Human evolution (Part 2): My response to the arm chair experts and their criticism

This 2nd thread is a direct result of various comments appearing in my preceding thread entitled
Human evolution: A simple calculation indicates that human evolution may have been turbo charged !
and to which I now wish to respond. I've decided a 2nd thread is more appropriate as these following comments of mine would most likely have been missed by the majority of readers if I had simply inserted them into that original thread.


From Edrick:

Supercharged Evolution, eh? This is what happens when you extrapolate from a position of Ignorance.

From VonDoomen:

In all honesty, i think you just dont fully understand evolution and thats why your having a hard time figuring this out.

From Thermo Klein:

Not trying to be rude, per se, but I think this OP is a mockery of science.

From spookfish:

A monstrous deficit of understanding has been shown by the OP

How easy it is to make comments such as the above, when the authors themselves are nothing more than "armchair experts" with no real world qualifications or expertise of their own that would enable them to pass judgment one way or another. If such qualification are possessed by any of them, please feel free to mention them.

The most important part of my previous thread is that I saw what I considered to possibly be an interesting aspect in evolutionary development and decide to throw out my personal thoughts regarding it.
At no point did I claim to be an expert on evolutionary theory and so anything I say is obviously to be taken with that understanding, into consideration.
However, even someone with only a lay persons knowledge of genetics can observe, theorize and attempt to draw conclusions ... and that's exactly what I was doing. I saw something unusual and therefore wished to highlight it and bring it forward for scrutiny.


Now before I continue, there's one more point I'd like to make.

Nature operates on the genetic structure of all organisms in a completely random fashion ... basically by trial and error. What works, stays ... what doesn't work, is discarded.
At no point does nature have or need a PhD or any other kind of scientific accreditation to do it's work. Nature operates on THE lowest level of "hit and miss" with no grand plan or design in mind. Nature is blind and simply shuffles things around until something works, and then moves on from there.


Ok, in that previous thread, I've received a fair bit of criticism regarding my apparent "dismal lack of understanding" on how genetic evolution works, as if it's some kind of esoteric principle able to be understood by only a select few. Sure, there's a heck of a lot of detail wrapped up in genetics and a lot of time and effort has been put into the attempt to unravel it but take a step back and take a look at the ways that an organisms genome can "evolve" by increasing their DNA length. Surprisingly, it's pretty straightforward.


1. Nucleotide base pairs are added to existing DNA one pair at a time randomly.
2. Entire sections of nucleotide base pairs are inserted into existing DNA at a given instance due to viral vectors.
3. Entire sections of nucleotide base pairs are copied and inserted into existing DNA from existing base pairs within the same DNA.


I think the above basically covers the ways that a new "rung" or "rungs" can be added to an existing DNA "ladder".
Naturally, I'm open to any of the earlier quoted "experts" to correct me if I'm wrong and they know of other common ways of increasing the length of a DNA strand.


Ok, now we're also told that in the majority of instances, that mutations occuring on a chromosome strand are deleterious to the organism and more than likely to result in the organisms incapacitation or death and that it's only rarely that the mutation is beneficial in some way.

From this observation, the immediate conclusion is that the greater the degree of mutation i.e. adding many new nucleotides at a single time, has a much greater probability of resulting in a significant reduction in the organisms genetic stability, if not resulting in out right death.
The corollary to this is that the organism has a much greater chance of survival if a minimum number of new nucleotides are introduced into it's existing genetic structure at any given point in time.

So, we can see that there is obviously a "selection factor" at work at the genetic level that favours those mutations involving the minimum of additions, being actively selected for. This does not mean that every addition of multiple nucleotide base pairs is potentially lethal to the organism as such "multiple additions" undoubtedly do occur over time. However it does mean that as the number of simultaneous nucleotide additions increases, the probability of the organisms survival decreases accordingly.

Again, any "ATS expert" is more than welcome to chime in and dispute the above observations.


Moving right along ....


Ok, lets now take ourselves back to that dim dark past of approximately 3.8 billion years ago when the 1st single celled organisms evolved.

Without dispute, it can be assumed that such organisms were just that small step above what separates the organic from the inorganic. These simple cells being able to reproduce, would by definition have a simple variation of the DNA molecule that served to encode all the information pertaining to that cells functionality and reproducibility.

From the very instance of that 1st cells creation, it's DNA structure would have been subjected to many external stimuli and environmental pressures, any or all of which could, and most certainly did, cause changes by addition, to it's DNA.

