Copyright (c) 2013 All rights reserved. http://works.bepress.com/wstansfi Recent documents in William D. Stansfield en-us Sun, 24 Feb 2013 01:32:19 PST 3600 http://works.bepress.com/wstansfi/28 http://works.bepress.com/wstansfi/28 Fri, 22 Feb 2013 12:00:49 PST Before beginning a series of presentations on evolution, it would be prudent to survey the general level of students’ understanding of prerequisite basic concepts of reproduction, heredity, ontology, and phenotypic diversity so that teachers can avoid devoting time to well-known subjects of general knowledge and can spend more time on subjects that are unknown, forgotten, or misunderstood by most students. This article outlines a Socratic method for surveying and teaching to address these concerns.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/27 http://works.bepress.com/wstansfi/27 Mon, 16 Apr 2012 12:09:54 PDT Science requires the acquisition and analysis of empirical (sense-derived) data. Given the same physical objects or phenomena, the sense organs of all people do not respond equally to these stimuli, nor do their minds interpret sensory signals identically. Therefore, teachers should develop lectures on human sensory systems that include some common examples of sensory limitations, variations, deficiencies, malfunctions, and diseases (as discussed herein) because they have important implications for conducting scientific investigations, science education, and introspection that are seldom included in biology textbooks. Students need to be made aware of the human tendency to self deception in order to avoid the cognitive error of confirmation bias.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/26 http://works.bepress.com/wstansfi/26 Thu, 16 Feb 2012 08:19:35 PST A creationist has called Dobzhansky's dictum a myth. Discussion of this debate could be used as an object lesson for critical thinking.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/25 http://works.bepress.com/wstansfi/25 Thu, 02 Feb 2012 12:51:45 PST The nature of scientific research sometimes involves a trial-and-error procedure. Popular reviews of successful results from this approach often sanitize the story by omitting unsuccessful trials, thus painting the rosy impression that research simply follows a direct route from hypothesis to experiment to scientific discovery. The discovery of insulin is a classical case study in this genre that begs for an explanation to our students because it is so often ignored or misrepresented even in biology and physiology textbooks.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/24 http://works.bepress.com/wstansfi/24 Fri, 23 Sep 2011 15:41:54 PDT Mandated biology curriculum standards and standardized tests may vary widely from one state to another, making academic-performance comparisons among the states problematic. This report outlines the effects of the “No Child Left Behind” law and uses California as a test case against which teachers in other states may make comparisons of their own biology curriculum standards and tests. Several sources are cited that offer sample multiple-choice questions that have appeared on previous California standardized tests for sciences/life sciences/biology. These examples, and critique thereof, may help teachers better prepare their own tests to improve student performance in meeting the state's curriculum standards in individual science classes and in mandated statewide tests.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/23 http://works.bepress.com/wstansfi/23 Thu, 19 May 2011 14:03:10 PDT We question the use of mechanical models, such as coin flipping, to represent the probabilities of gender distributions in sibship families consisting of two children. Both the assumptions of the models and the reliability of the data should be evaluated. Using models without these critical evaluations may tend to perpetuate myths rather than elucidate biological realities.

]]> William D. Stansfield et al. Articles http://works.bepress.com/wstansfi/22 http://works.bepress.com/wstansfi/22 Wed, 16 Feb 2011 11:40:30 PST Most biology texts villify Lamarck's concept of “inheritance of acquired characters” and leave the impression that all acquired characters are never transmitted to offspring. However, recent research indicates that this is not true! Some “acquired” traits are inherited. I profile some of these striking cases and their importance for evolution and for understanding a broader epigenetic context for heredity and ontogeny (the emerging field of “evo-devo”). Further, I discuss how such cases, even considered as exceptions, contribute to understanding the nature of science, both the role of general rules in biology and the occurrence of conceptual change, or paradigm shifts.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/21 http://works.bepress.com/wstansfi/21 Sun, 11 Apr 2010 12:04:10 PDT French naturalist J.B. Lamarck is most commonly known for popularizing the theory that some traits acquired during the life of an organism can be inherited in his 1809 book. German biologist A. Weismann presented evidence in his 1891 book that acquired traits were not heritable in sexually reproducing animals. But so little was known about bacteria that they were considered to be the last stronghold of Lamarckism. The “fluctuation test” of S. Luria and M. Delbrück in 1943 seemed to confirm that Lamarckism in bacteria was indeed dead. This review, however, proposes that today bacteria may be viewed as the source from which much of our present knowledge of epigenetics, evolutionary developmental biology (evo-devo), and the induction or inheritance of acquired characters has grown.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/20 http://works.bepress.com/wstansfi/20 Wed, 13 Jan 2010 11:29:43 PST William D. Stansfield Articles http://works.bepress.com/wstansfi/19 http://works.bepress.com/wstansfi/19 Wed, 13 Jan 2010 11:29:42 PST Viable mice homozygous for two recessive autosomal genes, hairless (hr) and obese (ob) were produced with an average life span of 538 ± 34.1 days. On the average, hairless-obese mice weighed about 73 percent as much as obese mice. Since obese mice consumed approximately 73 percent as much oxygen per gram body weight per hour as hairless-obese mice at about 24°C, the weight averages appear to be closely inversely related to the oxygen consumption averages. The presence or absence of pelage seems to make a negligible contribution to oxygen consumption in these two types of obese mice. The hairless condition of the hr/hr genotype seems to contribute to increased oxygen consumption beyond that expected as a consequence of their lower average body weight. The average oxygen consumptions for seven female mice in each of four phenotypic groups (hairless, normal, hairless-obese, and obese) were 3.87, 3.12, 2.39, and 1.74 ml/g/hr, respectively. The two mutants appear to interact in a simple additive way and not as a mutant suppression system. On an absolute basis, the hr/hr genotype seems to have approximately 54 percent as much affect on oxygen consumption as the ob/ob genotype. Litter records at about 60 days of age for four kinds of matings did not reveal any statistically significant deviations from expected ratios.

