The case for Evolution.

Sarky

Innumerable transitional fossils HAVE been found though. Fossils are pretty rare due to the circumstances required for their creation. Taking that into account we've discovered a huge number of them, easily more than enough to cement evolution as the way things happened.

Darwin was perfectly right to be skeptical at the time, but a shedload of evidence has been found since then. If he were alive today he'd agree that he was right about evolution.

Sarky

Ooh, moar genetics plz. I never studied non-bacterial genetics in any great detail, I wouldn't mind seeing some.

darjeeling

Oranage2 wrote: »

To be honest, I was expecting cute little monkey men running around.

Well, ok, but the point is that the phrase 'missing link' has gotten into the culture without really being defined. I think that we've found a lot of fossils with a pattern of features telling us that humans evolved from earlier apes. These fossils have some features that are shared with the other apes but not with humans, and other features shared only with humans. They seem to fit what many people might consider missing links.

Oranage2 wrote: »

After doing a bit of looking up it seems that there's not much fossil evidence that we have evolved from any sort of chimp man. Even the great pioneer of evolution Charles Darwin doubts his theory

Darwin didn't have most of the evidence we have now, and was inclined at times to moderate what he thought, and initially wrote, for expedient reasons. However, he did predict - on the basis of human and African ape similarity - that we'd all have a common ancestor in Africa:

Darwin, The Ascent of Man wrote:

[SIZE=-1][SIZE=-1]"It is therefore probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; as these two species are now man’s closest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere."[/SIZE][/SIZE]

As we now know, the first evidence for the presence of humans and chimps is seen in the same area of the world. Humans and chimps have very similar genomes, such that (as posted by others above) you can find lots of chance mutations that are present in both humans and chimps, but not in the more distant gorillas and orang-utans. This is what you would expect to see if humans and chimps had evolved from a common ancestor that was more recent than the common ancestor with the other apes.

Going much further back in time, no apes are seen in the fossil record before the Miocene, around 23 million years ago. No primates are seen before ~65 million years ago at the earliest. No mammals are seen before around 220 million years ago, no land vertebrates before around 370 million years ago, and so on. This pattern of new forms of animal appearing and then diversifying over time is consistent with the current evolutionary model.

Oranage2 wrote: »

I'm not convinced we or the other species have all evolved from a single celled organism. [...] Again I do believe that species like humans can evolve through genetic selection, I just dont think there's enough evidence to believe we all evolved from the same ancient organisms.

When it comes to asking if all of life has a common ancestor, we can look again at the level of DNA. We find that all organisms use the same genetic code (with a couple of minor differences), the same set of 20 amino acids for making proteins, and that all have a set of core genes for protein synthesis and some other fundamental elements of life. This is, again, consistent with life having a common ancestor.

Sarky

I understand DNA from mitochondria (little cellular organs that have a load of useful functions but most importantly generate the chemical adenosine triphosphate, which pretty much every animal/plant cell uses for fuel) has been particularly useful with regards to looking at human evolution, although I'm not very well up on the specifics. I'd imagine that mitochondrial DNA is subject to fewer changes over time as it's essential to a functioning cell, so you can look further back into its history before the changes become too fuzzy to infer anything. Am I close?

dlofnep

Oranage2 wrote: »

Interesting indeed, though I'm not convinced we or the other species have all evolved from a single celled organism. After doing a bit of looking up it seems that there's not much fossil evidence that we have evolved from any sort of chimp man. Even the great pioneer of evolution Charles Darwin doubts his theory

Ok, I have to nip this in the bud before it gets out of control. A few things. Firstly - a few posts back, you were under the impression that Evolutionary biologists claimed that humans evolved from chimps. This indicates to me, that your understanding of Evolution is extremely limited.

So with that being said - You make the claim that you don't see much evidence in support of it, but you clearly have not researched Evolution in the detail that it requires to validate such a statement.

What Charles Darwin stated on Evolution is not relevant. Darwin lived in the 1800's, when there was a very poor fossil record. His theories based on observation were later validated as the fossil record grew stronger, and we came to understand DNA. While for his time, Darwin's theories were ground-breaking - we have since then built upon them - with much stronger evidence.

