Ch 11 Becoming Human

Question 1

Homo sapiens

Answer 1

The species name for modern humans.

Question 2

Taxon (pl. taxa)

Answer 2

A unit of biological classification into which related organisms are classified. Taxa are arranged in a hierarchical rank from kingdom down to species, where members of a specific taxon typically share certain morphological characteristics.

Question 3

Mammals

Answer 3

Warm-blooded vertebrates belonging to the taxonomic class Mammalia that have mammary glands, hair/fur, three middle ear bones, and one lower jawbone.

Question 4

Primates

Answer 4

The highest order of mammals, comprised of about 400 different living species who share a number of features including opposable digits and binocular vision.

Question 5

Hominoids

Answer 5

Members of the superfamily Hominoidea that includes apes and humans.

Question 6

Hominins

Answer 6

Members of the taxonomic tribe Hominini that includes modern humans and our upright-walking ancestors.

Question 7

Cranium

Answer 7

The part of the skull that covers the brain.

Question 8

Prehensile

Answer 8

The ability to grasp objects.

Question 9

Opposable digit

Answer 9

A digit (either the thumb, big toe, or both) that is able to touch all the other digits on the same appendage.

Question 10

Precision grip

Answer 10

A type of grip involving the tips of the thumb and finger, used by primates (to varying extents) for precise manipulation of objects of various sizes.

Question 11

Power grip

Answer 11

A type of grip involving the palm and the fingers, used by primates (to varying extents) for moving and manipulating objects. The power grip generates more force due to the significant use of the palm.

Question 12

Bipedalism

Answer 12

Using two legs for walking upright.

Question 13

Genus (pl. genera)

Answer 13

A taxonomic rank above species and below family. Modern humans belong to the genus Homo.

Question 14

Foramen magnum

Answer 14

The hole in the base of the skull through which the spinal cord passes. A more centralised foramen magnum indicates bipedal locomotion.

Question 15

Biped

Answer 15

An individual that moves on two legs (upright-walking).

Question 16

Arboreal

Answer 16

Living in or amongst trees.

Question 17

Cerebrum

Answer 17

The largest part of the brain, which comprises two-thirds of the brain’s entire weight and is responsible for a large range of vital functions including sensory processing, motor control, and visual and spatial learning.

Question 18

Sagittal crest

Answer 18

A ridge of hard bone running lengthwise (front to back) along the top of the skull. A pronounced sagittal crest indicates strong jaw muscles.

Question 19

Arm to leg ratio

Answer 19

The ratio of arm length to leg length. Tree-dwelling hominids have longer arms and shorter legs, or a larger arm to leg ratio.

Question 20

Inference

Answer 20

Conclusions or assumptions reached by analysing and extrapolating from evidence.

Question 21

Transitional fossil

Answer 21

A fossil that shows traits that are common
to both its ancestral group and its descendant group. They are particularly important when the descendant species is physically very distinct from the ancestral species, such that the transitional fossil can help demonstrate evolutionary changes between the two.

Question 22

Interbreeding

Answer 22

Refers to the mating between different species (e.g. between Homo sapiens and other closely related species such as Neanderthals and Denisovans). Also known as crossbreeding.

Question 23

Multiregional hypothesis

Answer 23

A model for the geographical spread of Homo sapiens which suggests that separate human populations evolved independently from earlier hominins that had spread throughout Eurasia and experienced gene flow. Also known as the regional continuity model.

Question 24

Out of Africa hypothesis

Answer 24

A model for the geographical spread of Homo sapiens which suggests that humans first developed and evolved in Africa before migrating outwards and expanding their colonies, replacing the earlier hominins that had spread prior. Also known as the African replacement model.