Skip to comments.Study Detects Recent Instance of Human Evolution
Posted on 12/10/2006 2:44:11 PM PST by Alter Kaker
click here to read article
"I don't believe anybody's ever claimed cats turn into birds or lizards turn into zebras."
No, nothing that crazy, they just claim that prokaryotes turned into humans. You're right to point out how delusional any poster is if they joke about how lizards turned into zebras. Clearly, it was dinosaurs that turned into zebras. There, now we've straightened out that problem.
Human tastes are not necessarily shared by animals. For instance, goats like the taste of poison ivy.
I guess that's why they can't duplicate Darwinism in the lab--cause that wouldn't be natch'rl.
1. Presumably they didn't originally domesticate cattle for milk, they domesticated them for meat.
2. As has already been noted, early humans could digest milk products, just not raw milk -- cheese and butter and fermented milk (tastes nasty but will keep you alive) were always edible.
And it only took 3.5 billion years, too. Nobody pretends that a prokaryote will grow two arms and two legs over night and graduate from the Harvard Law School. Your incredulousness stems from a poverty of vision on your part, not from any problem with evolutionary theory.
OK, lessee if I've got this right: humans, who already had domesticated cattle for meat, cheese, butter and fermented milk, selected a gene that would allow them to digest whole cow milk, in order to have better nutrition, by being around milk. Not drinking it after a certain age, just by being around it. And this tolerance for that dairy product, unlike those other dairy products, made them candidates for survival, while those who... didn't stand close enough to the whole milk... died before reproducing. It makes perfect sense. Those creationist idiots will probably make fun of that logic.
No, natural selection isn't random variation. You're confusing mutation (which sometimes occurs because of random variation) with natural selection, which is something altogether different.
would not favor anyone it selects, and how would it know to select milk drinkers.
On the contrary, if milk drinkers were better nourished than their non-milk drinking neighbors, then they would be more likely to survive to reproductive maturity and natural selection would certainly favor them.
Natural selection is a random act that brings everything back to the average.
You got it backwards. Better genes tend to survive. If someone has mutated genes that increase their chances of survival over the average, natural selection will favor them.
how would it know to select milk drinkers
It doesn't. People who are better nourished are more likely to survive. People who can drink milk are more likely to be well nourished. That's natural selection.
. But the 3000 year thing is close to Biblical flood time of around 4500 years when God told man to eat meat.
Did you read the article? There were at least two independent mutations. One that allowed East Africans to drink milk, about 3000 years ago. An earlier mutation allowed Northern Europeans to drink milk, 6000 years ago. You are really a one-track record --- you'll read your creation myth into anything. If you were a contestant on Jeopardy, I suspect every answer would be "What is the Noahic flood."
"Your incredulousness stems from a poverty of vision on your part, not from any problem with evolutionary theory."
Yep, it's my own inability to accept the impossible that makes me so stubborn. It couldn't be that evolution can never answer the big questions, like how did life form from inanimate matter? I'll tell you what. You get all your PhD's together, gather up all the water, oxygen, nutrients, and anything else you want, all of it inanimate, and make a single-celled form of life, then give me a call.
It's very easy to spot evidence of recent human evolution. Some humans evolved...the rest remained democrats.
Humans didn't do anything. A mutation just happened in an individual, and the offspring of that individual were able to receive better nutrition than the offspring of other individuals without the mutation.
Standing close to whole milk didn't do anything -- the mutation would have occured in any event. However, in a culture without cattle, the mutation would have not been beneficial and would have conferred no benefit on individuals with the mutated gene. In that circumstance, the gene would have probably disappeared. Selection is what favors a particular random mutation within a given environemnt.
I don't think you have any idea how long 3.5 billion years is. I can get creationists to accept that incremental changes do occur to genotypes, but you people are inevitably lost on the cumulative effect of those changes over many generations. That stems entirely from a poverty of vision -- the numbers just get too big and you just throw up your hands and say "Prokaryote! Human! It's just too complicated for me to imagine!"
t couldn't be that evolution can never answer the big questions, like how did life form from inanimate matter?
Evolution also doesn't explain why the earth is round, why peanut butter sticks to the roof of your mouth, or why beer tastes better out of a tap than it does in a can. It simply explains a change in allelle frequencies over time, and that's not a failure on its part.
You get all your PhD's together, gather up all the water, oxygen, nutrients, and anything else you want, all of it inanimate, and make a single-celled form of life, then give me a call.
In any event, wouldn't that be Intelligent Design?
Wild cattle were being caught, corraled and milked long before it occurred to anyone to domesticate them.
This is a sample of the kind of evolution very few will argue with. Although I don't know that the word "mutation" would be accurate. All people are slightly different in some ways. If something happened in our environment that favored people less than 5 feet tall, the population would shrink in height in a few generations. If something happened to suddenly favor those over 6' in height, the general population would increase again in height in a few generations.
