delboy

Thanks. Matthew seems a bit of a character - natural selection was obvious, why didn't everyone see it!

I've only just learnt that Patrick Matthew pre-empted Darwin and Wallace on natural selection. Surprised it wasn't in the Desmond/Moore biography. Is this theory that they deliberately stole his idea taken seriously at all: http://britsoccrim.org/new/volume14/pbcc_2014_sutton.pdf Seems unconvincing and unscientific to me. It seems the only real evidence is that 3 naturalists known to Darwin and Wallace cited his book - 'On Naval Timber and Arboriculture', where he gives a brief but perfect description of natural selection in an appendix - in their literature. Sutton appears to think this is proof of deliberate and concealed plagiarism, since, in his opinion, they must have known of it.

My guess is that if all prokaryotes were suddenly removed, then eukaryotes would soon become extinct. But remove all eukaryotes, and some prokaryotes would survive. Any thoughts?

Maybe a mess is a bit strong, but undergoing change that makes some things a bit problematic? I can understand that applying strict cladistic principles is important in evolutionary study. And I think that many (evolutionary) biologists may only be interested in closeness of relationships and branch points and less interested in naming and grouping things. But I'm also wondering how important it is that new insights into relationships filter through to the lay person. Do people need to understand the slightly unscientific nature of groupings such as reptile, bird, mammal or dinosaur in their traditional meaning. Or can we go on using these names without a problem? Is it that classification and evolution are incompatible concepts. Birds are a good clade. But traditional reptiles now need to include birds, so birds have to become reptiles. But going back a couple of steps, reptiles evolved from lobe-finned fish so have to be called lobe-finned fish (as do all tetrapods). Taking it to extreme, everything needs to be called a bacteria (or archaea, which ever came first). Is classification based on strict cladistics problematic? For example referring to ray finned fish is not much problem - as a clade everything is 'fishy'. But when referring to lobe-finned fish (or whatever name you might invent for the group) you would have to include bats, birds, frogs, dinosaurs and whales. In strict science terms this is true, but it's never going to filter through to general public use surely. Where is classification going? Is there room for continued use of grade as well as clade? For example if you say 'mammal' you are naturally assumed to include antelopes within that definition. Likewise, with strict cladistics, if you say 'lobe-finned fish' you must be assumed to include all tetrapods and there should not be any concept of lobe-finned fish that are exclusively 'fish-like' and aquatic.

Because frogs and salamanders are 'advanced' amphibians. The first amphibians appeared before reptiles but frogs and salamanders didn't evolve until some time later.

Sounds like an exam question. Lobefin, reptile then (probably) frog, salamander. Source - Vertebrate Palaeontology, Benton.

Over the millions of years that reptiles evolved from amphibians the various reptilian features must have evolved at different times. There were probably a whole load of species that would have been difficult to put in one box or another. Beta keratin was probably one of the last features to evolve and synapsids branched off just before then. As Moontanman says, there would have been lots of different species with a whole mix of features. Plus it's about the arbitrary nature of classification. Evolution is gradual and various features evolve at different times. Classification likes to put things in sharply defined boxes, which just doesn't fit with how evolution works. I guess it has been deemed that to be a reptile it must have beta keratin. To my mind you would only have to be slightly less strict about it to include those with alpha keratin (plus any other minor differences synapsids have) - in which case synapsids would be reptiles, no great stretch of the imagination. In which case strict cladists would also need to call mammals reptiles too. Also, as far as I know reptiles didn't strictly evolve from amphibians! I think it was a group that wouldn't quite fully identify with modern amphibians.

I doubt fossil evidence. I assume it's known that alpa keratin is the more primitive form (if amphibians have alpha keratin this would prove it). So synapsids must have branched off before beta keratin (which all extant reptiles/birds have) evolved. So if amphibians and mammals both have alpha keratin then all synapsids must have had too.

I think that the keratin difference is useful to infer the early split of synapsids from the reptilian line, before beta keratin had evolved. And it seems it's a difference that has remained over a long time. The jaw bone changes are a beautiful example of evolution. Synapsids started with a reptilian arrangement and over time two bones migrated into the ear to create the mammalian arrangement (in the mammalian offshoot anyway). Fossils certainly preserve well, but I'm sure chemicals are equally useful (in a different way) when you have extant species - maybe even more useful?? I don't think I implied any of the things you say. I think I agree with everything you say (assuming you mean that mammal like reptiles are falsely identified as dinosaurs). Your beef is with the strawman.

