Research into inherited characteristics?

Factual Questions
21

The human species in it’s natural environment (hunter-gatherer bands) is weakly polygamous, meaning most people only have one mate at a time but a few highly successful men might have multiple women attached to him at a time, but it’s not common as hunter-gatherers don’t amass the resources needed to have actual harems. It takes civilization - specialization, cities, and amassing of resources - to have multiple men with multiple wives being fairly common, and even then it tends to be the wealthy and powerful. Poor men might have no mate at all as the wealthy and powerful are keeping them all to themselves.

The upshot is that the size of men and women are less divergent than, say, in gorillas where one large male has a harem of females (for as long as he can hold that position - eventually he gets deposed by a younger, stronger male).

Sexual dimorphism ratio in great apes:
lowland gorillas: 2.37
orangutans: 2.23
bonobos: 1.36
chimpanzees: 1.29
humans (on average): 1.15

(It should be noted that different human groups range from 1.09 to 1.28 sexual dimorphism ratios, but in all cases that would still mean the size of adult men and women are less divergent than for all other great apes).

It should be noted, though, that mating strategy is not the sole determinant of sexual dimorphism. Horses are strongly polygamous, but have a roughly 1.1 ration for that, which means they’re less sexually dimorphic than humans, which are only weakly polygamous as a whole and often monogamous as individuals (well, as pairs).

When less food is available everyone who is smaller tends to survive better. See insular dwarfism for a classic example.

22

The same adaptation is likely (together with several other factors such as environment, skeletal, and tradition) responsible for the success of Ethiopians and Kenyans in long-distance races. I read recently that lung capacity is a major factor in running sports.

23

Is the creationist in question disputing heritability of traits ?

I ask because heritability isn’t the whole of evolution, and it’s not usually the part that creationists dispute - its normally more the idea that mutation plus heritability plus selection can ever combine to do anything novel or beneficial.

24

No, they’re usually just challenging me to produce some evidence that humans, in particular, have shown clear signs of having evolved, which for the reasons cited (long lifetimes, spotty historical records, etc.) is difficult, so I thought maybe there is an area or two in which humans have demonstrably changed in a relatively short, recorded period of history.

Again, this won’t persuade any of these “thinkers” but it will persuade me that I’ve given them a bit of evidence that satisfies their unreasonable demands.

25

Evolution - at least, the evolution of the human species - doesn’t really happen in short recorded periods of history.

There is, I think, an error in your very first post where you talk about tall parents having even taller offspring. That’s not the mechanism by which evolution works. All that evolution requires is that tall parents should tend to produce equally tall offspring. Then, if tallness confers an evolutionary advantage, the tall offspring will survive and reproduce more effectively than the short offspring of short parents, so each successive generation will have more and more tall people in it, thus leading to an increase in the average height of the population, even though the tall people are no taller than they ever were.

Added to that, if a random genetic mutation produces people who are extra-tall, because of the evolutionary advantage that this confers those people will be more successful at surviving and reproducing than the unfortunate schlubs whose random genetic mutation means that they are extra-short. But such a mutation may never occur or, if it does occur, it may be associated with offsetting disadvantages so that it doesn’t, on balance, confer an evolutionary advantage.

How long does all this take? It partly depends on how much of an advantage tallness confers. If it’s only a very modest advantage, then it will take many generations for tallness to spread through the population. But if it confers a massive advantage then it might happen quite quickly. Suppose there is a worldwide pandemic of the highly infectious and invariably fatal short people’s disease, to which tall people are immune. Then, tallness might become a near-universal characteristic of the human species in as little as a couple of generations. But, absent a factor like that, you’re usually talking very, very long periods of time.

We have the further problem that the period of “recorded history” is also the period in which humans have been able to reduce evolutionary pressures on themselves. We have developed a huge capacity to alter our own environment - much more so than any other species. So humans who are susceptible to, say, low temperatures don’t die during a cold spell in the way that equally susceptible birds or insects or animals would, because we can light fires and build houses and skin other creatures and wear their skin for added insulation, and so forth. These means that even the susceptible-to-cold people survive, and reproduce, and so evolutionary pressures do not cause the human race to become more and more impervious to cold.

So, I think evidence of evolution of the human species within the period of recorded history is hard to come by. There is abundant evidence of the evolution of the human species before that period, but it comes from the archaeological and fossil record.

26

Yes, of course. But that’s the standard the evolution-deniers seem to want–at least, that’s the one they demand, and I was wondering if there’s anything that might begin to meet this unreasonable demand. It looks like adaptation to high-altitudes might come close.

27

Yeah, unless they’ll accept evidence from genetics that we have shared ancestry with other apes, or fossil records (spoilers: they won’t, because why would they?), it sounds like you’re going to end up making their arguments for them that microevolution is a thing, but macroevolution is not*

*In reality, nature doesn’t know the difference - there is no mechanism to constrain microevolution, or tether it to an imaginary point where small variations from a ‘kind’ cannot wander a long way from their starting point over longer periods.

That might be a productive avenue of discussion - if they agree that there is such a thing as microevolution, but it can’t add up to big changes over time, have them show their workings - what constrains it?

28

Yes, the people with unreasonable beliefs also demand an unreasonable level of proof. This is by… design.

