How could we have stopped evolving?

[PocketLint]

Originally Posted by CraigD

It’s even reasonably to speculate that poor vision might have resulted in early social specialization, as humans unable to see well enough to run and hunt assumed “high tech” roles of a more intellectual nature (ie: “cave geeks” ).

CraigD, you gave me a new way to look at it (pun intended).

After all, If I was unable to join the hunt, then I'm the one left behind with all the women folk in the cave. maybe that explains why all the kids keep bumping into the walls and calling the nearest tree dada.

If what you propose has merit, then nearsightedness might be the first genetic defect that works opposite of natural selection.

You actually have caused me to do a 180 in my thought process on this one.

Originally Posted by CraigD

This is less surprising when one considers that, compared to other heritable disorders, such as diabetes, nearsightedness has very little lethality, and, as wearers of very thick glasses and recipients of radial keratomy surgery know, can be very effectively managed.

My point exactly, NOW we have effective ways of dealing with nearsightedness. Prehistoric times? Well I can not be sure but I doubt RK was an option.


-Bob

[Michaelangelica]

Originally Posted by Moontanman

While I am not sure about the other things you are proposing strike the vitamin C thing. All great apes share this trait with us and it almost certainly evolved several million years ago.

Whatever you say
The other five traits have evolved in the last 10,000 years

One order as a whole (Chiroptera) seems to lack synthetic ability. All the families tested (5) from one suborder of Primates lack the ability, whereas those (2) from the other suborder make the vitamin in the liver.

McCluskey, E. S. --- Which Vertebrates Make Vitamin C?

Homo sapiens, guinea pigs, monkeys, bats, some fish and many birds, do not produce their own vitamin C. The rest of the animal kingdom synthesizes their own vitamin C. For them, ascorbic acid is a hormone, not a dietary-acquired vitamin. Animals employ different organs to produce vitamin C

. Can Humans Live Longer?: The Missing Anti-Aging Hormone

[CraigD]

Originally Posted by Michaelangelica

There have been a number of genetic changes in the last 10,000 years.
EG:-
1. Ability to digest lactose
2 Loss of ability to manufacture Vitamin C
3. Among those who live in high altitudes, the ability to access oxygen more efficiently.
5. The ability to digest gluten.
6. Resistance to many diseases such eg AIDs, due to exposure to c 10-15C plague virus. Also small pox and measles resistance among Europeans.

Originally Posted by Moontanman

While I am not sure about the other things you are proposing strike the vitamin C thing. All great apes share this trait with us and it almost certainly evolved several million years ago.

Originally Posted by Michaelangelica

Whatever you say

I think MTM’s claim that the lack of vitamin C synthesis in all great apes, including humans, and a origin of this shared trait far older than 10,000 years ago, is well supported.

McCluskey, E. S. --- Which Vertebrates Make Vitamin C? (which Michaelangelica cites) shows via direct biological measurement that the ability to synthesize vitamin C is present in the prosimian (eg: lemurs, lorises, and tarsiers), but not the anthropoid (eg: monkeys and apes, including humans) branch of the primate evolutionary tree. The prosimian-anthropoid split is believed to have occurred 37 to 55 million years ago (sources: http://www.hopkinsmedicine.org/geneticmedicine/plos.pdf, PLoS Genetics: Population Bottlenecks as a Potential Major Shaping Force of Human Genome Architecture), making it likely that this anthropoid primate trait is very old, nearly as old as the primate order itself, which is believed to be about 60 to 65 millions years old (source: Early Primate Evolution:* The First Primates).

Interestingly, the prosimian-anthropoid division is somewhat taxonomologicaly incorrect. A genetically more descriptive taxonomy replaces the prosimian and anthropoid suborders with Strepsirrhini (eg: lemurs) and Haplorrhini (eg: monkeys, apes, and tarsiers). So the seeming exception of tarsiers (which are classified under the older nomenclature as prosimian) inability to synthesize vitamin C is resolved, tarsiers having spit along haplorrhini-strepsirrhini lines with monkeys, apes, etc. from the other prosimians, lemurs, lorises, etc. The vitamin C synthesis trait is one of the key data that lead to this change in taxonomy.

Originally Posted by Michaelangelica

The other five traits have evolved in the last 10,000 years

Though I’ve not checked them in detail, I believe Micheaelangelica is right about these, though I’m uncertain if all of these traits can be considered human species-wide or unique among primates.

