Question 1

All of the genetic differences between humans and chimpanzees are responsible for making us human.

Accepted Answer

While genetic differences are certainly responsible for some of the unique traits that make us human, there are also many aspects of our behavior and anatomy that are shaped by environmental and cultural factors. Additionally, not all genetic differences between humans and chimpanzees are necessarily related to our "humanness" - some may code for traits that are more specific to one species or the other.

Question 2

We can conclude that natural selection must have acted in favor of large brains in humans because:

Accepted Answer

Large brains are metabolically expensive, so their presence suggests that natural selection favored them due to the advantages they provided, outweighing the costs.

Question 3

The evolutionary process in which the timing of development is altered so that a sexually mature organism retains the physical characteristics of the juvenile form is called:

Accepted Answer

Neoteny is the evolutionary process in which the timing of development is altered so that a sexually mature organism retains the physical characteristics of the juvenile form. This results in adult organisms possessing features like large eyes, small noses, and round faces that are typical of baby animals.

Question 4

Although the FOXP2 amino acid sequence is highly conserved, humans have two unique amino acids that chimpanzees don't have. These unique amino acids are highly correlated with differences in _____ seen between chimps and humans.

Accepted Answer

Studies have shown that FOXP2 plays a crucial role in the development of speech and language, and the two unique amino acids in humans are highly correlated with differences in speech and language abilities seen between humans and chimpanzees.

Question 5

Which of the following statements about the evolutionary trends from ape-like ancestors to modern humans is NOT true?

Accepted Answer

The evolution of bipedal posture is believed to have facilitated, among other things, the evolution of larger brain sizes in humans, rather than larger brain sizes facilitating bipedalism. Bipedalism likely arose for reasons such as energy efficiency in locomotion and freeing the hands for tool use, which then could have created a context in which larger brains were advantageous.

Question 6

Which of the following is an example of neoteny?

Accepted Answer

Neoteny refers to the retention of juvenile or embryonic traits in adult individuals. Relatively little body hair on adult humans is an example of neoteny as humans have less body hair than other primates even as adults, which is a retention of a juvenile trait of primates. The other choices are not examples of neoteny. Bipedal locomotion of adult humans and opposable thumbs are evolutionary adaptations and hair turning gray or dying/graying hair blond are examples of age-related changes rather than neoteny.

Question 7

Which of the following is NOT an anatomical change that would be associated with a transition from four to two legs?

Accepted Answer

A transition from four legs to two involves several anatomical changes to support bipedalism. An S-shaped spine (A) helps balance the body directly over the pelvis, and a repositioned foramen magnum (B) allows the skull to balance on the spine, both adaptations for upright walking. A narrower foot (C) provides more efficient support and balance for bipedal locomotion. A wider stance, however, is not associated with bipedalism; instead, a narrower stance is more efficient for walking on two legs, as it aligns the body's center of gravity over a smaller base of support.

Question 8

The neoteny hypothesis is supported by which of the following characteristics of humans?

Accepted Answer

The answer of The neoteny hypothesis is supported by which...

Question 9

Neoteny refers to:

Accepted Answer

Neoteny refers to the retention of juvenile characteristics in a sexually mature organism. Therefore, option A is the correct choice. Option B refers to peramorphosis, option C refers to paedomorphosis, and option D refers to acceleration.

Question 10

Based on King and Wilson's findings of the similarities in the genomes of chimps and humans as well as genome sequencing studies that have found that all of our genes are present in chimpanzees, what do researchers now think is driving the most significant evolution along the hominin lineage?

Accepted Answer

Researchers now believe that changes in gene regulation, rather than an increase or decrease in gene number or loss of mitochondrial DNA, drove the most significant evolution along the hominin lineage. This is based on the similarities in the genomes of chimps and humans and the fact that all of our genes are present in chimpanzees.

Question 11

The shift to bipedalism required changes to the architecture of which of the following?

Accepted Answer

The answer of The shift to bipedalism required changes to...

Question 12

Provide three hypotheses for why selection would favor metabolically expensive large brains in early humans.

Accepted Answer

The answer of Provide three hypotheses for why selection would...

Question 13

Complex tool use, spoken language, and complex foraging strategies were all important hallmarks of human evolution. Current thinking is that each of these was a consequence of:

Accepted Answer

Bipedalism and freeing the hands from locomotion allowed for the development of complex tool use, spoken language, and complex foraging strategies.

Question 14

An excess of nonsynonymous differences between the FOXP2 sequence of humans and that of chimpanzees implies that:

Accepted Answer

An excess of nonsynonymous differences (changes in the amino acid sequence of the protein) between the FOXP2 sequences of humans and chimpanzees suggests that the protein's function has been under positive selection in humans. This means the changes likely provided some adaptive advantage, affecting the protein's function rather than its expression pattern. The data on nonsynonymous differences do not provide information about the selection on the gene's expression pattern.

Question 15

Some traits evolve for one particular function, but then become co-opted for another function. For example, it is hypothesized that bird feathers originally evolved for thermoregulation or insulation, but then later became adapted for flight. In the text it is suggested that evolution of group activities such as hunting resulted in a brain that is able to play the piano or solve calculus problems. Please support or refute this statement.

Accepted Answer

The answer of Some traits evolve for one particular function,...

Question 16

Phenotypic differences between humans and chimpanzees may be explained by the time during development when genes are turned on in humans and chimpanzees.

Accepted Answer

There is increasing evidence that differences in gene expression during development can explain many of the phenotypic differences between humans and chimpanzees. For example, genes involved in brain development are turned on for longer periods of time during human fetal development compared to chimpanzee fetal development, potentially contributing to differences in cognitive abilities.

Question 17

Which of the following organisms has the LARGEST brain for its body size?

Accepted Answer

Humans have the largest brain relative to body size among all animals. The human brain makes up about 2% of the body's weight and consumes about 20% of the body's energy. While elephants have larger brains than humans in terms of overall size, they also have much larger bodies, so their brain-to-body ratio is not as significant as humans'.

Question 18

Neoteny is the acquisition of sexual maturity in an otherwise _____ state.

Accepted Answer

Neoteny refers to the retention of juvenile traits into adulthood, including the delay or even absence of sexual maturity. Therefore, the best choice is A - juvenile. The other choices are not accurate as they do not reflect the concept of neoteny.

Question 19

Becoming bipedal requires more anatomical changes than simply being able to stand on hind legs.

Accepted Answer

Becoming bipedal requires extensive changes to the skeleton, including the alteration of the pelvis and spine to support an upright posture and the adaptation of the foot to allow for walking and running on two legs. It also requires changes in muscle and brain function to coordinate movement and balance in the upright position.

Question 20

Which of the following exerted selective pressure that may have acted in favor of having a large brain in humans?

Accepted Answer

All of these factors, tool use, social living, and language, could have played a role in favoring larger brains in humans. Tool use allowed for more complex problem-solving and innovation, social living required the ability to keep track of multiple relationships and social hierarchies, and language required the ability to process and communicate complex ideas. All of these factors likely contributed to the evolutionary pressure for larger brains.

Quiz 24: Human Origins and Evolution