Hi Dr Tesla; awesome moniker, BTW.
As a science nerd, I love this topic. Thanks for giving us another chance to talk about it! You don't have to understand evolution to benefit from it every day. If you have ever had a flu shot or a blood transfusion or were tested for allergies, or have eaten corn, or had a vaccination, you have benefited from the theory of evolution. Police solve crimes using forensic biology--based on the theory of evolution-- to identify human remains. They locate criminal suspects using DNA--the discovery of DNA is also based on the theory of evolution.
The basics of evolution are not that hard. All life came from a common ancestor, which is why all living things-- including plants, insects, mammals, birds, fish, reptiles and bacteria-- have basic similarities at the cellular and molecular level. Every life form alive today came from a previous ancestor.
The closer two species are to each other genetically, the more characteristics they share. You see it all around you-- most kids look kind of like their biological parents, and closely related species can have offspring (lions and tigers are both a type of cat, and can have offspring--ligers!) while species that are very far apart cannot (dogs and cats, or birds and snakes, can never have offspring).
Humans, gorillas and chimps are all primates who share a common lemur-like ancestor. The three are too distantly related to have offspring, but are close enough to have similar characteristics in appearance and social organization-- and even to share diseases. When we look at the DNA of different species of primates, it is much more similar than when we compare any primate DNA to canine or feline or reptile DNA. We can even locate the exact places in the DNA where chimps diverged from humans in the evolutionary line.
All of that supports the theory of evolution--TOE. If distantly related species like cats and lizards could produce offspring, that would mean the theory was false
. If kids routinely looked nothing like their parents, that would mean the theory was false
. Imagine how strange it would be if two dachshunds mated and produced a litter made up of poodles, black labs and collies. An event like that would falsify evolution. If the TOE was false, there would be no way to breed animals with any kind of certainty.
It is a mistake to think that an individual animal or plant or insect "decides" to evolve in one way or another. Otherwise we humans would have "decided" to evolve wings so we could fly or eyes that could see more of the color spectrum. It is not about individual choice. It is about what makes it possible for an organism to survive long enough to reproduce and pass on its characteristics to its offspring.
The eye is a great evolutionary example. A critter that can sense light and dark has an advantage over those that are completely blind. The blind ones get eaten and the more light sensitive ones live and reproduce more. Over time, the light sensitivity becomes more refined until some critters are being born with cells that can detect movement as well as light.
Then some are born with cells that detect colors and distance as well as movement and light. It is not hard to see how various kinds of eyes will evolve from this process. The human eye is not the best, just sort of average--better than dogs and cows, worse than most birds. Eagles can detect rodent movement from thousands of feet in the sky; owls can see mice in a pitch dark night.
And even then, some animals survive well without seeing, using smell and hearing instead. Bats that live in caves don't use their eyes much and have evolved other senses, like radar. Some fish and moles that live in total darkness can't see at all, but have vestigial eyes
that used to see but don't anymore because they don't need them. They live where other animals-- those that rely more on seeing-- can't survive.
So, evolution-- "survival of the fittest" is not always about being the meanest, fastest, biggest or smartest. Being "fit" is what helps the species survive when something in the environment around them changes. Plants evolve to resist pesticides, repel insects, survive drought or cold. Some animals are not fast or strong, but they taste bad, or look like they might taste bad. Turtles are not fast, but they have evolved hard shells to protect themselves.
Lots of prey animals are small and quick so they can burrow and hide from predators. Humans are physically weak, have no protective claws or fur, but have evolved big brains instead to invent tools and make clothes. One bee or ant can't survive very successfully alone, but in groups they do very well. Whales are enormous mammals that evolved from big land animals and now can live in water. We know this because, unlike fish, whales breathe air, have foot bones they don't need, give birth to live young and nurse them with milk.
The discovery of genes reinforced the theory of evolution by showing exactly how similarities pass from parent to offspring. Genetics is about as much proof as science needs that evolution is true. Anytime a person says that "x runs in my family", or looks for a certain breed of dog that is good with children, they are accepting that genetics is real, and they are also accepting the theory of evolution.
There is a bacteria that has evolved the ability to eat plastic! If that is not good evidence for evolution, I don't know what is.
It would be very simple to prove evolution false: find one organism without the DNA characteristics of its ancestors. Or one example of a species out of evolutionary order, like evidence of primates in the era of dinosaurs. That's it.