Question

what was darwin first big idea? How does fossil evidence support this idea

7. Darwin first developed his Theory of Evolution in 1839, but did not publish his theory until 1859. Why did he wait so long to publish his book? What stimulated him to finally publish? ՍՍՍՍՍՍՍՍՍՍՍՍՍնն 8. What was Darwin's first "Big Idea? How does fossil evidence support this idea? 9. What was Darwin's second "Big Idea"? How does the presence of two color forms in the rock pocket mouse support the theory of natural selection? Geologic Time Scale Time can be measured in several ways. Geologists first used fossils and geologic assumptions to create a relative measure of time called the geologic time scale. Earth's approximately 4.6 billion years have been divided into eras, then periods, and finally epochs through the study of rock layers, geologic events and fossil finds. See Figure 9.1. The time periods are referred to as relative because they lack the exactness that we might think we need. Keep in mind that 4.6 billion years is an enormous amount of time and being a few million years off one way or the other really does not matter. Fossils primarily form in sedimentary rocks which are formed in watery environments as sediments sinks to the bottom and are compacted. Horizontal rock layers, called strata (singular, stratum) form over time, one on top of another, with the oldest stratum on the bottom (see Figure 9.3).

Answer 1

Answer 1He took so long to publish his work because –

1. Religious implication- Many researcher believe that this delay was because of the fear over public reaction he might have got after the publication. With his theory he was to declare that species evolved from one another which stand in contrast to the creation story of Bible which state that God created the world in 6 days. While evolution theory would state that the world and all creature progressed and developed in millions of years.
2. Timing issue- Some scientist completely refute the ideas that he was afraid his project was highly ambitious and he needed time to garner the necessary evidence. And meanwhile he was also working on other project – his Beagle related and then work of barnacles that might have pushed him to take some time.

And finally when he got all the related evidence and after relieving from rest of the work he might have thought to go with publishing .

Answer 2. The first big idea of Darwin was associated with the origin of species. Diverse group of animal evolved from one or a few common ancestors and fossil evidence support his idea as fossil are important evidence for evolution because they show that life of earth once different form life on earth today. The age of fossil can be determined using method like carbon dating and radiometric dating and categorize them to link the evolutionary relationship between organism.

Answer 3. Theory of Natural selection was his second big idea.

The rock pocket mouse is one of the 19 species of pocket mice. It is found in the rockey outcrop in the desert of south western USA and Mexico. Most mouse population has light, tawny fur consistent with the color of desert rock they live. And darker color rock pocket mouse live amid black basaltic rock.

Scientist took DNA from both colored mouse from areas in Pinacate Peaks, Mexico and USA. In Pinacate mice they discovered different version of Melanocortin 1 receptor gene and coat color. Later studies discovered that there is strong selective pressure that maintained Mc1r Allele and coat color frequency across the geographic distance between light and dark colored rock island.

Hence two color form in rock pocket mouse support the theory of evolution.