↑ Log In to contribute
0
Brent (9)

Human Evolution


Just finished reading Bill Bryson's "A Short History Of Nearly Everything". Near the end he deals with the evolution of intelligent beings. He mention that the human brain comprises about 2% of our body mass and uses about 20% of the enegery yielded by our digestion. This means that the development of a large brain is not the expected outcome of evolution. The increased enegy requirement of the larger brain would make a species less likely to survive rather than more likely.

This has to be coupled with the idea that the larger brain makes intelligence possible. It is a precondition of intelligence. That is to say that having a slightly larger brain, does not make one slightly more intelligent. Rather intelligence, 'the ability to acquire and apply knowledge and skills' 1 is something that only comes after having a large brain for a good long time.

So when first an early humanoid developed a slightly larger brain, it would have had no effect other than to make them more hungry for glucose and more likely to perish for the need of it.

This is a common theme that comes out in Bryson's excellent book - that the way things are is an extremely unlikely outcome of the machine that we understand brought them into being - the whole system from the big bang through to the mechanisms of natural selection and biological evolution.

It seems that the more often we have to accept that the way things are is an unlikely outcome, expecially in a ladder of features that are all essential for life, the more we are pushed to consider that the way things are is intended. 


more

0
Brent (9)

The Emergence of Life


I was watching BBC's "the Wonders Of Life". Brian Cox explains very briefly the complexity of life, DNA, the cell and etc. Then, he describes how somewhere, perhaps near an undersea volcanic vent, where the amino acids were all present, a little sack of chemicals giggled and became animate. I can't recall his exact words but it seemed a tad dismissive of this profoundest of mysteries. Everything else I've learned indicates that life is mind-blowingly complex, that the chances of it coming about spontaneously are very small, so small in fact as to be mathematically approaching impossible.

This post doesn't challenge evolution. Evolution is the theory of how life develops or adapts through natural selection. For evolution to be possible there must be reproductive life to begin with. Evolution doesn't explain how that life first came to be. So we have to get from dirt and slime to a reproductive organism without any vehicle. Every failed attempt leaves no lesson behind for the next attempt. It seems that it must have been purely accidental.

Allow me to refer to Bryson's book again, "A short History of Nearly Everything". He explains how complex proteins are. My understanding is that proteins are essential building blocks of cellular life and that amino acids are the essential building blocks of proteins. There are 22 amino acids that make up the proteins in cells. What makes each protein unique is the amino acids used and the sequence in which they string together. This sequence has to be precise. Not one amino acid can be in the wrong location. 

The mind blowing mathematics comes in when you find out that the average protein length is about 200 amino acids long. So mathematically the number of possibilities when trying to make a single molecule of protein of the average length is 22 to the power of 200. About 305 with 266 zeros after it. Bryson explains that that huge number is greater than our estimate of all the atoms in the universe. And should you be lucky enough to get that right atom, you've only got one protein molecule - the tiniest part of a living reproductive cell.

How then did a little giggling near that deep sea vent ever pull it off without a little guidance.

Some speculate that perhaps life is inevitable - kind of anthropomorphising dirt and slime to give it a desire or a sense of fate or purpose. Astro-biologists hope that perhaps life has broken out on many other planets throughout our galaxy. I kind of hope so too. But if that be true, if life kind of happens fairly predictably given the right ingredients, then you would expect that it happened several times, maybe even thousands of times over the last 3.8 billion years since the earth's crust solidified.

But it didn't. Biologists and geneticists, I'm told widely agree that all living things share genetic code, that we all descended from a common parent. Every bacteria, virus, plant, fish, animal and insect. Every cell came from one single parent. There are not two trees of evolution. Only one tree with many branches.

The fact that it happened only once should come as no surprise given the infinitesimal chance of it happening at all, but the fact that it only happened once should put to rest any idea of the inevitability of life's emergence.

More and more, this seems to fit more neatly into the idea that life was a gift from somewhere - indented to be here on this planet and perhaps elsewhere too. Whether or not you think this is a reasonable conclusion seems to rest with how you define impossible in terms of chance.

We've seen how unlikely it is to create one protein molecule without some engineering. 305 plus 266 zeros. What if we needed 100 such coincidences to occur simultaneously to create a cell of reproductive life, which I'm guessing is far fewer than the reality. Would that inconceivably small chance be defined as impossible? 

If you begin by excluding the possibility of any external engineering, then you are left with that tiny tiny chance. For me, once the chance gets too tiny, it is reasonable, perhaps even wise, to question that exclusion. It seems to me that the maths is begging me to label that chance as 1/infinity ie. "impossible". What do you think?
more

0
Brian (8)

Odds, Homochirality and the Argument from Biology


Brent
I also find this subject fascinating. Sadly never studied biology at school so it's difficult to understand much of it.

But I do understand those odds. Just to put them in perspective the total number of particles (eg protons, neutrons etc) in the visible universe is approximately 10^80. So that's 1 with only 80 zeros after it. Hmmmmm.

