If you assume there was a common ancestor and assume that only unaided evolution produced humans and chimpanzees then you must come to the conclusion that it was within reach; but then that’s circular reasoning or begging the question.
However Richard Buggs has shown there is a significant difference between human and chimp genomes and Behe and Stanford have shown Darwinian evolution is downwards, not up. Given the evidence it would appear that either
there was no common ancestor, or
an intelligent designer provided an input of complex specified information, or
something else, but not unaided Darwinian evolution
The thread on Nylonaze touches on the evidence that Darwinian evolution is not good at producing the dozens of orphan genes that separate us from chimps, and in the thread on information I have argued that entropy does not produce new information as Swamidass claims.
Randomness mixed with intentional, teleological selection, not natural selection, tough! There’s nothing about the dice themselves that would let unaided nature select for the 6s. I think you just demonstrated ID…
Firstly, it isn’t simply that there are a “mere” 60,000,000 - 120,000,000 (!) differences between human and chimp genome. It is that you have to get the right 60,000,000+ changes in order to accomplish the absolutely astounding feats. Or at least, pretty close to very particular kinds of changes. Presumably, not just any 60,000,000 random mutations across ~3billion bases pair will allow a chimp (or HCLCA) to develop the astounding intelligence we possess, and adjust the skill set to be able to do all we do as humans. While there is certainly some flexibility, we can nonetheless presume there are very specific mutations that would be necessary to make that kind of change.
Thus, I would grant, if I understand the math rightly, sure, getting any 30,000,000-120,000,000 mutations within the population over 4-6 million years is “easily obtainable.”
Getting the precisely right 60,000,000-120,000,000 mutations on the other hand? The precise mutations needed to establish the skills to engage in music composition, music appreciation and recognition, music instrument performance, higher level math, higher logic, visual arts, vocabulary across languages, speech production, speech recognition, literature, poetry, morality, visual arts, etc. etc…
But moreover… given that many of these specially developed skills could not have been of exceeding advantage to our proto-human troglodyte ancestors, I have serious doubts about how much natural selection could have assisted the process.
This is essentially my difficulty with the entire theory: we look at the human genome, look at the chimp genome (and infer the HCLCA), see there is “only” a “mere” ~60,000,000 mutations different, look at the population and consider that this number of mutations could have conceivably happened in the timeframe involved, and consider the case closed.
There doesn’t seem any recognition or acknowledgement of the astronomical problems involved just to get the right 60,000,000 mutations. The right mutations, in the right places, have to arrive serendipitously by complete accident just for natural selection to have anything to work with. Even if we determined that only 1 / 1,000,000 of those mutations were in fact necessary to produce uniquely human intelligence and skills (that is, only 60!)… there are still 4.2 x 1028 possible combinations of mutations within those 60 genes.
Even allowing natural selection to choose them one by one if and when they arise, we have to wait for each specific mutation to arise in the population. Then it then has to be the right mutation, otherwise, repeat step 1. Then we have to give it time to spread through the population. Then this process has to be repeated with all 60 bases.
And heaven help us if any two or more need to happen simultaneously to confer any benefit.
500,000 generations or so starts to be far, far, far too short a span to expect this to happen. And I imagine it safe to guess our intelligence over other primates is likely the result of > 60 mutations. The problem becomes insurmountable to me after I crunch some of the numbers involved.
I’ve actually mused a bit about Yahtzee being a pretty good example of natural selection, and it seems to me it matches up pretty well. While your point is taken that there is some intelligence involved in winning, overall it is a game of chance. When, say, a full house fills a niche in the environment of the score card, then you have to look at unfilled niches and see where things go. Got a couple of 2’s? they move into the empty 4 of a kind niche and hope random chance make them successful in rolling one or two more 2’s. Intelligent design? Perhaps a bit, but I would argue it is more selective pressure relating to the environment of what spots are available. fun to consider anyway.
The vast, vast majority of the differences between humans and chimpanzees are not selected changes. There is no need to get the “right” millions and millions of differences. The number that actually make a difference are small - perhaps in the thousands.
You’re also still saying that we have to wait for mutations to arise. Why? Why would the founding population not have variation within it?
As @DennisVenema says, the vast majority of these differences have no effect. To set the scale, note that any two unrelated humans have five or six million genetic differences between them. (Your number seems high for human/chimp differences, by the way. When the chimp genome was originally sequenced, 40 million differences with human were found. The genomes are more completely sequenced now, and I’d expect the final number to be in the neighborhood of 50 million.)
