia dated to between 30,000 and 50,000 years ago.

Define genetic bottleneck.

A sudden reduction in the number of alleles in a population.

What are some pieces of evidence that we have discussed in this class that complicate the idea that during hominin evolution brains got bigger and cognitive ability/complexity increased with this big brain?

Stone tool use, Homo floresiensis and Homo naledi are small brained.

What is the difference between absolute brain size and relative brain size? Why is the distinction important in comparing brains across species?

Absolute brain size is the actual size of the brain, and relative brain size is the size of the brain compared to the size of the entire body. The distinction is important

Is the encephalization quotient an example of an absolute brain size calculation or a relative brain size calculation? What does encephalization quotient tell us?

Relative brain size: the ratio of the actual brain size of a species to its expected brain size.

Are our brains energetically expensive? What kinds of evolutionary tradeoffs might have occurred for us to have a big brain? (hint: guts vs brains)

The Expensive Tissue Hypothesis; relatively large brains lead to a reduction of the other tissues, such as gut size.

What is the main prediction of Dunbar's Social Brain Hypothesis? Is there evidence in living primates that does not support this prediction?

Natural selection has favored large brains to negotiate large complex social groups and interactions; apes live in small social groups but have large brains.

What kinds of predictions do researchers make from the Ecological Brain Hypothesis?

Primate brain size will correlate with the percentage of fruit in the diet, home range size, percentage of extractive foraging, etc. Fruit eaters have bigger brains than leaf eaters.

What is an example of a lemur study that supports the Ecological Brain Hypothesis?

Fruit eaters have bigger brains than leaf-eaters.

Are the Social Brain Hypothesis and the Ecological Brain Hypothesis mutually exclusive (meaning does it have to be one or the other)?

No, some studies support both.

What is the Behavioral Flexibility Hypothesis and what is an example of evidence supporting it?

Learn new solutions to problems from others, cope with both ecological and social challenges.

What else have researchers looked at besides brain size when comparing the human brain to other animals, and primate brains to other mammals?

Different amounts of neurons in the brain compared to humans.

Define cerebrum.

Largest part of the brain; responsible for voluntary muscular activity, vision, speech, taste, hearing, thought, and memory.

Define cerebral cortex.

Largest part of the brain; responsible for voluntary muscular activity, vision, speech, taste, hearing, thought, and memory.

Define cerebellum.

The "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance.

Define frontal lobe.

The area at the front of each cerebral hemisphere; includes tissue crucial for many aspects of planning, problem-solving, memory, language, judgement, impulse control, and social and sexual behavior.

Define temporal lobe.

The areas in each cerebral hemisphere lying below the temples; includes tissue crucial for hearing and many aspects of language use.

Define occipital lobe.

The rearmost area of each cerebral hemisphere; includes tissue crucial for processing visual information.

Define parietal lobe.

The area in each cerebral hemisphere that lies between the frontal and occipital lobes; includes tissue crucial for receiving information from the senses.

Define absolute brain size.

The actual size of the brain.

Define relative brain size.

The side of the brain relative to body size.

Define encephalization.

An evolutionary increase in the size and complexity or relative size of the brain.

Define encephalization quotient.

The ratio of the actual brain size of a species to its expected brain size.

Define the Expensive Tissue Hypothesis.

A relatively large brain leads to a reduction of the other tissues, such as gut size.

Define Social Brain Hypothesis.

Natural selection has favored large brains to negotiate large, complex social group and interactions.