Now for every mutation of the DNA, the organism would have to survive long enough to reproduce. If it failed to reproduce for whatever reason, then that particular mutation would be lost and evolution at that point in time forced to take one step backwards. Nature would now be required to select another cell that had NOT received that "fatal" mutation and randomly generate (hopefully) a different chromosomal mutation. Again, if the mutation was lethal, then that latest evolutionary change would again be lost and evolution yet again forced to take a step backwards.


Now for single celled organisms, the above trial and error method used by nature to "evolve" the organism, with a correspondingly high failure rate, is quite acceptable as such organisms can reproduce themselves at an astonishingly high rate given optimal environmental circumstances. So in a short space of time, nature can make many, many, many attempts at finding an "advantageous" mutation that can be passed along to succeeding generations.

However, the moment that complex multi-celled organisms appeared, their rate of reproduction would begin to decrease. This would result in longer and longer intervals between when a chromosomal mutation occurred and the time that the organism was able to reproduce and potentially pass on that mutation to its offspring. Consequently, the rate of successful mutation would also decrease.

So from having potential mutation rates of many per hour (single celled organisms), the mutation rate decreases in direct correspondence to increasing periods between reproductions. Organisms that have received a beneficial chromosomal mutation but don't reproduce for extended periods of time (days, weeks or months), stand a much greater chance of failing to pass on that beneficial mutation due to illness, environmental trauma, predation, etc, etc ... all of which essentially turn back the evolution clock by 1 tick.

So, what does the above mean in summary ?

It means that initially the increase of DNA length due to beneficial mutational additions would have been fairly rapid ... until multi-cellular organisms evolved at which the rate of DNA increase due to beneficial mutational additions would have begun to decrease initially, and then decrease much more rapidly as the complexity of the organism increased.


Let me ask you a question.

What major genetic mutations have occurred in the time period of 35,000 years thats elapsed since Cro-Magnon man, the earliest modern human, and present day humans ?

I'm certain some minor mutations have occurred but can you point to any significant mutations in all those thousands and thousands of years ? From what I've read, you could essentially take a Cro-Magnon individual, clean them up and give them some modern clothes and they'd be perfectly unnoticeable and unremarkable walking along the streets of any modern city.

And what about the 35,000 years preceding the appearance of Cro-Magnon man ? Were there any significant chromosomal alterations occurring during that period ?


So now, I come back to the original topic that I brought up in my preceding thread.

This was nothing more than an observation on my part that to account for the modern day humans tally of approximately 3.1 billion nucleotide base pairs contained in the ENTIRE genome, and using the established date of approximately 3.8 billion years since that 1st simple cell appeared, that

... on average, ONE NEW AND NON-LETHAL nucleotide base pair would have to be added on average PER YEAR to the genome of ALL the intermediary organisms that have existed and linking humans to that earliest single cell.

This takes into account the unimaginable number of mutational failures that must have been occurring continuously at the SAME TIME ...

In my opinion alone, and regardless of whether the DNA length increased gradually or in spurts ... no matter how you cut the mustard, thats one heck of an incredible success add rate that eventually resulted in us humans.

So whether those 3.1 billion DNA additions occurred gradually and steadily over time or whether the 3.1 billion DNA additions occurred in distinct spurts interspersed with relatively quiet periods ... I still find myself pondering the overall impressive rate at which DNA has successfully mutated since that 1st original simple cell ancestor and what type of evolutionary mechanism could possibly account for it.

reply to post by tauristercus


Exactly thought out and presented tauristercus. A great response to that unwarranted criticism !

I'm in complete agreement with you that such rapid mutation rates are somewhat difficult to explain.
It would appear that evolutionary theory is definitely somewhat lacking.

S & F for the great effort.

reply to post by tauristercus


viruses have the ability to effect DNA and RNA so your theory isn't so crazy. I wrote about this before and even saw your first post about evolution happening every year but i didn't write. Maybe this is the clue you are looking for and certain retro viruses are encoded into our DNA from our great grandfather cave men which they genetically passed on to us. Every year adding a new layer from some cold or flu. While the virus dies it leaves it genetic makeup carcass in our DNA slightly effecting our DNA structure maybe after so many copies of the virus encoded in our dna makes evolution happen so our bodies evolve to the virus so we don't get it anymore. Im also sure it makes mistakes along with its success but with nature its meant to die we try and find a cure. Have you ever heard about immortal cells? A lady in the 1940 died of cancer her doctors found that the cancer cells didn't die and multiplied. today their are more of her cells alive in laboratory's then when she was alive. I think maybe our bodies are trying to become immortal but the genetic mutation is killing the people who get it. I know odd right but think of it as a work in progress im sure some of the genetic mutations to inhale air ended in failure as well until nature got it right.

