EIVIDENCE FROM ANATOMY AND EMBRYOLOGY

EIVIDENCE FROM ANATOMY Deduction: If the hypothesis of evolution is correct then we should see evidence of this in the anatomy. Test: Study comparative anatomy Look for trends

EIVIDENCE FROM ANATOMY Aristotle noted: *Animals with fur also suckle their young *Animals with red blood also have backbones & similar skeletons. What is the cause of such patterns?

What is the cause of such patterns? Forelimb of vertebrates

The hypothesis of Devine Creation offers no scientific answer. What is the cause of such patterns? The hypothesis of Devine Creation offers no scientific answer. But the Hypothesis of Evolution does. The reason for such similarities are because these animals shared a common ancestor who had these traits.

Birds Mammals Reptiles Amphibians Fish 200 mya 160 mya 325 mya 375 mya

Homology=Similar structure from a common ancestor e.g. The basic structure of the limb evolved before the groups separated. It evolved in fish! Limbs from fins Amphibian Fish

Prediction (Deduction): Not only will we find a basic similarity in limb structure in vertebrates, we should find great similarity in all systems. Data: All vertebrates have the same basic organ systems: skeletons, muscles, nerves, circulation, respiration, kidneys, digestive tracts, biochemistry. And differences among vertebrates show trends that reflect evolutionary shifts.

DATA: Trends in organ structure Evolution of the vertebrate heart Number of Chambers 2 3 3 ½ 4 A V Fish Bird & Mammal Reptile Amphibian

DATA: Trends in organ structure Respiration Fish------------------------Gills Amphibian----------------Gills & Simple Lungs Reptile---------------------Complex Lungs Birds & Mammals--------Very Complex Lungs These trends are not expected with Devine Creation They are expected with the model of change through time= Evolution

This principle of homology allows us to predict that when we discover a new species of vertebrate or fossil that they too will have similar structures derived from a common ancestor.

The principle of homology allows us to use animals such as monkeys and rats in testing drugs and use them in experimental procedures as proxies for humans.

How can you tell if 2 structures are homologous ? Answer these questions: Are the two structures fundamentally similar in their basic structure? Do the structures have the same embryology? Does the common ancestor have a similar structure? If so, the structures are probably homologous even if they are performing different functions

REMEMBER In order for the structures to be homologous the organisms’ common ancestor had to have the structure ! All of the examples in the previous clicker question have classically been considered analogous. They perform similar functions but evolved independently

ANALOGY=Similar function of two structures independently evolved i. e ANALOGY=Similar function of two structures independently evolved i.e. not from a common ancestor Bird Bat Analogous Structures Homoplasies Fly

Homology in Leaf Structure

Vestigial Structures= Structures with no apparent function or reduced function e.g. Human Goose bumps when you are cold Tail bone--coccyx Muscles to move the ears & scalp Snakes’ lung Cave animals’ blind eyes Wings of flightless birds

Vestigial Structures= Structures with no apparent function or reduced function Why would a creator have formed a structure without function? How can we understand the Creator’s logic? There is a function but you just haven’t found it yet.

The Evolutionary model provides an answer for vestigial structures. These structures did have a function in an ancestor, but change in the life style led to the gradual disappearance. *There is a disadvantage to keeping the structure it “gets in the way” and costs energy to maintain.

EIVIDENCE FROM EMBRYOLOGY Deduction: If the hypothesis of evolution is correct then we should see evidence of this in the embryology. Test: Examine the development of embryos Look for trends Aristotle

Evidence from Embryology Von Baer (1866) The development of all vertebrate embryos is similar Law of Development General traits will evolve first Specific traits will evolve later

Vertebrate Embryos

Haeckel’s Principle of Recapitulation “Biogenetic Law” “Ontogeny Recapitulates Phylogeny” Ontogeny= Individual development of embryo Recapitulates= Repeats Phylogeny= Evolutionary History The individual development of the individual repeats the sequence of events that occurred during evolution So

Whale Examples Whale nostrils Whale teeth Whale hair

Human examples Gill Pouches Tail

Creation Model does not scientifically address these problems. Evolution Model provides a satisfactory explanation. These patterns are vestiges of development that once were functional. The genes are still present.

"Descent With Modification" Evaluation The data from anatomy & embryology support the hypothesis of evolution "Descent With Modification"