Maybe, although it’s really not clear that any particular set of mutations would be required for a broad trait like greater intelligence. More importantly, though, evolution wasn’t trying to achieve a certain kind of change. Species can change in all sorts of directions, depending on what mutations happen to occur and happen to work in the particular environment.
As noted already, the actual number is probably in the thousands, and there is such thing as the “right” mutations. Bonobos also diverged from chimpanzees, and they didn’t develop in anything like the direction we did.
You’re assuming these are all distinct traits, rather than particular developed skills based on a small set of positively selected traits like intelligence.
That’s why I narrowed down the mutations in my calculations to only 60. (That, and any number much bigger produced results too big for even my ipad’s scientific calculator to handle)
Doing the math, I found even 60 required mutations start to create an insuperable problem for the timescale involved.
Sir, to make sure I’m following you…
You’re suggesting that all of the changes needed to get to from the HCLCA to modern humans was extant within the natural variation within HCLCA population the whole time, simply spread across the diverse population as not yet combined into one organism?
Would we suggest the same of modern chimps, that selection working on population dynamics and/or genetic drift alone, given enough time, would conceivably be be sufficient for chimps to speak, read, write, play cellos, etc., without any need for mutations to arise?
When the studies confirm 2-4% (depending on methods) of our genome is different than chimps, these presumably are the differences that are not accounted for by variation within each species, no? Humans, I understand, are 99.9% similar. If chimps are also, this means that, even accounting for the variation among humans, and variation among chimps, there is still somewhere around 1.8% - 3.8% difference between us and chimps that cannot be accounted for simply by accumulating the right combination of variations already extant among the populations.
If the changes needed to get to both Chimps and humans from HCLCA were all present already spread across the population, that seems to imply that there was something like 2-4% variation even within HCLCA populations, in order for breeding and population genetics alone to account for the current variation between chimps and humans, if we are going to rule out having to wait for mutations?
Am I understanding this correctly as what you are suggesting, or am I misunderstanding the idea?
For what it’s worth, I did already note that, and for my own calculations I narrowed down the required mutations not down to thousands, but to a mere 60, as I described above…
And yes, there are “right mutations” needed to create certain particular skills. If using my hypothetical, and there are a mere 60 bases that were needed to change in just the right way from HCLCA to give humans all the skills and intelligence we need for you and I to have this particular conversation, then there are 4.2 x 1028 other ways those same bases could have mutated that would have come up with something different.
In one sense, sure, none of them would be “right” or “wrong,” they would have just made something different. But had any of those hypothetical 4.2 x 1028 other paths been taken, we wouldn’t be here having this conversation.
_(and, I’d add… natural selection has no preference on any one particular of those beneficial mutations as to whether it will eventually produce a human or a bonobo, no?)
This is a common error in thinking about evolution. You have chosen an endpoint then calculated some number that you assume is the probability of reaching that endpoint. What you have not done is explain why only that endpoint matters. Without that information, your math is meaningless.
So, I see two big mistakes you are making.
The minor mistake is assuming that there is exactly one “solution” to the “problem” of producing “uniquely human intelligence and skills.”
The major mistake is assuming that back-of-the-envelope calculations based on simplistic assumptions could produce major new insights into human evolution. This is staggering hubris.
This is how you announce that you don’t understand biology, much less evolution.
You’re proposing that (a) a certain number of specific mutations are required to achieve human skills, and that (b) we have to wait for all of these mutations to arise de novo after our lineage parts ways with the lineage leading to chimps.
Neither assumption is likely to be valid, sorry.
There are likely many ways to achieve human intelligence and skills from the starting point. It’s highly unlikely that a specific, precise set of mutations was required. There are usually many roads to Rome in evolution. Corvids, for example, have high intelligence and use tools, but they use a different set of variants to get there.
It’s also likely that at least some of the variation that was used in our lineage was already present in our last common ancestor. Recombination of that variation into new combinations of alleles is a powerful driver of new variation. Folks are always fixated on “new mutations” but recombination of standing variation within a population creates much more diversity than new mutations do.
The endpoint I’m examining is human intelligence, I thought that interesting and relevant because, if the evolutionary process had not arrived at that endpoint, we wouldn’t be here talking about it!
So, give me some very, very rough ballpark numbers…
Start with the HCLCA…
Roughly, how many paths are there that could lead to the kind of intelligence which would allow us to have this kind of conversation?
and for comparison, give me:
roughly, how many total paths are there that could have been trod instead?