Genetics is a very complex topic and lots of ways to approach and understand it. As a computer programmer I see it more about the community than the male / female or hermaphrodite reproduction. DNA amongst other things is about a search for improvement and sustainability. Have you noticed how people generally get married with people on the same social level. This allows for those at the top to maintain their winning physical traits while providing the opportunity for those lower down the social ladder to find a new combination to surpass and become the new leaders of the community. There is lots too it, well done and good luck in your search for understanding.

I agree with you entirely.

On the surface, it's obvious. Random genetic mutations, most bad but a few good, a few billion years, too easy.

This has bugged me too. With a little knowledge (dangerous I know) and some deep thought, one might conclude that a random mutation (apparently rare) proving to be an advantage to an organism (apparently much rarer) is a statistically unlikely event but is likely to occur given some time. Of course, an organism lucky enough to acquire a genetic mutation affording it some advantage over its competitors still has to live long enough to reach sexual maturity, successfully mate and pass on said mutation (its offspring must do the same). A mutation resulting in an advantage will give the organism a slightly better chance of survival but does not rule out death by any number of "accidents" or unfortunate circumstances.

It seems to me that the odds are stacked against a mutation not only being successful but passed on to future generations and cementing its place in the gene pool.

And that's just one.

One a year? I should buy more lottery tickets.

There is no doubt that extremely complex organisms such as ourselves will evolve, one painfully slow step at a time, I just can't help but feel that a few billion years is not nearly enough.

.

Originally posted by OZtracized
I agree with you entirely.

It seems to me that the odds are stacked against a mutation not only being successful but passed on to future generations and cementing its place in the gene pool.

And that's just one.

One a year? I should buy more lottery tickets.

There is no doubt that extremely complex organisms such as ourselves will evolve, one painfully slow step at a time, I just can't help but feel that a few billion years is not nearly enough.

Up until just yesterday, I really had no problems with the generally accepted modus operandi of genetics ... that being acquire a mutation that slightly enhances your chances of survival ... then pass it on to your offspring.

Whats so difficult to understand about such a simple and clear cut process ? Couldn't get any simpler, could it ?
All these years, the "standard model" of evolutionary adaptation made perfect and logical sense to me until yesterdays simple calculation blew that long standing belief clean out of the water for me.

3.1 billion advantageous mutations spread over 3.8 billion years = approximately one advantageous mutation each and every year.

No matter how you juggle the figures, that's what I call a massively run-away mutation rate.

Somewhere, somehow ... something simply doesn't add up.

reply to post by tauristercus


Well rats. I try to defend you and you start a new thread! Here's my last post from your last thread:

reply to post by tauristercus

...the 1st evidence of life (simple cells) dates back to approximately 3.8 billion years. So we can see that life appeared not to long after the creation of the Earth !.

I've always assumed that genetic mutations tended to occur relatively slowly and accumulated over long periods of time through a process of natural selection ... but here's the hard to believe part ... at least for me.

We have a total of approximately 3.164 billion nucleotide base pairs.
We have a period of approximately 3.8 billion years since the dawn of life.

So, a simple bit of maths shows that to get from that original extremely simple cell to a human, means that random evolution coupled with natural selection pressures had to SUCCESSFULLY add a completely new rung to the ladder on average almost EVERY SINGLE YEAR !!

tauristercus - You've taken a lot of heat here over your apparently simplistic equation. Never mind the trolls, you've been told by "educated" experts that you don't understand the concept of evolution, the science, yada yada. There's something you need to know...

ATS has a core group of "experts" equipped with degrees, dogma and the consequential, requisite closed minds. They are so busy vaunting their own expertise and fortifying their cloistered little enclave, they have virtually NO ability to recognize legitimate new ideas. They cannot accommodate alternate perspectives; they cannot evaluate original thinking; they cannot tolerate "heresy." In general, the most vicious attacks are generated by these self-proclaimed "educated" experts defending their turf.

Ignore their vitriol, keep moving, keep thinking and keep posting.

Your numbers make perfect sense from the farthermost perspective - when the human species is considered to be a superorganism. In this context, a superorganism is a collection of individual agents like viruses and bacteria, which come together and work cooperatively to create a complex organism (eg., the human superorganism).

Arguably, any legitimate review of a superorganism's evolution must consider the distinct evolutionary path of the superorganism's originally discrete components. ...As well, we need to recognize that these components maintain the ability to evolve discretely.

