Thursday, July 28, 2011

Models of Embryological Development

A post by 'Evolution News and Views' - a site discussing intelligent design and evolution - which deals with a classic 'proof' of evolution: embryogenesis. Good summary of the issues, discussion might be needed to flesh out the details if anyone is interested. It is part of a series, if you're interested in reading the whole lot.

I personally left this article with a bad taste in my mouth - despite agreeing completely with all the points they made - because of some slight arrogant undertones I thought I detected. Shouldn't complain though, I often feel the same after hearing/reading myself ;) Lord help us to present the truth in love and humility, boasting only in the cross of Christ and not our own 'rightness'!

Three Flawed Evolutionary Models of Embryological Development and One Correct One

Throughout this series on PZ Myers, evolution, and embryology, we have discussed four models of vertebrate embryo development. To help further simplify this debate, these four models are illustrated below and described. Please note that the first three models are flawed in varying degrees, and that some of the descriptions adapt language from the arguments of PZ Myers and various scientific papers.

Model 1 -- Haeckelian Recapitulation: Totally Flawed

Pasted Graphic.tiff

Discussion: According to this model of embryogenesis, evolution predicts that development will conserve the evolutionary history of an organism, which is replayed as an organism develops. As Haeckel's famous dictum said, ontogeny (development) recapitulates (replays) phylogeny (evolutionary history). This model is now essentially universally discarded by evolutionary biologists. Although Haeckelian recapitulation was abandoned long ago, many people have been taught it was true over the years. ID proponents recognize this fact, which is why we point out its falsity. However, we have a lot more to say than merely critiquing Model 1.

Unfortunately, PZ Myers typically misrepresents our arguments as if we're only and always attacking Model 1, when in fact we're usually attacking Models 2 and/or 3. Our main gripe with the usage of Haeckel's ideas in the modern era is not that they are used to bolster Model 1 (after all, Model 1 is rarely promoted these days), but rather that Haeckel's inaccurate drawings, which overstate the similarities between embryos, are still used to bolster Models 2 and/or 3. In any case, Model 1 is simply wrong because vertebrate embryos do not replay their supposed evolutionary history during development. The notion that 'ontogeny recapitulates phylogeny' is wrong.

Model 2 -- Funnel-Like Model: Highly Flawed

Pasted Graphic 1.tiff

(From Naoki Irie & Shigeru Kuratani, "Comparative transcriptome analysis reveals vertebrate phylotypic period during organogenesis," Nature Communications, Vol. 2:248 (2011).)

Discussion: According to this model, embryos start off developing similarly but become progressively different as time goes on. The evolutionary justification often given for this model is that precise developmental processes of the earliest stages of development are critical for later stages, and thus resistant to modification by mutation and selection. Evolution thus proceeds by modifying later stages of development since earlier stages which are more resistant to change. Under this model, evolution predicts that early development will be conserved (i.e. similar), and embryos will progressively diverge from one-another as development proceeds. This model is not supported by the data since early stages of vertebrate embryo development can vary widely.

Ideas inherent in this model are still found in many textbooks, which cite early similarities among vertebrate embryos as evidence of conserved stages of development which purportedly reflect their common ancestry. This model is inaccurate because early stages of development can vary greatly and show wide variation. PZ Myers also recognizes this fact. This means that he tacitly admits that a lot of textbooks are wrong.

Model 3 -- Hourglass Model: Flawed

Pasted Graphic 2.tiff

(From Michael K. Richardson et al., "There is no highly conserved embryonic stage in the vertebrates: implications for current theories of evolution and development," Anatomy and Embryology, Vol. 196:91-106 (1997).)

Discussion: Under this model, vertebrate embryos start off developing differently, but then converge at the phylotypic or pharyngular stage, showing substantial conserved similarities to one another that are said to provide evidence of common descent. According to this model, the specific morphology of the phylotype represents a literal foundation upon which the rest of development proceeds, and is resistant to evolutionary change, because there are too many later events that are dependent on it.

