Strong evidence for evolution is found in gene comparisons using molecular biology and fossils. It has been proven that genetic changes are passed on from generation to generation, the new species gradually replacing the older ones. Vestigial features, or parts of the body that no longer perform their original use, are found in several species today. The DNA and gene differences are compared for many species. We even see evidence for this today through artificial selection, as farmers genetically modify livestock by getting two of them to interbreed. The DNA can be traced back to the original source.