From this larger viewpoint, your observations are dead on. And you are right, humankind's evolutionary path is most properly understood as "beginning" with the first appearance of life on the planet, with the first microbe that became part of the super-organism that is us.

imho, your perspective is essential to a proper understanding of "evolution" - both in terms of "where we came from" and as well, to better grasp the concept, mechanics and potential directions of our continuuing evolution.



S&F btw

The mechanics of evolution are something that can be debated for the next ten thousand years, in all likelihood. About the best thing we can do is begin cataloging DNA within our own species and within others and wait to see what comes of the data. That is the main problem with the theoretical mechanics of evolution - a complete lack of data to develop any kind of model that can be tested.

It also doesn't help that we live in a microwave society that wants to have an answer for everything right now. This is partly stemming from our test-taking methods and education culture - an honest "I don't know" is not acceptable in our education climate. You are expected to know or to give it your best BS and pray it's acceptable. This has a very negative impact on our scientific research fields, as scientists and society demand that we know or give it our best BS attempt, rather than leaving it on the shelf to muse over.

In either case - your scenario is rather simplistic... averaging out genetic sequences in that way is probably not the best way to go about it. Most sources of mutation that I am aware of stem from viral vectors and reproduction - both in meiosis and the merger of the sperm and the egg (only applicable to sexually reproductive organisms, I know). In both cases - codons are, as if by design, swapped around by the forces around in what would seem to be an attempt to introduce mutations into the next generation.

Other causes for genetic code being introduced involve telomerasse - a process where additional "junk" DNA is added between the DNA instructions (usually a specific repeating pattern - but it may be possible that this process could 'run away' and insert unintentional codons).

You also have issues such as Down's syndrome, where entire chromosomes are added or missing. While most of these are detrimental - it could be possible for there to have already been (or that there will be, one day) born with a functional number of fewer or greater chromosomes (IE - 48 or 44).

I'm by no means an expert - but it would seem, to me, that we simply don't know enough about the mechanics of DNA mutations and how they impact populations to really have much to say on the issue.

I am not exactly of the opinion that our development was purely random. However - I think we are reaching a point where our own development is at "over-unity" - we will soon possess the ability to genetically modify our own species, and therefor open up an entirely new chapter. While knowing where we have been is pretty important... driving the car and staring at the rear-view mirror tends to result in rather bad things.

reply to post by Aim64C

The mechanics of evolution are something that can be debated for the next ten thousand years, in all likelihood.

In all likelihood, the debate will be over shortly, when the human species poisons itself to extinction along with the rest of life on earth. Another denial campaign, from LaMarck to epigenetics and beyond.

About the best thing we can do is begin cataloging DNA within our own species and within others and wait to see what comes of the data. That is the main problem with the theoretical mechanics of evolution - a complete lack of data to develop any kind of model that can be tested.

imho - the best thing we can do is drop the out-dated and already disproven notions of "genetic superiority" and "survival of the fittest," and just stop trying to use "genetics" to justify Eugenics policies.

Shift the focus to inter-disciplinary studies, pursue studies like microbiometrics and epigenetics, recognize that the old prejudices, biases, rationalizations and contortions don't properly explain bloody anything. Admit that there are NO superior bloodlines, that everything is an intrinsic part of the same whole, and that we are smack in the middle of the 6th Mass Extinction.

It also doesn't help that we live in a microwave society that wants to have an answer for everything right now. This is partly stemming from our test-taking methods and education culture - an honest "I don't know" is not acceptable in our education climate. You are expected to know or to give it your best BS and pray it's acceptable. This has a very negative impact on our scientific research fields, as scientists and society demand that we know or give it our best BS attempt, rather than leaving it on the shelf to muse over.

Erm. You are describing capitalism at work. Rule of thumb: Every study / project must lead to a profitable product - never knowledge for the sake of knowledge.

I'm by no means an expert - but it would seem, to me, that we simply don't know enough about the mechanics of DNA mutations and how they impact populations to really have much to say on the issue.

Saith the industry apologist.

...we will soon possess the ability to genetically modify our own species, and therefor open up an entirely new chapter.

We're already doing it - via industrialization and globalization. And the effects do NOT look good.

While knowing where we have been is pretty important... driving the car and staring at the rear-view mirror tends to result in rather bad things.

As in, "Nothing to see here. Move along now."

I prefer, "Those who do not know the past are condemned to repeat it."

reply to post by tauristercus

3.1 billion advantageous mutations spread over 3.8 billion years = approximately one advantageous mutation each and every year.

you are wildly conflating a change in phenotype with a single mutation event. the chance of a single mutation giving rise to a change in phenotype is very rare. but unfortunately, your confusion lies much deeper....

