A Magnolia experiment
3 hours ago in The Phytophactor
In BriefTattersall argues that human evolution has been unusually rapid in the last 7 million years, with many new hominin groups arising (and going extinct) and our lineage undergoing a lot of adaptive changes (tool use, brain size, anatomical modifications). Sharing cultural know-how is thought to have been under selection, steadily giving rise to humans. He then says this:
A new theory credits a combination of cultural advances and unpredictable climate change for the exceptionally fast rate of evolution in early humans.
Climate change repeatedly led to fragmentation of hominin populations, creating small groups in which genetic and cultural novelties were rapidly cemented, accelerating speciation.
Our own species, the anatomically distinctive Homo sapiens, was born out of such an event in Africa around 200,000 years ago.
About 100,000 years later an African isolate of our species acquired the ability to use symbols. It was almost certainly this unique symbolic cognition that made it possible to eliminate all hominin competition in little time.
But this sort of refinement, one generation at a time, would not have been fast enough to radically reshape the human line in seven million years.Why not? This is an assertion that Tattersall makes without any given justification. It may be so, but I don't think anyone can know this. 7 million years is maybe about 350,000 generations. That's an awful lot. If you start out with a brain that weighs just 40 grams and increase its size by one thousandth of a percent per generation for 350,000 generations, you would end up with a brain the size of humans (1,324 grams). I am not saying this is how it happened, as the fossil data suggest a doubling in between 1 million years ago and 200,000 years ago, for example. Just saying that small modifications can lead to big changes on long time-scales.
A little thought, however, suggests that there must have been more to it than that. One problem with this scenario is that it assumes that the pressures of natural selection—stresses to which the species were adapting—remained consistent over long periods. But in fact, Homo evolved during a period of Ice Ages, when the ice caps periodically advanced to what is now New York City and northern England in the Northern Hemisphere, and the tropical zone experienced periods of extreme aridity. Amid such environmental instabilities, no consistent directional selection pressures could have existed. [Emphasis added]Really? So because there are periodic fluctuations in climate there can't be a consistent directional selection pressure on brain size? That makes it sound like a colder climate pushes the size in one direction, a warmer climate pushes brain size in the opposite direction. That makes no sense to me. Rather, the environmental instabilities could all select for human ingenuity and intelligence no matter what direction the environmental changes were in. If his choice of words had not made him sound so dead-certain, and instead have made this new view more suggestive than so assured, I would not really have objected. I also don't know what actually happened, but asserting that "no consistent directional selection pressures could have existed" seems like overreaching. Tattersall continues with what I think is not an argument against directional selection at all:
The more we learn about these climatic oscillations, the more we realize just how unstable the ancient environments of our ancestors must have been. Cores drilled in the ice caps and in seafloor muds reveal that the swings between warmer and dramatically colder conditions became increasingly pronounced after about 1.4 million years ago. The result was that in any one location, resident hominin populations would have needed to react frequently to abruptly changing conditions.
Most notably, evidence of distinctively modern symbolic cognition emerged rather suddenly and only very late indeed. The earliest overtly symbolic objects—two smoothed ocher plaques with geometric engraving—show up at Blombos Cave in South Africa about 77,000 years ago, significantly after anatomically recognizable H. sapiens had entered the scene (some 200,000 years ago) [see box above]. Because the patterns involved are highly regular, researchers feel confident that they are not random but encode information. Such sudden breakthroughs are not the mark of steady intellectual advancement, generation by generation. [Emphasis added]What kind of encoding are we talking about? In kindergarten I doodled something much akin to this - regular parallel and crossing lines. I wasn't conveying any information. And yet this symbolic encoding is exactly what Tattersall proposes is the one thing that gave our lineage an edge over other hominins.
When the dust settled, we stood alone, the serendipitous beneficiaries of cognitive advances, cultural innovation and climate changes that allowed us to eliminate or outlast all hominin competition throughout the Old World in an astonishingly short time. Our competitive edge was almost certainly conferred by our acquisition of our unique mode of symbolic thought, which allows us to scheme and plan in unprecedented ways. Interestingly, this development seems to have occurred within the tenure of our species H. sapiens, evidently spurred by a cultural stimulus, quite plausibly the invention of language, which is the ultimate symbolic activity.It's not that I don't believe symbolic thought played a role. It's that I don't believe there is enough evidence that this is the case. Almost certainly this is pure speculation, and we cannot be even close to certain that what eliminated all hominin competition was ability to scheme and plan. Another hypothesis is that they were unable to cope with climate change.
