Arthur Smith

https://sandwalk.blogspot.com/2014/05/answering-creationist-questions-about.html

Ten years ago. Some good comments, including Joe Felsenstein.

On 1/27/2023 at 5:35 PM, TheVat said:

The most interesting question this study raises is asked at the end of the article: how did humanity go from zero blue eyes 10,000 YA to now 20-40% of European countries?  What was the selective advantage(s)?  Aesthetics?  Better night vision? 

A skeleton found in Gough's Cave, Cheddar (of the cheese), UK recently had remnants of DNA extracted and sequenced. According to press reports, this fully modern human, when living around 10,000 years ago, had dark skin and blue eyes.

Fixation by drift? Sexual selection? Niche change and population explosion from neolithic to now?

ETA: and there's no reason to suppose "either or" here.

On 1/27/2023 at 5:38 PM, Moontanman said:

Sexual selection? 

Ah, missed that. There was a discussion on Larry Moran's blog a while ago that might be of interest.

Sure. But I would find it difficult to remain optimistic, even though it is the outcome I expect. Where are they?

Anyway, the hiatus between yule and New Year will soon be over so much less time for me to comment.

Happy New Year everyone.

12 minutes ago, exchemist said:

OK thanks. (The link you supplied takes one to the middle of some piffling argument with a creationist, but scrolling to the top makes it clearer.)

Sorry, I corrected the link.

13 minutes ago, exchemist said:

But that's just about Mars. If there continues to be no sign of life there, I don't think it provides a basis for extrapolation to other bodies we have not yet detected. Of course it does detect evidence of past life, that's highly significant, hence the interest.

Extrapolation may be justified, I suggest. What if the mission brings back evidence of micro-organisms fundamentally unlike that found on Earth? On that basis, separate abiogenesis events on two adjacent planets in one solar system, abiogenesis seems inevitable given the right range of conditions.

3 hours ago, exchemist said:

 

It refers to the ongoing Mars Perseverance mission, of which one objective is to return physical samples to Earth. The article discusses possible results from examining those samples and the implications.

12 minutes ago, exchemist said:

You will need to explain the relevance of that link. 

Just now, Arthur Smith said:

It refers to the ongoing Mars Perseverance mission, of which one objective is to return physical samples to Earth. The article discusses possible results from examining those samples and the implications.

3 hours ago, exchemist said:

What you say you have noticed is wrong. We simply do not know whether life occurs elsewhere, due to the difficulty of making the necessary observations. 

Not sure if this blog post from 2021 is still valid or if budget cuts will cause the venture to be cancelled.

9 hours ago, TheVat said:

I think of genetic drift and gene flow as sort of the yin and yang of evolution, with gene flow increasing adaptive diversity while drift tends to reduce it with alleles sometimes dropping out completely, as in bottlenecks and founder effects. 

I wonder if the claimed positive effect of random genetic drift could be (or has been) measured. 

The hypothesis I imagine would be something like "Under the effect of selective pressure on a population of sexually reproducing organisms, a locus with fewer alleles lost to drift will move to fixation in fewer generations than a locus with more variants". 

Consider population 1. A gene is fixed in the population of 100 and 1 beneficial allele enters the gene pool. Consider then population 2 (also 100). A locus has 10 neutral alleles at 10% frequency and 1 beneficial allele enters the gene pool. Is the rate of selection of the beneficial allele going to be different between population 1 and population 2, all else being equal?

7 hours ago, sethoflagos said:

(Sorry, I've a bit of a thing about the 2nd Law)

You, me and Sir Arthur Eddington. 😉

4 hours ago, sethoflagos said:

Isn't it pretty well established that 'evolvability' is itself under strong selective control?

It wouldn't surprise me that evolvability would be a trait subject to selection.

4 hours ago, sethoflagos said:

Genetic drift is a particularly interesting case wrt the OP as it represents a steady source of decline in the diversity of a complex system running counter to the main thrust of the linked article.

Perhaps the message of genetic drift is to remind us that non-transitory structures in complex systems require sufficient energy flow passing through the system to maintain their low entropy configuration. 

Yes, it is my view that drift is not an adaptive process but becomes insignificant in large populations.

I'm not quite sure what you mean about energy and entropy in this context. Certainly one attribute of known living entities is that they maintain themselves out of thermal equilibrium with their immediate environment by using an available energy source

4 hours ago, exchemist said:

As I understand it, the thing about evolution through genetic drift is that it is not adaptive. Not all evolutionary processes are. They can be neutral or have negligible benefit and still become established in a population.

Indeed. Drift is the process by which an allele (a variant of a gene) will fix in a sexually reproducing population in the absence of selective pressure. The effect is noticeable, particularly in small populations lacking genetic diversity, and often results (or contributes to) in loss of a species by extinction.

Perhaps it would be an idea for commenters to identify what sort of evolution is being referred to. Biological evolution seems to be the subject of the thread, but there is also cultural evolution and using evolutionary algorithms to solve problems such as the evolved antenna.