...this whole bit about adding "one nucleotide at a time" is soooo freaking totally off the mark it is silly. this type of insertion mutation, if it should occur inside of a coding sequence, is nearly 100% deleterious. if an insertion occurs within a non-coding reigon then it will be neither advantageous or deleterious....it will simply become an inconsequential relic. again: a single nucleotide insertion does not have to result in an "advantageous" phenotype in order to result in an increase in size of the genome.

an increase in BOTH size AND phenotype most usually involves entire coding reigons in a single mutation event. the only two categories i can think of for this are recombination and chromosomal events.

it is totally possible to DOUBLE! the size of a genome, resulting in a new viable species, simply by a failure of the gametes to form properly during meiosis. with reference to your theory, then, a chromosomal doubling could account for potentially hundreds of millions of years.

please understand (and this goes for you, too, soficrow) that no one here is trying to be rude or closed minded, so far as i can tell. i am glad that you are interested, and i am always interested in hearing alternative science. you are right that we are only beginning to put this puzzle together.

if you understood the molecular mechanisms that give rise to mutation, it would be very clear to you why you are receiving such a negative response.


...best

you never responed to anythign i said...

athought it answered everything you were confused about. Strange isnt it... i dont think learning is your intention... and others have judged correctly.

reply to post by tgidkp


The OP is playing with idea - I'm suggesting that instead of shutting him down, you go with it. You might learn something.

To me, the salient feature of his view is that it starts at the beginning. Unusual, potentially productive. And it fits with notions that complex organisms are super-organisms. Very important.

...it is totally possible to DOUBLE! the size of a genome, resulting in a new viable species, simply by a failure of the gametes to form properly during meiosis. with reference to your theory, then, a chromosomal doubling could account for potentially hundreds of millions of years.

I think we can be fairly confident that this scenario does NOT account for the numbers of species that have arisen and gone extinct over life's history on this planet.

please understand (and this goes for you, too, soficrow) that no one here is trying to be rude or closed minded, so far as i can tell. i am glad that you are interested, and i am always interested in hearing alternative science. if you understood the genetic mechanisms that give rise to mutation, it would be very clear to you why you are receiving such a negative response.

A few years ago, I met a molecular biologist who is a professor at a local university. When I asked him how the curriculum covers the role prions play in evolution, he responded in a completely patronizing manner saying, "I don't know anything about prions. I'm a molecular biologist - I teach genetics."

...This year Susan Lindquist received the National Science Award for her work with prions, in large part for her investigations into the roles prions play in genetics and evolution.

From Lindquist's lab's homepage:

Work in our lab covers a broad range of topics unified by one theme: the protein-folding problem. Through biochemistry and genetics we investigate the mechanisms of protein folding and the consequences of misfolding.

Because protein-folding problems are universal, we move back and forth between simple and complex organisms (yeast, fruit flies, plants, mice, and human cells). We investigate how protein conformational changes provide epigenetic mechanisms of inheritance, sculpt phenotypic landscapes, shape evolutionary process...

...and I am glad you are interested.

Originally posted by soficrow
reply to post by tauristercus

 

Well rats. I try to defend you and you start a new thread! Here's my last post from your last thread:

Hahahaha ... so sorry for that but I certainly do want to thank you enormously for your support, positive attitude and constructive feedback. Believe me I definitely appreciate it ... especially after being inundated with so much negativity.

You know, perhaps I'm the one being particularly dense regarding my conclusions and it's being reflected in my choice of topic within this and the preceding thread. After all, we apparently have so many experts here ready to weigh in with "how evolution REALLY works" so that surely must mean I'm talking rubbish.

However, in my personal opinion, I get the distinct impression that so many seem to be looking for some kind of inherent "super complexity" to be at work within evolutionary theory to make it look extremely mysterious and capable of being understood and comprehended only by a select few.

Many have responded that I simply don't get it, and yes, in a fashion they're totally correct. I don't get it.
I don't get why they have such an aversion to coming to terms with the inevitable logical conclusion that results from THE most basic maths. I don't get why they have to insist on denying what's so plainly before their eyes.

It would be different if I was arguing from a position of weakness but the following is our basic and verifiable data and it leads to a singular result:

The unalterable and indisputable fact is that approximately 3.8 billion years ago, the 1st simple cellular organism arose.
The unalterable and indisputable fact is that approximately 3.1 billion nucleotide base pairs are contained within the human genome.

