Module 2 Blog Post: Compelling evidence of evolution

                                            Good Old Earth

    Earth is around 4.6 billion years old. We can figure this out by analyzing and comparing objects in space and the light they emit, and radiometric dating, which measures the amount of decay a uranium isotope has experienced. Scientists can tell decay has happened by looking for elements that result from the decay like radium and radon isotopes. By knowing how long an object takes to decay means we can measure time from observing this object; kind of like knowing how old food hiding in your fridge may be by looking for new products and decay that results from the passage of time. This live science article (How is Earth's Age Calculated? | Live Science) has quite a few interesting facts concerning the different calculations of earths age and the universes age in the past 200 years. According to the article, a geologist named Arthur Holmes, in the early 1900s, proposed that the earth was around 1 billion years old and was later confronted by a large amount a disagreement from the low estimate. The universe was also quite young apparently; about 1.8 million years old as was proposed in the 1920s. Today, scientists propose the universe is more than double the age of Earth. The large margin of error could be due to differences in technology and techniques used to measure decay and detecting specific materials.

    Species on average seem to last around 1 million years (How long do most species last before going extinct? | Live Science). With all the changes that the Earth's climate has been through composition and temperature wise; life would have had to change to some degree (sometimes a severe degree) to become viable. Many forms of life today require oxygen to live, but oxygen was not abundant on the planet until certain life forms came about and produced it as a by product, like plants and microbial life. The Smithsonian article mentions the debate scientists have over the current extinction rate and the different real world factors that make it difficult to measure. Some of those factors include, a sparse species being difficult to find or animals that are extinct in the wild but kept in a zoo. Some species may last a couple million years according to the article.

    After comparing the rate of these two values; the earth being billions of years old and the average rate of time a species lasts before going extinct (a few million), there has to have been changes that allowed life to carry on. The life that did carry on had millions of years to adapt to changing temperatures, air and water composition, and changes in their ecosystems (life evolving alongside each other).

 How Old Is Earth? | EarthDate

(This is a fragment of meteorite found in the Canyon Diablo that helped scientists create a method to radioactive dating)

This resource also includes the fact that it is easier to find undisturbed samples on the moon, as the moon does not have plate tectonics.