Evidently, then, we have to look away from processes occurring within individual lineages to explain the rapid change among Ice Age hominins. Yet the same elements implicated in the gene-culture coevolution story—environmental pressures and material culture—may still have been in play. They simply operated rather differently from how the traditional portrayal suggests. To understand how these factors may have interacted to trigger evolutionary change, we must first recognize that a population needs to be small if it is to incorporate any substantial innovation, genetic or cultural. Large, dense populations simply have too much genetic inertia to be nudged consistently in any direction. Small, isolated populations, on the other hand, routinely differentiate.No. Just no. Populations do not need to be small to incorporate new genetic or cultural changes. Genetic inertia (= genetic homeostasis) is the maintenance of genetic variability within a population. But we know that even though random changes have a small effect on large populations, smaller changes in fitness can be discerned by the selective agents (the environmental causes of selection) in large populations. Genetic drift can indeed nudge a small population in one direction or other, but that direction is then random with respect to what is adaptive. Rather, in large populations trait changes that are adaptive (conferring a benefit in terms of survival and reproductive success) can actually become established in a large population. For example, the current human population is very large, and there is no problem sharing and establishing drastic cultural changes.
Seeing our amazing species as an evolutionary accident, though, contains a profound lesson. For if we were not shaped by evolution to be something specific—fitted to our environment and tailored to a purpose—then we have free will in a way that other species do not. We can indeed make choices about the ways in which we behave. And this means, of course, that we must accept responsibility for those choices.Free will, all of a sudden?! Then if we were shaped by evolution to be something specific, then we would not have free will, like other species? All other species do not have free will because they were shaped by evolution to be something specific? And because we are able to make choices, then we must take responsibility for them? How does that follow?
What Led to This Change?I guess that it favors his rhetoric to phrase these different world views as being religions (Ham will say 'atheism' here, but he should say humanism -which is not a religion as much as a word view). Devious, though, how he basically dismisses all other religions by this false dichotomy.
In essence this change reflects a shift between the world’s two opposing religions. Ultimately there are only two religions—one starts with God’s Word and the other starts with man’s word. America—and the whole Western world—once built its worldview predominantly on the Bible. Now a shift has occurred, as the West’s worldview is being built on man’s word. This change is reflected in a shift from Christianity’s absolutes to the relative morality of human opinions.
Whatever we once were we are no longer! These words really mean that America as a nation no longer builds its thinking on God’s Word, but man can determine truth for himself. America has changed religion—from Christianity to a man-centered religion. This spiritual disaster is now reflected in this nation’s economic and moral disaster.Of course, man has long been able to determine "truth" (i.e., moral values, in this case) by selecting reading the Bible, as Ham does himself. Does he call for God to smite the shellfish eaters, per chance? It really seems much more easy to explain the various Biblical laws as arbitrary human inventions (e.g., forbidden to eat leavened bread during the Feast of Unleavened Bread, Exodus 12:15 - what is the point?).
So What is the Solution?Really?! Whatever we once were? You mean, like slave-owning racists? Gullible peons? Disease-ridden and ignorant of the world? Perhaps that is what he means, as long as the word of God is taken literally. Sounds like Hell-on-Earth to me, ironically.
Whatever we once were we need to return to. The only solution for this nation (and every other nation) is to return to the authority of God’s Word as the foundation for our individual and cultural worldviews.
As Psalm 11:3 states, “If the foundations are destroyed, what can the righteous do?”
Results: We found that the degree of religiosity mattered significantly more than education when predicting students’ understanding of evolution. When we focused on acceptance of evolution only, students taught evolution or neither evolution nor creationism in high school had significantly higher acceptance than those taught both evolution and creationism or just creationism. Science majors always outscored non-science majors, and not religious students significantly outperformed religious students. Highly religious students were more likely to reject evolution even though they understood that the scientific community accepted the theory of evolution. Overall, students in two of three biology classes increased their acceptance of evolution, but only those students that seldom/never attended religious services improved. K-12 state science standard grades were significantly and negatively correlated with measures of state religiosity and significantly and positively correlated with measures of state educational attainment. [Emphasis added]So, I submit that the problem is not that we don't know what to do about the problem of creationism in America, but it is that no one wants to touch it with a ten-foot pole.
|Dr. Gerald Bergman
Northwest State Community College
|Dr. Donald DeYoung
Grace College and Theological Seminary
|Dr. Charles Jackson
Points of Origin Ministries
|Dr. John Sanford
|Mein Kampf||- -||archive.org/stream/meinkampf035176mbp/meinkampf...|
(particularly page 84 and 392)
|Giant impact hypothesis||wikipedia.org/wiki/Giant_impact_hypothesis|
|The Big Bang||wikipedia.org/wiki/Big_Bang|
Papers listed as “Contributed” by NAS members (at least one of the authors is an NAS member) account for only 5% of submissions and less than a quarter of published papers. NAS members are only allowed up to four Contributed papers per year. Member-contributed papers must have at least two independent reviews and are evaluated by the Editorial Board.So only two reviewers chosen by one of the authors, and the editor/author makes the final decision anyway. Hmm. Just saying*...