This is the model preferred by PZ Myers and many other leading evolutionary biologists, and it is also commonly promoted in textbooks. This model recognizes that early and late stages--and to a significant extent middle stages--of development can vary greatly and show wide variation. However, it claims that vertebrates go through a highly similar stage - the pharyngular, phylotypic, or tailbud stage - midway through development. This pharyngular stage is said to reflect important developmental patterns which have been resistant to evolutionary change ("conserved"), and thus the pharyngular stage is said to reflect their common evolutionary heritage.

But in the past 15 years or so, a number of leading evolutionary biologists have recognized that the phylotypic stage is simply "assumed to be particularly resistant to the action of natural selection" and "often discussed in terms that emphasise conserved features, and ignore variable features." When biologists carefully compare embryological data, they find that there is considerable variability at the purported phylotypic stage, leading increasing numbers of biologists to question whether this pharyngular stage exists. As a paper in Nature said last year: "both the model and the concept of the phylotypic period remain controversial subjects in the literature." PZ generally refuses to address this literature, but it nonetheless calls into question the very concept that defines this model and gives PZ's Pharyngula blog its name.

Model 4 -- Reality: Correct

Pasted Graphic 3.tiff

(From Jonathan Wells, Icons of Evolution (Regnery, 2000), Image Copyright Jody F. Sjogren 2000.)

Discussion This model simply lets the data speak for itself and does not try to force-fit some evolutionary interpretation to the data. This model acknowledges that there is wide variation in embryos at fertilization. Variation can and does occur between vertebrate embryos at every stage of development, and early and late stages -- and to a significant extent middle stages -- can and do vary greatly. Vertebrate embryos show some similarities -- but also many significant differences -- during the purported phylotypic stage. However, differences in body size, body plan, growth patterns, and growth timing show wide variation in morphology among vertebrate embryos which is difficult to reconcile with the idea of a phylogenetically-conserved stage. At best, there is a period of development where some general similarities emerge, but this looks very different than what is taught in most textbooks. These differences lead top embryologists to argue against the existence of a phylotypic stage in vertebrates. There is not a consistent pattern that is amenable to an easy evolutionary interpretation.

While there are some general hourglass-like patterns in vertebrate development, the pharyngular stage is called into question. Moreover, evolutionary biologists have struggled to explain how Darwinian processes could lead to hourglass-type patterns of development in the first place. As a 2011 paper in Nature Communications states:

One unanswered question in this field is how pharyngular stages became conserved. ... [H]ow did vertebrate embryos allow the early developmental stages to diverge while keeping the following stage essentially unchanged? For example, in spite of considerable phylogenetic divergence in the mechanisms of vertebrate germ layer formation and gastrulation among the four species we analysed, all these embryos pass through the conserved pharyngula stage.


As noted previously, from an evolutionary vantage, the evolution of vertebrate development almost appears goal-directed, where embryos if many taxa start off developing very differently but then converge on a somewhat similar stage midway. So how could Darwinian evolution preserve a midpoint of development as similar, when embryos start development so differently? The authors of this 2011 paper aren't sure, and their article grasps for an evolutionary explanation that almost hints at a goal-directed evolutionary process:

For example, in spite of considerable phylogenetic divergence in the mechanisms of vertebrate germ layer formation and gastrulation among the four species we analysed, all these embryos pass through the conserved pharyngula stage. How did vertebrates establish divergence of early embryogenesis while keeping pharyngular stages conserved? One reasonable deduction from this observation is that early vertebrate embryogenesis reduces the developmental fluctuations, which tend to occur around these stages, much like earthquake-resistant buildings that are built with the 'flexible structure'.


So early stages of development are "built" to divergently evolve in a way that reduces changes to later stages of development? And we find this same pattern of development repeated throughout many different species of vertebrates? This almost sounds like a goal-directed and non-Darwinian form of evolution, which is precisely why early differences between vertebrate embryos were not predicted or anticipated by many evolutionary biologists.