]]> William D. Stansfield Articles http://works.bepress.com/wstansfi/18 http://works.bepress.com/wstansfi/18 Mon, 05 Oct 2009 10:16:39 PDT In two-child families containing at least one boy, the expected probability that such a family has two boys is 1/3, provided that the boy/girl (B/G) ratio is 1.0 and the population to which they belong has a binomial distribution of BB, (BG + GB), and GG families. It is commonly known that in most human populations the sex ratio at birth (i.e., the ratio of the number of boys to the number of girls) is greater than 1.0. Teachers and textbook writers seldom discuss the more realistic expected distributions in populations where the sex ratio is greater than 1.0. We present data from two federal surveys with sex ratios greater than 1.0 and find that the observed proportions of two boys in families of size 2 with at least one boy range from 0.3335 to 0.3941. It has been reported in the literature that the probability (p) of a male birth is subject to both within-sibship variation (Poisson variation), for which our data are suggestive, and possibly also between-sibship variation (Lexis variation). These deviations (biases) from the assumptions of a simple binomial distribution are involved in the calculation of values of p and standard 95% confidence intervals, thereby foiling attempts to make reliable statistical inferences from the data. Analysis of the data is also complicated by family planning that falsifies the assumption of randomness in the binomial gender distribution model. Families of size 2 (and their sex composition) are often discussed in a wider context. Overpopulation in some parts of the world has caused mass starvation and threatens to do the same worldwide unless the birth rate drops to agriculturally sustainable levels. Even if every woman of fertile age has only two children on average from now on, the world’s population is predicted to continue growing toward 9 billion people by 2050. Other sociological problems are bound to follow. Although the birth rate in China has recently dropped, the average age of the population has risen, so that by 2035 it is projected that for each person over age 65 there will be just three working-age people. Furthermore, China’s one-child policy has already led to a sex imbalance where there is a large excess of men for whom marriage and parentage is denied.

]]> William D. Stansfield et al. Articles http://works.bepress.com/wstansfi/17 http://works.bepress.com/wstansfi/17 Tue, 26 May 2009 10:59:34 PDT William D. Stansfield Articles http://works.bepress.com/wstansfi/15 http://works.bepress.com/wstansfi/15 Tue, 26 May 2009 10:59:33 PDT We previously analyzed data from the U.S. National Health Interview Survey (NHIS, 1998 to 2002) on families with two biological children (10 years of age and younger) and found that the distribution of families with two boys, two girls, and one boy + one girl did not statistically conform to a binomial distribution regardless of the boy/girl sex ratio used. Using the best estimate of the sex ratio from the data, we found that there were significantly more families with opposite-sex siblings than families with same-sex siblings. No biological mechanism could explain these results at the time. In the present study we conducted an analysis of the first two children in sibships of size 3 from the same data source and found that there are significantly more same-sex sibships than unlike-sex sibships. Combining the two sets of data for the first two children produced observed numbers in close agreement with the expected numbers. A hypothesis of parental choice (family planning) appears to be strongly supported as an explanation for the discrepancies in the two sets of data individually. For example, parents who have a boy and a girl (either order) as their first two children are more likely to stop having children (“stopping rule”) than are parents whose first two children are of the same sex.

]]> William D. Stansfield et al. Articles http://works.bepress.com/wstansfi/16 http://works.bepress.com/wstansfi/16 Tue, 26 May 2009 10:59:33 PDT William D. Stansfield Articles http://works.bepress.com/wstansfi/13 http://works.bepress.com/wstansfi/13 Tue, 26 May 2009 10:59:32 PDT William D. Stansfield Articles http://works.bepress.com/wstansfi/14 http://works.bepress.com/wstansfi/14 Tue, 26 May 2009 10:59:32 PDT William D. Stansfield Articles http://works.bepress.com/wstansfi/12 http://works.bepress.com/wstansfi/12 Tue, 26 May 2009 10:59:31 PDT William D. Stansfield Articles http://works.bepress.com/wstansfi/10 http://works.bepress.com/wstansfi/10 Tue, 26 May 2009 10:59:30 PDT William D. Stansfield Articles http://works.bepress.com/wstansfi/11 http://works.bepress.com/wstansfi/11 Tue, 26 May 2009 10:59:30 PDT William D. Stansfield Articles http://works.bepress.com/wstansfi/9 http://works.bepress.com/wstansfi/9 Tue, 26 May 2009 10:59:29 PDT William D. Stansfield et al. Articles