It would be like citing the work of an astronomer from the 1800's, over NASA of today with their high-powered telescopes, rockets, and planetary rovers. To put simply - the Evolutionary biologists of 2012 are the people that you should be looking at, and not Darwin - who was still only getting to grips with the idea of evolution.

Since Darwin died - we have found a mass amount of transitional fossils. A partial fossil of Homo Erectus was found 10 years after Darwin's death, with Homo heidelbergensis about another 15 years after that. Neanderthal was the only fossil around when he was alive, which alone would not have given an overall view on the evolution of humans. In total, we have found the following species (in order by date found):

Homo neanderthalensis (1829), Homo erectus (1891), Homo heidelbergensis (1907), Australopithecus africanus (1924), Homo habilis (1949), Homo rhodesiensis (1953), Homo rudolfensis (1971), Australopithecus afarensis (1973), Homo gautengensis (1976), Homo sapiens idaltu (1997), Homo floresiensis (2003)

There's a few other species I have left out to save time, and obviously as time progressed more and more fossils have been found for each species, some more impressive than others. The point is, that all of these except one were found after the death of Charles Darwin. So to try and cite Darwin's lack of evidence while he lived as some sort of flaw in the theory of Evolution itself, or the evolution of humans is a logical fallacy.

Oranage2 wrote: »

Again I do believe that species like humans can evolve through genetic selection, I just dont think there's enough evidence to believe we all evolved from the same ancient organisms.

DNA confirms that we did. The fossil record gives is a glance at certain time periods, where we can see important evolutionary transitions - such as lobe-finned fish to tetrapods, reptiles to mammals, dinosaurs to birds, early primates up to modern primates, etc... This is all immensely powerful evidence to support a shared ancestor.

Solair

Of any area of science, evolutionary biology has to be one of the easier bits to demonstrate that it's clearly a very accurate and correct theory. There's heaps and heaps and HEAPS of evidence all around you. You can run experiments in the lab to prove it works with simple single-celled organisms with very short generational cycles etc etc.

I can't see how this is possibly controversial (and it's not in Ireland! This tends to be a debate that's had in the USA more than anywhere else in the 'developed world')

Where as perhaps some areas of highly theoretical astrophysics are a bit more tricky to prove!

Sarky

That's why it's called theoretical.

That's what theories do though. They don't prove things, they pretty much state "If this explanation is correct, then you should see it in XYZ".

That's what Darwin did. He said if evolution is right, you'll see transitional fossils. So people went out looking for transitional fossils and hey! They found loads across tonnes of species.

Most of the scientific process is about figuring out how to make a reliable test, figuring out what to look for, how to measure it and how to take into account all the factors that could screw with the measurement. People are still trying to invent ways to test some of Einstein's predictions on relativity, although everything they're managed to test so far has validated his theories pretty well.

And of course there's the peer-review, a real trial by fire as a load of scientists at least as knowledgeable as you tear into your work to see if it still holds up or if you missed anything. They're not kind, but they're thorough, and if they can't find a way to disprove your work, it's decent evidence that you might be onto something. The actual discovery is only an added bonus at the end of all that.


Science- It works, bitches.

Galvasean

sephir0th wrote: »

That would explain a lot. Presumably both lines would have adapted towards larger brains at some point right? A larger brain doesn't necessarily have to come at a cost to flexibility etc. or does it? Food sources may explain it.

A larger brain doesn't necessarily come at a cost of agility, but both require extra energy to maintain. As you allude to, they probably didn't have access to all of the nutrients required (in large enough quantities) to maintain both.

darjeeling wrote: »

Going much further back in time, no apes are seen in the fossil record before the Miocene, around 23 million years ago. No primates are seen before ~65 million years ago at the earliest.

