The family Hominidae is believed to have diverged from other primates between 4.5 - 6 million years ago and DNA sequences are well over 90% similar between humans and the closest primate relatives. With time frames like this, it will be a tall order to physically observe entire families diverging. Observation of changes at this level can only be done indirectly through genomic or fossil data.
Thank you sir. That basically corresponds to most assessments Iāve been reading. I was inquiring not about human ancestry alone ā¦ if you followed my inquiry it was, given the phenomenon of stasis, if in ANY plant or creature we can see discrete change from individual stasis number 1, then number 2 etc. I use stasis because that gives a āliving fossilā to compare and if we have enough stasis examples exemplifying the progression then there is much less doubt as to the reality of movement from variety within a species (or family if one prefers a narrower subject class) to another identifiable family. Fossils (which you suggest) just seem be a less adequate form of such proof. And the target, when studying fossils, often seem to keep moving that confuses dating the items under observation as well as dating themā¦even human, where, for instance, we find Laetoli footprints press the time frame for fully developed humans back to 3.7 million years. Or whale evolution where there seems to be a continuum, but Rodhocetus must be removed now that we know Rodhocetus did not have a tail fluke or flippers. My point is that the target with fossils is a moving one and one trying to find his way can get very frustrated.
I observe all that because you mentioned āfossilsā as one source for showing what I have been asking for ā¦ a few sure fire examples of transition from one family to another; or I asked ākindā or āspeciesā. And I just asked if anyone knew of a āstasisā example of many living fossils that would demonstrate transition.
One reply to me pointed out that the very best evidence is in the genetics. Iāve been reading a lot there too in the past five years. What a maze. It is a maze and amazing. I mean, how complicated. Iāve studies lots of facets of ālawā and thought some of that was tricky; not like genetics. The old formulation of neo-darwinism that I was taught when I was 16 years old is now apparently dated and nearly trivial if not flat out wrong. It used to be; gene mutation plus natural selection plus time = evolution into new species.
But with the advent of the likes of James Shapiro and Denis Noble who are evolutionists but anti the neo-darwinism of the āselfish geneā mentality, I perceive a new wave is coming that will relegate the old mutation idea that essentially with natural selection gives us evolutionā¦a thing of the past.
The point is this; if the best evidence for Modern Synthesis is found in genetics then the new-darwinists have, along with their evidence (ERV, similarity between genes of human and chimp, intron-exon, etc)ā¦along with those examples of evidence for common decent there is a two edged sword that existsā¦namelyā¦ now, I mean in 2017, we see ānetworksā at work within the Genome, with a sophistication unimaginable 50 years ago. It is not just ātheā genetic code but multiple inter related codes and crisscrossing relationships and interactions; apparently thousands of those interactions working in tandem. Iām currently immersed in one of Shapiroās papers, a pdf available on line, āHow life changes itself; The Read-Write genomeā and the sophistication I saw in the cell when a young biology student and was so amazed with, pales in comparison to what we know today. The totality is breath taking; mind boggling.
Well said, but a minor correction here. The Laetoli footprints were likely made by Australopithecus afarensis. Even though bipedal with a human-like foot, they were far from fully developed humans. Fully developed humans, meaning H. sapiens physically indistinguishable from us, are usually called āAnatomically Modern Humans,ā but they do not show up until ~200,000 years ago. This can get a little confusing because many resources, like the Smithsonian National Museum of History website on human evolution, seem to call almost every hominid āearly humans,ā which is a slightly misleading bit of propaganda, if you ask me. (They didnāt!)
Agreed! Although there are explainable scientific observations at every step along the way, the sheer complexity behind it suggests (to me, at least) an explanation beyond those explainable scientific observations.
Iām going to have to respectfully disagree a bit here. What Shapiro and Noble propose is not a new paradigm, but more of a recognition (and not a unique one) that there is a lot more to evolution than DNA mutation and selection. The thought that you mentioned, āgene mutation plus natural selection plus time = evolutionā was an easy way for the general public to perceive evolution, but this has not been the working paradigm for quite some time.
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Iād go further and call it a mere rebranding.
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I have to confess that I was not particularly enthusiastic about opening up this thread. The title left me a little cold. But when I read the article you linked to, I was QUITE interested!!!
