The points everyone has to realize about evolution:
- genetics, and so the characteristics of any living thing, can change randomly in response to random mutations. These happen by chance, cosmic or background radiation, chemicals or other environmental issues, etc.
-Most of these changes have no effect or are bad for the organism. It may not survive. Some changes are not passed on, as the change does not affect the genetic material that is passed on to offspring.
-if the mutation is beneficial, if it improves the odds the organism will survive, thrive, and improves the odds of the descendant organisms also surviving, then likely it will stick around; if it is really helpful, it may become a dominant trait. For example, colour vision. We have 3 sets of cones in our eyes that see 3 different wavelengths, making up colours. A predator that has 1 set sees black and white. A simple mutation where the gene is duplicated, but the second one is more sensitive for a different wavelength, may help a predator pick out food that is the same shade as the background but different hue. That becomes a useful charateristic; that animal and its offspring eat bette, live longer, find the food first.
-Organisms tend to evolve when there is an opportunity to exploit. If there is a food source, or a better way to hide, etc. - the animal best suited to take advantage of that survives, outcompetes the others.
-Humans are decendants of the tree-dwellers like monkeys, come down to wander the savannah and chase down prey. We evolved a very efficient mechansim - two feet good, four feet badder - that let use outrun wildbeests and make them food. We can’t beat them on speed, but we can keep up with and harrass quadrupeds until they fall over from exhaustion. Very few animals can run a marathon, day after day, like a human. As a consequence, we learned to eat meat - protein and fat - very efficient sources of food energy.
Why are there still monkeys? Because we suck at getting fruit from high branches. Why are there apes? Because we prefer the open plains to the denser forest areas, we don’t climb easily. Animals with very strong arms that can also climb trees are more efficient and survive better in that environment.
What there are not any more, is australopithecus and similar human types from 3 to 5 million years ago. Maybe they also chased down food and figured out how to use sticks to chase hyenas away from carcasses; but a bigger better version of themselves probably replaced them over the millenia.
It’s all about opportnities and ecological niches. Every advantage is also a disadvantage -trade-offs. A big brain helps us in many situations, but requires more food to keep working. Big muscles mean someone is much stronger, but starves faster when food is scarce. A predator may find colour vision an advantage, but if the main method of hunting is by sense of smell (dogs, cats) then it’s not a great advantage. A horse cannot normally survive with a broken leg, while a cat or wolf might, because the latter might eat by limping from abandoned carcass to carcass until the bone knits; while a horse that can’t run away from the wolves is basically Mother Nature’s drive-in diner…
Of course, if someone persists in believing the world is flat or evolution is not happening or the sun revolves around the earth… all the logic in the world will not work.