11 hours ago, studiot said:

1) There are several different types of evolutionary process.

2) Not all evolutionary processes involve selection.

3) Selection is itself a complicated process that involves criteria or standards to 'select' against.

4) Darwinian evolution involves what he dubbed Natural Selection, which was another word for the prevailing conditions.

5) For such a process to operate the prevailing conditions must remain sensibly constant for a long enough time.

6) The prevailing conditions can suddenly change (as with the dinosaurs) in the middle of such an evolutionary process.

1. Why not list them, then, for clarity?

2. Disagree. But I am open to correction by an example.

3. There's nothing complicated about the idea of selection in biological evolution. Darwin categorized three sorts of selection: artificial, natural, sexual. The process is change in allele frequency in all those cases.

4. Not really. I would use the word "niche".

5.  Allele variation and fixation can be a slow process where generation times are long, but evolution can be fast enough to be observable. Here is a classic.

6. Yes, biological evolution can be outstripped. Rapid climate change is a disaster for many species. Mass extinction events are unfortunate for those caught up in them, but the subsequent opportunities for survivors got us here.

5 hours ago, exchemist said:

My understanding is that genetic drift is now a recognised mechanism in the evolution of organisms.

Evolution simply means change over time, does it not? It is Darwinian evolution that relies on natural selection. That is just one kind of evolution, surely?

Well, I don't dispute that random genetic drift happens (or at least convincing models exist in the sphere of population genetics). But the clue is in the "random" bit. In small populations, genes may fix randomly which leads to loss of diversity and extinction. Resulting empty niches may be opportunities for other populations (the Chicxulub bolide did that for mammals around 65 million years ago) but without selection change does not produce the fit of species to niche. You need that feedback for change to be adaptive.

I'm curious to learn of other ways that feedback can lead to an evolutionary process.

5 hours ago, studiot said:

For example a smaller or larger elephant with a slightly longer or shorter trunk may have an evolutionary advantage, but is still an elephant.

Goodness me. All life on Earth, ALL life, is on the same branching tree. Admittedly the roots are a little tangled but the evidence is overwhelming.

Perhaps I should make a distinction between shovels and entities such as biological organisms that reproduce.

Tool use (not restricted to humans) evolves adaptively. If you want to access tubers, a stick is handy. A stick that doesn't break is better, a hardened point more so. Observing and learning from others even better. The bias is stronger when the learning is retained over generations. Human cultural evolution has swamped human biological evolution.

1 hour ago, studiot said:

I am suggestng the definition of the word evolution you are employing is too narrow to cover all possible/conceivable circumstances.

Not sure how much broader the idea could get. Selective bias on populations of reproducing individuals leads to change in time over those populations. Works with shovels, Covid virus, Great Auks, computer memory.

13 hours ago, swansont said:

Again: is there a point to this?

Yes. Evolution requires a selective bias for adaptive change to take place. Drift does not introduce selective bias. Your demand for a definition of "agency" may be perhaps answered by a selection process.

9 hours ago, swansont said:

Drift also does this.

In small populations, random genetic drift results in loss of allelic variation, which in turn can lead to extinction. I guess the empty niche left is an opportunity for another species. I'm yet to be convinced of how else drift contributes to adaptive evolution.

12 hours ago, studiot said:

External intervention, deliberate or otherwise.

Would that not be artificial selection?

On 12/26/2023 at 1:12 AM, swansont said:

We speak of language evolving, or technology evolving. Of course AI is going to evolve. It just won't necessarily be Darwinian.

Asking as a dyed-in-the-wool adaptationist, what other mechanisms can be substituted for selection that produce change over time?

Any explanation for the site being off-line?

ETA: never mind. Failed to scroll.

Tor works. Chrome doesn't.

So does Firefox? Yes.

Also bear in mind the unconceived alternative. 😉

9 hours ago, exchemist said:

 If people can generate at least a proportion themselves it could help a lot. 

My house is 42° N, with (maybe too) many sunny days. Plus the grant, zero interest loan and buyback scheme means there is no downside. Unless the plug gets pulled on the buyback scheme.

8 hours ago, studiot said:

Did you miss my last post ?

 

No.

8 hours ago, studiot said:

More power can be had by using a dedicated 30 amp supply, still at 230 volts. That is equivalent to one ring main direct wiring from a single fuseway in the box. This is nearly 7.5 kVA and is used for say 8 kVA instantaneous showers.

However the charging lead for my brother's car, like most uk electric vehicles limit the input current to 10 amps at 230 volts.

Ring mains! I'd forgotten about those. In France domestic sockets are fused at 16A (no ring mains) but single spurs can be 20A. When I lived in UK, the main fuse was rated at 100A. Here, my contract limits me to 9KVA, exceeding that for any length of time causes the system to trip. Just checking my app, I see my average consumption so far today is less than 1KVA. I haven't checked but I've heard one can installa 70KVA home charging point.