Hereās a summary from the article:
āAfter contact with the invasive species [from another island], the native [Florida] lizards began perching higher in trees, and, generation after generation, their feet evolved to become better at gripping the thinner, smoother branches found higher up.ā
āThe change occurred at an astonishing pace: Within a few months, native lizards had begun shifting to higher perches, and over the course of 15 years and 20 generations, their toe pads had become larger, with more sticky scales on their feet.ā
I found this fascinating! Why? Because this short article covers the two intersecting forces that we usually call āNatural Selectionā !
Here is the conclusion in a nutshell:
"Stuart also noted that the adults of both species are known to eat the hatchlings of the other species. āSo it may be that if youāre a hatchling, you need to move up into the trees quickly or youāll get eaten,ā said Stuart. āā¦ if you have bigger toe pads, youāll do that better than if you donāt.ā "
Apparently the invading species was better at eating hatchlings of the native species than vice versa (otherwise, we would have found a change in invading species) - - assuming of course, the invading species doesnāt already have optimum toe pads!
As the old joke goes, when a bear is charging you and your friend in the woods, you donāt have to outrun the bear ā¦ you just need to outrun your friend!
Any inadequately ātoe-paddedā lizard either perished by being the last ones to get away from the invading mauraders ā¦ or were the least able to prosper at the higher levels. The combined effect concentrated the ābigger toe padā alleles into a smaller population - - where the smaller populations become more responsive to pressures from natural selection!
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Thank you Jay. So called ādisplacementā is observable elsewhere (eg bird prints when they should not be)ā¦Wonder how many we never hear about. Some canāt be ignored, like Laetoli. Wonder if the imprint maker of Laetoli was an obligate bi-ped? A. Afarensis had curved fingers and could brachiate. Lucyās pelvis was apparently angled such that it could walk upright (assuming reassemble of the one hip was properly placed). Iāve tried to see other A. Afarensis fossils but canāt find the good sources that show more than skull and minimal partials such as Lucy. Also A. Afarensis was a knuckle walker; the wrists definitely had locking capability. I know that A. Afarensis was in same layer so it is natural to assume that the maker was A. Afarensis. However, the clarity of the print had arch evidencing the unique bone in the human foot that makes an arch like Laetoli possibleā¦ also at Laetoli, big toe in line and not flared out for holding limbs. Thatās why I ponder the obligate nature of the source of the print. That possibility leads to your point; āAnatomically Modern Humansāā¦but if it is then the āmodernā part would be the identical foot. However, we know human obligate walking is multi-functional. Heal to toe walkers (which is Laetoli) is not seen elsewhere among the apes. Not only must there be an arch, but also the hips must be correct and the spinal entrance into the skull must be centered to balance upright walk. Further, for obligate upright walking, the femur must be longer than the humerus or the gait will be unbalanced and the obligate would be forced to walk by awkward half steps. (Stride with the multiple creatures at Laetoli was perfect.) Also, the semi-circular canal would have to be adjusted for a āanatomically modern humanā to fit obligate biped walking. Overall, it is not merely walking, but running for distances is also a necessary ability if āanatomically modern humansā is achievable. Here is where I am going with thisā¦the Laetoli print is only part of the necessary picture to get what was necessary to be able to produce what we see. There is a lot going on with human walking so if A. Afarensis is the imprint maker then your assertion must carry lots of additional āmodernā features to accomplish the task. There are huge differences A. Afarensis but my little list only speaks to locomotion. And I didnāt complete that list. Just some highlights.
If you have any sources for showing full fossils of A. Afarensis, Iād love to see them to study. I just canāt find them. Any help you can give is appreciated.
Thank you CW.
Have you tried PubMed?
I havenāt paid that much attention to Shapiro, but my impression is that he goes further than that, arguing that organisms can direct mutations in beneficial ways that are contrary to standard evolutionary theory. If thatās true, than Iād say some of his ideas are not so much rebranding or a new wave as wrong.
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Thank you sf; Iāve used PubMed very often but not to find fossils.
