CHAPTER 22 DESCENT WITH MODIFICATION: A DARWINIAN VIEW OF LIFE On November 24, 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection. Two major points: Today’s organisms descended from ancestral species. ___________________ provided a mechanism for evolutionary change in populations. Came to the conclusion that the Earth was _______ and constantly _______.

Darwin’s views were influenced by 1. Fossils in sedimentary rocks. Fig Fig ________________ theory of ____________________ – earth processes are constant over time 2. A 5-year voyage around the world 4.Jean Baptiste _________ publication of a theory of evolution based on his observations of fossil chronologies in the Natural History Museum of Paris.

The Old Testament account suggests rapid creation, not evolution The Origin of Species challenged a worldview that had been accepted for centuries The Darwinian view of life has two main features. (1) The diverse forms of life have arisen by descent with modification from ancestral species. (2) The mechanism of modification has been natural selection working over enormous tracts of time.

Fig This evolutionary tree of the elephant family is based on evidence from fossils.

Natural selection in easily observed _________________________ in insects _________________ resistance in humans In each generation the percentage of resistant individuals increases. _________________ favors those characteristics in a variable population that fit the current, local environment. 3TC-resistant strains of HIV become 100% of the population in just a few weeks. Natural selection does not prove large-scale evolution and speciation, only adaptation

1. Homologous ___________________ For example, the forelimbs of human, cats, whales, and bats share the same skeletal elements, but different functions Fig What is the evidence for evolution? Evolution is inferred

2. _________________ in some creatures Example-some snake skeletons have vestiges of the pelvis and leg bones Fossil whales with vestigal legs and pelvis 3. ______________________ All vertebrates “look” the same as early embryos, then changes are observed later. 4. All of life shares the same ________________ 5. DNA sequences are more homologous in “like” creatures than ________ ones

6. The _________________ Different organisms appear at distinct times in the fossil record 7. Isolated places have distinct populations There are numerous unique creatures on isolated islands- Australia, Galapagos islands,…. Old World vs New World monkeys How does one reconcile evolution with Genesis account? Many scholars reject evolution theory outright. Others suggest vast periods of time between 1 st and 2 nd days of Genesis creation-. Others suggest God-directed evolution – Theistic evolution Michael Behe- suggests that life cannot “just happen”, but is “irreducibly complex” …..But transition creatures are almost non-existent

Uri Miller experiment- Mix NH4, methane, water in intense heat and electrical current Observe simple macromolecules are formed Is this evidence for a pre-biotic soup forming resulting in an organism? History suggests that our descendents will look back at this generation and say “they understood so little”