It is not evolution of the individual members of the populateion that is happening. It is simply a change in the numbers of a particular subgroup that was always there - and still is. It just became the dominant group.
Same thing here. If something happened to our environment that suddenly made it deadly to adults that could digest milk, in a few generations, the general population would again be unable to digest milk.
This isn't the type of evolution that stirs the fun debates here. ;)
I'm not an expert in cattle domestication (it's just a little bit outside my field :-) ), but my point is simply that I think we can imagine plenty of ways for humans to have exploited cattle before this mutation.
I'm guessing cheese was invented far earlier than these researchers imagine.
Why not? A genetic mutation clearly took place, in a specific individual 3000 or so years ago. Before that point, no adult in East Africa had the gene that would allow digestion of lactose. That gene resulted from a genetic mutation. Whether you believe that the mutation was natural or that God for whatever reason decided to intervene (in accordance with Intelligent Design) the mutation clearly took place.
Remember also that human children could digest animal milk all along (to at least some degree). Maybe animals were exploited in order to provide an extra food source for unweaned infants. Since infants were the most likely members of society to die, even a slight increase in infant nutrition would probably confer huge evolutionary advantages.
Even American Indians regularly milked wild bison.
Interestingly enough, no comprable gene change happened in the Americas.
What I think is going on here is a much more recent finding that vitamin D may be a natural antibiotic. If you don't get enough vitamin D you get sick and die. If you get enough, you thrive and live.
In parts of the world where normal human processes could provide sufficient Vitamin D, no variation in the lactose processing gene(s) would convey any particular advantage on anyone. On the other hand, where normal human processes could not provide sufficient Vitamin D, e.g. at high latitudes, inland, such a gene would definitely convey an advantage.
However, the "advantage" is not in terms of having a "superior process" that others don't, it's in having an "additional process" that confers equality of condition when it comes to living long enough to successfully reproduce.
There are about 600 such gene changes that have been found in European populations. Almost all of them seem to have something to do with "getting lighter and/or more transluscent", and that's gotta' be related directly to the business of producing enough Vitamin D to survive into adulthood.
That would be MICROGenetic alterations. Evolution doesn't exist, happen or be reality.
So evolution takes place for a while, until God smacks a giant red OFF button? Is that how you see it?
The genetic mutation described in the article occured among cattle raising populations in East Africa. I'm not sure I see access to Vitamin D being a problem in East Africa, as opposed to general nutrition.
Actually, it's green.
Three species already!
.......Very low threshold for this fairy tale of a theory.....
Mythical certainty is a far easier to swallow than natural selection.
Gosh. At this rate, in a gazillion years or so, we're all probably gonna be milk cows!
Hey! Does that mean it turns out that the Hindus were right?!
/s (added for the benefit of those lacking a sarcasm detector...)
Correct. That's the purpose of this study -- it traced back the existence of this one genetic mutation to a specific individual 3000 years ago. Now that doesn't mean that other individuals hadn't had analogous mutations at earlier points (remember that a similar mutation occured in Northern Europe 3000 years earlier), but if they did in East Africa, then their genes have not survived to the present day.
Ok, but do you have a substantive response? If evolution takes place on the small scale, then clearly something (again I'm picturing God with a big OFF button of the color of your choice) actively intervenes to stop it after a certain point. Otherwise you'd soon have large scale evolution.
That's a somewhat strange image, which is why I have trouble entertaining creationism as a serious explanation for much of anything.
Wrong. You seem to misunderstand what has happened. People have the innate ability to digest lactose. It is turned off. When it is needed it is turned on.
Fron the article.
The mutations Dr. Tishkoff detected are not in the lactase gene itself but a nearby region of the DNA that controls the activation of the gene. The finding that different ethnic groups in East Africa have different mutations is one instance of their varied evolutionary history and their exposure to many different selective pressures, Dr. Tishkoff said.
This is from Dr Shapiro showing how cells compute and it involves the same sugar. http://shapiro.bsd.uchicago.edu/21st_Cent_View_Evol.html
CELLULAR COMPUTATION AND GENOME SYSTEM ARCHITECTURE
There are many ways to visualize the systemic nature of genomic coding. One that is discussed in other parts of these PROCEEDINGS is the organization of protein molecules as systems of discrete structural and functional domains encoded in evolutionarily mobile DNA modules (14; these PROCEEDINGS, Symposia B6 and B7). Here we will examine the basic principles of gene expression and transcriptional regulation and the evolution of our one-dimensional concept of the gene into the more complex notion of a genetic locus.
The lac operon: A simple but illustrative example
Our example is the lac operon encoding the capacity for lactose utilization in the bacterium E. coli. Like virtually all classical genes, lac began existence as a point on a genetic map in the late 1940s, soon after the discovery of genetic exchange in bacteria (Fig. 1; see 15, 16, for detailed references to lac operon history).