Afarensis is not something that I have investigated very much. (@Jimpithecus may be able to help, if he has time.) A list of its major fossils is at this Australian National Museum website, but none of these look to be anywhere near complete. I think Lucy is still the best fossil example of the species. Your mention of running for distance reminded me of this article from Nature, Endurance running and the evolution of Homo.
I think this blog post about H. naledi from earlier this year will be of interest to you, simply because it points out the āmosaicā nature of human evolutionary change:
http://biologos.org/blogs/deborah-haarsma-the-presidents-notebook/why-a-new-discovery-about-homo-naledi-has-far-reaching-implications-for-human-evolution
As you noted, a lot of āmodernā features have to develop even to allow for a normal human gait. Interestingly, the development of bipedalism was also crucial to the development of speech. Without the L-shaped vocal tract made possible by walking upright, we could not speak. A whole bunch of things had to come together, including the increased brain size that began with H. habilis and then, more dramatically, with H. erectus.
I wouldnāt bet the house on that one. All of their ideas boil down to mutations as well and it eventually comes down to differences in semantics. They really donāt bring anything new to the table.
For example, Shapiro might call transposon mutagenesis ānatural genetic engineeringā. However, it is just random mutation. Always has been. When a new transposon insertion occurs it can produce a neutral, detrimental, or beneficial change, what we define as random mutations with respect to fitness. I have yet to see anyone in the āanti-Neo Darwin Evolutionā camp actually present something that goes against that very theory. What they so often do is argue against a strawman version of the theory.
The analogy that biologists and geneticists use is āa bowl of spaghettiā. They tug on one noodle to see how the others respond, and by doing this you can get a better picture of the whole. However, such reductionist methods can and do miss larger emergent properties that occur due to the complexity of the whole thing. Figuring out how gene networks work and express themselves is a pretty complicated field, and it makes the genetic evidence for common ancestry look simple by comparison.
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I believe you are referencing some bird tracks that were originally assigned a Late Triassic date. As it turns out, that was wrong. What the original authors did was use the relationship between several different geologic formations to get a date for those bird tracks. They didnāt actually date the sediments that the bird tracks were found in. When scientists dated the actual sediments they found the bird tracks were from the Eocene, the correct age for birds. You can read more here:
āBird-like tracks from northwest Argentina have been reported as being of Late Triassic age1. They were attributed to an unknown group of theropods showing some avian characters. However, we believe that these tracks are of Late Eocene age on the basis of a new weighted mean 206Pb/238U date (isotope dilutionāthermal ionization mass spectrometry method) on zircons from a tuff bed in the sedimentary succession containing the fossil tracks. In consequence, the mentioned tracks are assigned to birds and its occurrence matches the known fossil record of Aves.ā
http://www.nature.com/nature/journal/v495/n7441/full/nature11931.html
Thank you T_ aquaticus
Iāve been impressed with the book, āEvolution 2.0ā in its dismantling of mutation dogma. Perry Marshall is a computer systems/code expert.
Also
The sophistication ENCODE has given us to appreciate a bit what lies ahead. What amazing NEW features will be foundā¦ The genome is just one of the databasesā¦ Function in biological systems depends on properties of matter that are not specified by genes. (Denis Noble)
For instanceā¦I distinguish these two mechanisms: random mutation and intron splicing. Intron splicing is one of the major distinctions between the neo-Darwinian mechanism and the Third Wayā¦ Intron splicing, with other non-mutation mechanisms is what I think of as one of the replacement modalities for the limited positive function of random mutation. Splicing introns try to delete out deleterious mutation or kill the whole section, replacing with a duplicate if possible. Overall, mutation will destroy; so alleles with increased frequency, if un-spliced out, will destroy, not build. Intron splicing has logic built in by even utilizing alternative code sections to accomplish the desired function. As I see it with my admittedly limited ability and knowledge, random mutation is useful in giving us variation within a species; size of dog, color of hair, color of eyes etc. But there is an end to mutation positives (microevolution).
Ten or fifteen years from now, there may not be a new name for Neo-Darwinism , but the theory will have expanded to say something like; Assorted processes 1,2,3,4,5,6,7,8,9, 10ā¦ plus random mutation at times PLUS natural selection PLUS time = MacroEvolution.