Again, the Reality Model simply lets the data speak for itself and doesn't try to force-fit some evolutionary pattern on to the data. While vertebrate embryos do show some similarities during the purported phylotypic stage, this model also reveals remarkable and significant differences at that supposed "stage." This model thus recognizes that there is wide variability and remarkable divergence at all stages of development.

Whether an evolutionary pattern can be fit to the actual data remains to be seen. But when PZ Myers is forced to say: "I wish I could get that one thought into these guys heads: evolutionary theory predicts differences as well as similarities," it seems clear that evolutionary biology is not predicting any model very well. If we just take the data at face value, the Reality Model is the most accurate model of vertebrate development.

Monday, July 25, 2011

Resolving Faint Sun Paradoxes

Hi guys,

This is an article from Hugh Ross at Reasons to Believe. Like many of their articles, it demonstrates two key things:

  1. The fallibility of our human interpretation of God's work, including creation.
  2. The incredible design inherent in the universe - enhanced (rather than diminished) by a thorough understanding of the creation events

Reasons to Believe is an evangelical Christian apologetics organization. They hold to a progressive creationist perspective of the Genesis account of creation (check out their website for details). Many of you will completely disagree with their perspective! I encourage you to ensure you fully understand it before criticizing it. But in any case, see the good in their arguments against pure naturalism.

Here's the text. Let me know your thoughts! I'll include a description of 'progressive creationism' in the comments.

P.S. If you get bored, just read the first two and the last few paragraphs ;)



by Dr. Hugh Ross

In part 1 of this series, I defined the faint young Sun paradox and described how, in the 1970s and 1980s, astronomers and physicists concluded that volcanic gas emissions pumped enough extra carbon dioxide into the early Earth’s atmosphere to sufficiently enhance the atmosphere’s greenhouse effect so as to compensate for the lower solar luminosity. In part 2, I explained how research teams discovered complications that made the faint Sun paradox seem unresolvable.

Here, in part 3, I will describe how recent observations of young solar analog stars enabled astronomers to pull together everything they know about the history of the Sun, Earth, Moon, and terrestrial life to provide a real, comprehensive resolution to the paradox. This research has also yielded some of the most spectacular evidences for the supernatural, super-intelligent design of the solar system.

Not So Dim After All

Throughout the 1990s and early part of the twenty-first century, it became increasingly evident to scientists there was no way to adjust physical and chemical conditions on early Earth to compensate fully for a Sun 25–30 percent less luminous at the time of life’s origin 3.8 billion years ago. Moreover, planetary scientists were experiencing the same frustrations in their attempts to explain growing evidence that the Martian surface was, for a brief time, warm enough to permit the existence of liquid water.1

These frustrations led certain teams of astronomers to question the Sagan-Mullen model for the history of the Sun (see part 1). In 2003, Caltech astronomers Juliana Sackmann and Arnold Boothroyd pointed out that helioseismology measurements establish that, during its youth, the Sun must have lost at least 4–7 percent of its mass.2 Since the luminosity of a star rises with the fourth power of its mass, Sackmann and Boothroyd determined that the Sun’s brightness 3.8 billion years ago was 15 percent, not 30 percent, dimmer than it is today (see figure 1).

Including early mass loss in the Sun’s history goes a long way toward resolving the faint Sun paradox. With the Sun no more than 15 percent dimmer, Earth would not require nearly so great a quantity of greenhouse gases to keep the planet surface warm enough to sustain life, Thus, as Sackmann and Boothroyd note, the quantities of greenhouse gases needed are within reasonable possibility.

In support of their not-so-faint Sun model, Sackmann and Boothroyd made reference to several observational studies establishing that very young stars equivalent to the Sun’s mass are indeed losing mass at rates consistent with their model. They called for more extensive and definitive observational programs to determine the mass loss history of solar-type stars.