FWIW, the first primates are believed to have shown up around 85 million years ago, based on molecular clock studies (something anyone with an interest in learning about modern evolutionary theory should seriously consider checking out).

darjeeling

Sarky wrote: »

I understand DNA from mitochondria (little cellular organs that have a load of useful functions but most importantly generate the chemical adenosine triphosphate, which pretty much every animal/plant cell uses for fuel) has been particularly useful with regards to looking at human evolution, although I'm not very well up on the specifics. I'd imagine that mitochondrial DNA is subject to fewer changes over time as it's essential to a functioning cell, so you can look further back into its history before the changes become too fuzzy to infer anything. Am I close?

It has its own little circular genome, which has shrunk down the evolutionary ages as more of its genes have transferred into the nucleus (the process is a a one-way street). The genes it retains code for the mitochondrial ribosome and the electron transport chain, used to produce energy. From memory, if you look at sufficiently divergent taxa, you can find different sets of genes retained in the mt genome.

mtDNA has useful features that allow it to be used for different scales of evolutionary analyses. It comes down the female line, so it doesn't recombine. It has regions under weak selective constraint (faster evolving) and regions under strong constraint, so it can be used to look over different timescales.

In humans, all people alive today have mtDNA that coalesces to a single ancestor around 170,000 years ago (the famous 'Mitochondrial Eve'). The diversity we see today has all arisen since mtDNA Eve lived, and has been used to trace pre-historic human movements around the world. We find that the greatest diversity is in Africa, and that the first modern human migrants leaving Africa carried within them only a part of that diversity. Once established around the world, new variations arose that can distinguish between people whose ancestors had settled in different regions.

When we got the first Neanderthal mtDNA sequences, they lay outside the human mtDNA family tree, as did the new Denisovan mtDNA genome. However, when trees were made using chimp mtDNA as an outgroup, the human and Neanderthal appeared as the closest relatives, with Denisovan more distant, and chimp the least related to any other.

For constructing overall family trees of life, I think that one of the nuclear ribosomal RNA genes (18S rRNA) from eukaryotes was initially used to compare with the corresponding prokaryotic gene (16S rRNA) URL="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC432104/?page=1"]link[/URL. Other key genes most essential to life have also been used since. These genes are so fundamental that they change very slowly, allowing comparisons between the most distant living organisms.

.

oldrnwisr

Sarky wrote: »

Ooh, moar genetics plz. I never studied non-bacterial genetics in any great detail, I wouldn't mind seeing some.

Ask, and ye shall receive.

OK, leading off from the example of the chromosome fusion in human chrosome 2, one of the more recent examples of common descent based on chromsomal analysis is the study of a neocentromere on human chromosome 6. An ancient chromosome at some point about 17 million years ago moved position and was rendered functionless. This change is shared in primates and the various mutations in the centromere sequence allowed the chromosome to be dated to between 17 and 23 million years ago. The image below is a simplified version of the graphic presented in the paper which shows how the analysis from each primate allowed the phylogeny of the original centromere to be determined.



Original paper:

Evolutionary descent of a human chromosome 6 neocentromere: A jump back to 17 million years ago

Some primers on neocentromeres:

Neocentromeres: New Insights into Centromere Structure, Disease Development, and Karyotype Evolution

Chromosomal dynamics of human centromere function

Centromere repositioning in mammals


In keeping with Sarky's recent posts on the "other" thread, one of the more elegant pieces of evidence for common descent is the presence of endogenuous retrovirus insertions in modern primates. Basically, ERVs inject a random piece of their DNA into the host genome which then gets passed on. Most of the time these insertions are functionless, causing no harm to the host animal. There is a growing body of research, however, which suggests that some human ERVs (hERVs) play a role in the development of certain autoimmune diseases such as MS.
Genetic sequencing has found that all primates share quite a few identical or near-identical ERV sequences. The image below shows where different ERV sequences have been inserted over time, showing up in all subsequent branches:




Primer on ERVs:

Endogenuous retrovirus

Research papers:

Differences in HERV-K LTR insertions in orthologous loci of humans and great apes

Genomewide screening for fusogenic human endogenous retrovirus envelopes identifies syncytin 2, a gene conserved on primate evolution

Human Endogenous Retrovirus Family HERV-K(HML-5): Status, Evolution, and Reconstruction of an Ancient Betaretrovirus in the Human Genome


More genetics later when I have some more time.