Remember only ten years agoā¦even five years agoā¦ a whole set of biologists were still calling most of the non-coding sections of DNSā¦Junk. Change is coming.
The limitations on mutation and the inter-relatedness between biological systems and how mutation is ānoiseā that ādestroysā is discussed in.the book āEvolution 2.0,ā
And they still are. IMO, easily 70% of the human genome is junk, or more accurately, itās accumulated parasitic mobile DNA.
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Since youāre aware of the ENCODE project, you may have heard different figures about how much of the human genome is āfunctionalā. You may also be aware that āfunctionalā can be interpreted in a lot of different ways. Just because a segment of DNA may be transcribed (this counted as functional in the ENCODE project) does not require that the RNA product actually serve a role in the cell - there is a lot of transcriptional ānoiseā.
Stephen is more of an expert than I, but 70% seems like a reasonable, and possibly even conservative, estimate.
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Iād concur about the ājunkā percentage. Most solid estimates put it even higher. Iād recommend Larry Moranās Sandwalk blog for a read. The link points to articles related to junk DNA.
A number of prominent articles on ENCODE really whiffed on what āfunctionalityā meant in the context of the actual results. Consequently, this has given rise to a false meme in the popular press (and even some science commentary), that hasnāt shown signs of fading yet.
From the Judge Starling (aka Dan Graur) blog here:
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Not to sound too dogmatic, but it hasnāt even come close to being dismantled. Humans are different from other species due to the DNA differences between our genomes. This is true of all species.[quote=āsenatorthomas, post:75, topic:36182ā]
The sophistication ENCODE has given us to appreciate a bit what lies ahead. What amazing NEW features will be foundā¦ The genome is just one of the databasesā¦ Function in biological systems depends on properties of matter that are not specified by genes. (Denis Noble)
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What ENCODE found was widespread spurious transcription. In other words, they found junk RNA. ENCODE has since walked back a lot of their findings, saying that about 10% of the human genome has selectable function. Before, they were defining function by the mere presence of an RNA transcript which made no sense. Junk DNA will be transcribed at low levels, so finding an RNA molecule that matches up to a DNA sequence does not automatically indicate function.[quote=āsenatorthomas, post:75, topic:36182ā]
For instanceā¦I distinguish these two mechanisms: random mutation and intron splicing. Intron splicing is one of the major distinctions between the neo-Darwinian mechanism and the Third Wayā¦ Intron splicing, with other non-mutation mechanisms is what I think of as one of the replacement modalities for the limited positive function of random mutation.
[/quote]
Like junk DNA, there is also junk splicing. Most of the evidence I have seen points to the majority of alternate intron splicing as just being mistakes made by the cellular machinery. Also, the rate at which different splice variants appear is determined by sequence with different sequences leading to different intron usage. The function of those new RNAs is also still determined by sequence. This is all still well within the standard theory.[quote=āsenatorthomas, post:75, topic:36182ā]
As I see it with my admittedly limited ability and knowledge, random mutation is useful in giving us variation within a species; size of dog, color of hair, color of eyes etc. But there is an end to mutation positives (microevolution).
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There is no end to beneficial mutations, at least not that life has found. The physical differences between species is due to sequence differences, and those beneficial differences are also due to sequence differences.[quote=āsenatorthomas, post:75, topic:36182ā]
Overall, mutation will destroy;
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Overall, the majority of mutations are neutral since they occur in the 80-90% of the genome that has no selectable function. The mutations that are deleterious are selected against, so they are removed from the population. Beneficial mutations are the ones that are kept due to selection.[quote=āsenatorthomas, post:75, topic:36182ā]
Ten or fifteen years from now, there may not be a new name for Neo-Darwinism , but the theory will have expanded to say something like; Assorted processes 1,2,3,4,5,6,7,8,9, 10ā¦ plus random mutation at times PLUS natural selection PLUS time = MacroEvolution.
[/quote]
Every theory is added to over time, but the raw material for long term evolution continues to be random mutations.
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The way I usually explain it is if we use ENCODEās definition of functional, then the trash in your kitchen trash can is also functional. That trash releases odor molecules into the air, which means it is doing something. That meets ENCODEās definition of function, because it merely does something instead of being entirely inert.
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