In the April 20, 2011 edition of Astrophysical Journal Letters three astronomers reported on the latest observations of young solar analogs.3 These stars consistently exhibit strong activity phenomena. These phenomena produce a huge variability in X-ray and ultraviolet emission, accompanied by inevitable mass loss. The three astronomers estimated that the loss of mass in the young solar analogs reaches up to 30 percent. Thus, they conclude that the Sun during its youth lost at least 20 percent of its mass. This much mass loss implies that, shortly after it formed fully, the Sun was about 85 percent brighter than it is today (see figure 2).

The research team then took note of the few remaining discrepancies between the standard solar model (SSM) and their observations. Specifically, sound speed determinations from helioseismology do not agree with predictions from the SSM. Likewise, there is disagreement between the observed and the predicted lithium abundance of the Sun. The three astronomers, along with other research teams,4demonstrated that pushing the mass loss of the early Sun up from 4–7 percent to about 20 percent does much to eliminate not only these two discrepancies but a few more minor ones as well.

A Sun that loses 20–25 percent of its mass during its youth seems to solve all the outstanding issues concerning the faint Sun paradox. Evidently, the faint young Sun label needs to be replaced with a more accurate term like the “dimming young Sun.” This new model has another advantage. It explains why Mars would have been warm enough to experience a brief wet episode at some point during its first few hundred million years.5

To be clear, I am not saying the new model by itself solves all the faint Sun paradox problems. Rather, each suggested solution proposed over the past 40 years probably plays a contributing role. That is, it takes a combination of the Sun losing at least 20 percent of its mass during its first billion years, extra greenhouse gases in the atmosphere, an altered albedo for Earth, a carefully controlled and timed introduction of specific life-forms, and perhaps extra atmospheric nitrogen to explain why life could be sustained so ubiquitously and so diversely throughout the past 3.8 billion years.

The next step in building a better dimming young Sun model is to make measurements on a much larger sample of young solar analog stars. Astronomers need to make these measurements all across the electromagnetic spectrum, from gamma-ray wavelengths to long radio wavelengths. Furthermore, they need to make measurements over a few years so as to determine the short-term variability of these stars. Such observations will enable astronomers to determine precisely how much the Sun actually dimmed during its youth, over what time scale it dimmed, and whether or not the degree of dimming varies over the wavelength of solar emission.

One such observational program is already underway. A team of radio astronomers is using the Expanded Very Large Array, or EVLA, (see figure 3) to measure the interaction of stellar winds emanating from young, nearby solar analogs with the interstellar medium. With such measurements, astronomers will be able to calculate the rates of mass loss from these stars.6

The new model does place a new constraint on origin-of-life models. A much-brighter young Sun is a Sun with more dramatic flaring activity, greater variability, and greater X-ray and ultraviolet radiation emission. These features, combined with a rapidly falling solar luminosity, effectively rule out any possibility for life existing on Earth previous to the late heavy bombardment (see here and here). The date for the late heavy bombardment’s end, 3.8 billion years ago, is the same for the first evidence of Earth life; that means the origin of life took place within a geological instant of time. No time for life’s origin implies there’s no possibility for a naturalistic explanation.

As King David declared 3,000 years ago, “The earth is the Lord’s, and everything in it.”7 The new dimming young Sun model proves David’s declaration in a broader context. Sustaining abundant, diverse life throughout the past 3.8 billion years requires multifaceted fine-tuning. As the Sun’s luminosity dims or brightens, certain features on Earth must be fine-tuned correspondingly.

  1. The amount of carbon dioxide in Earth’s atmosphere
  2. The amount of methane in Earth’s atmosphere
  3. The amount of nitrogen in Earth’s atmosphere
  4. Earth’s albedo
  5. The quantity and diversity of Earth’s life to contribute or remove just-right amounts of greenhouse gases, erosion, and albedo

No set of natural processes can possibly keep all these factors perfectly and continuously balanced for billions of years. It takes a Mind of great intellect and knowledge who knows the solar system’s present and future conditions and who has the power and the love to provide Earth’s life with everything it needs to thrive.

Tuesday, July 19, 2011

Faith and Reason

Here's another blog post which is quite insightful, by Kenneth Richard Samples from Reasons to Believe.