Oh and before I forget, again, big thanks to dlofnep for starting this thread and for an awesome OP.

Sarky

Awesome stuff, thanks!

dlofnep

I read that - RE: Functionless chromosome still present and shared today across modern primates. Can't remember where but it's a powerful indication of shared ancestry. Another great post by one of the most accurate names on boards

Pace2008

You've got to realise that when evolution skeptics ask for "proof" they're not looking for mountains of literature, morphological analogies or molecular evidence. They want to see a cat give birth to a dog.

Galvasean

Pace2008 wrote: »

You've got to realise that when evolution skeptics ask for "proof" they're not looking for mountains of literature, morphological analogies or molecular evidence. They want to see a cat give birth to a dog.

The irony being that such would pretty much turn everything we knew about evolution topsy-turvy!
I recall one such 'skeptic' stating that he would believe in evolution when he saw a butterfly spontaneously turn into a lion!
But hey, there have been a couple of pretty decent questions asked on this thread with some interesting answers. Let's hope the standard can keep up.

dead one

Dades wrote: »

As alluded to here, undercover-creationists are not welcome. And rest assured they are pretty easy to spot.
Will try to avoid lockage and just use jackbooted censorship instead.

Hi Dades, I'm Neither a Creationist Nor an Evolutionist.. What about me?. I am not creationist because i reject YEC, .... I am not evolutionist because i believe God as the Creator.

Dades wrote: »

Doctor Jimbob

Galvasean wrote: »

The irony being that such would pretty much turn everything we knew about evolution topsy-turvy!
I recall one such 'skeptic' stating that he would believe in evolution when he saw a butterfly spontaneously turn into a lion!
But hey, there have been a couple of pretty decent questions asked on this thread with some interesting answers. Let's hope the standard can keep up.

dead one wrote: »

Hi Dades, I'm Neither a Creationist Nor an Evolutionist.. What about me?. I am not creationist because i reject YEC, .... I am not evolutionist because i believe God as the Creator.

That old saying about temping fate comes to mind.

robindch

dead one wrote: »

[...]

You were warned yesterday about making content-free posts. Your content-free post has been deleted, you have been carded and your next infringement will result in you being banned from the forum.

Galvasean

dead one wrote: »

Hi Dades, I'm Neither a Creationist Nor an Evolutionist.. What about me?. I am not creationist because i reject YEC, .... I am not evolutionist because i believe God as the Creator.

For the record, one can be a theist and still believe in evolution.
What dead one is doing here is conflating evolution with abiogenesis - a common enough misconception.

dlofnep

On a side note, I'd implore anyone who's looking for a good read on Evolution on a broad range of topics to check out "Why Evolution is true" by Jerry Coyne. I've read a few books on Evolution, including alot of Dawkins work - but I felt that Jerry Coyne's work was absolutely the the best. Easy reading, and broken down very well.

joseph brand

dlofnep wrote: »

On a side note, I'd implore anyone who's looking for a good read on Evolution on a broad range of topics to check out "Why Evolution is true" by Jerry Coyne. I've read a few books on Evolution, including alot of Dawkins work - but I felt that Jerry Coyne's work was absolutely the the best. Easy reading, and broken down very well.

Thanks for this post. I found a YouTube video where Jerry Coyne explains the proof of evolution. (He reminds me of Egon Spengler)

The Dolphin slides of the embryo's and the photo of the rare dolphin with developed hind limbs is fascinating. (25 mins):

http://www.youtube.com/watch?v=w1m4mATYoig

WOW, just WOW.

dlofnep

Yes - Jerry Coyne is a brilliant man. I don't see how anyone with an open mind could read his book and not accept Evolution as a fact. It's so compelling.

dlofnep

Ok - I was going to keep this for that other crackpot of a thread to demonstrate why Creationists idea of a 'kind' system as a way to classify animals is not workable.

Take a glance at this photo.



