05. July 2017 · Comments Off on BLOG, July 5, 2017 · Categories: Blog

EVOLUTION

Here’s a question many people are asking:  “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 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 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 only 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:  “DNA is a very large molecule built up from smaller molecules known as nucleotides. The exact sequence of these nucleotides, much like the sequence of words in a recipe, tells the living cell how to put organic molecules together to form proteins.  Unlike a blueprint, to which DNA is often compared, slight changes to DNA can dramatically affect the end product, making the process dependent on the sequence of steps, as in a recipe.”

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, six thousand six hundred 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 comes from fossilized remains of prehistoric animals.  Many fossils (which is what we call pieces of bone from animals that lived long ago) have been dug up and studied, and DNA has been useful in determining what class of animal the living creature would have been.

For instance, someone in rural England (maybe in present times, maybe years and years ago) wished to dig holes in his land in order to change something; he might have wanted to build a fence or wall, or he may have simply wished to plow the land for planting.  But while he was digging, he happened on a fossil.  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), and was 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”).

Scientists believe that an asteroid landed in what’s now Central America 65 million years ago, causing fires and leading to what they call a “nuclear winter.”  This means that the dust and debris kicked up by the impact, and smoke and ash from the fires, filled the air and created a barrier to sunlight for a long time, so that plants and animals that depended on sunlight could not grow.  This in turn was believed to be the cause of the disappearance of dinosaurs that lived at that time all over the earth.  They died off eventually from starvation, or dehydration, or other unknown causes (e.g., battles for the last vegetation).

About the author: Harriet Darling

A 75-year-old retired Executive Assistant and Research Editor, I live in Lodi, California, and transport foster kids to family visits and court appearances. I have a son, who is married to Cathy, and they live in Sacramento with Sheldon, their cat, and Penny, their dog. No children, so no grandchildren for me.

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