A few of my thoughts upon reading this:

1) Christian faith is NOT the same as Christian belief. Belief is inherent in all worldviews - including materialistic and 'scientific' ones. Faith, in Christianity, is a personal and emotional response to holding a particular worldview. Having Christian knowledge and belief does not equal 'faith'. Likewise, having a particular personal or emotional response to a worldview - without actually holding it - does not equal 'faith'.

2) Reason is complementary, not antagonistic, to belief. In fact they are intimately related, and thus faith is also intimately related to reason.

3) There are many aspects to our 'humanity' (including reason), which impact on which worldview we hold and how we emotionally respond to various worldviews and beliefs.'Reason' is the only method which can be involved in the pure pursuit of 'true knowledge'. HOWEVER, real faith (including reason) is good - regardless of what 'unreasonable' factors may have been implemented along the path leading to it. 'Un-reasonable' factors may precede 'reason' in many steps, but reason eventually catches up (or faith can never actually develop). Even from a purely 'knowledge-pursuit' perspective, ALL of these 'un-reasonable' factors can lead to the construction and improvement of competing worldviews. This is good (not necessarily for the person implementing these factors, but certainly for those who need competing worldviews for reason to act upon, in the pursuit of knowledge).

4) Thus none of the 'un-reasonable' aspects of our cognitive/emotional processes should be intrinsically despised. But they all need to be recognised for what they are, and brought into loving, Holy-Spirit empowered submission to our Lord Jesus Christ - just like everything else!

I hope to flesh these topics out in future philosophical posts :)

Here's the text, please let me know what you think about these issues!

HomeBlogsReflections Blog › Faith, Reason, and Personal Persuasion


Reflections - Tuesday, July 19th, 2011

Recently a newspaper reporter asked me to respond to two provocative questions: (1) “Is it necessary to leave reason and move to faith in order to embrace Christianity?” and (2) “If there are strong arguments in support of Christianity’s actually being true, then why aren’t more people, particularly intelligent, well-educated people, persuaded as to its truth?”

As to the first question, historic Christianity doesn’t require believers or nonbelievers to choose between faith and reason, as though the two are unalterably separate spheres. Rather, Christianity is uniquely a reasonable faith (a trustworthy and reasonable belief system). The events that form the core of Christian belief—the life, death, and resurrection of Jesus of Nazareth—are rooted in history. For 2,000 years Christian apologists have presented diverse evidences and arguments for embracing Christian truth-claims.

While specific doctrines such as God’s triune nature and the union of Christ’s two natures certainly transcend human comprehension, Christian belief never violates reason itself. In fact, Christian philosophers have argued that the God of the Bible uniquely provides the metaphysical foundation for logic and rationality.1 The consensus throughout church history is that faith and reason are compatible and complementary.

The New Testament word for “faith” or “belief” (Greek: pisteuo, the verb; pistis, the noun) is rich in meaning. To have biblical faith in Jesus Christ for salvation includes:

  1. a genuine (factual and historical) knowledge of the gospel events, namely, Jesus’ life, death, and resurrection;
  2. a personal assent to the truth and importance of those events; and
  3. a confident trust in the object of that faith (the risen Lord Jesus Christ).

Faith, in a biblical context, is therefore not separated from authentic human knowledge of truth and reality.

As to the second question, it is true that some highly educated people are not persuaded of historic Christianity’s truth. However, many of the world’s leading intellectuals from various academic and professional fields doembrace historic Christianity as a rational and viable world-and-life view.2 Early twentieth century Christian apologist and writer G. K. Chesterton makes this comment about those who reject Christianity: “The Christian ideal has not been tried and found wanting; it has been found difficult and left untried.”3 When it comes to the “ultimate issues of life,” personal persuasion involves more than exposure to rational arguments typically presented via the public educational system, even higher education.