These guys look similar, right? At first glance - you might consider them to be the same species.. Or maybe, close relatives, right?

Wrong. The actual reality is, humans are more closely related to the animal on the left, than the animal on the right is. Why is this? Well - One is a mammal (Flying Squirrel), and the other is a marsupial (Sugar Glider). Marsupials have been deemed so different to standard mammals, that they have been allocated their own Infraclass - Marsupialia. They deviated from mammals all the way back during the Cretaceous.

In fact, to demonstrate how different they really are - have a glance at the scientific taxonomy of each animal.

Flying Squirrel

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Subfamily: Sciurinae
Tribe: Pteromyini

Sugar Glider

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Diprotodontia
Family: Petauridae
Genus: Petaurus
Species: P. breviceps

So how could such a thing happen, where two animals with completely different lineages look almost identical? Well - the real answer is called Convergent evolution.

Convergent evolution explains exactly how two animals, who are not otherwise related - have faced similar selective pressures and evolved to have similar features. Another simple example would be bats and birds. Both can fly - both neither are of the same taxonomic class.

But in the case of the sugar glider and the flying squirrel, they look so incredibly similar - that this is where the importance of a real classification system, like the biological species concept comes into play.

A creationist might class both of these guys as the same 'kind'. But the genetic make-up tells a complete different story. This is why the biblical method of classifying animals has absolutely no purpose in modern biology, and should never be treated with anything but ridicule.

markfla

Pace2008 wrote: »

You've got to realise that when evolution skeptics ask for "proof" they're not looking for mountains of literature, morphological analogies or molecular evidence. They want to see a cat give birth to a dog.

I wish that wasn't true, I work in arizona and the guys I work with (creationists) asked me why a human can't give birth to a plant if we share a common ancestry. They gave me a creationist dvd to take home....it's cringe worthy stuff. The sad part is the guys are nice and outside of their religion they are smart which is what gets me angry. They keep bringing up the cambrian explosion too and to be honest I struggle to articulate it to them....I explained that evolution or change doesn't occur in a linear timely fashion, it can speed up or slow down based on environment, length of life span or gestation periods....any better ways to explain it to them.
It's really frustrating. But the most annoying thing is they get a half day on sunday for church!

Galvasean

markfla wrote: »

I wish that wasn't true, I work in arizona and the guys I work with (creationists) asked me why a human can't give birth to a plant if we share a common ancestry. They gave me a creationist dvd to take home....it's cringe worthy stuff. The sad part is the guys are nice and outside of their religion they are smart which is what gets me angry. They keep bringing up the cambrian explosion too and to be honest I struggle to articulate it to them....I explained that evolution or change doesn't occur in a linear timely fashion, it can speed up or slow down based on environment, length of life span or gestation periods....any better ways to explain it to them.
It's really frustrating. But the most annoying thing is they get a half day on sunday for church!

Re: the Cambrian 'explosion'. Tell them that (As discussed on this thread already) the Cambrian 'explosion' took about 70 million years to occur (compare this to how the giant dinosaurs were wiped out 65 million years ago and since then our ancestors more or less evolved from a mouse to a man), which is a REALLY long time. Many will say that all of the phyla suddenly appeared during this 'explosion'. Of course that is not the case as several phyla have been shown to have existed before said event.
Creationists like to make the Cambrian 'explosion' out to be this big event where everything sprang from nothing. In reality it took many millions of years and is not even considered to be a period in time where evolution worked faster than normal. many (myself included) hate the term 'explosion' as it implies something that simply did not occur.

Galvasean

dlofnep wrote: »

Take a glance at this photo.


These guys look similar, right? At first glance - you might consider them to be the same species.. Or maybe, close relatives, right?

Wrong. The actual reality is, humans are more closely related to the animal on the left, than the animal on the right is. Why is this? Well - One is a mammal (Flying Squirrel), and the other is a marsupial (Sugar Glider). Marsupials have been deemed so different to standard mammals, that they have been allocated their own Infraclass - Marsupialia. They deviated from mammals all the way back during the Cretaceous.