Another interesting fact I ran into which helps explain those fantastic odds of life getting a start:
Of the aminoacids which make up the proteins of life all bar one have a "left handed" configuration. (The one exception only exists in one configuration).
Aminoacid molecules have a geometric shape a bit like a coil spring. You can get the same spring with either a RH or a LH spiral. One is the geometric mirror image of the other.
In the non-living world these aminoacids exist in equal quantities of LH and RH configurations all mixed together. So in order to get life going there needed to be some way of isolating the LH configuration and building the proteins of life from that carefully selected raw material. This phenomenon is called homochirality.    



2
Cheryl (2)

The Odds are even worse if you consider Genetic mutations.


Brian & Brent
Wow, my brain hurts! 
However, I would like to tell you a story about a family I'm supporting. They have 6 children, all except one have a disability caused by a genetic mutation, a duplication that occurs on the X chromosome. The girls are carriers & have a mild intellectual disability and the boys gave profound impairments. They are non verbal, have severe intellectual disability and have characteristics consistent with severe autism. They don't have any dismorphic features and look completely "normal". This is unusual. Most people with genetic abnormalities have physical features consistent with the syndrome. There are only 2 identified families in the world with this genetic mutation. Hunter Genetics are researching the condition along with a research team from Cambridge in the UK. My point in saying all this is to argue that the top researchers in the world do not understand why this genetic duplication has occurred. They are struggling to even map the genes accurately, initially thinking the condition was fragile x, let alone be able to replicate, model or explain what has happened fir thus family. Even allowing that at some point the condition may be understood, it will never result in something positive for this family or for the advancement of humanity. My question is therefore, how did we evolve so well if God or someone or something didn't have a design or plan? I struggle with the biblical explanation as much as the theory of evolution. How do I make sense of this?



1
Brent (9)

The mechanics of evolution


Thanks Cheryl,

I too have long struggled with the mechanics of evolution though natural selection. From a broad view the theory of evolution makes sense, tiny changes in genetic material slowly diverging, concreted by natural forms of isolation until we finally have a new species. But then when we think about specific significant changes between species, it's very hard to see how natural selection could select for these until they were complete and functional.

Take a wing. A small mutant limb or two is actually a weakness to the poor creature not a strength and yet it must be fitter to survive for millions of years while that limb changes again and again into something useful. The spider's web glands and spinning skills are only useful for it's survival once complete and functional and not a minute before. How could natural selection achieve this?

What's more, any mutation must be both dominant and isolated. So in sexual creatures, the parents have to produce offspring with the defect that either strengthens or does not weaken their chances of survival. The  the family has to be isolated from the remainder of the species by some geographical boundary for so long that the genetic change can make them unable to breed with their x-fellow species, otherwise, as I understand it, the mixing of that genetic material will dissolve the change over time. The numbers make it impossible for that change in the minority to persist in the majority.

This scenario, though possible would not be common, especially for creatures that survive in herds or packs or schools. The isolation itself is a weakness let alone the inbreeding which is essential for evolution to produce a new species. Almost every time, the mutant will die out far more quickly than the original community if not in one generation.

Please someone explain how theorists overcome these hurdles.

0
Brent (9)

The God Of The Gaps - Is He Being Explained Away


I was with a friend recently who said something like: "I have been convinced by science that God exists and intended the natural world to be the way it is." 

"The God Of The Gaps" idea is that when science cannot explain how or why something happens we attribute it to God and therein lies the reason to believe in God. Lightening was the work of Thor. Dark matter or dark energy might be the work of Yahweh.

The God Of The Gaps idea was a bad one in times past because, eventually and seemingly inevitably, the mystery that necessitated God's existence would be explained and understood by scientific breakthroughs and God would suffer another round of dying.

Lord Kelvin is quoted to have said: "There is nothing new to be discovered in physics now. All that remains is more and more precise measurement." There was a golden era for science, mid-way through the industrial revolution perhaps, where so much headway was being made, and it's application creating so much power and wealth, that the scientific mind could quite understandably foster the notion that science would triumph everywhere in all things.

Now, though we know so much more than we did at the start of the 20th century, we also understand that we know proportionally less of what is to be known, than scientists used to think. It's quite a credit to the scientific method, and to scientists in general, that the region of the unknown is so honestly declared. 

So here's my question: Is it likely that there will come a time when everything we now consider mysterious will be explained? Will string theory reveal somewhere in the theorised dimensions of a reality we cannot measure, why or how the universe is fine-tuned or why it began at all? Will we ever find a theory for the emergence of life or will micro-biology continue to astound us with the awe-inspiring complexity of the simplest cell?

In some of these areas, the more we study the nature of reality, the further we are removed from understanding a theory of it's origin, or even of how to engineer it. Is it likely that this trend will continue? Will The God Of The Gaps find more and more space to occupy, or will She be chased into a corner of insignificance?

It seems clear that the former seems more likely to us now that it did to the likes of Kelvin. What do you think?
more