Human Origins Exam 2

When did the first apes likely evolve?

At the end of the Oligocene in Africa.

What epoch is known as the 'golden age' of hominoids?

The Miocene epoch (23-5 million years ago).

What are Proconsulids?

A group of multiple ape species from Africa (22-17 million years ago) with monkey-like postcranial features but no tail.

What is the molar pattern of Proconsulids?

Y-5 molar pattern (2/1/2/3).

What are the notable Asian apes of the Miocene?

Sivapithecus and Gigantopithecus.

What is significant about Gigantopithecus?

It is the largest ape that ever lived, reaching up to 3 meters tall.

What characterized the late Miocene period (12-5 million years ago)?

A trend of global cooling and drying, with the first appearance of grasslands.

What defines a Hominin?

The primate group that includes modern humans and now-extinct bipedal relatives.

What is a key characteristic of Hominins?

They walk upright, a form of locomotion known as bipedalism.

What is nonhoning chewing?

A dental adaptation where hominins do not have honing canines and experience wear on the tip of canines.

What are the advantages of bipedalism?

Freed hands for tool use, wider view of surroundings, energetically efficient for long distances, and better cooling.

What skeletal changes are associated with bipedalism?

An S-shaped spine, repositioned foramen magnum, broad basin-shaped pelvis, angled femur, and stouter foot with arches.

What is Sahelanthropus tchadensis?

An early hominin found in 2002, dating to the late Miocene (7-6 million years ago), known for its small braincase and bipedal characteristics.

What characterized the Pliocene Epoch?

Continued global cooling and drying, leading to greater expansion of grasslands in Africa and ecological diversity.

What are the main features of Australopiths?

All are bipedal, have relatively small brains, and possess large teeth with thick enamel.

What is the genus Australopithecus known for?

Being more gracile than Paranthropus and including multiple species such as A. afarensis and A. africanus.

What is significant about Australopithecus afarensis?

It lived between 3.6-3.0 million years ago and is known for its bipedalism and fossilized footprints found in Laetoli, Tanzania.

Who is 'Lucy'?

A famous Australopithecus afarensis specimen discovered in Ethiopia in 1974, dating to 3.2 million years ago.

What is the Dikika Child?

An infant Australopithecus afarensis discovered in 2006, dating to 3.3 million years old.

What are the two types of Australopithecines?

Gracile and robust Australopiths.

What genus is known as the robust australopiths?

Paranthropus

Name three species of the Paranthropus genus.

Paranthropus boisei, Paranthropus robustus, Paranthropus aethiopicus

Where were Paranthropus boisei and aethiopicus primarily located?

East Africa

Where was Paranthropus robustus primarily located?

South Africa

What is the time range for the existence of Paranthropus species?

2.3 to 1.2 million years ago

What adaptations did Paranthropus have for their diet?

Small canines and incisors, large premolars and molars, and strong muscle attachments for chewing

What is a sagittal crest and its significance in Paranthropus?

A ridge of bone on the cranium that serves as an attachment for large temporal muscles, indicating strong chewing

How did Paranthropus and Homo differ in their dietary strategies?

Paranthropus used teeth and strong jaws for hard foods, while Homo used brainpower and tools for high-quality food sources

What is the significance of Homo habilis in human evolution?

It is considered the first species of the genus Homo, known for its larger brain and evidence of tool use.

What does the name 'Homo habilis' mean?

'Handy man'

What type of tools are associated with Homo habilis?

Oldowan tools, which include simple flakes and choppers

What is the time range for the use of Oldowan tools?

Approximately 2.6 million years ago to 1.7 million years ago

What evidence suggests early tool use before Homo habilis?

Cut marks on a bovid jaw bone indicating stone-tool-assisted consumption of animal tissues before 3.39 million years ago.

What dietary changes occurred with Homo habilis?

A mostly plant-based diet with increased meat consumption due to tool use and greater dietary flexibility.

What are the main trends observed from Homo habilis to Homo erectus?

Reduction in teeth and face size, increase in brain size, and changes in body proportions.

What tool industry is associated with Homo erectus?

Acheulean Tool Industry

What are Acheulean hand axes known for?

Being multi-purpose tools useful in animal butchery and plant processing.

What cognitive implications are associated with Acheulean tool-making?

Sophisticated cognition is required for creating a mental template for tool design.

Who was the Turkana boy, and what is significant about his discovery?

An exceptionally complete Homo erectus skeleton discovered in Kenya, providing insights into growth and development.

What does the variability among Homo erectus specimens suggest?

It supports the lumpers' perspective that different specimens may represent a single evolving lineage.

What is the significance of Dmanisi in the study of Homo erectus?

Fossils found there represent some of the earliest evidence of Homo erectus outside Africa.

What major evolutionary change occurred in the genus Homo?

An increase in brain size and dietary versatility to adapt to variable environments.

What is the estimated brain size of Homo habilis?

Approximately 600cc

Fossils

The preserved remains or traces of animals, plants, and other organisms from the past.

Mineralization

The process where water carrying minerals seeps into bone, partially or completely replacing the original bone minerals.

Anoxic environment

An environment with low oxygen where decomposition is limited, facilitating fossilization.