Christian philosopher Ronald H. Nash argues that it is important to distinguish between arguments and personal persuasion.4 People come to their beliefs about reality and truth based upon various factors, some rational and some nonrational. A good argument provides reasonable and truthful support for its claim. Just because a person is not persuaded by a given argument doesn’t necessarily mean that the argument is somehow logically defective. Nonrational factors such as ignorance, bias, self-interest, fear, or pride may stand in the way of a person genuinely understanding and feeling the full force of a powerful argument and thus being persuaded by it. A person’s noetic (belief-forming) faculties are seldom as neutral, detached, and coolly objective as many people—especially intellectuals—would like to think. This subjective, egocentric predicament is shared by all people, regardless of educational level.

Persuasion, then, seems to be “person-relative,”5 and no single argument will likely persuade everyone—especially when it comes to the big issues. And simply because some questions are hotly contested does not mean that all positions on them are equally valid and none superior; hence, the importance of the biblical imperative to put beliefs to the test (1 Thessalonians 5:21; 1 John 4:1).

It would be fair to say that few people accept or reject Christianity based purely upon rational factors. After all, human beings are far from purely rational creatures. Scripture indicates that a person’s coming to (or conversion to) faith in Christ is never a solely intellectual decision (Acts 13:48; 1 Corinthians 12:3). God’s efficient grace works in remarkable ways to draw people to Himself (John 6:44, 65).

In conversation with nonbelievers, one might ask why they reject specific Christian truth-claims. Is their unbelief based upon rational or nonrational factors? Instead of a reasonable faith, it may be that nonbelievers have, in effect, an unreasonable lack of faith.

---Kenneth Richard Samples

1. Kenneth Richard Samples, Without a Doubt (Grand Rapids: Baker, 2004), see chapters 1 and 2.
2. See, for example, Kelly James Clark, ed. Philosophers Who Believe (Downers Grove, Ill.: InterVarsity, 1993); and Eric C. Barrett and David Fisher, Scientists Who Believe (Chicago: Moody, 1984).
3. G. K. Chesterton, What’s Wrong with the World (Charleston, SC: Forgotten Books, 2010) 39.; accessed July 14, 2004.
4. Ronald H. Nash, Faith and Reason (Grand Rapids: Zondervan, 1988), 108–10.
5. Nash, 109.

This article originally appeared in RTB publication Connections 6, no. 3, 2004.

Friday, July 15, 2011

Arguing is important

Hi all

I read this post by Jon Bloom from Desiring God, and was reminded of two things: the importance of arguing WELL for the sake of Christ, and the importance of arguing well for the sake of CHRIST (as opposed to, say, our own sakes, or for the sake of humanity, or for the sake of truth and knowledge, or personal holiness, etc).

The challenging thing is that the world is under a formidable delusion because of its own sin and the manipulation of powerful demonic forces. The message of Christianity is foolishness to them, because it approaches everything (in their eyes) from a completely alien knowledge and belief paradigm. Part of the reason for this site is to provide resources that God can use to break the delusion - possibly dramatically, but more likely in a subtle way by inspiring the consideration of radically different new paradigms. My challenge is not so much the arguing part ;) but making sure I keep my focus on Christ - the goal of it all.

Here's the text. Let me know your thoughts on this issue:

We Destroy Arguments

July 15, 2011 | by: Jon Bloom | Category: Commentary

"BELIEVE IN ME." (John 14:1)















Because our most important battles are won and lost with arguments.

Tuesday, July 5, 2011

"Who designed the designer?" by Common Sense Atheism

World in hand
Image by Beniamino Baj

A controversial article by this atheist site, and I think a rather good one. I especially like how he finishes...
"Third, because I want atheists to focus on objections that really matter. When a believer offers “God did it” as the best explanation for something, our question should not be “Well then who designed the designer?” but instead “Why is God the best explanation for that? Will you explain, please?”
The theist has a good answer to the first question. He won’t have a good answer for the second one. Not if you’re prepared:"

A huge assumption though at the end to assume the theist won't have a good answer. We all have explanations without explanations, if we didn't, we would be omniscient. He should probably change his phrase "When a believer offers" to "when a theist offers". Why? Because he is a believer also, just not of the same objective.