And let us not forget Volaticotherium who lived over 150 million years ago and has no living relatives.

sbsquarepants

Galvasean wrote: »

many (myself included) hate the term 'explosion' as it implies something that simply did not occur.

There's a lot of us hate the term "creationism" for the very same reason!:D

As a side note, i'd never seen a sugar glider before - he's a cute little critter isn't he. It's amazing how closely they resemble flying squirrels!
I remember reading before that ant eaters and aardvarks are not related despite looking and behaving very similarly. (I'm open to correction here, thats just one of those useless "facts" that rattle around in my head!)

MagicMarker

Oranage2 wrote: »

I just dont think there's enough evidence to believe we all evolved from the same ancient organisms.

Holy ****, have you presented these findings to any scientific peer reviewed journals!?

It's amazing how much of a quick learner you are, going from not realizing that humans didn't evolve from apes to forming the conclusion that there's not enough evidence that ''we all evolved from the same ancient organisms'' in 24 hours is truly remarkable.

sbsquarepants

Oranage2 wrote: »

I just dont think there's enough evidence to believe we all evolved from the same ancient organisms.

Have you seen any evidence of our design and manufacture?

Ask yourself a simple question. If we were designed by an omnipotent being, capable of creating an entire universe - why do so many things go wrong with us? Without even getting into things like aids and cancer and so on, why do so many peoples eyes not focus correctly? They're a very important part of the overall "design" yet they seem very badly "designed" Even the ones that do work perfectly, can't see in the dark for a start!
I personally had to shell out a lot of my hard earned cash to a nice man with a laser to fix mine for me. How come he was needed, to correct the work of an all powerfull perfect creator? That makes no sense!

Cossax

Have a bit of an interest in human evolution but it's very much in a 'watch documentaries and occasionally read wiki' vein.

Is this the first time (well, since the first Human ancestor) that we're the only living species of homo?

Has evolution in humans slowed down (I suppose it's probably never happened at a constant rate anyway but still) due to advances in medicine and due to the size of the population and thus the slowness of changes propogating through a large chunk of the population?

Are we becoming more gracile? Did this happen in many/any/all of our pre-HSS ancestors?

Are we significantly different to our HSS ancestors pre-behavioral modernity? Do we know what caused it?

Were HSS just the right species in the right places at the right time or are we significantly more adapted/adaptable to the world around us than previous incarnations of homo species?

darjeeling

Cossax wrote: »

Is this the first time (well, since the first Human ancestor) that we're the only living species of homo?

Yes, it seems to be the case, though different people disagree over calling some of our extinct relatives species or sub-species of our own (e.g. Neanderthals).

Anyway, the last peoples who weren't modern humans seem to have died out around the start of the 'holocene' era, around 12,000 years ago. We've evidence that the 'hobbit people' (Homo floresiensis) on the island of Flores in Indonesia survived until then, and - just today - a paper suggesting that people who weren't fully modern humans were living in South-West China around the same time.

Going back in time, the Neanderthals survived in Europe until perhaps as recently as 24,000 years ago, and the enigmatic Denisovans (distant cousins of Neanderthals) were living in Asia ~40,000 years ago.

Much earlier fossils from Africa all seem to point towards a bushy family tree with many offshoots, one of which (we don't know exactly which) would go on to give rise to us.

Edit: I should add that recent genetic work has shown that the wave of modern humans leaving Africa interbred with both the Neanderthals and the Denisovans, so a little of them lives on in some of us today.

muppeteer

So it seems that there were at least 3 human species living at once fairly recently. Possibly 4. It's fascinating to think of how the different species interacted, obviously well enough interbreed.

I do wonder how the later "civilised" homo sapiens would have interacted with the others had they survived until more recently though. Our own history with slavery/racism might suggest it would not have gone well.

darjeeling

muppeteer wrote: »

So it seems that there were at least 3 human species living at once fairly recently. Possibly 4. It's fascinating to think of how the different species interacted, obviously well enough interbreed.

Yes, that's the picture that's emerging: more different populations of ancient humans than we knew about, branching off at different times and moving to parts of the world we hadn't expected, and also more interbreeding than we knew about.