Sedimentary rock

Rock formed when deposition of sediments creates distinct layers or strata.

Taphonomy

The study of what happens to an organism's remains after death.

Differential preservation

The varying likelihood of fossilization in different environments.

Snapshot of life

The fossil record presents a limited view of life in the past.

Punctuated equilibrium

A theory that proposes species remain stable for long periods, interrupted by brief periods of rapid change.

Gradualism

A theory that suggests species evolve slowly and steadily over time.

Relative dating

Methods of determining a basic time sequence of sites without providing exact ages of fossils.

Steno's law of superposition

The principle that in a stratigraphic sequence, lower layers were deposited before upper layers.

Stratum

A single layer of soil or rock, sometimes called a level.

Biostratigraphic (faunal) Dating

Uses known ages of associated animal remains to assign approximate age to geological layers.

Index fossils

Fossil remains of known age used to estimate the age of the geological layer in which they are found.

Cultural dating

Finding cultural items that help determine the era in which they were active.

Dendrochronology

An archaeological dating method based on the study of yearly growth rings in ancient trees.

Radiometric dating

Methods of estimating the exact date of fossils or sites based on radioactive decay.

Radiocarbon dating (14C)

Uses the decay rate of carbon-14 to calculate the age of once-living organisms.

Half-life

The time required for half of the radioactive isotopes in a sample to decay, which for 14C is 5,730 years.

Potassium-Argon Dating (K-Ar)

Used mostly on volcanic rocks; involves the radioactive decay of K into Ar, measuring the ratio of K/Ar to date rock formation.

Half-life of Potassium-Argon Dating

1.25 billion years.

Geologic time scale

Used to describe the timing events in Earth's history, divided into Eon, Era, Period, and Epoch.

Eon

The biggest chunks of time in the geologic time scale.

Era

A time period within an Eon.

Period

A time period within an Era.

Epoch

A time period within a Period.

Paleocene Epoch

65-56 million years ago; characterized by a warm Earth, rise of flowering plants, and radiation of mammals.

Plesiadapiforms

Small, arboreal, nocturnal tree shrew-like mammals, debated whether they were true primates.

Non primate like features of plesiadapids

Front teeth set far apart like rodents; eyes face out toward the side instead of front.

Fossil discoveries (Carpolestes simpsoni)

Complete skeletons found in Wyoming, dating to 55 million years ago; features include a grasping foot with an opposable big toe.

Eocene Primates

56-33 million years ago; increase in fruit and seed sizes and numbers, with over 200 recognized primate species.

Euprimates

Most Eocene primates that appeared strepsirrhine-like, most went extinct by the end of the Eocene.

Eocene primate characteristics

Stereoscopic vision, grasping hands, reduced snout, teeth closer together, postorbital bar, larger brains.

Ida

Genus: Darwinus; female found near Frankfurt, Germany, dating to 47 Mya with preserved stomach contents of fruit and leaves.

The Oligocene

33-23 million years ago; characterized by continents in similar positions to today and a global climate change to colder temperatures.

Aegyptopithecus spp.

Medium sized (59-92cm) with ape-like and monkey-like features, low crowned molars, and a 2.1.2.3 dental formula.

First primates in the Oligocene

New world monkeys that made it across the ocean; anthropoid fossils in New and Old World are similar.

What are the main costs of social grouping in mammals?

Competition over resources and the spread of diseases.

What are the benefits of social grouping in mammals?

Ability to defend resources, access to potential mates, and protection against predators.

How does sociality serve as an anti-predator strategy for diurnal primates?

Through detection, deterrence, and dilution.

What does 'detection' refer to in the context of primate sociality?

In larger groups, there are more eyes to detect predators.

What are some deterrence strategies used by primates?

Sleeping in trees or cliffs, using defensive weaponry, having a large body size, making alarm calls, and mobbing.

What does 'dilution' mean in terms of predator protection for primates?

In groups, a single individual is less likely to be caught by a predator.

What is the strongest reason for primates living in social groups?

Protection from predators.

What is the residence pattern of gorillas?

Single male, multifemale (polygyny).

What is the residence pattern of common marmosets?

Single female, multimale (polyandry).

What is the residence pattern of bonobos?

Multimale, multifemale (promiscuous).

What is the residence pattern of baboons?

All male (bachelor).

What is the residence pattern of **** monkeys, gibbons, and owl monkeys?

One male, one female (monogamy).

Which primates are known to be solitary?

Orangutans and tarsiers.

What is sociobiology?

The study of the evolution of behavior, emphasizing that natural selection favors behaviors enhancing survival and reproduction.

What are the male reproductive strategies in primates?

Males face little reproductive costs and compete with other males for access to females.

What are the female reproductive strategies in primates?

Females incur higher reproductive costs and compete with other females for access to resources.

What is sexual selection?

A form of natural selection based on the attractiveness of traits to the opposite sex and competition dynamics related to reproduction.

In which group is infanticide primarily seen?

One-male, multifemale groups.

What is sexual dimorphism?

Differences in physical attributes between males and females of a species, often due to sexual selection.

What is the cultural significance in non-human primates?

Culture refers to socially learned and shared behaviors, traditions, or knowledge transmitted across generations, independent of genetic inheritance.