Chapter 10: Early Hominin Origins and Evolution: The Roots of Humanity

Identify the statements that correctly describe Australopithecus platyops.

- Australopithecus platyops is associated with a woodland habitat. - Australopithecus platyops is one of the most poorly represented hominins. - Australopithecus platyops had a relatively flat face.

Identify the statements that best characterize the patchy forest hypothesis.

- Some forests became patchy, requiring greater distances to be traveled between food sources. - Bipedalism is more efficient for medium- and longer-distance travel than is quadrupedalism.

This bipedal pelvis differs in shape from the pelvis of a quadrupedal primate in several important ways. Identify which of the following are characteristic of a bipedal pelvis.

- The curved shape brings the medius and minimus gluteal muscles to the sides to increase stability. - The pelvis is short compared to that of a quadrupedal primate.

Examine the 3D model of the femur (upper leg bone) here. Be sure to rotate the model to examine it from several angles. Then, select all of the following statements that are true.

- The femur is short, a characteristic of quadrupedal pongids. - When placed on end, this femur stands straight up and down, a characteristic of quadruped pongids.

Identify the statements that accurately describe both Australopithecus aethiopicusand Australopithecus boisei.

- They had very large molars (cheek teeth). - They are also known as robust australopithecines. - They had enormous chewing muscles indicated by the large attachment areas and a sagittal crest. -

Place the following important evolutionary events in chronological order. These events define hominins as a group.

- evolution of bipedalism - increase in enamel thickness - regular use of stone tools - enlargement of brain to around 1,4500 cc

Place the following australopithecines in the chronological order in which they likely lived, from oldest to most recent.

1. Australopithecus anamensis 2. Australopithecus afarensis 3. Australopithecus garhi 4. Australopithecus sediba

Australopithecus robustus was a 1._____ australopithecine found in 2._____

1. Robust 2. Swartkrans, South Africa

Several 1_____ especially the well-represented Australopithecus afarensis, had lower limb morphology indicating very 2____ locomotion.

1. australopithecines 2. humanlike

Evidence from the early hominin fossil record has proved that 1___ and not human 2____was the foundational behavior of the Hominini. This attribute distinguishes hominins from the apes and other nonhuman primates.

1. bipedalism 2. intelligence

In this Anthropology at Work video, Dr. Brophy highlights a key aspect of research on human evolution and one that fascinates her the most. That is, the evolution of the genus 1._____ is so much more complex than we thought, and with every new fossil find comes 2._____.

1. homo 2. more questions than answers

Humans lack the diastema found in the jaws of apes. Indicate the spot where the diastema would be, if humans shared the ape diastema and canine honing complex.

A diastema is a gap between teeth. In the canine honing complex of apes, there is a diastema between the lower canine and the front-most premolar.

Identify the features that are associated with bipedalism as seen in humans.

Associated with Bipedalism in Humans: S-shaped curve of spine, short ilium

Match each anatomical feature of Australopithecus sediba to the genus that usually shows the most similarity to that feature.

Australopithecus: long arms, small brains, Homo: broad pelvis, noncurved phalanges

Match the physical features on the left to the type of locomotion on the right.

Biped: shortened pelvis, valgus knee Quadruped: straight knee, elongated pelvis

Identify the characteristics associated with Australopithecus afarensis.

Characteristics of Australopithecus Afarensis: - diverse diet indicated by diverse tooth wear - nondivergent big toe

Identify the dental traits that characterized the hyper-robust australopithecines.

Characterizes Hyper-Robust Australopithecines: Large Molars, large lower jaw

Examine the 3D model of the femur (upper leg bone) here. Be sure to rotate the model to examine it from several angles. Then, select all of the following statements that are true.

Correct: When placed on end, this femur angles inwards to the knee, a characteristic of bipedal hominins, The femur is long, a characteristic of bipedal quadrupeds.

Identify the statements that correctly describe Lovejoy's provisioning hypothesis.

Describes Provisioning Hypothesis: - With the freeing of the hands, males could contribute to parental investment in their young. - If males provision the females who raise their young, then they increase their viable mating opportunities. - Female devotion to one single offspring at a time negatively affects male reproductive success.

Drag the dentition features to show which ones are similar between humans and nonhuman apes and which ones are different.

Different: thickness of enamel, shape of canines Similar: molar morphology

Compare the 3D models of the female human and the female chimpanzee. There are a number of differences between the two. Which features in the human skull do you see that are directly related to being bipedal?

Directly Related to Being Bipedal: The foramen magnum in the human skull is farther forward than in the chimpanzee skull.

Match each species of pre-australopithecine to the appropriate map showing where its fossil remains have been found.

Ethiopia: Ardipithecus kadabba, Ardipithecus ramidus Kenya: Orrorin tugenensis Chad: Sahelanthropus tchadensis

Identify the muscle that is only vertically oriented in hominins to allow for a crushing ability.

Human Skull

The evolution of bipedality involved a trade-off, resulting in both positive and negative effects. Match each effect of bipedality to "positive" or "negative" as appropriate.

Positive: free hands, ability to see greater distances Negative: ability to be seen in the landscape, strain on body

Many features distinguish modern humans from the nonhuman apes. However, only two of these features define hominins. Identify the reasons why.

Reason Why Two Features Define Hominins - These two traits arose in the common ancestor of all hominins, but are not found in the nonhominin apes. - Proper taxonomic groups are always defined by the traits that are shared among members of the group but not found in closely related species. - The evolution of hominins involved several different changes that happened at different times. Only two of these features evolved early enough to apply to all the hominins.

Ardipithecus ramidus was a transitional species in many ways, with some features that were apelike, some humanlike, and others that were a mosaic of both. Place "apelike," "humanlike," or "mosaic" on the correct feature.

Teeth: Humanlike Hands: apelike Feet: Mosaic

Which of the following statements is true about nonhoning chewing and bipedalism?

They preceded speech and the use of stone tools by several million years

You are an anthropologist who has studied early hominin bones and concluded that there is a high degree of sexual dimorphism in body size in those species. What are the implications of your argument?

Your argument falsifies Owen Lovejoy's provisioning hypothesis because his hypothesis requires a decrease in sexual dimorphism

Identify the two features that primarily and consistently distinguish hominins from apes.

bipedalism, canines

Match the following food acquisition behaviors to the hominin tool type or technology most likely used to carry it out.

chipped stone tool: cutting meat or other foods cobbles or choppers: smashing bone to access marrow South African bone tools: digging into termite mounds or digging for roots

Differentiate the characteristics of hominin (including human) canines from those of nonhuman, ape canines.

nonhuman ape: hominin: wear on the tip of the canines