Fig. 1. The lac gene, site of mutations affecting lactose utilization by E. coli (1947).
In the following years, Jacques Monod studied lac genetics because he had discovered that E. coli could discriminate between glucose and lactose; when given a mixture of the two sugars, the bacteria would invariably consume all the glucose before starting to consume the lactose. In 1961, Monod and his colleagues proposed the operon model. In the operon, lac had evolved into a system of "structural genes" encoding the proteins of lactose transport and metabolism (lacZYA), a "regulator gene" encoding a repressor (lacI), and a completely novel type of genetic element, the "operator" (lacO) (Fig. 2).
Fig. 2. The lac operon (1961)
It is important to recognize that lacO was not a "gene" encoding a product. Instead, it was a site on the DNA where the repressor bound to block the initial step of lacZYA expression from the adjacent DNA. This conceptual development was revolutionary in its impact on our understanding of genome function. Such cis-acting binding sites for proteins are now recognized as key components of the genome, essential for processes such as replication, transcription and genome distribution to daughter cells.
After the operon model, other scientists discovered additional binding sites in lac, including the site of RNA polymerase binding or "promoter" (lacP), a site for binding the Crp transcription factor that mediates glucose control of lacZYA transcription (CRP), and two additional operator sites that permit cooperative binding of the repressor (lacO2, lacO3). Thus, by the mid 1980s, molecular genetic analysis had decomposed the dimensionless lac gene into a structured system of protein-coding and cis-acting regulatory sites (Fig. 3).
Fig. 3. The lac operon (1990)
The importance of the organization of the various lac regulatory sites is that they permit the molecular computations that allow E. coli to discriminate glucose from lactose ? that is, to control expression of the lactose metabolic proteins so that they are only synthesized once glucose is no longer available. The basic biochemical reactions and molecular interactions involved in this computation can be stated as logical propositions that can then be combined into partial computations (Table III). These partial computations illustrate the molecular logic allowing the cell to execute the following overall computation: "IF lactose present AND glucose not present AND cell can synthesize active LacZ and LacY, THEN transcribe lacZYA from lacP."
Table III. Computational operations in lac operon regulation
Operations involving lac operon products
? LacY + lactose(external) ==> lactose(internal) (1)
? LacZ + lactose ==> allolactose (minor product) (2)
? LacI + lacO ==> LacI-lacO (repressor bound, lacP inaccessible) (3)
? LacI + allolactose ==> LacI-allolactose (repressor unbound,lacP accessible) (4)
Operations involving glucose transport components and adenylate cyclase
? IIAGlc-P + glucose(external) ==> IIAGlc + glucose-6-P(internal) (5)
? IIAGlc-P + adenylate cyclase(inactive) ==> adenylate cylase(active) (6)
? Adenylate cyclase(active) + ATP ==> cAMP + P~P (7)
Operations involving transcription factors
? Crp + cAMP ==> Crp-cAMP (8)
? Crp-cAMP + CRP ==> Crp-cAMP-CRP (9)
? RNA Pol + lacP ==> unstable complex (10)
? RNA Pol + lacP + Crp-cAMP-CRP ==> stable transcription complex (11)
? No lactose ==> lacP inaccessible (3)
? Lactose + LacZ(basal) + LacY(basal) ==>lacP accessible (1, 2, 4)
? Glucose ==> low IIAGlc-P ==> low cAMP ==> unstable transcription complex (5, 6, 7, 10)
? No glucose ==> high IIAGlc-P ==> high cAMP ==> stable transcription complex (5, 6, 7, 8, 9, 11)
Two aspects of this particular genomic computation deserve special mention. The first aspect is that the computation involves many molecules and compartments of the cell, not just DNA and DNA binding proteins. For example, the membrane transport proteins LacY and IIAGlc are essential. The second noteworthy aspect is that the computation involves the use of chemical symbolism as information is transmitted. Thus, the presence of allolactose inducer represents the availability of lactose and the ability of the cell to synthesize functional LacY and LacZ. Similarly, the concentrations of IIAGlc-P and cAMP represent the availability of glucose to the cell. Both whole cell involvement and transient chemical symbols are typical of cellular computation and signal transduction in general.
This isn't a speciation event as individuals with and without the mutation can obviously interbreed succesfully. Don't be fatuous.
Not true. People may have the gene that allows them digest lactose as children, but if you lock a man without the mutation that in a room with nothing but milk, he'll never be able to digest it no matter how long you leave him there, no matter how great the need. A mutation has to occur.
People keep calling it a mutation. Why is that? I am thinking the concept of recessive genes may be a mitigating factor here, coupled with previous rarity of the gene.
IOW, this article is opinion.