Papadimitriou: I will pray for answers, but please give me your questions.I did not stick around to talk with him afterwards. I had other obligations, plus I had basically gotten the answers that I was looking for. My conclusion is, based on this presentation and on reading the papers, that the three components at play in mixability
Me: So, you said you met Adi Livnat in 2006...
Me: In 2005 there's a paper also in PNAS by Guy Sella and Aaron Hirsch . Are you familiar with this paper?
Papadimitriou: Yes, I am familiar.
Me: They introduced the concept of free fitness analogous to the free energy.
Me: And that seems to me to be curiously identical to mixability.
Papadimitriou: Not really, no. I mean...
Me: The point is that they update both fitness and entropy at the same time, yes?
Papadimitriou: We have two conclusions that seem to... First of all they came up with [?], supposedly do that. We came to this conclusion 1) through simulations. So, we came up with the concept of mixability, in other words that the alleles that are favored are not the ones that have the best combinations, but the ones that have the best average performance. By analyzing fitness landscapes. Please, when we published our paper we got six reviews. Two of them, they could have been from that group [i.e., Sella and Hirsch]. One of them said that this is well known, and the other one said it is wrong. The point is that once you have to articulate the theory. Let's take Kimura's neutral theory. Of course you'll find hunters in the literature. The point is that theories are cheap. Coming up with a model that says "well we know physics, so let's apply the free energy principle to evolution". The point is that it's the force of argument informed by the theory that eventually becomes the cradle of science.
Me: But you don't even cite them, which is...
Papadimitriou: Yeah, we didn't know at the time. So the second part is where we explicitly say it's a derivation. It's a derivation from the equations of Fisher and Wright. In other words, its a proof. Not a postulation. You understand what I say?
Me: I Understand what you're saying, but it also rests on the fact that - something that biologists all agree on, which is that variation in a population is a good thing. And it's important for evolution. Without it evolution basically does not work, and you're saying that you are getting that through sex, but you're also ignoring mutations, which you said in the beginning as well. Everybody knows that this is something that happens as well, and especially in the bacterial populations that you were talking about where you said in the beginning that they are all sexual with conjugation and so on. But largely they are not. They are getting a lot of their variation from mutations, and this is known from experimental evolution as well.
[Here the moderator asked us to take it offline.]
Papadimitriou: So, mutations are paramount. Mutations in eukaryotes are also... relevant mutations are relevant. It's like meteorites: its important to understand what happens in everyday evolution, which means the evolution in populations. I'd be delighted to chat with you after the question session.
There had been no satisfactory explanation of the advantages of sex in evolution, and yet sex is almost ubiquitous among species despite its huge costs. Here we propose a novel explanation: Using standard models, we establish that, rather astonishingly, evolution of sexual species does not result in maximization of fitness, but in improvement of another important measure which we call mixability: The ability of a genetic variant to function adequately in the presence of a wide variety of genetic partners.So the claim to novelty remains, and that seemingly includes a rediscovery of epistasis (the genetic interaction between genes)!
If sex is tied to the nature of genes, then one may reconsider the question of the origin of sex. Although it is common to imagine evolution as an originally asexual process that became sexual at some point, it is possible that sex had existed in a primitive sense of mixing before the emergence of genes as we know them, and that the interaction of sex and natural selection played a role in the shaping of the genetic architecture .In other words - and I also have this from him verbally at the 2014 Evolution conference - Livnat thinks that sexual reproduction came first, followed by asexual reproduction later in the history of life. Papadimitriou mentioned this in his talk as well, saying that there are basically next to no species that are asexual - even bacteria have sex - and those that lost the ability to have sex are evolutionary dead ends. If you think evolution without sex is impossible, I dare you to explain why Lenski's E. coli populations - which do not exchange genetic material laterally (i.e., between individual cells) - have been successfully evolving and adapting since 1988 [source].
Speciation generally involves a three-step process—range expansion, range fragmentation and the development of reproductive isolation between spatially separated populations1, 2. Speciation relies on cycling through these three steps and each may limit the rate at which new species form1, 3. We estimate phylogenetic relationships among all Himalayan songbirds to ask whether the development of reproductive isolation and ecological competition, both factors that limit range expansions4, set an ultimate limit on speciation.Grrlscientist has a nice write-up about it in The Guardian. However, I have to mention that I am taken aback by three things in the above quote from the first lines of the abstract:
Speciation in sexually reproducing organisms generally involves a three-step process—range expansion, range fragmentation and the evolution of reproductive isolation between spatially separated populations1, 2. Allopatric speciation relies on cycling through these three steps and each may limit the rate at which new species form1, 3. We estimate phylogenetic relationships among all Himalayan songbirds to ask whether the evolution of reproductive isolation and ecological competition, both factors that limit range expansions4, set an ultimate limit on speciation.That'll be $20.