What did charles darwin discover as a result of his experiments with breeding pigeons?

The earth formed roughly 4.5 billion years ago, yet evidence of life dates back to about 3.5 billion years ago. which one is not a possible hypothesis of how life on earth arose?

Choose the best definition of allele. a. one of several possible versions of a gene, which each produce a different phenotype b. an organism that's purebred for a given trait c. the process of fertilizing a plant with pollen from another plant d. a set of genes that are located on the same chromosome and so are tightly linked

The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the correspondingbones in whales have very different shapes and proportions. however, genetic data suggest that all three kindsof organisms diverged from a common ancestor at about the same time. which of the following is the mostlikely explanation for these data? a) humans and bats evolved by natural selection, and whales evolved by lamarckian mechanisms. b) forelimb evolution was adaptive in people and bats, but not in whales. c) natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy. d) genes mutate faster in whales than in humans or bats. e) whales are not properly classified as mammals.