Evidence for Evolution and Speciation

what are vestigial organs?

A feature that an organism inherited from its ancestor but that is now less elaborate and functional than in the ancestor.

how long ago did they live?

About 3.3 to 2.1 million years ago Between about 1.89 million and 110,000 years ago

where did the earliest humans evolve from?

Africa

one component of the Cell Theory (which you learned last semester) is that all organisms are made of cells. How does this statement provide evidence for the theory of evolution: all living organisms share a common ancestor?

All living things are fundamentally alike. At the cellular and molecular level living things are remarkably similar to each other. This shows that they have a common ancestor.

what do different species share besides common anatomies?

Different species share genetic homologies as well.

what occurs during some stages of development?

During some stages of development, organisms exhibit ancestral features in whole or incomplete form.

what does evolutionary theory predict (hypothesize)?

Evolutionary theory predicts that related organisms will share similarities that are derived from common ancestors.

fossil evidence

Fossils are the preserved remains or traces of animals, plants, and other organisms from the past. Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today.

what are transitional forms?

Fossils or organisms that show the intermediate states between an ancestral form and that of its descendants are referred to as transitional forms.

why are the forelimbs of frogs, rabbits, birds, and other tetrapods (4-limbed animals, including us!) considered homologous structures, even though they look so different?

Frogs, birds, rabbits and lizards all have different forelimbs, reflecting their different lifestyles. But those different forelimbs all share the same set of bones - the humerus, the radius, and the ulna. These are the same bones seen in fossils of the extinct transitional animal, Eusthenopteron, which demonstrates their common ancestry. So, they are considered homologous structures.

how can homologies be revealed?

Homologies can be revealed by comparing the anatomies of different living things, looking at cellular similarities and differences, studying embryological development, and studying vestigial structures within individual organisms.

how is the DNA code itself a homology?

In fact, the DNA code itself is a homology that links all life on Earth to a common ancestor. DNA and RNA possess a simple four-base code that provides the recipe for all living things. In some cases, if we were to transfer genetic material from the cell of one living thing to the cell of another, the recipient would follow the new instructions as if they were its own.

what is comparative anatomy?

Organisms that are closely related to one another share many anatomical similarities, and sometimes the similarities are conspicuous. Other times, considerable study is needed for a full appreciation of relationships.

an example of homologies

People (and apes) have chests that are broader than they are deep, with the shoulder blades flat in back. This is because we, like apes, are descended from an ancestor who was able to suspend itself using the upper limbs. On the other hand, monkeys and other quadrupeds have a different form of locomotion. Quadrupeds have narrow, deep chests with shoulder blades on the sides.

example of vestigial organs

People (and apes) have chests that are broader than they are deep, with the shoulder blades flat in back. This is because we, like apes, are descended from an ancestor who was able to suspend itself using the upper limbs. On the other hand, monkeys and other quadrupeds have a different form of locomotion. Quadrupeds have narrow, deep chests with shoulder blades on the sides.

what shares ¼ of its genes with humans?

Roundworms share 25% of their genes with humans

what is the evidence that supports thehypothesis: snakes had ancestors with legs?

Some species of living snakes have hind limb-buds as early embryos but rapidly lose the buds and develop into legless adults. The study of developmental stages of snakes, combined with fossil evidence of snakes with hind limbs, supports the hypothesis that snakes evolved from a limbed ancestor.

Why do you think stone handaxes are evidence of early human behavior?

Stone hand axes are evidence of early human behavior because they can tell us where and how early humans lived and how they interacted with the world around them. These stone hand axes show early humans' ability to survive in a variety of habitats with the supplies of that time.

what does the amount of difference between DNA sequences in different species show?

The amount of difference in DNA is a test of the difference between one species and another - and thus how closely or distantly related they are.

what species do we all belong to?

The billions of human beings living today all belong to one species: Homo sapiens.

what are 3 things you learned?