For example, taking

3. Among those who live in high altitudes, the ability to access oxygen more efficiently.

This trait, to the best of my knowledge, is fairly well understood to be related to genetic variance in Myoglobin genes, most notable in comparisons of high-altitude-dwellers (eg: Tibetans), with low-altitude-dwellers (eg: most humans). Although there are distinct, recognized gene variants (alleles) among these different populations, (see, for example, Mary Ann Liebert, Inc. - High Altitude Medicine & Biology - 3(1):39) they’re readily cross-heritable – One or a few generations of interbreeding between, say, Tibetans and Texans, the genes would be present in both sub-populations, along with many other, more visible ones, such as height, complexion and hair color. Although I’ve seen no studies of it, I suspect that this genetic diversity is present in the wide human population, among other primates, and even among the whole mammal class and more widely in the animal kingdom. In short, I suspect that a population of gorillas, rats, or even birds or other animals dwelling at high altitude for several generations would show an increased frequency of myoglobin genes optimized for the thinner air, and that these genes were present with about the same frequency in our ancestors 10s of thousands and millions of years ago.

Originally Posted by Michaelangelica

Can Humans Live Longer?: The Missing Anti-Aging Hormone

This and other writing on genetics and life-extension therapy by health journalist Bill Sardi, should IMHO be taken with great skepticism. Statements such as “humans have the capacity to live for hundreds of years” and “of course, mutations are destructive and regressive, not progressive advancements of the genome.” supported only by references such as “An examination of the historical records of the Holy Bible reveals that Adam was recorded to have lived for 930 years (Genesis 5:5), and Noah for 950 years (Genesis 9:29)” fail to meet the usual standard for biological or medical writing – although some of Sardi’s health care advice (in articles other than the linked one), such as the tharaputic use of dietary supplements containing resveratrol, is not unreasonable, and supported by preliminary scientific evidence. In this article, however, Sardi fails to even address the question of whether, as he suggests, “the enzyme to produce vitamin C be re-installed in humans” or other animals is in way more beneficial than receiving it in our usual diet. His unsupported claim that “Humans once made vitamin C in their liver by the production of four enzymes which convert circulating sugars into ascorbic acid (vitamin C).” entirely contradicts the conventional theory described early in this post. While intriguing, his claim that “mammals who make their own vitamin C can live 8-10 times beyond their age of physical maturity. Mammals without this ability have a difficult time reaching 3-4 times” is likewise unsupported and incredible.

[HydrogenBond]

The inability to make vitamin C does not seem evolutionary. It appears to be the opposite. This lost may have been an artifact of having a food source containing vitamin C, such that the body didn't need to produce it like it used to. The same thing could happen to solar based vitamin D. If we avoid the sun and use high level sunscreens we may de-evolve this ability. It would be de-evolutionary in the sense that it limits human options for survival. It is hard for me see how this brings humans selective advantage.

One area where evolution seems to be targeting is the brain. This is subtle but is easy to see with an analogy. If the liver suddenly was able to process a whole new range of chemicals, one would call that evolutionary. The brain has evolved in the sense it is able to process a wider range of neural interactions. Neural interactions are not specific chemicals that are easy to differentiate as x or y, but these increasingly complex interactions are the stuff the brain is designed to process.

It may our inability to see a specific memory or the how this memory is organized in the brain, that makes this harder to see. We tend to look for a new chemical instead of changes in dynamic structures.

[Kayra]

Originally Posted by HydrogenBond

One area where evolution seems to be targeting is the brain. This is subtle but is easy to see with an analogy. If the liver suddenly was able to process a whole new range of chemicals, one would call that evolutionary. The brain has evolved in the sense it is able to process a wider range of neural interactions. Neural interactions are not specific chemicals that are easy to differentiate as x or y, but these increasingly complex interactions are the stuff the brain is designed to process.

What I do not understand (please, no jokes on this point ) is what is the selection pressures for modern evolution in man? (The last 100 years)

As I understand it, evolution's chief means of bringing about a change in our genetic structure is to weed out the chaff or encourage higher reproductive rates. Weeding is likely to be FAR more effective and would produce more drastic results in a shorter time scale while more successful reproduction would be more effective in long term fine tuning to an environment in which most individuals can survive in past reproductive age.

With the exception of social bias and 3rd world countries, I do not see any environmental pressures that would bring about an evolutionary change in man anymore. Even those people that are more successful in our society are not more likely to reproduce then those that are not. As a clan we provide for our less successful members and assure their survival, to our ultimate genetic deficit.

With such a large population base and no means of long term isolation, advantageous genetic changes would likely have near 0 statistic impact as well.

So my question is, What is driving modern evolution in our day and age?

