"I hate to tell you this but people have known how for millennia. Men seem to enjoy it more than women, and both seem to enjoy it more than animals, but we have all understood the process pretty well.
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An excellent point. Sexual reproduction is a good teacher regarding evolutionary changes. We see it in small ways every time we reproduce. The new human being created by two people is never identical to its parents. That's the amazing thing about sexual reproduction. It enables changes in each new organism.
Sometimes those changes are benificial to the survival of the new organism. Such changes are passed along, genetically, to its offspring. These changes are cumulative.
Go in a time machine to the land of your ancestors, about 1000 years ago. Stand in a crowd there. You will find, if you are typical, that you are head and shoulders above that crowd. Height is a positive attribute. It is selected for by the environment. In just 1000 years, the average human being is considerably taller than its ancestors. Remarkable.
And that's just 1000 years. Imagine what can happen in millions of years.
Yes, sexual reproduction is very important in evolutionary theory. Things moved much more slowly before sexual reproduction evolved. Sharing of the genetic code of two different individuals was a great accelerant for the process.
Not the ones that keep these threads alive. The dog breeders create a fascinating variety of dogs. But they always get dogs. Everyone knows this and NOBODY is arguing about it.
As you said, things change.
The sticking point is where the dogs came from, what mechanism introduced the change from what they were to dogs, and where the long series of proto-dogs is that connects dogs to slime.
Shalom.
Wrong. (I can't leave a blanket statements such as that unchallenged.)
My ancestors of A.D. 1000 had the same genetic height potential as I do.
They suffered from nutritional deficiencies. Cf. 1940's Japanese vs. today's generation: A 7" height increase in some cases. Look at today's American kids. Same with French. Romans, too--modern ones are tall due to better nutrition.
Our genetic code doesn't change that quickly.
And as for the blanket statement that height is a positive attribute:
Forest deer are shorter than Elk. Why? They have to navigate undergrowth.
Pygmies are shorter than Watusies. Why? They live in dense jungles, and have to navigate undergrowth.
Height is a selective adaptational advantage only if you life in a savanna world. Else: It's a way to die young, without progeny.