Interbreeding may not just have happened after our modern human African ancestors left Africa. There's a strange result from the Siberian 'Denisovan' people that may point to them interbreeding with distant human relatives too.

Two Denisovan genetic papers were published, the first on the very small maternally-inherited mitochondrial genome, and the second on the much larger nuclear genome. The family trees revealed by the two were very different. The first (mtDNA genome) paper seemed to show that Denisovans were the outliers, and last had a common ancestor with humans and Neanderthals around a million years ago. The second, though, showed Denisovans to be more closely related to Neanderthals than to humans.

A plausible explanation is that an early Neanderthal-like people moving into Asia met and interbred with a distant relative that had left Africa long before. In this scenario, the descendents' genes come mostly from the Neanderthal-like side, but also include some that come from that distant relative.

sephir0th

Cossax wrote: »

Has evolution in humans slowed down (I suppose it's probably never happened at a constant rate anyway but still) due to advances in medicine and due to the size of the population and thus the slowness of changes propogating through a large chunk of the population?

The same selection pressures aren't there for humans now. We live in societies where a larger brain, for instance, isn't going to lead to greater reproduction for that individual. The only way to analyze the shift of the gene pool is to study which races, or which human characteristics are now reproducing at a higher frequency.

Galvasean

sephir0th wrote: »

The same selection pressures aren't there for humans now. We live in societies where a larger brain, for instance, isn't going to lead to greater reproduction for that individual. The only way to analyze the shift of the gene pool is to study which races, or which human characteristics are now reproducing at a higher frequency.

Don't forget we can use technology to alter our characteristics (outwardly at least). For example, I could get plastic surgery to give myself a mighty man chin, use it to reproduce with many women and pass on my weak boy chin DNA to the next generation - tricking evolution in a sense.
Re: brains & intelligence, many studies have shown that people of lesser intellect tend to breed at a higher rate (see: Jersey Shore) while those of higher intelligence reproduce less (and are also more prone to depression and suicide). So it would appear natural selection does not really favour intelligence among humans anymore.

Sarky

In the coming decades it'll be very interesting to see how things progress. Transhumanism is actually starting to become viable as we gain a better understanding of our own genetics. There are even rudimentary cybernetics in development, like prosthetic eyes, ears and even limbs. Increased life expectancy causes all sorts of problems for a body designed to live for half the time most of us manage these days. The selective pressures affecting most humans these days are generally of our own making. If we can control our own evolution, any speciation that might occur in future will likely be down to ideological differences rather than environmental pressures. That'd be downright strange.

Mark Hamill

Galvasean wrote: »

I could get plastic surgery to give myself a mighty man chin, use it to reproduce with many women

Chicks dig mighty man chins .

wench

Galvasean wrote: »

I could get plastic surgery to give myself a mighty man chin, use it to reproduce with many women

I think you need to read the chapter on reproduction again, thats not quite how it works

seamus

I think the most probable natural change at this stage is a natural increase in the body's longevity. As reproductive ages move ever higher, this puts a selective pressure on one's ability to survive (or at least on one's ability to bear children) into your late 20's/early 30's, which means that those who are fertile for longer and less susceptible to age-related disease in their 30's, 40's and 50's, are more likely to procreate successfully.

Of course, this really only applies in the developed world and would require our current level of peace and affluence to continue for a few thousand years to properly "embed" it.

However, I wouldn't be surprised if studies in 100 or 200 years started showing that people of European and American ancestry naturally experience menopause and age-related disease at a measurably later age than those of African ancestry.

Galvasean

wench wrote: »

I think you need to read the chapter on reproduction again, thats not quite how it works

I dunno... If it walks liek a duck... quacks like a duck...

wench

Galvasean wrote: »

I dunno... If it walks liek a duck... quacks like a duck...

That is an impressive appendage, but I'm still not convinced...

Galvasean

wench wrote: »

That is an impressive appendage, but I'm still not convinced...

Now, i'm not saying Quentin Tarantino is a dickhead or anything...