"They're trying to find themselves an audience. Their deductions need applause." - Genesis: The Lamb Lies Down on Broadway.
No need. It won't matter if your eyes are closed...
It's an additional food source in a famine. Being able to drink milk could easily be the the difference between life and death.
>>If evolution takes place on the small scale, then clearly something (again I'm picturing God with a big OFF button of the color of your choice) actively intervenes to stop it after a certain point.<<
I disagree. We are not talking about speciation here. We are only talking about natural selection and evolution of the "population" as a unit, not the individual members of the population. No evolution took place here in that sense.
Your statement also assumes that any evidence of small scale evolution ipso-facto proves large scale evolution. It doesn't. It only implies it or, more precicely, leads some to infer it. It is opinion, which is fine. We all have one. But when it is discussed as proven fact by some (not suggesting you did it here though), it causes others to bristle.
No, he can't, but what if this happens with his grandchildren:
Seems that 'evolution' went through an awful lot of trouble building the 'childhood lactose tolerance with subsequent switch-off' system when it is such an obvious 'advantage' not to have it.
It was "snake root" and was responsible for the death of many of the early settlers in the Midwest including Abe Lincoln's mother.
I fail to understand how the evidence is convincing that the genes followed diligently such a commonsense assumption that after weaning, the enzyme would be no longer needed and then made unavailable.
Humans consume many things that are not perfectly digestible without any great ill effect.
The domestication of mammal herds makes available a source of excess milk but by itself doesn't prove that the enzyme had remained switched off thousands of years before.
Absolutely true, I gave you a specific example. And a mutation is a change. What do you think turning something on or off is? It is a change. Here is the composition of HUMAN breast milk.
Major nutrients. Lactose, 5.5-6.0g/dL, is the most constant nutrient in human milk (Table I). Its concentration in breast milk is not affected by maternal nutrition. Proteins amount to about 0.9g/dL in mature milk.Recent studies comparing the impact of nutrition on lactation in industrialized and developing countries suggest that neither maternal diet nor body composition affects milk protein level. However, limited data from earlier studies seem to indicate that short-term, high-protein diets can increase the protein and nonprotein nitrogen content of human milk, while limiting maternal food intake can lead to lower milk protein levels.[13-15]
Lactose tolerance is the mutation.
Lactose intolerance is the normal biological system.
"However, certain human populations have undergone a mutation on chromosome 2 which results in a bypass of the common shutdown in lactase production, allowing members of these populations to continue consumption of fresh milk and other milk products throughout their lives."
Lactose tolerance is just a normal 'loss-of-function' mutation. Nothing supporting evolution here.
Wow, an actual reasoned response. OK, that makes sense. Believe it or not, I have no problem with that part. A certain trait, already present, becomes dominant among one group when they are able to procreate more successfully than the other group. Just for the sake of info, how do these researchers know when this took place? It seems to me that knowing when a particular gene moderator became the dominant expressed trait in any group, has to be, well... questionable?
I don't tolerate high amounts of alcohol like I used to. Am I evolving?
I don't think so. Mother's milk is lactose rich. The ability to metabolize the sugar is innate. Look at the computation example for E. Coli. It is in my post 79.
Do you know how long 3.5 billion years is? Can anyone really grasp such a huge number? I can't accept evolution as fact because there is no proof that it's fact. There are tons of fossils, lots of evidence of what happened, with some pretty good evidence of when it happened, but practically nothing but raw speculation, ever changing, about how it happened. Creation is an obvious answer; if a thing exists, it must have been created. We know that hydrogen didn't evolve, that it was somehow created. We know that sub-atomic particles didn't evolve, that they were created. We know that all the evo theories of how life began have never been recreated in any lab, despite some very earnest tries. Things that exist were somehow created. That leads me to believe that there is a creator. This simple logic has yet to be intelligently refuted by evolution apologists. Tell me how the first bits of life came about. Then show me your proof. Tell me why, if simple organisms can spontaneously pop into existence, that more complex organisms can't also pop into existence? How do you know that species didn't just show up, whole and unevolving, all at once? For all science knows, our creator is still creating different species, all the time. The evidence for evolution fits this perfectly. And you wonder why folks question your theories.
'La bonne cuisine est la base du véritable bonheur.' - Auguste Escoffier
(Good food is the foundation of genuine happiness.)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
Since evolution is generally considered in the context of speciation I don't think you can call selective breeding "evolution" unless you can cite a case where selective breeding has actually resulted in a new species that cannot interbreed with its ancestral stock.
"Even American Indians regularly milked wild bison"
Can you link to a source. I have a hard time envisioning anyone getting close to a 2000 lb wild animal (with a baby since otherwise she wouldn't be lactating) and milking it.
I'm genuinely curious, I grew up on the Great Plains and have never heard this before. Maybe I can learn something new....
Who created the creator? After all, if something exists, it must have a creator.