8 hours ago, studiot said:

So your neighbour has 9 kVA in good daylight. Jolly good if he is a night worker and charges hois car in the day otherwise he would have to layout for storage capacity equal to a day's charge, if he wanted to work in the day and sleep at night. say anothe £15000 on top of the panels and vehicle.

There's a buyback scheme. Excess electricity is money in his pocket and avoids having a battery storage system.

OK, so charging cables and home charging points are a bit of a minefield. EVs have a maximum charge rate (single phase) that maxes at 7KW for top of the range. A 32A point also gives 7KW. Charging cables vary in carrying capacity, with type 1 capable of handling up to 7KW.

1 hour ago, exchemist said:

From what I have read, it is better to keep an old IC vehicle as long as you can, before trading it in for an EV, due to the large and unavoidable carbon footprint of manufacturing a new vehicle, of any type. But your next purchase, whenever it is necessary, should be an EV. The longer you can leave it , the greener the EV will be , since the renewable proportion of the electricity it consumes will grow as the years pass. Also the charging network will get better over time. I'm currently running a 19yr old petrol VW Golf, (the 1.4l one with both supercharger and turbocharger, which performs like a 2l but with much better fuel economy). It still works fine and does what I need it to do, so I intend to hang onto it for another year at least. 

My runabout is a twenty-two-year-old golf 1.6 (naturally aspirated) and I have the same plan: hang on to it until something major breaks while watching developments in electric cars. There is currently also a scheme to subsidize photovoltaic installation, with the ability to sell excess back to the grid. My neighbour already has a roof installation that delivers 9KVA in good daylight. The idea of charging my car with free electricity appeals very much.

Z

2 hours ago, studiot said:

I do this all the time with both my own petrol car and my brother's all electric car.

Simple question How many litres of petrol or Kwh of electricity do I need to tget to Bristol / Plymouth and back ?

Really I want to know whether to top up before I go or not.

 

So yes please @Arthur Smith  What are you actually trying to do  -   The answer is unclear to me.

Not so because this is incorrect maths .

There is indeed a typo in my comment. I meant "cubic millimetres" where I wrote "cubic millilitres". I believe the arithmetic is correct, though.

And to clarify, I think representing fuel consumption as an area is trivial and unhelpful.

I'd be much more interested in how to compare holding on to a reasonably economic, well maintained IC car or swapping for an all-electric, taking into account all the relevant factors, including the overall carbon footprint.

Eta including the carbon cost of manufacturing an electric car and its batteries.

Integration, not differentiation, for the area under a curve. Sorry to have misled you.

32 minutes ago, swansont said:

You could measure the effect of varying braking but simply subtracting or extrapolating that effect wouldn’t give you the answer, since there is air resistance as well, so you haven’t accounted for all of the dissipative losses.

 

Ah but am I not simulating total drag force by using the output from my "instantaneous" fuel consumption gauge on the dash to set the power equivalence to that necessary to drive the car at 100 kph (and speedo to 100 kph) as I already know the car consumes an average of 5L/100  kph? If the rolling road is set to simulate that, surely it simulates total drag, including air resistance.

An ad on Spotify telling me if I swap to Spotify premium I can avoid listening to ads.

40 minutes ago, swansont said:

Yes, but why would you do this? What insight does it provide?

You don’t always simplify units. Torque and energy are both N-m in metric units, and N-m is a joule, but it’s not considered proper to express torque in joules, because it’s not energy.

Having come across the "problem" elsewhere, I asked to confirm my take that it is a pointless exercise. Thanks for confirming 

I chose "brainteasers" presuming it to be not for serious issues.

1 hour ago, Sensei said:

That's yet another question. The easiest way to answer it is when someone uses a biofuel: bioethanol.

When someone uses the word "fuel" it is too ambiguous. 5L/100km, liters of what?

The question is the same for any fuel. I have a car that I run on petrol/gasoline with 10% "bio" ethanol added. I get, on average, about 5 litres burnt for 100 km of travel. My larger-engined turbo diesel also returns around 5L per 100km. Of course the calorific content of fuel and the thermal efficiency of internal combustion engines is a whole subject (as is carbon emissions)in itself. The more interesting question is overall fuel economy, thermal efficiency, and carbon footprint. I can bypass all of that in buying an electric vehicle. But factor in the construction of a new vehicle when comparing carbon footprints and the comparison is not so easy.

But I'm derailing my own thread...

48 minutes ago, Arthur Smith said:

Torque and energy are both N-m in metric units, and N-m is a joule, but it’s not considered proper to express torque in joules, because it’s not energy.

If I wanted to measure the actual thermal efficiency of an IC vehicle moving at a reasonable constant speed (say 100 kph) and I had access to a rolling road, and able to apply a variable braking load (that I could measure as a drag force) that I could regulate so that the "instantaneous" fuel consumption settles at 5l/100km, do I then have enough information to calculate the torque at the driving wheel, the net power output of the engine and, hence the thermal efficiency of the vehicle and fuel?

One bonus of moving to France. Crystalline oxalic acid, copper sulphate as Bordeaux mixture, and sulphuric acid of sufficient strength for most purposes