Here’s a question many people have asked: “How do we know we evolved from the ape family millions of years ago, and did not just appear 6,600 years ago exactly as we are now?”
The answer can be complicated. First, humans evolved from a creature whose descendants eventually became two species of primate – apes and humans. So the fact is that we did not evolve directly from “an ape family,” but from an ancestor of both the ape family and the human family. These two families split from one another many hundreds or thousands of years after the original primate lived, and then split again many thousands of years later, and kept on splitting until now, when we have both apes and humans. And many scientists believe that there will continue to be new splits in the future.
Some of the tests that have proven the “theory” of evolution include the fossil record, DNA similarities, geographic patterns, embryonic similarities, various methods of dating (e.g., carbon, tree-ring, radiometric, coral, etc.), and quite a few other factors.
Evolution is a “theory” and a fact. This seems contradictory to many since in everyday terminology, the word “theory” is often used in place of words like “hunch,” or “inclination.” But in science, the word represents an idea, or a set of ideas, that explain facts or events. Evolution is the best theory that can explain the diversity of life, and how it came to be. It explains why fossils are arranged in the strata (a bed of sedimentary rock that represents continuous deposits) in the very order that they are, and how this correlates to modern fauna, even in terms of geography.
We know all this because of DNA, which is organized into chromosomes. A simple definition of DNA is that it’s a large molecule derived from smaller molecules, nucleotides. The exact sequence of these nucleotides, similar to the sequence of ingredients in a recipe, tells the living cell how to put organic molecules together to form proteins. DNA is not a blueprint because slight changes to DNA can have a dramatic effect on the end product.
Every living thing has DNA, and this is how we can identify what type of living thing, or what person we’re looking at. Chromosomes vary in number and shape among living things. Humans, along with other animals and plants, have linear chromosomes that are arranged in pairs within the nucleus of the cell. Humans have 23 pairs for a total of 46 chromosomes. In fact, each species of plants and animals has a set number of chromosomes. A fruit fly, for example, has four pairs of chromosomes, while a rice plant has 12, and a dog, 39.
The fact that we did not just appear exactly as we are now, 6,600 years ago, is proven by the fossil record. This is the collective record of biological development reflected in the fossilized remains of organisms through geological history. The fossil record in fact refers to the collection of physical and research evidence that paleontologists and geologists have used to prove the truth of evolutionary theory. The physical evidence in the fossil record (which is what we call pieces of bone from animals that lived long ago) comes from the study of tools and fossilized remains of prehistoric animals. Many fossils and artifacts (e.g., tools) have been dug up and studied, and DNA has been useful in determining what class of animal the living creature was.
For instance, someone in rural England (maybe years and years ago) might have started to dig holes in his land so as to make a change. Perhaps he wanted to build a fence or a wall, or he may have simply wished to plow the land for planting. But while he was digging, he found a bone. Wondering how this bone got onto his land, this person might have sent the bone to a research facility of whatever type (maybe a friend who was interested in things people found in their yards, or a sterile laboratory set up specifically to study fossils). He might have been told that tests (including DNA and carbon-dating) proved the bone was from an apelike creature that lived seven million years ago (e.g., the small ape-like primate scientists have nicknamed “Lucy”).