Not a book but the doc that National Geographic, The Human Family Tree covers this in a way that is easy to understand by those without a science background.

You know, geneticists have calculated that we all have common ancestors that go back 4,000 years. Incidentally, that fits perfectly with the story of Noah and his wife. Humans adapt quickly to their environments. An example of this are the Gothic tribes who came out of Scandinavia who wandered a bit before ending up in what is now Spain. They look Mediterranean today but have Scandinavian DNA. I digress…

There is only one race of modern humans. Are melatonin and facial structure really different enough to categorize? I don’t think so. I mean, you could say something like, “People who look like this are generally from there,” but that would be the only difference. People are people.

Unless you’re writing the book you’re looking for I doubt it exists. If it does it’s probably full of conjecture and racial bigotry. I’m not sure if you’re looking for lineage or specific people groups. As you’re probably aware the largest “ethnic” people group in the world are the Hmong of SE Asia. They are spread across several countries and are thousands of years old. I would not consider them to be isolated.

Anyway, I looked up “genetic drift” on Google and all I got was a bunch of evolution hogwash and that’s not very helpful. I mean, there’s a lot of sites explaining what it is and the effects but I couldn’t find any practical applications that I thought you could use. Especially being that you want a book. Searching around a bit more…

I got a hit… It’s a bit technical but I think it will meet your needs. The best I could do. Sorry I rambled but I’m waiting on an Ebay auction to end so answering the crap out of your question helped me kill a few minutes. I do apologize that it seems to be so technical as your question stated “non scientist” but I think it’s the best fit.

“Human Population Genetics”
By John H. Relethford

http://www.amazon.com/Human-Population-Genetics-John-Relethford/dp/0470464674

Disclaimer: I have not studied this topic at all. I have no idea how current or how respected the views of these authors are.

Given that you seem to be primarily interested in the human diaspora and differences between “races”, here are a few that might interest you:

Deep Ancestry: Inside the Genographic Project by Spencer Wells

The Social Conquest of Earth by E.O. Wilson

The Accidental Species: Misunderstandings of Human Evolution by Henry Gee

It also occurs to me that Ian Tattersall has written many books on human evolution (qv), one of which is called Race? Debunking a Scientific Myth.

@uberbatman Thanks. That’s a great website, and one I will enjoy reading. But she’s an old fashioned reader. She wants to be able to curl up on the couch with a dead tree version of the story. My son got her a Kindle Fire a couple of Christmases back, and after playing with it for a bit, she set it aside never to be booted again.

@DWW25921 Thanks for the link. It’s not working, but you gave me plenty of details to find the book on Amazon. Anyone wanting to use the above link can click it, then remove the text string, ”&tag=fluthercom-20” from the end of it to get it to work. Looks for the review posted there that the book is targeted at upper-level undergraduate students in biology and requires a strong understanding of statistical analysis. That’s probably not reading my wife can manage. But I do appreciate the effort.

I do realize that we are all the same species and that our so-called “racial” differences are minor. We do have genetic flags to race, however. DNA analysis can tell us the race of the sample donor. Police agencies the world over use this to help them narrow down their search for a suspect.

Sorry to burst your young Earth bubble, but real geneticists have traced the Mitochondrial Eve back as far as 140,000 to 200,000 years ago. The span in estimates is driven by just how much alike a strand of mitochondrial DNA has to be to another to count as showing ancestral linkage. Our last common ancestor before the split between great apes and hominids lived at a minimum 4 million years ago.

BTW, next Sunday’s Bible question will be one dealing with literal timetables in the Bible, and why fundies insist some are literal while insisting others are figurative time periods. I’ll send you a link to it and hope you choose to chime in. For my part, I promise that if we disagree, I will do my level best to do so agreeably. It’s hard enough to win a debate with logic, facts and persuasion. It’s unheard of to win a debate by out-insulting your opponent.