I'm sure it would have been a reliable reference. There is a brief mention here https://en.wikipedia.org/?title=Keratin

You've got me wondering now. I had thought I'd read it in Dawkins' Ancestor's Tale but I've looked in the likely bits and couldn't find it. So I Googled and it came up with a thread I started here! I said I'd just found a reference to it but I've now forgotten where that was!! Very annoying, it's bugging me now!

It kind of illustrates the point that all classification is slightly arbitrary. I was using the accepted classification that separates synapsids as non-reptiles (though my uninformed gut feeling is that they could easily be included). My understanding is that reptiles (to include anapsids and diapsids) are a good clade (if you include birds), unlike 'fish'. And dinosaurs evolved within that clade and mammals did not. The main difference I have heard is that synapsids have alpha keratin in the skin and anapsids/diapsids/birds all have beta keratin.

Everything has a common ancestor if you go back far enough. But mammals did not evolve from dinosaurs or even true reptiles. Mammals evolved within a group which branched off before all the reptilian features had evolved - the synapsids, often called 'mammal like reptiles'. They had many reptilian features but there were some they lacked.

So the planet gave birth to life. I like it.

Of course. Just a chemically much simpler one I guess.

I like pondering this too. Since life created quite a lot of the rock beneath us and changed the composition of the atmosphere, the boundary is pretty blurry. I like to think of life as simply part of the substance of the planet, which it is really.

When DNA/RNA is used to date common ancestors I understand that fossils are needed for calibration since rates of mutation vary considerably. I know fossils can normally be dated accurately but I don't understand how they help. If a fossil is found that resembles what the common ancestor must have been like I assume it cannot be known for sure if it came before or after the split in evolutionary lines, so I don't see that that helps. Can anyone explain?

We both evolved from a common ancestor which existed very roughly something like 80-100 million years ago (it's probably known more accurately). So a species existed then that was neither mouse nor human. It became divided and evolved into 2 species. One of those evolutionary lines eventually led to mice and one to humans. So the genetic changes that happened along each of those lines accounts for the differences, having started at an identical point. Which is why the genetic differences between us and chimpanzees is much less since our common ancestor with them existed only 6 million years ago.

I was going on what I read in Richard Dawkins' 2004 book The Ancestors Tale. He estimated that the most recent single human (or two humans I guess) to be ancestor to all present humans was some tens of thousands of years ago. Things go out of date pretty quickly.

Theoretically this could be true. But in practice I'm pretty sure it can't since for most of the period there was little or no migration between Europe/Asia/Africa and the Americas/Australia/Tasmania.

He should be a scientist... … no, hold on. He wouldn't make a scientist, he doesn't listen to answers. That's why he's a creationist.

I think religion on balance was good thing back then. It worked so it outweighed the downsides. What about the many wars that have religion as a major part of the underlying cause? Is that a good reason to get rid of religion? I just feel that if decisions are made based on untruths written in a very old book then there's something wrong.

There are plenty of things that science comes as close to proving wrong as you can get - the world isn't 10,000 years old, it wasn't created in 7 days, things do evolve, the world isn't the centre of the universe etc etc.

Religion has taught these things. But I think it's very important to recognise the difference between morality and religion. Morality can teach these things perfectly well without religion. In fact atheistic morality can certainly teach them far better since it is able to very quickly move with the times. If religion respects science it would realise it cannot exist because there is no scientific evidence for it's core beliefs. If decisions are made in the modern world based on writings from 2000 years ago, which have largely been proven wrong, then what hope is there that these decisions are good ones. A religious morality is on decidedly dodgy ground.

Maybe because that's how it comes over to me sometimes. I have a huge respect for Dawkins and yes, the foundation does have specific aims which I would support. I guess there's a bit of a conflict in my own mind I'm trying to resolve. Over the years Dawkins personal attitude can seem like a bit of a crusade (almost obsessional?), and whilst I would support everything he says, including a desire for a world without religion, a part of me is probably saying - 'hey, what about live and let live'.