No matter how you look at it, the most BASIC maths tells us, using the above 2 data points, that ON AVERAGE, nature had to insert one brand new and NON-LETHAL nucleotide base pair into the organisms genome each and every year.

Sure, there are variations such as perhaps large numbers of nucleotide base pairs were inserted at once and then very little additional insertions for many hundreds or thousands of years afterwards ... or perhaps smaller numbers of nucleotide insertions were occurring more frequently ... or perhaps one insertion every year or so.

But the actual number of insertions is of no consequence.
The final result is all that matters and it's been proven conclusively that after a period of approximately 3.8 billion years of evolution, that the most advanced organism on the planet (we humans), have managed to acquire just over 3.1 billion nucleotide base pairs within our genome.

And as I have mentioned a few times already, these 3.1 billion nucleotides are the result of random insertions that did NOT result in the organisms death ... these insertions were either neutral or beneficial to the organism and increased the size of the genome.

In fact, the calculated rate of evolution of an average of one new nucleotide base pair inserted each and every year is actually extremely inaccurate. The reason being that that the final tally of 3.1 billion nucleotides are only those mutations that did not kill the organism.
When we also factor in the much larger percentage of lethal mutations that inevitably had to happen ... and this kind of mutation greatly outnumbers the beneficial type, then we have no choice but to conclude that the TOTAL number of nucleotide insertions (both good and bad) would result in an average much higher than 1 per year. We could in reality be looking at 1 new attempted insertion every 9 months .. or 6 months ... etc.


So in conclusion, I challenge the "armchair experts" out there to demonstrate where the fallacy lies in my line of reasoning. I conclude that the human genome had to either (A) increase at a fairly constant rate of 1 insertion (or more) per year or (B) the human genome went through massive spurts of growth in incredibly short periods of time, then followed by long stretches of almost no growth.

If you believe that 3.1 billion insertions over a period of 3.8 billion years does NOT equate to an average of 1 insertion per year, then I'll be very interested in seeing your mathematical reasoning.

reply to post by tauristercus


You're welcome.

…perhaps I'm the one being particularly dense regarding my conclusions and it's being reflected in my choice of topic within this and the preceding thread.

You're treading on sacred ground, challenging turf.

After all, we apparently have so many experts here ready to weigh in with "how evolution REALLY works" so that surely must mean I'm talking rubbish.

Like I said.

If you believe that 3.1 billion insertions over a period of 3.8 billion years does NOT equate to an average of 1 insertion per year, then I'll be very interested in seeing your mathematical reasoning.

Your terms are precise; your math impeccable. …The "experts" imply that such 'averages' are irrelevant, but fail to address your observation directly. And NONE tackle the most basic points of contention: 1. You assume the human species' origination coincides with the genesis of life; and 2. Your approach implicitly questions the notion of genetic superiority in humans.

I do enjoy your observation - as accurate and most likely, pertinent. However, I question one of your assumptions:

…the most advanced organism on the planet (we humans), have managed to acquire just over 3.1 billion nucleotide base pairs within our genome.

Arguably, humans are NOT the most advanced organism on the planet.

From Seth Horowitz, Faculty, Neuroscience, SUNY Stony Brook, in response to the question, Are humans the most complex organism??

…"The most complex" doesn't really mean anything unless
you focus it down quite a bit, …

If you mean at a genetic level, the answer is clearly no. The genome of
an organism consists of the complete DNA sequence, including coding and
non-coding genes. Of the number of animals for which is there is good
genome data (about 3800 so far), the smallest known genome is about 39
million base pairs (Mb) in Trichoplax adhaerens, a placozoan. Placozoans
are very tiny organisms whith only about 20-30 cells. On the other hand,
the largest genome is not in an elephant or a whale or a human, but rather
in Protopterus aethiopicus, the marbled lungfish (about 130,340 Mb). Mice
and humans come in at quite a modest 3000 Mb. A good place to look at
this information can be found here:

www.genomesize.com...
or here
www.web-books.com...

Horowitz also looks at brain complexity:

The only manner in which humans might be considered to be the
most "complex" organisms on the planet is in mental cognition and
neocortical complexity, and even here it's contentious. Humans do not
have the biggest brains on the planet - our brains are about 1.4 kg (3.08
pounds). That honor goes to the Sperm Whale (physter catadon) at 7.8 kg
(17 lbs 3 oz). However, whale brains have less neocortex and seem to be
laid out on a simpler, less densely interconnected plan. So it's not just
size, it's also brain/body ratios, number of layers of cells, number of
interneuronal synapses, organization, and a very large host of other
factors. Humans do not always come out on top with these types of
comparisons (in several elephants and orcas come out way ahead).