@glacial Thank you so much for the list. I asked on Goodreads.com as well, joining the Human Origins—Explorations and Discussions in Anthropology, Biology, Archaeology, and Geology discussion group to do so. One of that group’s members also suggested The Accidental Species so I an going to target it. Here’s what he said. “I have to make an unreserved recommendation of a new book on human evolution by Nature’s former editor, Henry Gee: The Accidental Species—Misunderstandings of Human Evolution. It is just brilliant, iconoclastic and very funny, too.”

@ETpro Yes, I’ll confess that I put it on my list as well. Things like this make me miss being in bookselling, but they make my pocketbook not miss it, you know? ;)

@ETpro There was a geneticist that studied the development of bird species on islands that had become separated by continental drift. I don’t think it was Mandel, but it could have been. He followed the species as they changed over time. That study really helped me understand how certain traits emerge in a population over time. I can’t think of the name of the book though. I’ll try to find it.

@Adirondackwannabe I think you’re thinking of Peter and Rosemary Grant, studying Darwin’s finches on the Galapagos Islands.

Oh – unless you mean MacArthur and Wilson’s theory of island biogeography (same island, same finches, older study). But then, if you want to go back as far as Mendel’s time, perhaps you’re thinking of Darwin himself.

@glacial Yes exactly! Give that jelly a cigar.

Those finches have had a lot of visitors. :)

@glacial I’m a familiar face at the reference desk of the loacl library. I use the heck out of the Interlibrary Loan System. If it weren’t for that, my wife and I would read ourselves out of house and home.

@Adirondackwannabe I cited that example to my wife by way of explaining what genetic drift in isolated populations means, and where we see it in operation. Here’s a more recent example of it.

@ETpro Thanks for the acknowledgement. I did try. It seemed like a challenge as it’s not a subject I generally give a lot of thought to.

@DWW25921 If I’m not mistaken the aborigines marooned themselves on australia some 40–50,000 years ago, and as different in appearance as they are they are still genetically almost identical to us.
I have a pet theory why humans look so different, even individually, compared to, say dogs, where the differences inside each breed are pretty minuscule. It’s because dogs can smell the difference on each other. but since we gave up the smelling part of our brain (the fore brain) up to higher cognition, and our seeing brain became better developed as we left the trees and had to scan the savanna, we had to develop different facial features so we could recognize individuals.

@drhat77 That’s all kinds of fascinating! I’m glad I decided to answer this question because it opens up a whole new field of study that I didn’t even know existed!

@drhat77 But between individuals who live closely together (where you’d need to be able to distinguish one person from another), there is less difference… your idea wouldn’t explain why the most obvious differences are between groups which are long distances away from each other.

My theory is our skin evolved to somewhat match our natural background. Camoflauge made us safer in the wild. Black skin in thick jungles. White skin, fair hair, and blue eyes in very snowy climates, and when the sun shines in the summer the skin tans to match the tree bark. Desert climate people have a sandy color, thinknpaces like Egypt, red clay areas their skin has redder undertones, think some of our Native Americans.

As far as features, broader noses or rounder faces, all I can figure is the features were favored as good looks in diifferent group and continued the gene pool that way.

All my own theories that most people don’t agree with. I wish I had a book to recommend, it would be interesting to read up on, but my ideas usually are not part of the evolution of man when exlained by scientists, so I would be frustrated probably.

@drhat77 I think dogs are some of the most varied animals on the planet.

@glacial at the risk of touching the third rail, when dealing with a race your are unaccustomed to, “they all look alike”, but when dealing with your own or one you are accustomed to, you notice the individuality quite easily. I think the fact that there had to be enough permutations for individuals to be recognizable even when inbreeding was a high possibility, plus when separated islands of population could get exaggerated differences caused this phenomenom.
@JLeslie that would not explain facial differences, or why those of the same race would need to look different. I always thought skin color was to strike the right balance between protection from skin cancer and vitamin D production. as for dogs looking different, see my third rail remark above!

@drhat77 That… doesn’t make sense to me. Mainly because you are trying to explain why there are great differences between races, and then you are saying that within one race individuals are easily distinguished. It is a contradiction.

