Study Detects Recent Instance of Human Evolution

The New York Times is running a Sunday article regarding new evidence about 'recent' human evolution. A research team at the University of Maryland has done some work looking at the rise of lactose tolerance in the human populations of Africa. From the article: "The principal mutation, found among Nilo-Saharan-speaking ethnic groups of Kenya and Tanzania, arose 2,700 to 6,800 years ago, according to genetic estimates, Dr. Tishkoff's group is to report in the journal Nature Genetics on Monday. This fits well with archaeological evidence suggesting that pastoral peoples from the north reached northern Kenya about 4,500 years ago and southern Kenya and Tanzania 3,300 years ago ... Genetic evidence shows that the mutations conferred an enormous selective advantage on their owners, enabling them to leave almost 10 times as many descendants as people without them. The mutations have created 'one of the strongest genetic signatures of natural selection yet reported in humans,' the researchers write. "

Re:Why is it always "mutation"

[Vreejack]

Most mutations are not fatal, they are neutral, having no observable effects in the offspring. Elsewise, you would probably be dead. It is these random mutations that build up the gene pool, giving natural selection something to work on, and without which crossover would have no effect.

Actually, strong selection pressures are identified on a gene by the absence of crossover. When a gene is strongly selected the other genes and junk near it tend to be carried along intact, instead of being carved up by recombination.

Or are you suggesting that the gene for lactose tolerance arose through crossover? And if so how is that not a mutation?

Re:Why is it always "mutation"

[cnettel]

Actually, major crossover events, creating a different chromosomal makeup, can be a very efficient barrier against fertile off-spring. We can observe lots of single nucleotide polymorphisms (SNPs), the "purest" mutation you can achieve, in humans. Some of them cause known phenotypical differences, far from all of them lethal. Then, we also have all those mutations that really just replace one codon for an amino-acid with another one for the same residue, with very limited effects, if any.

Don't think so.

[Ihlosi]

The leading cause of death for infants less than 100 years ago in developed nations (and STILL the leading killer today in underdeveloped countries) was diarrhea. How do you get diarrhea? Hmm, lactose intolerance causes - guess? Diarrhea. Baby can't drink breast milk, so you give it something else - something more likely to be contaminated with diarrhea causing viruses. Net result? More diarrhea.

Erm. You're confusing general lactose intolerance with adult lactose intolerance.

General lactose intolerance is a bad thing. Any mammal that doesn't tolerate lactose while still nursing is in very deep doodoo. It's a mutation that'll basically kick you out of the gene pool immediately.

Adult lactose intolerance is, for most mammals, a normal thing (which is why you shouldn't give milk to cats/hedgehogs/etc). Adult mammals aren't supposed to seek out sources of milk, for obvious reasons, which is why the production of lactase usually stops once the mammal is old enough to eat real food. Of course, this mechanism evolved loooong before humans got the idea of domesticating goats/sheep/cattle and use the milk of a completely different species to supplement their diet. This made a mechanism that would have been faulty (adult mammal that tolerates lactose) suddenly become a genetic advantage.

Re:No way!

[bkr1_2k]

There are no passages in the Bible that "very clearly condemn homosexuality" as each passage can be interpreted in several different ways, as the parent suggested. You will also find most of those passages up for debate are from the Old Testament, which isn't from the teachings of Jesus. You will find much in the New Testament that directly contradicts the Old Testament.

So if I read you correctly, he's not a Christian worthy of your disdain because he bothers to think for himself (as the New Testament suggests he should) and not simply "obey the word"? That's very tolerant of you.

Re:Speculation, I don't see how it makes a differe

[jacquems]

Says YOU. Tell me, what is it that babies were supposed to drink 6000 years ago? Formula? Diet Coke?

Breast milk, either from their mother or from another woman. A quote from the History of Breastfeeding [wikipedia.org]:

"In the early years of the human species, breastfeeding was as common as it was for other mammals feeding their young. There were no alternative foods for the infants, and the mother, along with other lactating females, would have no choice but to breastfeed the children. This process is still seen in many developing countries and is known as shared breastfeeding."

It's very rare for a baby to be intolerant to the lactose in its mother's milk (see Myth 21 at this page [lalecheleague.org]), and as another poster pointed out, babies that couldn't digest human milk didn't live very long.

The leading cause of death for infants less than 100 years ago in developed nations (and STILL the leading killer today in underdeveloped countries) was diarrhea. How do you get diarrhea? Hmm, lactose intolerance causes - guess? Diarrhea. Baby can't drink breast milk, so you give it something else - something more likely to be contaminated with diarrhea causing viruses. Net result? More diarrhea.