A good basic web site on this is here:
serendip.brynmawr.edu...

An excellent site comparing mammalian brain neuroanatomy can be found here:
brainmuseum.org...

Humans also are not the only (or sometimes even the best) problem
solvers. Chimps and dolphins use tools, dogs and primates have been shown
to be able to lie (a very cognitively complex function, meaning they
understand truth and how to manipulate it to get what they want) and
african gray parrots show a remarkable ability at language use.

...Thanks for posting.

So whether those 3.1 billion DNA additions occurred gradually and steadily over time or whether the 3.1 billion DNA additions occurred in distinct spurts interspersed with relatively quiet periods ... I still find myself pondering the overall impressive rate at which DNA has successfully mutated since that 1st original simple cell ancestor and what type of evolutionary mechanism could possibly account for it.

Well... I think you may miss a few things, here.

Mutations occur in living cells all the time. In multicellular organisms (like humans) we are constantly generating cells with mutations. Some of these mutations simply cause dead cells. Some affect the way we live. Some affect our survival rate (this has been shown in some recent twin studies.)

Now... it's a good question to ask if humans are evolving faster these days. However, we may not be able to determine this for a number of reasons: we don't know what the outcome will be, nor is there any way to predict "if you have this, it evolves into that." We are no longer isolated populations. We're mixing and breeding with other people across the globe, and this could actually scale or change the rate of change in humans (one mutation can affect the shape of a selected breeding population if that population is small (say, "purebred cats". you can change the way Siamese cats look in 80 years because the population is small and you control who breeds with whom.) With a population of billions, it will be difficult for any particular mutation to take over the global society (barring something like a horrible global epidemic where the mutation is the only thing that saves you and there is no medical cure.)

What causes it -- I don't think you can point to one easy factor (or two or three.) Off the top of my head:
* Social norms change it (who is allowed to have children with whom... who gets what food (rich live better and longer than the poor))
* Environment changes it.
* Medicine changes it (we live longer and survive things that would have killed our great grandparents.
* Technology changes it (it takes a much longer attention span to sit at a pool and wait to spear a fish than it does to sit at your keyboard and kill off marauding Ice Giants.)
* Personal attitude changes it (because things like risk taking also affect your children and your ability to pass along genes.)
* Personal and group power affects it (access to resources)

I think it will vary by culture and I think humans are too complex to get a tidy answer. My initial guess would be that some answers will be found in both Network Theory and Chaos Theory (this is an educated guess; my dissertation is on an aspect of social network theory and the above points are something I'm having to factor in there (and I will get howled at by a variety of professors if I get it wrong or make stupid connections.))

Interesting question, though. I'll probably wander in and pontificate in this thread occasionally (though genetics is not my strong point. I took it, but that was last century at a very small school.)
edit on 28-12-2010 by Byrd because: (no reason given)

Originally posted by Byrd

Mutations occur in living cells all the time. In multicellular organisms (like humans) we are constantly generating cells with mutations. Some of these mutations simply cause dead cells. Some affect the way we live. Some affect our survival rate (this has been shown in some recent twin studies.)

Thanks for your input Byrd ... as always it's full of interesting information and valid points. And every bit of additional input cannot help but improve our understanding of complex processes.

Now, I get the point you're making that mutations occur in cells virtually all the time ... cancer being one of the most obvious signs of a deleterious mutation causing a cell to run amock.

However, the ONLY mutations that we should be considering here are those that occur within the germline cells only - the cells involved directly in reproduction and capable of passing on genetic material to their offspring. These are the mutations that are inherited whereas somatic mutations are entire local and restricted to affecting the parent organism only.

So the 3.1 billion nucleotide base pairs that humans currently possess are mutations that occurred specifically in the sperm or ova of the organism. Every other mutation that occurred in any other non-germline cell are of consequence only from the point of view as to whether the organism was able to survive long enough to mate and reproduce.
Sure, the organism could have a non-germline cell mutate and become cancerous, but as long as the cancer allowed the organism to survive long enough to reproduce, then that particular mutation was not evolutionary significant and could be disregarded.
But should the somatic cell mutation prove to be fatal to the organism before it could reproduce, then any additional germline mutations that the organism may have also just gained would be immediately lost to evolution and effectively evolution kicked back 1 step.