I completely grant with what Dr. Venema said above, that there are many roads to Rome in evolution. But that observation is also essentially meaningless if I can’t compare it to the total number of roads total that exist, to see if it is likely or unlikely for evolution to find any particular working road.
I tried to work that into my bery simplified ballpark math by reducing the number down to a ridiculously small 60 required mutations. but the math would end up similar if I hypothetically granted, say, 1028 possible ways of achieving human intelligence from a HCLCA, but still observed there were 1056 Alternate paths for evolution to have trod.
So, any chance you’d have even rough ballpark numbers for me?
Most traits can be achieved by a wide variety of molecular mechanisms. There may have been a particular 60 mutations required, but I see no reason to think so.
I don’t know what you’re calculating here. If we restrict ourselves to single-base mutations, there are 216,000 different ways that 60 bases could mutate (3 per base, or 60^3 total combinations). More relevantly, each of the 60 specific mutations occurred roughly 100 times during the evolution of humans after splitting from chimpanzees.
Even if your number were correct, so what? If assume that I had to be born sometime within a 2 year window, then there were trillions of possible combinations of sperm and ovum that could have led to some child; if any one of those other trillions of possibilities had occurred, we wouldn’t be having this conversation either. Add in more contingencies, a few more generations . . . the probability that we would both be here is astronomically low. Why is that fact interesting?
I’m not sure what you mean. Some mutations might have been beneficial in one group living in one environment but not in another, while some might have been beneficial in both – but the actual effect will have depended on which earlier mutations had occurred.
No. What’s typically measured is the genetic distance between a particular human genome and particular chimpanzee genome. (In the case of the original chimpanzee genome study, it was the genome of chimp named Clint, compared to the reference human genome, which is a mosaic of various individuals, with the largest share coming from an anonymous African-American donor in Rochester, NY.) If you compare any two humans for single base differences you will find they differ at about 0.1% of sites. The total difference between their genomes (measured in base-pairs) is at least several times that because of less common but larger insertions, deletions and duplications. If you compare a human and a chimp for single-base differences, you will find that they differ at about 1.2% of sites, with a similar several times larger overall difference in DNA.
The total amount of genetic variation that’s present in the entire human population, however, is much larger, especially now that we’ve got such a large population. Nearly every single-base substitution that’s compatible with life has probably occurred in some currently living human.
No, that’s your mistake. The endpoint you calculated was a specific set of mutations. Your assumption was that those are the mutations you need, and that all the other options wouldn’t work. You couldn’t have calculated the endpoint of “human intelligence” because we don’t know yet what underlies it.
Since it’s a simple fact, I guess it’s good that you “granted” it.
No, that observation is a plain fact of evolution. Your inability to know all the different roads is simply a reflection of our human inability to know all of the roads. What we do know is a little about what some of the new human genes do, and a fair amount about evolutionary convergence, which tells us that it is foolish in the extreme to assume that a vague phenotype like “intelligence” could only arise in one single genotype.
And this is exactly why I try to work some calculations on the back of my envelope, since, true enough that your summary is, it just doesn’t communicate anything tangible to this inquisitive skeptic just how likely or unlikely the process is.
If there’s say, only 50,000,000 differences in the genome b/w HCLCA and humans, then, that is 350,000,000 different possible variations of those particular bases, so yes, we’re talking a really big number.
To vastly, vastly oversimplify, if I limit my mental experiment to only those 50,000,000 bases, and assume all those variations are viable and selectable, and only explore what happens if those 50,000,000 bases get mutated… of that extremely overly-limited and overly simplified sample…
If, say, some 349,999,900 of those combinations would produce intelligence, we’d agree that there are vast, vast, vast, vast many roads that “lead to Rome,” and would produce intelligence. But even that vast number is meaningless unless I compare it to the total number of options.
So if, hypothetically, there were, say, 349,999,900 combinations that lead to intelligence, but 350,000,000 total possible variations, then the fact that there are vast, vast options to intelligence is all but meaningless.
That would still mean that for every one road that “works” to produce intelligence, there are still 5.1 x 1047 other roads that don’t arrive at intelligence. At that point, my serious skepticism in the power of the process remains.
If, rather, there were, say, 349,999,990 combinations that lead to intelligence, with 350,000,000 total options, then for every road that leads to intelligence there are “only” 59,000 other roads. And given enough time, number of organisms, and with the help of natural selection, the idea itself would seem to warrant serious consideration.
That’s like saying that I have 5 million single nucleotide differences between me and you and the odds of getting those specific 5 million are one in 3^5,000,000. Therefore we can be confident that you and I don’t share common ancestry.