Ice Age Ancestry May Keep Body Warmer and Healthier

A team of California geneticists has found that many of the world's peoples are genetically adapted to the cold because their ancestors lived in northern climates during the Ice Age. The genetic change affects basic body metabolism and may influence susceptibility to disease and to the risks of the calorie-laden modern diet.

The finding also breaks ground in showing that the human population has continued to adapt to forces of natural selection since the dispersal from its ancestral homeland in Africa some 50,000 years ago.

The genetic adaptation to cold is still carried by many Northern Europeans, East Asians and American Indians, most of whose ancestors once lived in Siberia. But it is absent from peoples native to Africa, a difference that the California team, led by Dr. Douglas C. Wallace of the University of California, Irvine, suggest could contribute to the greater burden of certain diseases in the African-American population.

Other experts praised the findings about adaptation to cold but said the role of mitochondria, relics of captured bacteria that serve as the batteries of living cells, in these diseases was less certain.

The genetic change affects the mitochondria, which break down glucose and convert it into the chemical energy that drives the muscles and other body processes. But the mitochondria will generate heat as well, and less chemical energy, if certain mutations occur in their DNA that make the process less efficient. Just such a change would have been very helpful to early humans trying to survive in cold climates.

Dr. Wallace and his colleagues have now decoded the full mitochondrial DNA from more than 1,000 people around the world and found signs of natural selection. By analyzing the changes in the DNA, they have been able to distinguish positive mutations, those selected because they are good or adaptive, from negative or harmful mutations. In today's issue of the journal Science, they report that several lineages of mitochondrial DNA show signs of positive selection.

These lineages are not found at all in Africans but occur in 14 percent of people in temperate zones and in 75 percent of those inhabiting Arctic zones. Dr. Wallace and his colleagues say this correlation is evidence that the lineages were positively selected because they help the body generate more heat.

Until now, most genetic change in the human population since it left Africa has been thought to be either random or just the elimination of harmful mutations. The evidence of the new analysis is that positive or adaptive selection "played an increasingly important role as people migrated out of Africa into temperate and Arctic Eurasia," the California team writes.

One implication is that everyone is adapted to a particular climate zone, and that moving to different zones may cause certain stresses. Mitochondria of the lineages found in Africa, Dr. Wallace suggests, may contribute the extra burden of certain diseases found among African-Americans, like diabetes and prostate cancer.

His reasoning is that African lineage mitochondria have never had to develop a mechanism for generating extra heat. So when an African-American and a European-American eat the same high calorie diet, the European's mitochondria burn some calories off as heat but the more efficient African mitochondria are liable to generate more fat deposition and oxidative damage, two results that could underlie the higher disease rates, Dr. Wallace said.

Separately, some of the European mitochondrial lineages appear to protect against Alzheimer's and Parkinson diseases and to be associated with greater longevity.

"Therefore," the California team writes, "to understand individual predisposition to modern diseases, we must also understand our genetic past, the goal of the new discipline of evolutionary medicine."

While many scientists study the genes of the human cell's nucleus, Dr. Wallace has focused on the tiny mitochondrial genome for 33 years. Along with the late Dr. Allan Wilson, he has pioneered the tracing of the 20 or so mitochondrial lineages found in the human population, all of which link back to a single individual known as the mitochondrial Eve.

Several other experts said that Dr. Wallace's ideas were promising but that the role of mitochondria in degenerative diseases had yet to be established. "It's a very attractive idea and may well turn out to be right, although the biochemical evidence of uncoupling differences between the mitochondrial lineages has yet to be nailed down," said Dr. Lawrence Grossman, a mitochondria expert at Wayne State University.

Dr. Mark Seielstad, a population geneticist at the Genome Institute of Singapore, said the positive selection was likely to have been a "major architect" in shaping mitochondria and that Dr. Wallace's work should throw open discussion of the subject.

Two experts on mitochondrial disease, Dr. Michael Brown of the Mercer University School of Medicine in Macon, Ga., and Dr. Gino Cortopassi of the University of California, Davis, said Dr. Wallace's ideas about African mitochondria made sense but had yet to reach practical significance. "We've not yet got to the stage of being able to give advice to African Americans," Dr. Brown said.

Dr. Wallace says that climatic selection may have operated on the human population from the moment it moved north of the African tropics. Most such pioneers died but two lineages, known as M and N, arose in northeast Africa some 65,000 years ago and might have been adapted to temperate climates. Almost everyone outside of sub-Saharan Africa has mitochondria descended from the M and N lineages.

"Bear with me, the hour is late."

I understand. I went to bed myself and woke up about an hour ago. Aaah, the joys of vacation.

"I believe you're saying Darwin is/was correct. I hope so because natural selection from random, natural mutations explains the antibiotic resistance of formerly sensitive pathogenic organisms after exposure to a previously lethal antibiotic, i.e. to the organism, if the patient finished the prescription, e.g. a patient didn't finish the complete course of treatment prescribed by the physician because the patient started to feel much better and didn't finish her/his medicine."

Actually, no. I was saying that Darwin was incorrect, and proved so, at least with the method of evolution that he proposed. Darwin never considered mutations as the means by which evolution occurs. From his amazing grip on scientific principles Darwin INVENTED a means by which evolution (which he admittedly knew to be impossible to observe - a theory developed from another set of theories = scientifically FUBAR)that neither he nor any other scientist of the time could prove or disprove and called them "pangenes."