No matter how we try to explain the evolutionary process, there's simply no hiding from the obvious fact that every one of those 3.1 billion nucleotide base pair additions occurred ONLY in the germline cells of the respective organisms. And again, we need to bear in mind that those 3.1 billion additions represent ONLY the successful and non-lethal additions to the genome.If we added all the multitude of additions that proved lethal to the organism, then that figure of 3.1 billion rises considerably.

Oh, and another point.
Everyone of those 3.1 billion nucleotide base pairs were ADDITIONS to the ENDS of existing chromosomes and making them longer. In other words, all the other mutations that resulted only in a change to an existing location WITHIN a germline chromosome and did not alter it's length, are ignored. We're only interested in mutations that extended the lengths of the chromosomes from their original tiny lengths in the 1st primeval cells to arrive at the current, many times longer, chromosomal lengths in humans.

So no matter how we try to side-step or sweep under the rug the evidence, we're left with the visible fact that nature was flat out for 3.8 billion years enlarging the chromosomal lengths at an astonishingly rapid rate and in those 3.8 billion years, succeeded in enlarging the total chromosomal length from essentially zero to 3.1 billion.

reply to post by tauristercus


nothing pleases me so much as typing out a lengthy reply that is totally ignored.

...these 3.1 billion nucleotides are the result of random insertions that did NOT result in the organisms death...

here, i believe, is your most basic confusion. mutation is NOT a totally random process. it is a result of predictable mechanical molecular processes gone awry. the cellular mechanics of replication and recombination were the very first processes to have evolved. thus, there is a bit of structure involved. it is this marriage between pre-determined rules and randomness that accounts for species variability. one hand giveth and the other hand taketh-away.

if one were to consider the situation as you have presented it, as one isolated random insertion after the other, than i feel pretty confident in saying that functional processes would absolutely NEVER arise. the model you have presented is totally non-functional.....and so i can see why you might be amazed about it. like the number PI, going on and on forever totally random with no recognizable structure at all.

it is this constant interplay of randomness and structure feeding back upon one another around and around.

and, really, that is one of the most general observations that can be made about any aspect of reality: one part mechanics and one part chaos. no?

...Everyone of those 3.1 billion nucleotide base pairs were ADDITIONS to the ENDS of existing chromosomes and making them longer....

now you are just making me angry. never, and i mean NEVER is an insertion mutation observed at the end of a chromosome. fundamental misunderstanding.

below is a picture of "cellular automata" made popular by stephen wolfram. in it is shown how a very basic set of predetermined rules, combined with random input, can produce extremely complex structures.


[atsimg]http://files.abovetopsecret.com/images/member/00e3577797ca.gif[/atsimg]

I didn't read your previous thread and only parts of this. Your understanding of the issue is very limited. Somehow you think that only increase in genome size leads to evolving. Why is this? Are humans, bears, ducks, dogs, insects, etc. not mostly made of the same proteins? Sure there's an alteration here and there in the polypeptides that form the proteins, but essentially it's the same stuff. What differs us all is in what quantities these proteins are made and in what time during our development. So it's mostly control of gene expression, not the number of genes that matters.

As for this 3.8 billion years / 3.1 billion bp issue. You do understand that the vast majority of our ancestors had very short generation times. Our single celled ancestors probably had generations times of 10s of minutes. Moving on to multicellular some 500 million years ago generation times started increasing gradually, but even some 100 million years ago we're probably talking something like 1-2 year lifespans. You know.. something like mice sort of beings that our ancestors were around then.. This gives lots of time for mutations to accumulate into germline..

Originally posted by tauristercus
Oh, and another point.
Everyone of those 3.1 billion nucleotide base pairs were ADDITIONS to the ENDS of existing chromosomes and making them longer. In other words, all the other mutations that resulted only in a change to an existing location WITHIN a germline chromosome and did not alter it's length, are ignored. We're only interested in mutations that extended the lengths of the chromosomes from their original tiny lengths in the 1st primeval cells to arrive at the current, many times longer, chromosomal lengths in humans.

So no matter how we try to side-step or sweep under the rug the evidence, we're left with the visible fact that nature was flat out for 3.8 billion years enlarging the chromosomal lengths at an astonishingly rapid rate and in those 3.8 billion years, succeeded in enlarging the total chromosomal length from essentially zero to 3.1 billion.

1. Like virtually all bacteria and archaea our early unicellular ancestors had almost certainly circular, not linear chromosomes, thus they had no ends.

2. You never ever get any meaningful mutations/additions at the ends of linear chromosomes, because that is where the telomere sequences must be.

3. Thus all mutations that increase the length of chromosomes happen within them. IE. a gene gets duplicated.