[HydrogenBond]

Maybe the confusion is because the brain produces a different type of output than purely biochemical, i.e., thought or action. These can lead to biochemical changes, in an indirect way. For example, learning to cook meat with fire was a brain output product. The affect of the output activity changed the way we digest meat. This change was not the big buck getting the females to make babies. It could be an old buck (man) with an activity that helps all the babies.

Have you ever heard of the saying brain children. This sort of hints upon the evolutionary parallel for the brain. The brain does not make biological children, but it can make brain children, which are ideas, art, etc. It is sort of analogous to asexual reproduction, where the mental womb is formed through education and experience. One of the brain children of Thomas Edison was the light bulb. He was a very prolific procreator of brain children. The light bulb created a drastic change in the human environment allowing a higher level of nocturnal activities. It may take some time for this to show up in genetic changes. These genetic changes, if they do occur, will not be traced to Edison having all the females. That type of evolution is more geared toward animals.

If you look at the pace of brain child output, it is accelerating. Culture and education are playing a role, but it also may be genetic changes in the brain that allow this brain child population explosion. Look at it this way, if a herd of deer started to multiply like crazy beyond anything before, we would assume some type of genetic change. With the brain, the idea of the light bulb is not based on one gene or protein. It more complicated. Whatever genetics were involved were made to stick through education.

[Michaelangelica]

Originally Posted by Kayra

As I understand it, evolution's chief means of bringing about a change in our genetic structure is to weed out the chaff or encourage higher reproductive rates.

What you say implies a moral, ethical or 'judgemental' attitude (not quite the right word sorry).

It may be that we are all evolving to be similar to those in power like dopey NY bankers and President Bush.

Evolution makes no judgements.

[HydrogenBond]

If we base evolution on reproduction rates, does that imply poor people are more evolved since they reproduce more? Christ did say blessed are the poor. Does than mean he was the original person to come up with the correlation for humans? I am just pocking fun at the human equals animal assumption for evolution.

I am not saying this is true, but it may be a historical possibility. The reproduction assumption may have been a result of repressed desire, in compensation for the strictness of the Victorian times. It may have been sort of a wish forfillment, allowing the kings of science to go at it. They may have seen themselves leading the herd because of their evolved brains. It could have started out as a pick-up line. If it works keep using it, until finally it was carved into stone, with the original motivation lost to time.

[Kayra]

Originally Posted by Michaelangelica

What you say implies a moral, ethical or 'judgemental' attitude (not quite the right word sorry).

Interesting, but I inferred no such thing intentionally.
What I was speaking of was the two best known mechanisms of evolution, without which the concept could not even exist. Evolution is not driven by purpose or intent, but statistics. The simplest game of odds.

Originally Posted by HydrogenBond

Have you ever heard of the saying brain children. This sort of hints upon the evolutionary parallel for the brain.

HydrogenBond: Very interesting perspective. Are you saying that ideas that change our environment will likely have an effect on our genetic evolution? I agree but only when there also exists selective pressures for the new environment. What would cause someone who is unfit to be productive in the evening to be statistically less likely to reproduce then someone who is? The bias probably exists, and likely in surprising ways we have not thought of.

Or have I missed the point entirely

If you are speaking of Memes, I personally believe that they exist outside of our chemically driven evolution and exist purely as thought.

Hmm, I take that back, as some Memes may drastically affect reproduction if they affect concepts of what a good mate is. In this light, Memes may very well be the single largest driving force for evolution in modern societies in 1st world countries.

[charles brough]

Hello you all, I just peeked back in. . .

You know, Darwin was mistaken in applying his theory to us modern humans. He claimed that natural selection occurred among the various races and this process fostered further changes which he assumed were continuing on. It was a natural mistake and does not, to me, cast any shame on him even though it is the type of thinking that eventually led to Adolf Hitler. The fact is that all the races have built or function in or contributed to the various civilizations we study in world history. One the black races seem to get short-shift in history, but they built civilization in North Africa and along the East central coast of Africa.

More attention needs to be focused on the subject of epigenetic change. What can too easily be credited to biological evolution in us turns out to be mere epigenetic changes that are eventually reversed. They never get into the genes. They tend to be small and to be passed on only to a few generations or to be eliminated, eventually, through the trials of war, famine and disease. A luxurious society like our own leads to a growing accumulation of weaknesses. We see the growing prevalence of diabetes, autism, poor sight, celiac disease, etc. It is epigenetic, not genetic. When it is reversed by brutal times that hit civilizations in their decline, we cannot then say we are “evolving forward!”

I propose that it is the ideologies we agree on that evolve. Those ideologies bind us into societies that compete with each other in a process of natural selection.

charles