Until fairly recently in the history of human beings, if babies didn't get breast milk from their mothers, they were usually nursed by another lactating woman (see wet nurse [wikipedia.org]). Although breast milk substitutes were already available in the mid-1800s (see a history of baby formula [wikipedia.org] here) it was only about in the 1940s, when women were needed in the workforce, that the use of baby formula really became widespread. Incidentally, one major way babies get diarrhea in developing countries today is from drinking formula mixed with contaminated water. Breast milk is definitely a safer alternative.

Humans have recently (in the evolutionary time scale) started doing something that few (if any) other mammals do: drinking the milk of another animal. The fact that adult humans are developing a better tolerance for lactose is quite significant.

Re:No way!

[kiracatgirl]

Following the law isn't how you get sent to Hell. Hell is, to put it simply, a place where there is an absence of God. As the Christian God is everywhere, and in everything, a place WITHOUT Him is the place designated as "Hell". It was initially described as a place filled with overwhelming sadness and loneliness, but future church officials found that insufficient to motivate their congregation to 'do the right thing', and started making up the whole fire and brimstone story. And the way to go to Hell, the only way to go to Hell, is to completely reject God. Basically, you go to Hell if you CHOOSE to go to Hell, i.e. choose to be entirely separate from God.

Secondly, something that many people forget is that the Old Testament is, quite honestly, a Jewish book. In order to be Christian, you don't have to follow the Old Testament; you have to follow JESUS. Jesus' example and his laws (few that they are) and teachings. One can completely ignore any laws in the Old Testament and still be Christian, as being Christian means you believe that Jesus is God, the Saviour, etc. and you worship and follow him and the God he preached about.

As for claiming that the entire group of Christians has a specific stance on the Bible is particularly naive. Compare, for example, the Catholics to the Fundamentalists. The Catholics follow the precepts presented in the Bible, but only to a point and focusing mainly on the New Testament, and have much external doctrine unrelated to the Bible that is far more important than laws in the Old Testament. Fundamentalism, on the other hand, believes that you should follow what the Bible says by the letter. They tend to be the ones you read about mentioning the anti-homosexuality clauses and the like.

"So, if you're not a member of a church, then you're free?"
I don't get what you mean by that, honestly. If you're not a Christian, why would you follow Christian laws and Christian morality? That's like saying if you live in Australia, you have to follow Chinese law. You aren't a Chinese citizen, so why would you follow their laws?

well said, mr. entitlement

[teh_chrizzle]

it's not the christian religion itself that irks me... what drives me crazy about christianity is the sense of entitlement that it creates in it's followers. i'm not usually one to go off on religion, especially someone as progressive in their thinking as you... but even your words smack of good old christian entitlement. that's the problem i have with christianity.

christians can spout off all they want about how they have been persecuted and excluded and whatever and feel entitled to point that out to us all, much like you have here. i don't know where you live, but here in midwestern america there is chirstianity plastered [google.com] all over every flat surface, and we all just accept it... and yet that's still not enough. you still feel entitled to share your chistianity with us, as if we had forgotten for a moment that christianity is alive and well in america.

looking past the kooks and the bible thumpers, to the average rank and file christian, there is still that that self rightous sense of entitlement. the extremist rehetoric no longer phases me, in fact i much prefer it because it's so easy to tune out. but that subtle sense of entitlement, present in so much of american culture, always rings in my ears.

Re:No way!

[MECC]

Secondly, something that many people forget is that the Old Testament is, quite honestly, a Jewish book. In order to be Christian, you don't have to follow the Old Testament; you have to follow JESUS.

Not really, it you read Matt 5:17-19. But, if you choose to interpret Luke 16:16, Eph 2:15, & Rom 7:6 literally, then no, you don't have to follow the OT.

As for claiming that the entire group of Christians has a specific stance on the Bible is particularly naive.

Believing that the bible - any part - is a canon of god or god's instructions on how to live is what's actually naive. Pick any christian sect, and they canonize some part of the bible to fit their tastes. That's just trying to translate personal preferences into divine will - something nearly all christian sects have in common (along with a slew of other religions). That was actually the underlying point.

Re:Micro vs Macro

[jackbird]

I say that the Bible is factual and true. It is of God, it is God's word and the Gospel of Christ and if evolutionists are going to be critical of the Bible they should at least try reading it with understanding first.

Dollars to donuts you don't read it in the original Hebrew.

The bible is a compilation of texts, and the records of the compiling process exist (hence we know that the book of Esther, for example, was considered and rejected for inclusion.) This process leads to the myriad inconsistencies (or continuity errors, if you want to be glib) in the text. The seven days of creation comes from a different author than the Adam and Eve story, and still other rejected stories exist where Eve is Adam's second wife, etc.