The most common explanation for pangenetic evolution is the popular "Giraffe Story" (at least it used to be popular). Millions - billions, trillions - of years ago a horse ate all the grass from the ground that surrounded him. He was still hungry so he ate from the low branches of a tree. "Memory Genes" or Pangenes 'remembered' through the generations that the leaves provided more nutrition than grass so the horses developed a taste for the leaves instead of grass. Eventually the leaves from the bottom of the trees began to deplete, so the horses had to stretch their necks for higher leaves. The pangenes 'remembered' that necks had been stretched and subsequent generations were born with longer necks. Absurd? Yes. Disproved? Of course. When crimsons were able to be observed microscopically and the helix model of DNA developed, these pangenes were proved to never exist.

So, here is the theory of evolution hanging out in the late 1940's early 50's without so much as a theory for the method by which it occurs. So does the theory die. Of course not. Why? Because it hasn't been true science for years, why should it be now? Suddenly, NEO-DARWINISM is born, or the BELIEF that mutations are the driving force behind evolution.

I'm going to come back later with documentation that I don't have in front of me know. I haven't looked at this subject for years, so it may take some time, especially since I don't have access to my books (which I have labeled, marked, etc.). I'm in transition between duty stations and my Household Goods are somewhere between Darmstadt, GER. and Ft. Drum, NY.

Pathogenic resistance to antibiotics has never been proved to happen due to mutations. No one knows whether pathogens are genetically programmed to defend themselves by attaching to proteins that block antibodies or if a mutation actually occurs.
Let's assume that mutations are the means by which pathogens develop a defense against antibody's. What you read is that these pathogens have developed, after an intensive lab study, a defense against antibiotics through mutation. So is neo-Darwinism correct? No. Why? Because that is one beneficial mutation. It would take scores of subsequent beneficial mutations to ever change that pathogen into minnow - or more realistically a Super Disease immune to everything. Well, where is this Super Flu? Why haven't we seen a Super Virus mutate from the most common and most commonly mistreated virus? Because it doesn't happen. The pathogens develop a resistance to one kind of treatment at a time (sometimes 2 or 3 if it develops the right proteins) , simultaneously losing the ability to guard against other treatments. This is micro-evolution, better described as genetic variation within the genetic ability of a kind.
Micro-evolution is an observable, real process. Ex: An English Bull Mastiff and a Doberman Pincher are mated. Certain genetic qualities bred out of the offspring and after thirty generations you have new TYPE of the KIND dog... A Rottweiler. Now Rottweilers mated with Rottweilers will only give birth to Rottweilers because the genetic pool has been thinned so that the dominate, bred traits, win out during gestation. However, because of their lineage, Rottweilers do have the genetic ability to birth Berman's, and could be bred to do so. In all of this, a new species was never evolved, nor could have evolved. The same is true for the pathogens, however on a grander scale as thousands upon thousands of generations of pathogens can occur in the amount of time it took to develop Rottweilers.
By the way, a mutation did develop during the breeding of the Rottweiler. Two as a matter of fact. Both are debilitating. The first is that funny, extra finger we call the dewclaw which can immobilize an older dog, due to poor muscle development caused by the extra claw, if not removed early on. The other is a slightly wider hip placement caused by developing the Doberman's bone structure but the Mastiff's posture and mass, which cause Rott's hips to slip under their own weight too often.
Oh yeah, speaking of mutations... we are still assuming that mutations are the means that pathogens develop resistance to antibiotics. As you say, "natural selection from random, natural mutations explains the antibiotic resistance of formerly sensitive pathogenic organisms after exposure to a previously lethal antibiotic.." So does available genetic variations, however, neither has been proved nor disproved.

Again, I'm sorry for the lack of documentation. I hope these sound like well read arguments, because they are, and not babble. I search the Internet for supporting work.

Have you, by the way, read THE MIS MEASURE OF MAN by Stephen Gould, it has a lot to say about the subject you originally posted from one of the leading evolutionist minds of the past 50 years.

"Well, this makes sense empirically. All of my ancestors came from arctic regions (if you go back far enough), none that I can recall were extremely fat, most only required one blanket for sleeping even during the coldest winters, all of them lived well into their late 80s and 90s but had brittle bones. Guess I'd better start taking more calcium and magnesium."

When naturalist and explorer Alexander von Humboldt toured the Tierra del Fuego region (Southern most tip of Argentina), he described two different people who lived in the same region. One was tall and thin (...he went on to describe their abundant clothing) the other was short and stocky, almost fat.
The short stocky people were practically naked and two women rowed their canoe up to his ship to ask for supplies and he noted that both were topless and one was breast feeding an infant while the icy rain bounced off her shoulders and the babys' head.
The short stock people lived off the sea while the tall thin people lived off the land.

There were two different people living in harmony because they were not competing for the same resources.
Also, of the short stocky people, he noted that the women were in charge of the canoes and would tether them off-shore in the kelp beds and swim back to the shore when they were not in use by the men. (There was a sharp rocky coast that would destroy the canoes if tethered on the coast)
He thought this was so because women have more body fat than men and the water was icy cold.

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