The most powerful evidence in support of any theory is its ability to correctly make predictions.  It is these predictions that can act as a means of testing a theory to determine its validity. Today, we'd like to talk about how one could disprove evolution. Here are three ways to test the theory of evolution for yourself to see if it holds up.  I'll provide some examples to illustrate the idea, but I encourage you to test it out on your own.

What Are the Tests?

Test # 1 - Similarities

• If common ancestry is correct, we would expect related species to share similarities inherited from their common ancestors.  Most evolutionary changes take time  (a lot of time). As such, when two species finally separate from each other, we can predict that a number of shared traits will not have altered simultaneously, so many will remain with the same.  With that in mind, the more recently they shared a common ancestor, the more frequent and intense the similarities will be.
  • How common ancestry could be disproved: demonstrate that there is a species fundamentally unlike any other species.

Test # 2 - Progressions

• If species have changed over time, we would expect to see evidence for this in the form of progressions of change within a species in the geologic column, recorded history, and across geography.  For instance, we should be able to observe trends within a trait going from low expression, to medium expression, to high expression.
  • How descent with modification could be disproved: Show that the fossil record is mixed up and doesn't show evolutionary trends.  Find a single fossil out of order.   Show that species are incapable of changing.

Test # 3 - Remnants

• If species are the products of past generations, and if they are descended from other species, we would expect to see imperfections in the creature's design.  A species can only have the remnants of what mutation and past generations have left them.  We can expect that they will often lack sensible adaptations (like whales not having gills), have harmful traits (like an appendix that ruptures), and repurposed traits (like our tailbone).
  • How the natural origins of species could be disproved: Species have no signs of having descended from other species. Species demonstrate perfect designs.

For more information on viewing evolution evidence through this lens, please pay a visit to this post.

How to Conduct the Tests:

Let's apply these three predictions (of similarities, of progressions, and of remnants) to a well known animal (perhaps the animal you know best!) to see how the theory of evolution holds up.  The principles that are being used here could be used on any species (and I encourage you to try).

First prediction:

If humans are the product of evolution, we would expect for them to share similarities with other animals that they shared a common ancestor with.

Similarities Evidence: 

• Humans have a single temporal hole, like all synapsids.
• We have hair and mammary glands, like all mammals.
• We also have 7 cervical (neck) vertebrae, like almost all mammals (except sloths and manatees).
• Humans have placentas to nourish our offspring in utero, like all eutherians.
• We have five fingers, like almost all tetrapods (even bats and whales!).
• We share a nearly identical bone structure with chimpanzees and about 96% of the same genome.

Second prediction:

If humans are the product of evolution, we would expect to find evidence of changes over time within the geologic column, recorded history, or across geography.

Progressions evidence: The human fossil record is far more complete than one might expect for such a small, formerly low population species.

• Roughly 7 million years ago there was a genus named Sahelanthropis that had a small cranium and a neck, hips, feet, and hands adapted to tree climbing.
• 2 million years later a genus of ape existed that had a larger cranium and a neck, hips, feet, and hands that were more  adapted to mostly upright walking and dextrous hand manipulation.
• Another 3 million years pass and cranium reaches near human size and the ape is now fully adapted to upright walking and tool use.

Could these all just be separate species of ape?  No. The 38 species of Homininae found in the fossil record are far too sequential for this to be the full story.  Please visit websites like these to get a detailed and interactive explanation of the human evolution fossils: BecomingHuman.org, and the Smithsonian National Museum of Natural History.

Third prediction:

If humans are the product of evolution, we would predict that they would have traits and genes that are remnants of past generations. This section also deals with organisms not having any flaws.

Remnants evidence: (I'll try to start at the top of the head and work my way down.) 

• Our ears have vestigial muscles intended to direct them towards a sound, as other mammals can.

• The stapedial artery goes right through our inner ear stapes bone.  The position of this artery used to make sense when our ancestors used what is now the stapes bone as part of their jaw.
• Our retinal nerves and blood vessels go over our retina, thus blocking out certain portions of our vision that our brain blurs over to create a seamless image. You may be familiar with this, as it is known as our "blind spot."
• We have the left overs of a nictitating membrane in the corner of our eye called the "plica semilunaris."
• Our maxillary sinus has a drainage position designed for a quadruped that  stooped over.  That being the case, it often turns into a cesspool of trapped fluid and bacteria.
• Most people's jaws no longer have space for all of their molars.
• We have canines, teeth that were once beneficial for capturing prey and for display.
• Our esophagus and trachea branch below our mouth, thus creating a choking hazard.

• Our recurrent laryngeal nerve descends from our brain, past our larynx, does an unnecessary loop around our aorta and then finally goes back to the larynx.  This is a leftover from when our fish ancestors were arranged differently.  The oddity of development is most comical in the giraffe that has the nerve travel an extra 4.5 meters out of the way.
• As a fetus, we had pharyngeal gill arches that are homologous to those in a fish.
• We also had a vestigial yolk sac.
• Male humans have nipples.
• We get goose bumps when we get cold or aroused. In our ancestors this was used to stay warm and appear large in front of threats.
• Human testes start out internally (like in our ancestors) and then exit the body after birth, but take an inefficient route looping over the kidney's ureter and leaving males very vulnerable to hernias.
• We have a tail bone.
• Many infants are covered in a hair layer that gets shed after birth called lanugo.
• The distribution of our sweat glands is ideal for quadrupedal locomotion.
• We have non-functioning pseudogenes for scent receptors that we no longer have, as well as a pseudogene for vitamin C synthesis.

This exercise of making predictions and then testing them can be carried out on just about any species.  Try it!  See what you find out! Some quite weird species make this challenging, but this process of 'evolutionary thinking' is extremely valuable in its ability to make predictions and teach us about the biological realm around us.  It is a beautiful and humbling experience to look around at life and be able to see 3.5 billion years of history looking back.  Enjoy it and share this wonder with others!

This post is by www.EvolutionEvidence.org.  Visit them on the web and on Facebook at fb.com/EvolutionEvidence.org.