Today’s New Reason To Believe

Previously Posted on January 11th, 2008 by David H. Rogstad, Ph.D.

In the television series Cosmos: A Personal Voyage, originally broadcast in 1980, Carl Sagan, the highly successful popularizer of astronomy, coined the phrase “we are made of star-stuff.” While not a new idea, nevertheless, it called attention to a remarkable fact related to our growing understanding of how the universe began and developed over time.

Dr. Sagan outlined this process, beginning with the Big Bang, where the lightest elements, hydrogen and helium, were produced. He then proceeded to describe the various generations of stars that were formed, aged, and eventually “went supernova,” finally coming down to the formation of our solar system made from the ashes of these earlier stars. The end result is that humans, who are made from “the dust of the Earth,” originally came from material that was “cooked” from lighter elements in the very heart of stars and their subsequent supernova.

With NASA’s 1999 launch of the Chandra X-ray Observatory into orbit around the Earth astronomers have been able to use this new tool to detect many different objects in a band of light beyond what’s visible to human eyes, and at a much higher resolution than previously available. A recent press release revealed a spectacular new image of the supernova remnant G292.0+1.8. A supernova remnant is the expanding debris field blasted out from the parent star as it explodes. G292.0+1.8, which contains large amounts of oxygen, is one of only three remnants in our Milky Way Galaxy. The image shows an intricate structure in its debris field that contains element such as oxygen, neon, and silicon that forged before and during the explosion.

Understanding the details of G292.0+1.8 is especially important because astronomers have considered it to be a “textbook” case of a supernova created by the death of a massive star. Supernova events such as this have been determined to occur in the neighborhood of our solar system prior to its collapse, seeding the cloud out of which the Earth formed with elements critical for life (see the 23 January 2007 edition of Today’s New Reason To Believe ).

With instruments like the Chandra telescope, astronomers are developing a deeper understanding of the processes that clarify in detail Sagan’s observation that we are made from material that originated in stars. At the same time, the evidence supports the fine-tuning necessary for the “star-stuff” to have just the right amounts of the various elements to allow life to exist and survive. Not only do we have spectacular images of the “stuff,” which “declare the glory of God,” but we also have better understanding of the processes for making that stuff that reflects the hand of an elegant designer.

Previously Posted on January 27th, 2008 by Fazale ‘Fuz’ Rana, Ph.D.

Dental Anatomy Gives Important Clues on Hominid Growth and Development

For a little kid, losing teeth is a rite of passage. Each tooth that falls out (or gets unceremoniously yanked loose) serves as a sign that the child is growing up, as, one by one, baby teeth make way for permanent teeth.

The same is true for hominids, which are often interpreted as transitional intermediates between an ape-like creature and modern humans. Hominid tooth eruption, deposition of microanatomical structures, and tooth wear occurred at characteristic times during their growth and development and throughout adulthood. Because of the relationship between dental anatomy and life history, paleoanthroplogists study these features to gain important clues about the behavior and lifestyle of these now-extinct creatures.

Two recent research projects examined dental features of Paranthropus robustus and Neanderthals. Both studies indicate that these two hominids developed and behaved in decidedly nonhuman ways, extending the separation between the hominids and modern humans in accord with RTB’s human origins model.

RTB Human Origins Model and the Hominids

Instead of viewing these creatures as evolutionary intermediates, RTB’s biblical creation model regards the hominids found in the fossil record as animals created by God’s direct intervention. These primates existed for a time and then went extinct. RTB’s model considers the hominids to be remarkable creatures that walked erect, and possessed some level of limited intelligence and emotional capacity. This allowed these animals to employ crude tools and even adopt a type of ‘culture’ much like baboons, gorillas, and chimpanzees. While the RTB model posits that the hominids were created by God’s divine fiat, they were not spiritual beings made in His image. The model reserves this status exclusively for modern humans.

The RTB’s conceptual scheme treats the hominids as analogous to, but distinct from the great apes. Because of this, the model predicts that anatomical, physiological, biochemical, and genetic similarities will exist among the hominids and modern humans to varying degrees. But since the hominids were not made in God’s image, they are expected to be clearly distinct from modern humans, particularly in their cognitive capacity, behavior, “technology,” and “culture.”

In summary, the RTB model predicts that the hominids, including Neanderthals, should be biologically and behaviorally distinguishable from modern humans.

One study examined facial features and tooth wear for 19 specimens assigned to Paranthropus robustus. This hominid lived between about 2 and 1.2 million years ago in South Africa. (Evolutionary biologists don’t think that this hominid is part of the lineage that led to modern humans. Instead they place P. robustus, along with its two sister species, P. boisei and P. aethiopicus, as an evolutionary side branch and dead end.)