29

Just take the route Darwin did (both himself and his audience had zero knowledge of genetics).

First introduce the idea of selective breeding and inheritance. You can recall Gregor Mendel’s work with isolating traits of his pea plants and the Punnett squares used to calculate their frequency of occurrence.

However you can drop a simple general remark that humans have been selectively breeding all manners of useful plants and animals for our own benefit (from now to before all recorded history). Isolating and encouraging the breeding of plants and animals, forms the basis of all domestication. We breed dogs, cats, corn, pigeons, chickens, cows, wheat, roses,… We do this by simply searching nature, finding a plant/animal with a desired trait, and encouraging its breeding. Nature has a lot of variety. We are simply ARTIFICIALY SELECTING those, who have the traits we like, to multiply and breed.

Now that you’ve highlighted humanity’s long history of “artificial” selection (of traits for multiplication). Point out that humans are not the only things that isolate, encourage, and discourage plants and animals to breed. The changing effects of nature itself is a much more powerful force than humans. An area prone to drought will NATURALY SELECT animals and plants which are more hardy to drought-like conditions. After some time, you will see plants take on forms like cacti, simply because those traits are preferred by nature.

Natural selection is really the same as artificial selection (humans).

30

Additionally, all light-skinned people of European descent have a defect in one particular gene that regulates the production of melanin in the skin. There is more than one gene involved in skin color, and lighter-skinned people who are not of European descent have changes to different genes and do not have the same genetic defect common to Europeans.

The implication here from an evolutionary or Darwinian point of view is that light skin evolved at least twice, separately and completely independent of each other, both in northern climates.

31

I have only skimmed the responses but this seems to me to be an odd question. What is the purpose? Although humans have not been artificially selected for breeding for specific inherited traits, we are no different, genetically, from other animals, including domestic ones, which have been so selected for thousands of years, and most recently, using genetic information as well as phenotype.

For an easy example, due to inbreeding in many domestic animal populations, undesirable recessive traits can become a problem, and there are now often genetic screenings available to find breeding animals free of these mutations. Breed two clear animals and the trait will not appear in their offspring.

Since we have acres of data about inherited characteristics of domestic animals, as well as plenty of data about humans, why is this even a question? Is the OP trying to prove evolution to science deniers? That’s an utterly pointless endeavor.

32

Just to see if there is any useful evidence, or the most nearly useful evidence, to present to science deniers.

Probably not.

But after reading the responses to the OP, I’d now say “Very probably not.”

It is somewhat surprising to me though if no one’s ever tried researching the subject, even if they’ve come up with no useful results. You’d think it would be handy, if any provisional evidence could be found.

33

This is straying into GD territory but there’s a difference between doing the research to a high scientific level (which, yes, has been done, for longer than any of us have been alive) and putting that research into an easily understood format acceptable specifically to you or to people who have a vested personal interest in denying or ignoring such evidence.

Instead of evolution, try the same thing with relativity or perhaps evidence for a round earth to flat earthers. The evidence is there and there’s plenty of it. And with those, there’s even some very impressive yet relatively simple direct demonstrations. And yet flat earthers (the ones who aren’t trolling, anyway) still persist.

The direct FQ response to the OP is still - the evidence is there and some high level overviews have even been given in the thread.

Everything else is about how well it is presented and formatted and how best to present and format it to people who do not wish to accept it, to which there is no objective, factual response

34

Researching the subject of inherited characteristics in humans? There’s tons of research, some in this thread, and at pretty approachable levels.

35

Which piece of evidence, or which argument, in this thread is, in your view, the most easily understood and/or the most persuasive to present to a science denier?

36

None. But that’s just my opinion.

If there were such a convenient, simple way to do it, those denialists wouldn’t still be around. Or at least not in such numbers.

It’s like arguing a round earth to a flat earther. Flat earth denialism is a lot more straightforward with more direct evidence against and yet useless to attempt. You aren’t going to logic somebody out of a position they did not logic themselves into.

37

Again use Darwin’s approach. Artificial selection through our breeding of tomatoes, or kennel clubs, or roses, or horses, or goats, or whatever. Humans domesticate → breed for desirable traits.

Then hit 'em with the selective forces of nature → droughts, swamps, oceans, lakes, forests, deserts, jungles, etc all require different traits for animal/plant survival.

Nature selects too. Nature is stronger. Nature lasts longer.

38

I think many evolution doubters come from what might be termed the entropy argument: they simply don’t see how anything new or more complex can arise from something simpler. Yes you can argue the technical definition of entropy and try to explain how dynamic living systems work but it’s above their heads; all they can see is the claim “worm + 1 billion iterations = human being”, which strikes them as self-evidently absurd.

39

The long and the short of it is, where incontravertable evidence is no obstacle to believing something stupid, it’s best to just walk away.

40

You’re not wrong to say that this is how to approach a discussion to enlighten someone about how the basics of evolution work, but it probably won’t work on someone who is actively resisting the idea. You’ll get as far as artificial selection and get shut down by “yes but nobody has ever artificially selected a dog to become a cat” or some other spurious argument that is designed (or perhaps an argument that has evolved) to be effective at insulating creationists from looking too hard or too long at reality.