Biological Anthropology Chapters One and Two The Essentials of Physical Anthropology

Evolution “The gradual development of something. Advancement, progress, expansion, growth.” “The physical, mental, and biological transformation of a species in order to adapt to a living environment.” “Becoming more conscious/aware.” “[Evolution is] the change of an organism over time. [It] is caused by many factors: natural selection, mass extinction, adaptation, etc.” “[Evolution is how humans] developed from cavemen.” “Natural progression of people.”

Evolution Evolution does not equal development/progress. “Survival of the fittest” misunderstood. Evolution is about how change occurs over time among organisms/life.

Evolution “How living organisms have changed, or adapt, over time due to environmental and cultural changes.” “…It refers to the ‘survival of the fittest’... Creatures who have adaptive behaviors and attributes tend to survive.” “The way people, animals, and things change as time passes. They can either grow into more things, or stay the same.”

Evolution “Evolution is how we became who we are today from our ancestors.” Evolution is based upon the principle that all organisms share a common heritage, and more closely related organisms share a more recent common ancestor. Human/primate evolution

Chapter One Marco Polo 1200’s Asia Christopher Columbus late 1400s Americas Scholars begin speculating about these cultural differences: Anthropology

Chapter One Linguistic, Cultural, Archaeology, Biological (Physical) Unifying theme: CULTURE!!! Culture=learned behavior transmitted person to person, generation to generation (language)

Chapter One Why does biological anthropology incorporate culture? What separates humans from other animals (and primates)?

Chapter One CULTURE!!!

Chapter One You cannot study the evolution of the human species without investigating us both as cultural and biological beings!

Chapter One BIOCULTURAL APPROACH Biological physical anthropology examines the biological evolution and biocultural variation of human beings (h. Sapiens).

Chapter One Biocultural variation is the outcome of unique life histories.

Biocultural Variation

Biocultural Variation

Biocultural Variation

Biocultural Variation

Biocultural Variation

Genie

Chapter One So what separates us?

Chapter One Bipedalism Non-honing chewing Material culture Hunting Speech Domestication of plants and animals (10-11,000 years ago)

Chapter One All features are a product of the complex interaction of biology and culture.

Chapter One We are all dependent on culture for survival. Social learning is key element of human evolution!

Chapter One How do biological anthropologists acquire facts about human evolution?

Chapter One

Chapter One

Chapter One Scientific method=knowing through observation of natural phenomena Empirical Self-correcting

Natural Selection Natural selection (Darwin’s idea) A given trait or behavior can be “selected for” if it somehow enhances an organism’s survival and reproduction.

Natural Selection Presupposes three things: 1.) Variation—at least two traits. Options to create opportunity for selection to occur. 2.) Heritability—parents pass on traits through genes. 3.) Differential mortality—Probability of survival is somehow effected directly by this heritable (inherited from parents) trait.

Peppered Moth

Natural Selection

Evolution Myths https://www.youtube.com/watch?v=mZt1Gn0R22Q

Chapter Two 1800s “World discovers itself through collections” (Larsen 2014:23). This period of discovery lays the foundation for Darwin’s idea: descent with modification (parents pass traits from parents to offspring).

Chapter Two Scientists from various disciplines (geology, paleontology, taxonomy, systematics, and demography) lay the foundation for evolutionary biology, which Charles Darwin founded. These scientists helped correct three popular misconceptions about earth and its inhabitants:

Chapter Two Scientific realizations: 1.) The earth is ancient (Hutton and Lyell) 2.) The surface of it has changed a lot 3.) Plants and animals have changed a lot (Hooke and Cuvier)

Chapter Two Darwin discovered the primary process by which this change has taken place: natural selection.

Chapter Two Species show variation between members because organisms adapt to their habitat. Through cycles of reproduction, characteristics that enhance survival and reproduction within a given habitat/environment increase in frequency. This is natural selection, and it can lead to increased variation within a species.

Chapter Two Adaptive radiation: an ancestral group of organisms become more varied as members of the group adapt to specific environmental niches, leading to new forms of that original group of organisms.

Chapter Two Darwin’s finches

Unity in Diversity

Chapter Two Life is competitive—not everyone survives. (environmental pressures) https://www.youtube.com/watch?v=zNeZWhfG8B0

Chapter Two Thomas Malthus—population is limited by food supply. Traits enhance survival Competition for resources The best adapted survive, and population is kept in check.

Chapter Two AND… over time, new species can emerge! Common ancestors give rise to related species.

Chapter Two So, Darwin new these survival and reproduction enhancing traits were being passed down from parents to offspring, but he did not know quite how…

Chapter Two Lamarckian inheritance of acquired characteristics. New demand=new organ/modification This change is then passed on to offspring

Chapter Two

Chapter Two

Chapter Two Gregor Mendel provides the how of natural selection. Discrete physical unit Blending inheritance (gemmules)

Chapter Two: Mendel Unit=gene Two subunits=alleles Dominant (expressed) and recessive (hidden) Ex. Tallness and shortness in pea plants (Larsen 2014:39) Genes that determine these traits are located in reproductive cells!

Chapter Two: Mendel Johannsen and others expand upon Mendel’s theory of inheritance (which forms the basis of modern genetics). Johannsen labels allele pair “genotype” and physical appearance “phenotype” https://www.youtube.com/watch?v=Mehz7tCxjSE https://www.youtube.com/watch?v=CBezq1fFUEA

Exercise https://docs.google.com/file/d/0Bz9eBjqfJlfDOHUzV XkxeEhYVEk/edit

Chapter Two Mendel’s theory of inheritance triggers curiosity among biologists about origin of genes, variance, and change in characteristics over time. Population genetics

Chapter Two Thomas Hung Morgan—fruit flies Mutation: the only source of new genetic material!

Chapter Two Gene flow: the transfer of genes between populations.

Chapter Two

Gene Flow Con’t

Gene Flow Sickle Cell Anemia as an example of gene flow in humans. Gene flow decreases genetic difference between populations.

Chapter Two Genetic drift: random change in the frequency of alleles (forms of a gene). Acts more intensely on a small population, and can increase genetic difference between two genetically related but not interbreeding members of a population.

Genetic Drift Con’t

Chapter Two So, the four causes of evolution include: 1.) Natural Selection 2.) Mutation 3.) Gene Flow 4.) Genetic Drift

Chapter Two Remember, all organisms are related through common descent, but those that share a more recent common ancestor are more closely related. https://www.youtube.com/watch?v=rFxu7NEoKC8