The research team noted that for male specimens the most extensive dental wear correlated with fully developed adult features. Those males with underdeveloped adult characteristics showed little dental wear. This pattern was not noted for females in the sample. These observations indicate that males took a longer period of time to develop than females and imply that P. robustus displayed sexual dimorphism, with males possessing a significantly larger body size than females.

Sexual dimorphism impacts mating strategy. Primates like gorillas that display sexual dimorphism based on body size have a social organization centered on a large dominant male who mates with a harem of females. This means that Paranthropus, and by extension the other Australopithecines, employed a mating strategy similar to gorillas.

In contrast, modern humans display relatively limited sexual dimorphism. As a consequence, males and females form mating pairs.

This work indicates that the Australopithecines were biologically and behaviorally distinct from modern humans, in accord with predictions made by the RTB model. The study also widens the gap between the Australopithecines and hominids that belonged to the Homo genus. According to paleoanthropologist J. Michael Plavan:

The finding challenges a theory that early hominids had a relatively low level of sexual dimorphism, inherited from a common ancestor shared with chimpanzees…Instead, the primitive condition may have been more gorillalike, and our female ancestors may not have closed the gap until recently, perhaps in Homo erectus in the past 2 million years.

The implication: the transition in mating behavior (and the accompanying growth and development process) must have happened rapidly.

Another study examined microanatomical features of Neanderthal teeth as a way to assess the rate of growth and development for these hominids. Biological rhythms produce incremental features in the enamel and dentine throughout childhood that can be used as a record for the individual’s life history.

Earlier studies using these markers have been inconclusive about the growth and development of Neanderthals. Some studies indicate that these hominids grew into adulthood at a pace similar to that of modern humans. Other work suggests that the rate of growth and development was accelerated when compared to human beings.

The most recent study took the most-detailed and comprehensive look at the microanatomical characteristics of Neanderthal teeth. Based on this work, the researchers concluded that Neanderthals grew at a much more rapid rate than modern humans. To say it another way, a prolonged childhood and relatively slow life history appears to be unique to modern humans. And these differences in the length and pace of childhood have important consequences for social organization.

Based on this work, it appears as if Neanderthals are both biologically and behaviorally distinct from modern humans. Once again this finding comports with RTB’s human origins model. Scientific advance makes it increasingly possible to make a scientific case that human beings are distinct from the hominids in a way that harmonizes with the notion that humans are uniquely made in God’s image.

While it is commonplace for human children to put their baby teeth under a pillow in the hope that the tooth fairy will exchange it for “gold,” it’s unlikely that Neanderthal children ever went through such a ritual. They grew up too fast.

Previously Posted January 2nd, 2008 by Dr. Jeffrey Zweerink, Ph.D

In the sixteenth century, Nicolas Copernicus revived an idea originating with early Greek philosophers that the Sun, instead of the Earth, resided at the center of the solar system. Subsequent observations by Galileo and others validated the Copernican, or heliocentric, view (for a brief introduction to the conflict between Galileo and the Roman Catholic Church, look here.) In the early 1920s, Harlow Shapley correctly argued that the sun did not reside at the center of the Milky Way Galaxy (MWG). Shortly afterward, Edwin Hubble demonstrated that other galaxies similar to the Milky Way existed and that the MWG did not reside at the center of the universe.

Known as the Copernican Principle (or Cosmological Principle), it remains an uncontroversial statement that Earth occupies no special location in the universe—not the center, not near the edge, nor any other geometrically interesting point. However, many people extend this concept further, positing that there is nothing unique or special about Earth or the life inhabiting it. Scientists refer to this extension as the Principle of Mediocrity.

While the Copernican Principle is largely a philosophical statement, a large body of evidence supports its validity. Even so, scientists continue to put the principle to the test. An article posted to arXiv.org outlines a new test to see if the region of space to about 3 billion light-years exhibits any special or unique characteristics. One possible explanation for the current cosmological data (mainly the cosmic microwave background radiation, the large-scale structure of galaxies, and the Hubble diagram derived from Type Ia supernova measurements) is that the Sun resides at the center of a large void where the density inside is less than that outside the void.

Rather than focus on the details of the particular test outlined, I want to highlight how willingly and eagerly astronomers and cosmologists seek to test bedrock principles. While the tests explained in the paper rule out any voids with large density contrasts, the authors describe even more-detailed tests to discern any uniqueness of Earth’s location. A previous TNRTB further demonstrates this willingness to test foundational principles.

In contrast, as my colleague Fuz Rana points out, scientific disciplines related to the origin and development of life don’t seem as willing to test their fundamental assumptions and principles. Since testing is fundamental to scientific advance, RTB appreciates a willingness to test across all disciplines