The micro to macro myth
Before Mendel's experiments, most people believed that traits in offspring resulted from a blending of the traits of each parent. However, when Mendel cross-pollinated one variety of purebred plant with another, these crosses would yield offspring that looked like either one of the parent plants, not a blend of the two. For example, when Mendel cross-fertilized plants with wrinkled seeds to those with smooth seeds, he did not get progeny with semi-wrinkly seeds.
The concept of evolution as proceeding through the gradual transformation of masses of individuals by the accumulation of impalpable changes is one that the study of genetics shows immediately to be false. Once for all, that burden so gratuitously undertaken in ignorance of generic physiology by the evolutionists of the last century may be cast into oblivion. For the facts of heredity and variation unite to prove that genetic variation is a phenomenon of individuals.
It remains an open debate among scientists whether or not it [macroevolution] is solely the end product of microevolutionary processes or there is some other set of processes that causes higher level trends and patterns. ... For if there is enough change to form new species, and each species is slightly different from its ancestor, then simple addition shows that many speciation events can cause large-scale evolution over enough time.
Biostatistical modeling forms an important part of numerous modern biological theories. In the early 1900s, after the rediscovery of Gregor Mendel's Mendelian inheritance work, the gaps in understanding between genetics and evolutionary Darwinism led to vigorous debate between biometricians, such as Walter Weldon and Karl Pearson, and Mendelians, such as Charles Davenport, William Bateson and Wilhelm Johannsen. By the 1930s, statisticians and models built on statistical reasoning had helped to resolve these differences and to produce the neo-Darwinian modern evolutionary synthesis. The leading figures in the establishment of population genetics and this synthesis all relied on statistics and developed its use in biology.
... despite the larger victory of Mendelism - the micromutationist view won out among evolutionists by about 1930. To a considerable extent, this victory reflected the efforts of Ronald Fisher, a founding father of population genetics and a tireless champion of Darwinian gradualism. Fisher successfully fused micromutationism with Mendelism, producing a mathematical framework known as the infinitesimal model.
It was Darwin's chief contribution, not only to Biology but to the whole of natural science, to have brought to light a process by which contingencies a priori improbable, are given, in the process of time, an increasing probability, until it is their non-occurrence rather than their occurrence which becomes highly improbable. ... The million, million, million ... to one chance happens once in a million, million, million ... times no matter how surprised we may be that it results in us.
There are in fact two problems. The first is that current theory is limited in several ways - all the models that have been mentioned rest on important assumptions and idealizations... The second problem concerns testability.
The 'modern evolutionary synthesis' convinced most biologists that natural selection was the only directive influence on adaptive evolution. Today, however, dissatisfaction with the synthesis is widespread, and creationists and antidarwinians are multiplying. The central problem with the synthesis is its failure to show (or to provide distinct signs) that natural selection of random mutations could account for observed levels of adaptation.
How fundamental innovations (or novelties) originate in evolution remains one of the most enigmatic questions of biology. According to the proponents of the Synthetic Theory, the gradual process of evolution by natural selection that operates within populations and species also creates the unique traits recognizable at higher taxonomic levels, meaning that macroevolution is just microevolution extended over relatively long periods of time. However, it has been repeatedly pointed out that innovation is different from adaptation, and that the Synthetic Theory, which is largely based on population genetics, falls short of explaining innovations, novelties, and the evolution of body plans (Riedl, 1977; Gilbert et al., 1996; Bateman et al., 1998; Erwin, 2000; Wagner, 2000; Haag and True, 2001; Wagner and Müller, 2002; Wagner and Laubichler, 2004; Müller and Newman, 2005; Theissen, 2006).
Extended evolutionary synthesis
The extended evolutionary synthesis is a set of extensions of the earlier modern synthesis of evolutionary biology that took place between 1918 and 1942. The extended evolutionary synthesis was called for in the 1950s by C. H. Waddington, argued for on the basis of punctuated equilibrium by Stephen Jay Gould and Niles Eldredge in the 1980s, and relaunched in 2007 by Massimo Pigliucci. The extended evolutionary synthesis revisits the relative importance of different factors at play, examining several assumptions of the earlier synthesis, and augmenting it with additional causative factors.
Charles Darwin conceived of evolution by natural selection without knowing that genes exist. Now mainstream evolutionary theory has come to focus almost exclusively on genetic inheritance and processes that change gene frequencies. Yet new data pouring out of adjacent fields are starting to undermine this narrow stance. An alternative vision of evolution is beginning to crystallize, in which the processes by which organisms grow and develop are recognized as causes of evolution. Some of us first met to discuss these advances six years ago. In the time since, as members of an interdisciplinary team, we have worked intensively to develop a broader framework, termed the extended evolutionary synthesis1 (EES), and to flesh out its structure, assumptions and predictions. In essence, this synthesis maintains that important drivers of evolution, ones that cannot be reduced to genes, must be woven into the very fabric of evolutionary theory.