This article is a non-technical introduction introduction to modern linguistics pdf the subject. The earliest undisputed evidence of life on Earth dates at least from 3.
1 billion-year-old rocks in Western Australia. 2 million have been documented and over 86 percent have not yet been described. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described. The offspring differs from the parent in minor random ways. If those differences are helpful, the offspring is more likely to survive and reproduce. These differences accumulate resulting in changes within the population.
This process is responsible for the many diverse life forms in the world. The majority of genetic mutations neither assist, change the appearance of, nor bring harm to individuals. Through the process of genetic drift, these mutated genes are neutrally sorted among populations and survive across generations by chance alone. In contrast to genetic drift, natural selection is not a random process because it acts on traits that are necessary for survival and reproduction. If these differences are beneficial, the offspring is more likely to survive and reproduce.