You say you take your reasoning directly from the bible, but

• Your thousand years/one day argument is the same one used by the Clarence Darrow character in Inherit the wind to discredit the William Jennings Bryan character, saying that each day of creation could be a million years.
• Your reasoning destroys the moral force of the story of Cain and Abel. If humans had been living on earth for a thousand years, with no oversight from god, yet no murder or violence, but Adam and Eve's offspring commit fratricide casually, the implications are extremely problematic.
• Your 'literal' reading of the text does not stick to the text. You handwave into existence an entire society of people based on a single line.
• I see nothing in the bible to contradict evolution, and in fact find hardcore creationism to be unbiblical and arrogant. If God is really all-knowing enough to create perfectly balanced ecosystems, the wide variety of species on Earth, and an empirical cover story of dinosaurs as a test to man's faith, then why is God so consistently surprised by human behavior in the bible? Why would a god so omniscient need to send down a son to die in order to understand human suffering? It places humans above god intellectually and morally.

Re:No way!

[kiracatgirl]

A fairly uncommonly contextual quote, which follows that long list of "things not to do" that everyone loves to quote in the whole the-Bible-is-anti-homosexuality debate:

Lev 20:22 Ye shall therefore keep all my statutes, and all my judgments, and do them: that the land, whither I bring you to dwell therein, spue you not out. (KJV)

To simplify, those rules were rules he gave them in order to survive in the culture of the land they were moving to. It wasn't an expression of the Will of God or any such thing, it was just practicality for survival of His people.

Such are the dangers of quoting out of context.

Re:They don't explain WHY

[thePowerOfGrayskull]

Milk is generally THOUGHT to be a good source of calcium, but in fact is not: http://www.afpafitness.com/articles/MILKDOC.HTM [afpafitness.com]
The information in the above source seems reasonable enough, and well-backed with scientific reports. Please read it, I assure it is worth it.

So I've read this article, and all I can say is -- what complete crap! He draws conclusions with no evidence (I guess his say-so that he "read 500 scientific studies" is enough -- unreferenced studies, I might add.).

How would I summarize the articles? They were only slightly less than horrifying. First of all, none of the authors spoke of cow's milk as an excellent food, free of side effects and the "perfect food" as we have been led to believe by the industry. The main focus of the published reports seems to be on intestinal colic, intestinal irritation, intestinal bleeding, anemia, allergic reactions in infants and children as well as infections such as salmonella.

Wow, open right up with the scare tactics! Because we know in the countries where people drink a lot of milk, all of these things are epidemic! Note that he didn't say that milk caused these problems but inferred it by saying that they were the focus of the unsourced studies he allegedly read.

Our paleolithic ancestors are another crucial and interesting group to study. Here we are limited to speculation and indirect evidences, but the bony remains available for our study are remarkable. There is no doubt whatever that these skeletal remains reflect great strength, muscularity (the size of the muscular insertions show this), and total absence of advanced osteoporosis. And if you feel that these people are not important for us to study, consider that today our genes are programming our bodies in almost exactly the same way as our ancestors of 50,000 to 100,000 years ago.

The last I heard, our ancestors of 50,000 - 100,000 years ago did not commonly live for 30+ years. This is the typical minimum age for onset of osteoporosis.

Consider for a moment, if it was possible, to drink the milk of a mammal other than a cow, let's say a rat. Or perhaps the milk of a dog would be more to your liking. Possibly some horse milk or cat milk. Do you get the idea? Well, I'm not serious about this, except to suggest that human milk is for human infants, dogs' milk is for pups, cows' milk is for calves, cats' milk is for kittens, and so forth. Clearly, this is the way nature intends it. Just use your own good judgement on this one.

That's the way to do it. Make a comparison designed to get an emotional reaction, then reinforce that reaction. That's scientific.

It seems that the public is uneasy about this product and in one survey 43 per cent felt that growth hormone treated milk represented a health risk

Source? Oh, wait, he doesn't have one. And I'm sorry, is he citing a public survey in a 'scientific' paper?

Oh, and what kind of scientific discourse would be complete without anecdotal evidence?

I had one patient who did exactly that. He had no obvious vices. He didn't smoke or drink, he didn't eat meat, his diet and lifestyle was nearly a perfectly health promoting one; but he had a passion. You guessed it, he loved rich ice cream. A pint of the richest would be a lean day's ration for him. On many occasions he would eat an entire quart - and yes there were some cookies and other pastries. Good ice cream deserves this after all. He seemed to be in good health despite some expected "middle age spread" when he had a devastating stroke which left him paralyzed, miserable and helpless, and he had additional strokes and died several years later never having left a hospital or rehabilitation unit. Was he old? I don't think so. He was in his 50s.

So don't drink milk for health.

Wow. Here's a surprise. Guy eats like crap his whole life -- ice cream, mind you, not milk, and not in reasonable quantity -- and then dies from it. Blame milk! (Literally. Very next line. )