The earliest hearths are at least 790,000 years old, and some researchers think cooking may reach back more than 1.5 million years. Control of fire provided a new tool with several uses—including cooking, which led to a fundamental change in the early human diet. Cooking released nutrients in foods and made them easier to digest. It also rid some plants of poisons. As brains became larger and more complex, growing up took longer—requiring more parental care and the protective environment of a home.

what clues do fossil evidence provide?

The fossil record provides snapshots of the past that, when assembled, illustrate a panorama of evolutionary change over the past four billion years. The picture may be smudged in places and may have bits missing, but fossil evidence clearly shows that life is old and has changed over time.

how different is our DNA from that of a chimpanzee's?

The genetic difference between individual humans and the study of the same aspects of the chimpanzee genome indicates a difference of about 1.2%.

what is the amount of difference between yourself and every other human being on this planet?

The genetic difference between individual humans today is minuscule - about 0.1%, on average

DNA

a self-replicating material that is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

Embryological Development

also known as embryogenesis or the development of an animal or plant embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm cell. Once fertilized, the ovum becomes a single diploid cell known as a zygote.

4 different lines of evidence

fossil evidence, homologies, distribution in time and space, evidence by example.

what are some things we can learn from early human fossils? (List 3)

how well adapted an early human species was for walking uprighthow well adapted an early human species was for living in hot, tropical habitats or cold, temperate environmentsthe difference between male and female body size, which correlates to aspects of social behavior

Homology

organs or skeletal elements of animals and organisms that have their own similarities, suggesting their connection to a common ancestor. These structures do not have to look exactly the same, or have the same function

biogeography

the branch of biology that deals with the geographical distribution of plants and animals.

molecular biology

the field of biology that studies the composition, structure and interactions of cellular molecules - such as nucleic acids and proteins - that carry out the biological processes essential for the cell's functions and maintenance.

what are some pieces of evidence for human evolution? List 3.

"Study of human shows how closely related we are to other primates - in fact, how connected we are with all other organisms - and can indicate the prehistoric migrations of our species, Homo sapiens, all over the world.""Thousands of human fossils enable researchers and students to study the changes that occurred in brain and body size, locomotion, diet, and other aspects regarding the way of life of early human species over the past 6 million years." "Millions of stone tools, figurines and paintings, footprints, and other traces of human behavior in the prehistoric record tell about where and how early humans lived and when certain technological innovations were invented."

how do these things relate to human evolution? What adaptations evolved?

All of these things relate to human evolution because this information shows the process and the steps humans took in order to evolve over the years. When we look at how early humans lived compared to now we can really see the evolution and the difference between the two. These things as mentioned can relate to human evolution because it shows everything the early humans did and how they did certain stuff along with their mindset during this time period. An adaptation that evolved is the way we get food, the tools we create and the shelters we make. This has all undergone an adaptation because they have all better advanced along with humans thinking helping to let humans make better creations.

Artificial Selection

Artificial selection is the identification by humans of desirable traits in plants and animals, and the steps taken to enhance and perpetuate those traits in future generations.

what were their names? (2 species)

Australopithecus africanus Homo erectus

what is the evidence that supports the hypothesis: baleen whales had ancestors with teeth?

Toothed whales have full sets of teeth throughout their lives. Baleen whales, however, only possess teeth in the early fetal stage and lose them before birth. The possession of teeth in fetal baleen whales provides evidence of common ancestry with toothed whales and other mammals. In addition, fossil evidence indicates that the late Oligocene whale Aetiocetus (below), from Oregon, which is considered to be the earliest example of baleen whales, also bore a full set of teeth.

Why do people from different parts of the world have different skin color?

Variations in human skin color are adaptive traits that correlate closely with geography and the sun's ultraviolet (UV) radiation.

example of comparative anatomy

Whales and hummingbirds have tetrapod skeletons inherited from a common ancestor. Their bodies have been modified and parts have been lost through natural selection, resulting in adaptation to their respective lifestyles over millions of years.