@JLeslie There are indeed very noticeable differences between different dog breeds – because we artificially selected for them. How different populations of dogs would differ from each other if we had never done this is debatable. Perhaps not more different than the ends of the wolf-coyote spectrum.

@glacial I think @JLeslie meant that she speands enough time with a particular breed that she can tell differences between individuals based on sight alone, which I would not be able to do.

the problem with pet theories is they are always crystal clear prior to any attempt to articulate, and then they kinda fall flat.

Because we need a system that is strong enough to withstand the homogenizing effects of inbreeding, we end up with something that causes vast differences even when genetic differences a minimal.

@drhat77 Well, I know my big nose gets really burnt in the sun. Maybe black people are more likely to have flatter noses to not get a burn on the top of their nose? I know the vitamin D explanation, and I will agree possibly that is part of the explanation, but I can tell you this, I am extremely D deficient, and my darker husband isn’t. He goes in the sun and gets kissed all over to be a beautiful bronze. If I risk the sun I am burnt to a crisp. So, what do I do? Cover up and protect. I get much much less exposure in the end, and much much less D. The theiry that MS might be connected to D dificiency is interesting to me. MS clusters in cold climates and is seen more in caucasians. If there is a D connection, evolution isn’t working well.

Dogs are much more varied than people. A chiwawa and a St. Bernard or both dogs. I guess we can look at Pigmies in Africa and Vikings in Iceland and say they are very different too, but really the variety of dogs, the colors they come in, their different coats, their different shapes and sizes is much more varied than humans in my opinion.

Firstly, let me say that you guys know a lot of very big words and I’m both impressed and a little intimidated. Secondly, if I may try to add a tiny morsel… Humans really aren’t that different. Relative shape and size and all… Some are jerks and some are awesome…

It seems to me that there is really only 1 major deciding factor when it comes to the subtle differences of humans and it doesn’t make sense to me that it would have such a profound effect and that’s geography. I suppose different people in different places eat different things and that can account for different chemicals but is it really that simplistic? Maybe.

@JLeslie oh so @glacial was right. Obviosuly different dob breeds look different but inside the breed they look very alike. and wild dogs and their immediate ancestors look very alike, even inside a pack. They can do that because they all smell different, so they know who is who. Since our sense of smell has devolved, we need visual differences to pick up on who everyone is.

I’m working on The Selfish Gene right now, by Richard Dawkins. I really enjoy his writing style, because he makes everything easy to understand without going back to grade-school condescension.

(and he has what I consider an incredibly dreamy voice, so it’s extra-fun to reinforce the learning by falling asleep to the audiobook)

I’m about halfway through right now. It has a good section on sexual selection, which illustrates the likely reasons humans lack a penis bone. Once one can grasp how sexual preference contributes to genetic drift, it shouldn’t be hard to understand why people in this part of the world tended toward dark hair and one skin tone and people in another part to pale hair and another skin tone.

Poor erectile function betrays not only physical states such as diabetes and neurological disorders but mental states such as stress and depression
Pretty freaking awesome. I didn’t know we were only one of two primates without the bone in the er.

@DWW25921 What reading I’ve done on “racial” (or isolated population) differences chalks a bit up to diet, but a great deal up to environmental conditions. Sub-Saharan Africans needed a lot of melanin to protect them from the intense sunlight of their environment, and their coloring also helped them blend into and successfully hunt in the forest and savannas they inhabited. Flat noses and Asian style epicathic folds on their eyelids because those adaptations worked well for wind-swept steeps and desert areas they inhabited. They better shielded the eyes and respiratory system from wind-blown sand and dust. Northern Europeans needed light coloring to avoid vitamin D deficiency in low sunlight, and light coloring helped them successfully hunt in snow covered environments.

@Seek_Kolinahr Yeah, there is certainly that going on too. We humans self select. If we aren’t careful, well develop female breasts so huge their bearers can’t stand up without props.

At 98 lbs we have to be getting close.

@Seek_Kolinahr Awgh.